diff --git a/.vscode/settings.json b/.vscode/settings.json
index 2c32994c8..e25e20041 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -8,8 +8,8 @@
         "editor.formatOnSave": true
     },
     "editor.codeActionsOnSave": {
-        "source.fixAll.eslint": true,
-        "source.organizeImports": true
+        "source.fixAll.eslint": "explicit",
+        "source.organizeImports": "explicit"
     },
     "typescript.tsdk": "node_modules/typescript/lib",
 }
diff --git a/package.json b/package.json
index 13e4aaa02..21dabd5f3 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,8 @@
         "check:eslint": "eslint .",
         "fix:eslint": "eslint --fix .",
         "check:prettier": "prettier -c .",
-        "fix:prettier": "prettier --write ."
+        "fix:prettier": "prettier --write .",
+        "typecheck": "npx lerna exec --stream --no-bail --ignore=pyright -- tsc --noEmit"
     },
     "devDependencies": {
         "@types/glob": "^7.2.0",
diff --git a/packages/pyright-internal/package-lock.json b/packages/pyright-internal/package-lock.json
index 6dedf2826..bb5a0226a 100644
--- a/packages/pyright-internal/package-lock.json
+++ b/packages/pyright-internal/package-lock.json
@@ -23,7 +23,7 @@
                 "vscode-languageserver": "8.1.0",
                 "vscode-languageserver-textdocument": "1.0.10",
                 "vscode-languageserver-types": "3.17.3",
-                "vscode-uri": "^3.0.7"
+                "vscode-uri": "^3.0.8"
             },
             "devDependencies": {
                 "@types/command-line-args": "^5.2.0",
@@ -3887,9 +3887,9 @@
             "integrity": "sha512-SYU4z1dL0PyIMd4Vj8YOqFvHu7Hz/enbWtpfnVbJHU4Nd1YNYx8u0ennumc6h48GQNeOLxmwySmnADouT/AuZA=="
         },
         "node_modules/vscode-uri": {
-            "version": "3.0.7",
-            "resolved": "https://registry.npmjs.org/vscode-uri/-/vscode-uri-3.0.7.tgz",
-            "integrity": "sha512-eOpPHogvorZRobNqJGhapa0JdwaxpjVvyBp0QIUMRMSf8ZAlqOdEquKuRmw9Qwu0qXtJIWqFtMkmvJjUZmMjVA=="
+            "version": "3.0.8",
+            "resolved": "https://registry.npmjs.org/vscode-uri/-/vscode-uri-3.0.8.tgz",
+            "integrity": "sha512-AyFQ0EVmsOZOlAnxoFOGOq1SQDWAB7C6aqMGS23svWAllfOaxbuFvcT8D1i8z3Gyn8fraVeZNNmN6e9bxxXkKw=="
         },
         "node_modules/walker": {
             "version": "1.0.8",
@@ -6943,9 +6943,9 @@
             "integrity": "sha512-SYU4z1dL0PyIMd4Vj8YOqFvHu7Hz/enbWtpfnVbJHU4Nd1YNYx8u0ennumc6h48GQNeOLxmwySmnADouT/AuZA=="
         },
         "vscode-uri": {
-            "version": "3.0.7",
-            "resolved": "https://registry.npmjs.org/vscode-uri/-/vscode-uri-3.0.7.tgz",
-            "integrity": "sha512-eOpPHogvorZRobNqJGhapa0JdwaxpjVvyBp0QIUMRMSf8ZAlqOdEquKuRmw9Qwu0qXtJIWqFtMkmvJjUZmMjVA=="
+            "version": "3.0.8",
+            "resolved": "https://registry.npmjs.org/vscode-uri/-/vscode-uri-3.0.8.tgz",
+            "integrity": "sha512-AyFQ0EVmsOZOlAnxoFOGOq1SQDWAB7C6aqMGS23svWAllfOaxbuFvcT8D1i8z3Gyn8fraVeZNNmN6e9bxxXkKw=="
         },
         "walker": {
             "version": "1.0.8",
diff --git a/packages/pyright-internal/package.json b/packages/pyright-internal/package.json
index e2919a544..ba0b66895 100644
--- a/packages/pyright-internal/package.json
+++ b/packages/pyright-internal/package.json
@@ -30,7 +30,7 @@
         "vscode-languageserver": "8.1.0",
         "vscode-languageserver-textdocument": "1.0.10",
         "vscode-languageserver-types": "3.17.3",
-        "vscode-uri": "^3.0.7"
+        "vscode-uri": "^3.0.8"
     },
     "devDependencies": {
         "@types/command-line-args": "^5.2.0",
diff --git a/packages/pyright-internal/src/analyzer/analyzerFileInfo.ts b/packages/pyright-internal/src/analyzer/analyzerFileInfo.ts
index 785871346..05967b75b 100644
--- a/packages/pyright-internal/src/analyzer/analyzerFileInfo.ts
+++ b/packages/pyright-internal/src/analyzer/analyzerFileInfo.ts
@@ -13,13 +13,14 @@ import { TextRangeDiagnosticSink } from '../common/diagnosticSink';
 import { PythonVersion } from '../common/pythonVersion';
 import { TextRange } from '../common/textRange';
 import { TextRangeCollection } from '../common/textRangeCollection';
+import { Uri } from '../common/uri/uri';
 import { Scope } from './scope';
 import { IPythonMode } from './sourceFile';
 import { SymbolTable } from './symbol';
 
 // Maps import paths to the symbol table for the imported module.
 export interface AbsoluteModuleDescriptor {
-    importingFilePath: string;
+    importingFileUri: Uri;
     nameParts: string[];
 }
 
@@ -29,7 +30,7 @@ export interface LookupImportOptions {
 }
 
 export type ImportLookup = (
-    filePathOrModule: string | AbsoluteModuleDescriptor,
+    fileUriOrModule: Uri | AbsoluteModuleDescriptor,
     options?: LookupImportOptions
 ) => ImportLookupResult | undefined;
 
@@ -52,7 +53,7 @@ export interface AnalyzerFileInfo {
     lines: TextRangeCollection<TextRange>;
     typingSymbolAliases: Map<string, string>;
     definedConstants: Map<string, boolean | string>;
-    filePath: string;
+    fileUri: Uri;
     moduleName: string;
     isStubFile: boolean;
     isTypingStubFile: boolean;
diff --git a/packages/pyright-internal/src/analyzer/backgroundAnalysisProgram.ts b/packages/pyright-internal/src/analyzer/backgroundAnalysisProgram.ts
index d40d71100..f9af56470 100644
--- a/packages/pyright-internal/src/analyzer/backgroundAnalysisProgram.ts
+++ b/packages/pyright-internal/src/analyzer/backgroundAnalysisProgram.ts
@@ -13,12 +13,13 @@ import { BackgroundAnalysisBase } from '../backgroundAnalysisBase';
 import { ConfigOptions, ExecutionEnvironment } from '../common/configOptions';
 import { Diagnostic } from '../common/diagnostic';
 import { FileDiagnostics } from '../common/diagnosticSink';
+import { ServiceProvider } from '../common/serviceProvider';
+import '../common/serviceProviderExtensions';
 import { Range } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { AnalysisCompleteCallback, analyzeProgram } from './analysis';
 import { ImportResolver } from './importResolver';
 import { MaxAnalysisTime, OpenFileOptions, Program } from './program';
-import { ServiceProvider } from '../common/serviceProvider';
-import '../common/serviceProviderExtensions';
 
 export enum InvalidatedReason {
     Reanalyzed,
@@ -72,8 +73,8 @@ export class BackgroundAnalysisProgram {
         return this._backgroundAnalysis;
     }
 
-    hasSourceFile(filePath: string): boolean {
-        return !!this._program.getSourceFile(filePath);
+    hasSourceFile(fileUri: Uri): boolean {
+        return !!this._program.getSourceFile(fileUri);
     }
 
     setConfigOptions(configOptions: ConfigOptions) {
@@ -90,9 +91,9 @@ export class BackgroundAnalysisProgram {
         this.configOptions.getExecutionEnvironments().forEach((e) => this._ensurePartialStubPackages(e));
     }
 
-    setTrackedFiles(filePaths: string[]) {
-        this._backgroundAnalysis?.setTrackedFiles(filePaths);
-        const diagnostics = this._program.setTrackedFiles(filePaths);
+    setTrackedFiles(fileUris: Uri[]) {
+        this._backgroundAnalysis?.setTrackedFiles(fileUris);
+        const diagnostics = this._program.setTrackedFiles(fileUris);
         this._reportDiagnosticsForRemovedFiles(diagnostics);
     }
 
@@ -101,35 +102,35 @@ export class BackgroundAnalysisProgram {
         this._program.setAllowedThirdPartyImports(importNames);
     }
 
-    setFileOpened(filePath: string, version: number | null, contents: string, options: OpenFileOptions) {
-        this._backgroundAnalysis?.setFileOpened(filePath, version, contents, options);
-        this._program.setFileOpened(filePath, version, contents, options);
+    setFileOpened(fileUri: Uri, version: number | null, contents: string, options: OpenFileOptions) {
+        this._backgroundAnalysis?.setFileOpened(fileUri, version, contents, options);
+        this._program.setFileOpened(fileUri, version, contents, options);
     }
 
-    getChainedFilePath(filePath: string): string | undefined {
-        return this._program.getChainedFilePath(filePath);
+    getChainedUri(fileUri: Uri): Uri | undefined {
+        return this._program.getChainedUri(fileUri);
     }
 
-    updateChainedFilePath(filePath: string, chainedFilePath: string | undefined) {
-        this._backgroundAnalysis?.updateChainedFilePath(filePath, chainedFilePath);
-        this._program.updateChainedFilePath(filePath, chainedFilePath);
+    updateChainedUri(fileUri: Uri, chainedUri: Uri | undefined) {
+        this._backgroundAnalysis?.updateChainedUri(fileUri, chainedUri);
+        this._program.updateChainedUri(fileUri, chainedUri);
     }
 
-    updateOpenFileContents(path: string, version: number | null, contents: string, options: OpenFileOptions) {
-        this._backgroundAnalysis?.setFileOpened(path, version, contents, options);
-        this._program.setFileOpened(path, version, contents, options);
-        this.markFilesDirty([path], /* evenIfContentsAreSame */ true);
+    updateOpenFileContents(uri: Uri, version: number | null, contents: string, options: OpenFileOptions) {
+        this._backgroundAnalysis?.setFileOpened(uri, version, contents, options);
+        this._program.setFileOpened(uri, version, contents, options);
+        this.markFilesDirty([uri], /* evenIfContentsAreSame */ true);
     }
 
-    setFileClosed(filePath: string, isTracked?: boolean) {
-        this._backgroundAnalysis?.setFileClosed(filePath, isTracked);
-        const diagnostics = this._program.setFileClosed(filePath, isTracked);
+    setFileClosed(fileUri: Uri, isTracked?: boolean) {
+        this._backgroundAnalysis?.setFileClosed(fileUri, isTracked);
+        const diagnostics = this._program.setFileClosed(fileUri, isTracked);
         this._reportDiagnosticsForRemovedFiles(diagnostics);
     }
 
-    addInterimFile(filePath: string) {
-        this._backgroundAnalysis?.addInterimFile(filePath);
-        this._program.addInterimFile(filePath);
+    addInterimFile(fileUri: Uri) {
+        this._backgroundAnalysis?.addInterimFile(fileUri);
+        this._program.addInterimFile(fileUri);
     }
 
     markAllFilesDirty(evenIfContentsAreSame: boolean) {
@@ -137,9 +138,9 @@ export class BackgroundAnalysisProgram {
         this._program.markAllFilesDirty(evenIfContentsAreSame);
     }
 
-    markFilesDirty(filePaths: string[], evenIfContentsAreSame: boolean) {
-        this._backgroundAnalysis?.markFilesDirty(filePaths, evenIfContentsAreSame);
-        this._program.markFilesDirty(filePaths, evenIfContentsAreSame);
+    markFilesDirty(fileUris: Uri[], evenIfContentsAreSame: boolean) {
+        this._backgroundAnalysis?.markFilesDirty(fileUris, evenIfContentsAreSame);
+        this._program.markFilesDirty(fileUris, evenIfContentsAreSame);
     }
 
     setCompletionCallback(callback?: AnalysisCompleteCallback) {
@@ -163,34 +164,34 @@ export class BackgroundAnalysisProgram {
         );
     }
 
-    async analyzeFile(filePath: string, token: CancellationToken): Promise<boolean> {
+    async analyzeFile(fileUri: Uri, token: CancellationToken): Promise<boolean> {
         if (this._backgroundAnalysis) {
-            return this._backgroundAnalysis.analyzeFile(filePath, token);
+            return this._backgroundAnalysis.analyzeFile(fileUri, token);
         }
 
-        return this._program.analyzeFile(filePath, token);
+        return this._program.analyzeFile(fileUri, token);
     }
 
     libraryUpdated() {
         // empty
     }
 
-    async getDiagnosticsForRange(filePath: string, range: Range, token: CancellationToken): Promise<Diagnostic[]> {
+    async getDiagnosticsForRange(fileUri: Uri, range: Range, token: CancellationToken): Promise<Diagnostic[]> {
         if (this._backgroundAnalysis) {
-            return this._backgroundAnalysis.getDiagnosticsForRange(filePath, range, token);
+            return this._backgroundAnalysis.getDiagnosticsForRange(fileUri, range, token);
         }
 
-        return this._program.getDiagnosticsForRange(filePath, range);
+        return this._program.getDiagnosticsForRange(fileUri, range);
     }
 
     async writeTypeStub(
-        targetImportPath: string,
+        targetImportUri: Uri,
         targetIsSingleFile: boolean,
-        stubPath: string,
+        stubUri: Uri,
         token: CancellationToken
     ): Promise<any> {
         if (this._backgroundAnalysis) {
-            return this._backgroundAnalysis.writeTypeStub(targetImportPath, targetIsSingleFile, stubPath, token);
+            return this._backgroundAnalysis.writeTypeStub(targetImportUri, targetIsSingleFile, stubUri, token);
         }
 
         analyzeProgram(
@@ -201,7 +202,7 @@ export class BackgroundAnalysisProgram {
             this._serviceProvider.console(),
             token
         );
-        return this._program.writeTypeStub(targetImportPath, targetIsSingleFile, stubPath, token);
+        return this._program.writeTypeStub(targetImportUri, targetIsSingleFile, stubUri, token);
     }
 
     invalidateAndForceReanalysis(reason: InvalidatedReason) {
@@ -245,7 +246,7 @@ export class BackgroundAnalysisProgram {
     }
 
     private _ensurePartialStubPackages(execEnv: ExecutionEnvironment) {
-        this._backgroundAnalysis?.ensurePartialStubPackages(execEnv.root);
+        this._backgroundAnalysis?.ensurePartialStubPackages(execEnv.root?.toString());
         return this._importResolver.ensurePartialStubPackages(execEnv);
     }
 
diff --git a/packages/pyright-internal/src/analyzer/binder.ts b/packages/pyright-internal/src/analyzer/binder.ts
index 999e746f2..cb35a72bf 100644
--- a/packages/pyright-internal/src/analyzer/binder.ts
+++ b/packages/pyright-internal/src/analyzer/binder.ts
@@ -22,9 +22,10 @@ import { DiagnosticLevel } from '../common/configOptions';
 import { assert, assertNever, fail } from '../common/debug';
 import { CreateTypeStubFileAction, Diagnostic } from '../common/diagnostic';
 import { DiagnosticRule } from '../common/diagnosticRules';
-import { getFileName, stripFileExtension } from '../common/pathUtils';
+import { stripFileExtension } from '../common/pathUtils';
 import { convertTextRangeToRange } from '../common/positionUtils';
 import { TextRange, getEmptyRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { Localizer } from '../localization/localize';
 import {
     ArgumentCategory,
@@ -407,7 +408,7 @@ export class Binder extends ParseTreeWalker {
         const classDeclaration: ClassDeclaration = {
             type: DeclarationType.Class,
             node,
-            path: this._fileInfo.filePath,
+            uri: this._fileInfo.fileUri,
             range: convertTextRangeToRange(node.name, this._fileInfo.lines),
             moduleName: this._fileInfo.moduleName,
             isInExceptSuite: this._isInExceptSuite,
@@ -465,7 +466,7 @@ export class Binder extends ParseTreeWalker {
             node,
             isMethod: !!containingClassNode,
             isGenerator: false,
-            path: this._fileInfo.filePath,
+            uri: this._fileInfo.fileUri,
             range: convertTextRangeToRange(node.name, this._fileInfo.lines),
             moduleName: this._fileInfo.moduleName,
             isInExceptSuite: this._isInExceptSuite,
@@ -539,7 +540,7 @@ export class Binder extends ParseTreeWalker {
                             const paramDeclaration: ParameterDeclaration = {
                                 type: DeclarationType.Parameter,
                                 node: paramNode,
-                                path: this._fileInfo.filePath,
+                                uri: this._fileInfo.fileUri,
                                 range: convertTextRangeToRange(paramNode, this._fileInfo.lines),
                                 moduleName: this._fileInfo.moduleName,
                                 isInExceptSuite: this._isInExceptSuite,
@@ -613,7 +614,7 @@ export class Binder extends ParseTreeWalker {
                             const paramDeclaration: ParameterDeclaration = {
                                 type: DeclarationType.Parameter,
                                 node: paramNode,
-                                path: this._fileInfo.filePath,
+                                uri: this._fileInfo.fileUri,
                                 range: convertTextRangeToRange(paramNode, this._fileInfo.lines),
                                 moduleName: this._fileInfo.moduleName,
                                 isInExceptSuite: this._isInExceptSuite,
@@ -765,7 +766,7 @@ export class Binder extends ParseTreeWalker {
             const paramDeclaration: TypeParameterDeclaration = {
                 type: DeclarationType.TypeParameter,
                 node: param,
-                path: this._fileInfo.filePath,
+                uri: this._fileInfo.fileUri,
                 range: convertTextRangeToRange(node, this._fileInfo.lines),
                 moduleName: this._fileInfo.moduleName,
                 isInExceptSuite: this._isInExceptSuite,
@@ -806,7 +807,7 @@ export class Binder extends ParseTreeWalker {
         const typeAliasDeclaration: TypeAliasDeclaration = {
             type: DeclarationType.TypeAlias,
             node,
-            path: this._fileInfo.filePath,
+            uri: this._fileInfo.fileUri,
             range: convertTextRangeToRange(node.name, this._fileInfo.lines),
             moduleName: this._fileInfo.moduleName,
             isInExceptSuite: this._isInExceptSuite,
@@ -1414,7 +1415,7 @@ export class Binder extends ParseTreeWalker {
                     node: node.name,
                     isConstant: isConstantName(node.name.value),
                     inferredTypeSource: node,
-                    path: this._fileInfo.filePath,
+                    uri: this._fileInfo.fileUri,
                     range: convertTextRangeToRange(node.name, this._fileInfo.lines),
                     moduleName: this._fileInfo.moduleName,
                     isInExceptSuite: this._isInExceptSuite,
@@ -1745,9 +1746,9 @@ export class Binder extends ParseTreeWalker {
 
         AnalyzerNodeInfo.setFlowNode(node, this._currentFlowNode!);
 
-        let resolvedPath = '';
+        let resolvedPath = Uri.empty();
         if (importInfo && importInfo.isImportFound && !importInfo.isNativeLib) {
-            resolvedPath = importInfo.resolvedPaths[importInfo.resolvedPaths.length - 1];
+            resolvedPath = importInfo.resolvedUris[importInfo.resolvedUris.length - 1];
         }
 
         // If this file is a module __init__.py(i), relative imports of submodules
@@ -1756,7 +1757,7 @@ export class Binder extends ParseTreeWalker {
         // symbols below) in case one of the imported symbols is the same name as the
         // submodule. In that case, we want to the symbol to appear later in the
         // declaration list because it should "win" when resolving the alias.
-        const fileName = stripFileExtension(getFileName(this._fileInfo.filePath));
+        const fileName = stripFileExtension(this._fileInfo.fileUri.fileName);
         const isModuleInitFile =
             fileName === '__init__' && node.module.leadingDots === 1 && node.module.nameParts.length === 1;
 
@@ -1814,7 +1815,7 @@ export class Binder extends ParseTreeWalker {
                                 const aliasDecl: AliasDeclaration = {
                                     type: DeclarationType.Alias,
                                     node,
-                                    path: resolvedPath,
+                                    uri: resolvedPath,
                                     loadSymbolsFromPath: true,
                                     range: getEmptyRange(), // Range is unknown for wildcard name import.
                                     usesLocalName: false,
@@ -1834,7 +1835,7 @@ export class Binder extends ParseTreeWalker {
                                         const submoduleFallback: AliasDeclaration = {
                                             type: DeclarationType.Alias,
                                             node,
-                                            path: implicitImport.path,
+                                            uri: implicitImport.uri,
                                             loadSymbolsFromPath: true,
                                             range: getEmptyRange(),
                                             usesLocalName: false,
@@ -1845,7 +1846,7 @@ export class Binder extends ParseTreeWalker {
                                         const aliasDecl: AliasDeclaration = {
                                             type: DeclarationType.Alias,
                                             node,
-                                            path: resolvedPath,
+                                            uri: resolvedPath,
                                             loadSymbolsFromPath: true,
                                             usesLocalName: false,
                                             symbolName: name,
@@ -1926,7 +1927,7 @@ export class Binder extends ParseTreeWalker {
                         submoduleFallback = {
                             type: DeclarationType.Alias,
                             node: importSymbolNode,
-                            path: implicitImport.path,
+                            uri: implicitImport.uri,
                             loadSymbolsFromPath: true,
                             range: getEmptyRange(),
                             usesLocalName: false,
@@ -1942,7 +1943,7 @@ export class Binder extends ParseTreeWalker {
                         if (fileName === '__init__') {
                             if (node.module.leadingDots === 1 && node.module.nameParts.length === 0) {
                                 loadSymbolsFromPath = false;
-                            } else if (resolvedPath === this._fileInfo.filePath) {
+                            } else if (resolvedPath.equals(this._fileInfo.fileUri)) {
                                 loadSymbolsFromPath = false;
                             }
                         }
@@ -1951,7 +1952,7 @@ export class Binder extends ParseTreeWalker {
                     const aliasDecl: AliasDeclaration = {
                         type: DeclarationType.Alias,
                         node: importSymbolNode,
-                        path: resolvedPath,
+                        uri: resolvedPath,
                         loadSymbolsFromPath,
                         usesLocalName: !!importSymbolNode.alias,
                         symbolName: importedName,
@@ -2304,7 +2305,7 @@ export class Binder extends ParseTreeWalker {
                     node: node.target,
                     isConstant: isConstantName(node.target.value),
                     inferredTypeSource: node,
-                    path: this._fileInfo.filePath,
+                    uri: this._fileInfo.fileUri,
                     range: convertTextRangeToRange(node.target, this._fileInfo.lines),
                     moduleName: this._fileInfo.moduleName,
                     isInExceptSuite: this._isInExceptSuite,
@@ -2389,7 +2390,7 @@ export class Binder extends ParseTreeWalker {
                 node: slotNameNode,
                 isConstant: isConstantName(slotName),
                 isDefinedBySlots: true,
-                path: this._fileInfo.filePath,
+                uri: this._fileInfo.fileUri,
                 range: convertTextRangeToRange(slotNameNode, this._fileInfo.lines),
                 moduleName: this._fileInfo.moduleName,
                 isInExceptSuite: this._isInExceptSuite,
@@ -2438,7 +2439,7 @@ export class Binder extends ParseTreeWalker {
                 node: target,
                 isConstant: isConstantName(target.value),
                 inferredTypeSource: target.parent,
-                path: this._fileInfo.filePath,
+                uri: this._fileInfo.fileUri,
                 range: convertTextRangeToRange(target, this._fileInfo.lines),
                 moduleName: this._fileInfo.moduleName,
                 isInExceptSuite: this._isInExceptSuite,
@@ -2466,23 +2467,25 @@ export class Binder extends ParseTreeWalker {
         const aliasDecl = varSymbol.getDeclarations().find((decl) => decl.type === DeclarationType.Alias) as
             | AliasDeclaration
             | undefined;
-        const resolvedPath =
-            aliasDecl?.path && aliasDecl.loadSymbolsFromPath
-                ? aliasDecl.path
-                : aliasDecl?.submoduleFallback?.path && aliasDecl.submoduleFallback.loadSymbolsFromPath
-                ? aliasDecl.submoduleFallback.path
+        const resolvedUri =
+            aliasDecl?.uri && !aliasDecl.uri.isEmpty() && aliasDecl.loadSymbolsFromPath
+                ? aliasDecl.uri
+                : aliasDecl?.submoduleFallback?.uri &&
+                  !aliasDecl.submoduleFallback.uri.isEmpty() &&
+                  aliasDecl.submoduleFallback.loadSymbolsFromPath
+                ? aliasDecl.submoduleFallback.uri
                 : undefined;
-        if (!resolvedPath) {
+        if (!resolvedUri) {
             return undefined;
         }
 
-        let lookupInfo = this._fileInfo.importLookup(resolvedPath);
+        let lookupInfo = this._fileInfo.importLookup(resolvedUri);
         if (lookupInfo?.dunderAllNames) {
             return lookupInfo.dunderAllNames;
         }
 
-        if (aliasDecl?.submoduleFallback?.path) {
-            lookupInfo = this._fileInfo.importLookup(aliasDecl.submoduleFallback.path);
+        if (aliasDecl?.submoduleFallback?.uri && !aliasDecl.submoduleFallback.uri.isEmpty()) {
+            lookupInfo = this._fileInfo.importLookup(aliasDecl.submoduleFallback.uri);
             return lookupInfo?.dunderAllNames;
         }
 
@@ -2520,15 +2523,15 @@ export class Binder extends ParseTreeWalker {
             .getDeclarations()
             .find((decl) => decl.type === DeclarationType.Alias && decl.firstNamePart === firstNamePartValue);
         let newDecl: AliasDeclaration;
-        let pathOfLastSubmodule: string;
-        if (importInfo && importInfo.isImportFound && !importInfo.isNativeLib && importInfo.resolvedPaths.length > 0) {
-            pathOfLastSubmodule = importInfo.resolvedPaths[importInfo.resolvedPaths.length - 1];
+        let uriOfLastSubmodule: Uri;
+        if (importInfo && importInfo.isImportFound && !importInfo.isNativeLib && importInfo.resolvedUris.length > 0) {
+            uriOfLastSubmodule = importInfo.resolvedUris[importInfo.resolvedUris.length - 1];
         } else {
-            pathOfLastSubmodule = UnresolvedModuleMarker;
+            uriOfLastSubmodule = UnresolvedModuleMarker;
         }
 
         const isResolved =
-            importInfo && importInfo.isImportFound && !importInfo.isNativeLib && importInfo.resolvedPaths.length > 0;
+            importInfo && importInfo.isImportFound && !importInfo.isNativeLib && importInfo.resolvedUris.length > 0;
 
         if (existingDecl) {
             newDecl = existingDecl as AliasDeclaration;
@@ -2536,7 +2539,7 @@ export class Binder extends ParseTreeWalker {
             newDecl = {
                 type: DeclarationType.Alias,
                 node,
-                path: pathOfLastSubmodule,
+                uri: uriOfLastSubmodule,
                 loadSymbolsFromPath: false,
                 range: getEmptyRange(),
                 usesLocalName: !!importAlias,
@@ -2551,7 +2554,7 @@ export class Binder extends ParseTreeWalker {
             newDecl = {
                 type: DeclarationType.Alias,
                 node,
-                path: pathOfLastSubmodule,
+                uri: uriOfLastSubmodule,
                 loadSymbolsFromPath: true,
                 range: getEmptyRange(),
                 usesLocalName: !!importAlias,
@@ -2565,8 +2568,8 @@ export class Binder extends ParseTreeWalker {
         // See if there is import info for this part of the path. This allows us
         // to implicitly import all of the modules in a multi-part module name.
         const implicitImportInfo = AnalyzerNodeInfo.getImportInfo(node.module.nameParts[0]);
-        if (implicitImportInfo && implicitImportInfo.resolvedPaths.length) {
-            newDecl.path = implicitImportInfo.resolvedPaths[0];
+        if (implicitImportInfo && implicitImportInfo.resolvedUris.length) {
+            newDecl.uri = implicitImportInfo.resolvedUris[0];
             newDecl.loadSymbolsFromPath = true;
             this._addImplicitImportsToLoaderActions(implicitImportInfo, newDecl);
         }
@@ -2574,7 +2577,7 @@ export class Binder extends ParseTreeWalker {
         // Add the implicit imports for this module if it's the last
         // name part we're resolving.
         if (importAlias || node.module.nameParts.length === 1) {
-            newDecl.path = pathOfLastSubmodule;
+            newDecl.uri = uriOfLastSubmodule;
             newDecl.loadSymbolsFromPath = true;
             newDecl.isUnresolved = false;
 
@@ -2594,13 +2597,13 @@ export class Binder extends ParseTreeWalker {
                     : undefined;
                 if (!loaderActions) {
                     const loaderActionPath =
-                        importInfo && i < importInfo.resolvedPaths.length
-                            ? importInfo.resolvedPaths[i]
+                        importInfo && i < importInfo.resolvedUris.length
+                            ? importInfo.resolvedUris[i]
                             : UnresolvedModuleMarker;
 
                     // Allocate a new loader action.
                     loaderActions = {
-                        path: loaderActionPath,
+                        uri: loaderActionPath,
                         loadSymbolsFromPath: false,
                         implicitImports: new Map<string, ModuleLoaderActions>(),
                         isUnresolved: !isResolved,
@@ -2614,8 +2617,8 @@ export class Binder extends ParseTreeWalker {
                 if (i === node.module.nameParts.length - 1) {
                     // If this is the last name part we're resolving, add in the
                     // implicit imports as well.
-                    if (importInfo && i < importInfo.resolvedPaths.length) {
-                        loaderActions.path = importInfo.resolvedPaths[i];
+                    if (importInfo && i < importInfo.resolvedUris.length) {
+                        loaderActions.uri = importInfo.resolvedUris[i];
                         loaderActions.loadSymbolsFromPath = true;
                         this._addImplicitImportsToLoaderActions(importInfo, loaderActions);
                     }
@@ -2625,8 +2628,8 @@ export class Binder extends ParseTreeWalker {
                     // import all of the modules in a multi-part module name (e.g. "import a.b.c"
                     // imports "a" and "a.b" and "a.b.c").
                     const implicitImportInfo = AnalyzerNodeInfo.getImportInfo(node.module.nameParts[i]);
-                    if (implicitImportInfo && implicitImportInfo.resolvedPaths.length) {
-                        loaderActions.path = implicitImportInfo.resolvedPaths[i];
+                    if (implicitImportInfo && implicitImportInfo.resolvedUris.length) {
+                        loaderActions.uri = implicitImportInfo.resolvedUris[i];
                         loaderActions.loadSymbolsFromPath = true;
                         this._addImplicitImportsToLoaderActions(implicitImportInfo, loaderActions);
                     }
@@ -3486,7 +3489,7 @@ export class Binder extends ParseTreeWalker {
                 type: DeclarationType.Intrinsic,
                 node,
                 intrinsicType: type,
-                path: this._fileInfo.filePath,
+                uri: this._fileInfo.fileUri,
                 range: getEmptyRange(),
                 moduleName: this._fileInfo.moduleName,
                 isInExceptSuite: this._isInExceptSuite,
@@ -3561,7 +3564,7 @@ export class Binder extends ParseTreeWalker {
                         inferredTypeSource: source,
                         isInferenceAllowedInPyTyped: this._isInferenceAllowedInPyTyped(name.value),
                         typeAliasName: isPossibleTypeAlias ? target : undefined,
-                        path: this._fileInfo.filePath,
+                        uri: this._fileInfo.fileUri,
                         range: convertTextRangeToRange(name, this._fileInfo.lines),
                         moduleName: this._fileInfo.moduleName,
                         isInExceptSuite: this._isInExceptSuite,
@@ -3609,7 +3612,7 @@ export class Binder extends ParseTreeWalker {
                         isConstant: isConstantName(name.value),
                         inferredTypeSource: source,
                         isDefinedByMemberAccess: true,
-                        path: this._fileInfo.filePath,
+                        uri: this._fileInfo.fileUri,
                         range: convertTextRangeToRange(target.memberName, this._fileInfo.lines),
                         moduleName: this._fileInfo.moduleName,
                         isInExceptSuite: this._isInExceptSuite,
@@ -3701,7 +3704,7 @@ export class Binder extends ParseTreeWalker {
                         isConstant: isConstantName(name.value),
                         isFinal: finalInfo.isFinal,
                         typeAliasName: target,
-                        path: this._fileInfo.filePath,
+                        uri: this._fileInfo.fileUri,
                         typeAnnotationNode,
                         range: convertTextRangeToRange(name, this._fileInfo.lines),
                         moduleName: this._fileInfo.moduleName,
@@ -3774,7 +3777,7 @@ export class Binder extends ParseTreeWalker {
                         isConstant: isConstantName(name.value),
                         isDefinedByMemberAccess: true,
                         isFinal: finalInfo.isFinal,
-                        path: this._fileInfo.filePath,
+                        uri: this._fileInfo.fileUri,
                         typeAnnotationNode: finalInfo.isFinal && !finalInfo.finalTypeNode ? undefined : typeAnnotation,
                         range: convertTextRangeToRange(target.memberName, this._fileInfo.lines),
                         moduleName: this._fileInfo.moduleName,
@@ -4021,14 +4024,14 @@ export class Binder extends ParseTreeWalker {
                 ? loaderActions.implicitImports.get(implicitImport.name)
                 : undefined;
             if (existingLoaderAction) {
-                existingLoaderAction.path = implicitImport.path;
+                existingLoaderAction.uri = implicitImport.uri;
                 existingLoaderAction.loadSymbolsFromPath = true;
             } else {
                 if (!loaderActions.implicitImports) {
                     loaderActions.implicitImports = new Map<string, ModuleLoaderActions>();
                 }
                 loaderActions.implicitImports.set(implicitImport.name, {
-                    path: implicitImport.path,
+                    uri: implicitImport.uri,
                     loadSymbolsFromPath: true,
                     implicitImports: new Map<string, ModuleLoaderActions>(),
                 });
@@ -4095,7 +4098,7 @@ export class Binder extends ParseTreeWalker {
             symbol.addDeclaration({
                 type: DeclarationType.SpecialBuiltInClass,
                 node: annotationNode,
-                path: this._fileInfo.filePath,
+                uri: this._fileInfo.fileUri,
                 range: convertTextRangeToRange(annotationNode, this._fileInfo.lines),
                 moduleName: this._fileInfo.moduleName,
                 isInExceptSuite: this._isInExceptSuite,
diff --git a/packages/pyright-internal/src/analyzer/checker.ts b/packages/pyright-internal/src/analyzer/checker.ts
index dc0992c23..86654d517 100644
--- a/packages/pyright-internal/src/analyzer/checker.ts
+++ b/packages/pyright-internal/src/analyzer/checker.ts
@@ -20,9 +20,9 @@ import { DiagnosticLevel } from '../common/configOptions';
 import { assert, assertNever } from '../common/debug';
 import { ActionKind, Diagnostic, DiagnosticAddendum, RenameShadowedFileAction } from '../common/diagnostic';
 import { DiagnosticRule } from '../common/diagnosticRules';
-import { getFileExtension } from '../common/pathUtils';
 import { PythonVersion, versionToString } from '../common/pythonVersion';
 import { TextRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { DefinitionProvider } from '../languageService/definitionProvider';
 import { Localizer } from '../localization/localize';
 import {
@@ -233,7 +233,9 @@ export class Checker extends ParseTreeWalker {
         const codeComplexity = AnalyzerNodeInfo.getCodeFlowComplexity(this._moduleNode);
 
         if (isPrintCodeComplexityEnabled) {
-            console.log(`Code complexity of module ${this._fileInfo.filePath} is ${codeComplexity.toString()}`);
+            console.log(
+                `Code complexity of module ${this._fileInfo.fileUri.toUserVisibleString()} is ${codeComplexity.toString()}`
+            );
         }
 
         if (codeComplexity > maxCodeComplexity) {
@@ -1566,11 +1568,12 @@ export class Checker extends ParseTreeWalker {
             }
 
             const resolvedAlias = this._evaluator.resolveAliasDeclaration(decl, /* resolveLocalNames */ true);
-            if (!resolvedAlias?.path || !isStubFile(resolvedAlias.path)) {
+            const resolvedAliasUri = resolvedAlias?.uri;
+            if (!resolvedAliasUri || !isStubFile(resolvedAliasUri)) {
                 continue;
             }
 
-            const importResult = this._getImportResult(node, resolvedAlias.path);
+            const importResult = this._getImportResult(node, resolvedAliasUri);
             if (!importResult) {
                 continue;
             }
@@ -1667,22 +1670,22 @@ export class Checker extends ParseTreeWalker {
         return false;
     }
 
-    private _getImportResult(node: ImportFromAsNode, filePath: string) {
-        const execEnv = this._importResolver.getConfigOptions().findExecEnvironment(filePath);
+    private _getImportResult(node: ImportFromAsNode, uri: Uri) {
+        const execEnv = this._importResolver.getConfigOptions().findExecEnvironment(uri);
         const moduleNameNode = (node.parent as ImportFromNode).module;
 
         // Handle both absolute and relative imports.
         const moduleName =
             moduleNameNode.leadingDots === 0
-                ? this._importResolver.getModuleNameForImport(filePath, execEnv).moduleName
-                : getRelativeModuleName(this._importResolver.fileSystem, this._fileInfo.filePath, filePath);
+                ? this._importResolver.getModuleNameForImport(uri, execEnv).moduleName
+                : getRelativeModuleName(this._importResolver.fileSystem, this._fileInfo.fileUri, uri);
 
         if (!moduleName) {
             return undefined;
         }
 
         return this._importResolver.resolveImport(
-            this._fileInfo.filePath,
+            this._fileInfo.fileUri,
             execEnv,
             createImportedModuleDescriptor(moduleName)
         );
@@ -3087,7 +3090,7 @@ export class Checker extends ParseTreeWalker {
                                     if (diagnostic && overload.details.declaration) {
                                         diagnostic.addRelatedInfo(
                                             Localizer.DiagnosticAddendum.overloadSignature(),
-                                            overload.details.declaration?.path ?? primaryDecl.path,
+                                            overload.details.declaration?.uri ?? primaryDecl.uri,
                                             overload.details.declaration?.range ?? primaryDecl.range
                                         );
                                     }
@@ -3280,7 +3283,7 @@ export class Checker extends ParseTreeWalker {
                 }
 
                 if (primaryDeclNode) {
-                    diag.addRelatedInfo(primaryDeclInfo, primaryDecl.path, primaryDecl.range);
+                    diag.addRelatedInfo(primaryDeclInfo, primaryDecl.uri, primaryDecl.range);
                 }
             }
         };
@@ -4177,7 +4180,7 @@ export class Checker extends ParseTreeWalker {
         if (
             stdlibPath &&
             this._importResolver.isStdlibModule(desc, this._fileInfo.executionEnvironment) &&
-            this._sourceMapper.isUserCode(this._fileInfo.filePath)
+            this._sourceMapper.isUserCode(this._fileInfo.fileUri)
         ) {
             // This means the user has a module that is overwriting the stdlib module.
             const diag = this._evaluator.addDiagnosticForTextRange(
@@ -4186,7 +4189,7 @@ export class Checker extends ParseTreeWalker {
                 DiagnosticRule.reportShadowedImports,
                 Localizer.Diagnostic.stdlibModuleOverridden().format({
                     name: moduleName,
-                    path: this._fileInfo.filePath,
+                    path: this._fileInfo.fileUri.toUserVisibleString(),
                 }),
                 this._moduleNode
             );
@@ -4195,8 +4198,8 @@ export class Checker extends ParseTreeWalker {
             if (diag) {
                 const renameAction: RenameShadowedFileAction = {
                     action: ActionKind.RenameShadowedFileAction,
-                    oldFile: this._fileInfo.filePath,
-                    newFile: this._sourceMapper.getNextFileName(this._fileInfo.filePath),
+                    oldUri: this._fileInfo.fileUri,
+                    newUri: this._sourceMapper.getNextFileName(this._fileInfo.fileUri),
                 };
                 diag.addAction(renameAction);
             }
@@ -4245,7 +4248,7 @@ export class Checker extends ParseTreeWalker {
                 namePartNodes[namePartNodes.length - 1].start,
                 CancellationToken.None
             );
-            const paths = definitions ? definitions.map((d) => d.path) : [];
+            const paths = definitions ? definitions.map((d) => d.uri) : [];
             paths.forEach((p) => {
                 if (!p.startsWith(stdlibPath) && !isStubFile(p) && this._sourceMapper.isUserCode(p)) {
                     // This means the user has a module that is overwriting the stdlib module.
@@ -4254,7 +4257,7 @@ export class Checker extends ParseTreeWalker {
                         DiagnosticRule.reportShadowedImports,
                         Localizer.Diagnostic.stdlibModuleOverridden().format({
                             name: nameParts.join('.'),
-                            path: p,
+                            path: p.toUserVisibleString(),
                         }),
                         node
                     );
@@ -4262,8 +4265,8 @@ export class Checker extends ParseTreeWalker {
                     if (diag) {
                         const renameAction: RenameShadowedFileAction = {
                             action: ActionKind.RenameShadowedFileAction,
-                            oldFile: p,
-                            newFile: this._sourceMapper.getNextFileName(p),
+                            oldUri: p,
+                            newUri: this._sourceMapper.getNextFileName(p),
                         };
                         diag.addAction(renameAction);
                     }
@@ -4755,7 +4758,7 @@ export class Checker extends ParseTreeWalker {
                                 decl.type !== DeclarationType.Function || ParseTreeUtils.isSuiteEmpty(decl.node.suite)
                         )
                     ) {
-                        if (getFileExtension(decls[0].path).toLowerCase() !== '.pyi') {
+                        if (!decls[0].uri.hasExtension('.pyi')) {
                             if (!isSymbolImplemented(name)) {
                                 diagAddendum.addMessage(
                                     Localizer.DiagnosticAddendum.missingProtocolMember().format({
@@ -4881,7 +4884,7 @@ export class Checker extends ParseTreeWalker {
                         if (fieldDecls.length > 0) {
                             diagnostic.addRelatedInfo(
                                 Localizer.DiagnosticAddendum.dataClassFieldLocation(),
-                                fieldDecls[0].path,
+                                fieldDecls[0].uri,
                                 fieldDecls[0].range
                             );
                         }
@@ -5103,7 +5106,16 @@ export class Checker extends ParseTreeWalker {
         const updatedClassType = ClassType.cloneWithNewTypeParameters(classType, updatedTypeParams);
 
         const objectObject = ClassType.cloneAsInstance(objectType);
-        const dummyTypeObject = ClassType.createInstantiable('__varianceDummy', '', '', '', 0, 0, undefined, undefined);
+        const dummyTypeObject = ClassType.createInstantiable(
+            '__varianceDummy',
+            '',
+            '',
+            Uri.empty(),
+            0,
+            0,
+            undefined,
+            undefined
+        );
 
         updatedTypeParams.forEach((param, paramIndex) => {
             // Skip variadics and ParamSpecs.
@@ -5382,7 +5394,7 @@ export class Checker extends ParseTreeWalker {
                                 )
                             ),
                         }),
-                        secondaryDecl.path,
+                        secondaryDecl.uri,
                         secondaryDecl.range
                     );
                 }
@@ -5760,7 +5772,7 @@ export class Checker extends ParseTreeWalker {
                     baseClass: this._evaluator.printType(convertToInstance(overriddenClassAndSymbol.classType)),
                     type: this._evaluator.printType(overriddenType),
                 }),
-                overriddenDecl.path,
+                overriddenDecl.uri,
                 overriddenDecl.range
             );
 
@@ -5769,7 +5781,7 @@ export class Checker extends ParseTreeWalker {
                     baseClass: this._evaluator.printType(convertToInstance(overrideClassAndSymbol.classType)),
                     type: this._evaluator.printType(overrideType),
                 }),
-                overrideDecl.path,
+                overrideDecl.uri,
                 overrideDecl.range
             );
         }
@@ -6005,7 +6017,7 @@ export class Checker extends ParseTreeWalker {
                             if (diag && origDecl) {
                                 diag.addRelatedInfo(
                                     Localizer.DiagnosticAddendum.overriddenMethod(),
-                                    origDecl.path,
+                                    origDecl.uri,
                                     origDecl.range
                                 );
                             }
@@ -6030,7 +6042,7 @@ export class Checker extends ParseTreeWalker {
                             if (diag && origDecl) {
                                 diag.addRelatedInfo(
                                     Localizer.DiagnosticAddendum.finalMethod(),
-                                    origDecl.path,
+                                    origDecl.uri,
                                     origDecl.range
                                 );
                             }
@@ -6060,7 +6072,7 @@ export class Checker extends ParseTreeWalker {
                         if (diag && origDecl) {
                             diag.addRelatedInfo(
                                 Localizer.DiagnosticAddendum.overriddenMethod(),
-                                origDecl.path,
+                                origDecl.uri,
                                 origDecl.range
                             );
                         }
@@ -6123,7 +6135,7 @@ export class Checker extends ParseTreeWalker {
                                     if (diag && origDecl) {
                                         diag.addRelatedInfo(
                                             Localizer.DiagnosticAddendum.overriddenMethod(),
-                                            origDecl.path,
+                                            origDecl.uri,
                                             origDecl.range
                                         );
                                     }
@@ -6160,7 +6172,7 @@ export class Checker extends ParseTreeWalker {
                                             if (diag && origDecl) {
                                                 diag.addRelatedInfo(
                                                     Localizer.DiagnosticAddendum.overriddenMethod(),
-                                                    origDecl.path,
+                                                    origDecl.uri,
                                                     origDecl.range
                                                 );
                                             }
@@ -6247,7 +6259,7 @@ export class Checker extends ParseTreeWalker {
                         if (diag && origDecl) {
                             diag.addRelatedInfo(
                                 Localizer.DiagnosticAddendum.overriddenSymbol(),
-                                origDecl.path,
+                                origDecl.uri,
                                 origDecl.range
                             );
                         }
@@ -6306,7 +6318,7 @@ export class Checker extends ParseTreeWalker {
                         if (diag) {
                             diag.addRelatedInfo(
                                 Localizer.DiagnosticAddendum.overriddenSymbol(),
-                                overrideFinalVarDecl.path,
+                                overrideFinalVarDecl.uri,
                                 overrideFinalVarDecl.range
                             );
                         }
@@ -6353,7 +6365,7 @@ export class Checker extends ParseTreeWalker {
                         if (diag && origDecl) {
                             diag.addRelatedInfo(
                                 Localizer.DiagnosticAddendum.overriddenSymbol(),
-                                origDecl.path,
+                                origDecl.uri,
                                 origDecl.range
                             );
                         }
diff --git a/packages/pyright-internal/src/analyzer/circularDependency.ts b/packages/pyright-internal/src/analyzer/circularDependency.ts
index 0655c24da..441e52f67 100644
--- a/packages/pyright-internal/src/analyzer/circularDependency.ts
+++ b/packages/pyright-internal/src/analyzer/circularDependency.ts
@@ -10,10 +10,12 @@
  * by picking the alphabetically-first module in the cycle.
  */
 
-export class CircularDependency {
-    private _paths: string[] = [];
+import { Uri } from '../common/uri/uri';
 
-    appendPath(path: string) {
+export class CircularDependency {
+    private _paths: Uri[] = [];
+
+    appendPath(path: Uri) {
         this._paths.push(path);
     }
 
diff --git a/packages/pyright-internal/src/analyzer/dataClasses.ts b/packages/pyright-internal/src/analyzer/dataClasses.ts
index a08e08b42..a2d698736 100644
--- a/packages/pyright-internal/src/analyzer/dataClasses.ts
+++ b/packages/pyright-internal/src/analyzer/dataClasses.ts
@@ -867,7 +867,7 @@ function getDescriptorForConverterField(
         descriptorName,
         getClassFullName(converterNode, fileInfo.moduleName, descriptorName),
         fileInfo.moduleName,
-        fileInfo.filePath,
+        fileInfo.fileUri,
         ClassTypeFlags.None,
         getTypeSourceId(converterNode),
         /* declaredMetaclass */ undefined,
diff --git a/packages/pyright-internal/src/analyzer/declaration.ts b/packages/pyright-internal/src/analyzer/declaration.ts
index c5ef21ece..5a68c85dd 100644
--- a/packages/pyright-internal/src/analyzer/declaration.ts
+++ b/packages/pyright-internal/src/analyzer/declaration.ts
@@ -10,6 +10,7 @@
  */
 
 import { Range } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import {
     ClassNode,
     ExpressionNode,
@@ -31,7 +32,7 @@ import {
     YieldNode,
 } from '../parser/parseNodes';
 
-export const UnresolvedModuleMarker = '*** unresolved ***';
+export const UnresolvedModuleMarker = Uri.parse('unresolved-module-marker://**/*', /* isCaseSensitive */ true);
 
 export const enum DeclarationType {
     Intrinsic,
@@ -57,9 +58,9 @@ export interface DeclarationBase {
     node: ParseNode;
 
     // The file and range within that file that
-    // contains the declaration. Unless this is an alias, then path refers to the
+    // contains the declaration. Unless this is an alias, then uri refers to the
     // file the alias is referring to.
-    path: string;
+    uri: Uri;
     range: Range;
 
     // The dot-separated import name for the file that
@@ -222,10 +223,10 @@ export interface AliasDeclaration extends DeclarationBase {
 // This interface represents a set of actions that the python loader
 // performs when a module import is encountered.
 export interface ModuleLoaderActions {
-    // The resolved path of the implicit import. This can be empty
-    // if the resolved path doesn't reference a module (e.g. it's
+    // The resolved uri of the implicit import. This can be empty
+    // if the resolved uri doesn't reference a module (e.g. it's
     // a directory).
-    path: string;
+    uri: Uri;
 
     // Is this a dummy entry for an unresolved import?
     isUnresolved?: boolean;
@@ -285,5 +286,5 @@ export function isIntrinsicDeclaration(decl: Declaration): decl is IntrinsicDecl
 }
 
 export function isUnresolvedAliasDeclaration(decl: Declaration): boolean {
-    return isAliasDeclaration(decl) && decl.path === UnresolvedModuleMarker;
+    return isAliasDeclaration(decl) && decl.uri === UnresolvedModuleMarker;
 }
diff --git a/packages/pyright-internal/src/analyzer/declarationUtils.ts b/packages/pyright-internal/src/analyzer/declarationUtils.ts
index 4b2502f99..94228c624 100644
--- a/packages/pyright-internal/src/analyzer/declarationUtils.ts
+++ b/packages/pyright-internal/src/analyzer/declarationUtils.ts
@@ -8,6 +8,7 @@
  */
 
 import { getEmptyRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { NameNode, ParseNodeType } from '../parser/parseNodes';
 import { ImportLookup, ImportLookupResult } from './analyzerFileInfo';
 import { AliasDeclaration, Declaration, DeclarationType, ModuleLoaderActions, isAliasDeclaration } from './declaration';
@@ -78,7 +79,7 @@ export function areDeclarationsSame(
         return false;
     }
 
-    if (decl1.path !== decl2.path) {
+    if (!decl1.uri.equals(decl2.uri)) {
         return false;
     }
 
@@ -174,16 +175,16 @@ export function getNameNodeForDeclaration(declaration: Declaration): NameNode |
     throw new Error(`Shouldn't reach here`);
 }
 
-export function isDefinedInFile(decl: Declaration, filePath: string) {
+export function isDefinedInFile(decl: Declaration, fileUri: Uri) {
     if (isAliasDeclaration(decl)) {
         // Alias decl's path points to the original symbol
         // the alias is pointing to. So, we need to get the
         // filepath in that the alias is defined from the node.
-        return getFileInfoFromNode(decl.node)?.filePath === filePath;
+        return getFileInfoFromNode(decl.node)?.fileUri.equals(fileUri);
     }
 
     // Other decls, the path points to the file the symbol is defined in.
-    return decl.path === filePath;
+    return decl.uri.equals(fileUri);
 }
 
 export function getDeclarationsWithUsesLocalNameRemoved(decls: Declaration[]) {
@@ -199,13 +200,13 @@ export function getDeclarationsWithUsesLocalNameRemoved(decls: Declaration[]) {
     });
 }
 
-export function createSynthesizedAliasDeclaration(path: string): AliasDeclaration {
+export function createSynthesizedAliasDeclaration(uri: Uri): AliasDeclaration {
     // The only time this decl is used is for IDE services such as
     // the find all references, hover provider and etc.
     return {
         type: DeclarationType.Alias,
         node: undefined!,
-        path,
+        uri,
         loadSymbolsFromPath: false,
         range: getEmptyRange(),
         implicitImports: new Map<string, ModuleLoaderActions>(),
@@ -267,8 +268,10 @@ export function resolveAliasDeclaration(
         }
 
         let lookupResult: ImportLookupResult | undefined;
-        if (curDeclaration.path && curDeclaration.loadSymbolsFromPath) {
-            lookupResult = importLookup(curDeclaration.path, { skipFileNeededCheck: options.skipFileNeededCheck });
+        if (!curDeclaration.uri.isEmpty() && curDeclaration.loadSymbolsFromPath) {
+            lookupResult = importLookup(curDeclaration.uri, {
+                skipFileNeededCheck: options.skipFileNeededCheck,
+            });
         }
 
         const symbol: Symbol | undefined = lookupResult
@@ -284,11 +287,11 @@ export function resolveAliasDeclaration(
                     // when useLibraryCodeForTypes is disabled), b should be evaluated as Unknown,
                     // not as a module.
                     if (
-                        curDeclaration.path &&
+                        !curDeclaration.uri.isEmpty() &&
                         curDeclaration.submoduleFallback.type === DeclarationType.Alias &&
-                        curDeclaration.submoduleFallback.path
+                        !curDeclaration.submoduleFallback.uri.isEmpty()
                     ) {
-                        const lookupResult = importLookup(curDeclaration.submoduleFallback.path, {
+                        const lookupResult = importLookup(curDeclaration.submoduleFallback.uri, {
                             skipFileNeededCheck: options.skipFileNeededCheck,
                             skipParsing: true,
                         });
@@ -393,7 +396,7 @@ export function resolveAliasDeclaration(
             // the module is foo, and the foo.__init__.py file contains the statement
             // "from foo import bar", we want to import the foo/bar.py submodule.
             if (
-                curDeclaration.path === declaration.path &&
+                curDeclaration.uri.equals(declaration.uri) &&
                 curDeclaration.type === DeclarationType.Alias &&
                 curDeclaration.submoduleFallback
             ) {
diff --git a/packages/pyright-internal/src/analyzer/enums.ts b/packages/pyright-internal/src/analyzer/enums.ts
index 736d152c4..31f0f31b7 100644
--- a/packages/pyright-internal/src/analyzer/enums.ts
+++ b/packages/pyright-internal/src/analyzer/enums.ts
@@ -81,7 +81,7 @@ export function createEnumType(
         className,
         getClassFullName(errorNode, fileInfo.moduleName, className),
         fileInfo.moduleName,
-        fileInfo.filePath,
+        fileInfo.fileUri,
         ClassTypeFlags.EnumClass,
         getTypeSourceId(errorNode),
         /* declaredMetaclass */ undefined,
diff --git a/packages/pyright-internal/src/analyzer/importResolver.ts b/packages/pyright-internal/src/analyzer/importResolver.ts
index 53ed2ade0..3a22228ff 100644
--- a/packages/pyright-internal/src/analyzer/importResolver.ts
+++ b/packages/pyright-internal/src/analyzer/importResolver.ts
@@ -14,34 +14,14 @@ import { appendArray, flatten, getMapValues, getOrAdd } from '../common/collecti
 import { ConfigOptions, ExecutionEnvironment, matchFileSpecs } from '../common/configOptions';
 import { Host } from '../common/host';
 import { stubsSuffix } from '../common/pathConsts';
-import {
-    changeAnyExtension,
-    combinePathComponents,
-    combinePaths,
-    containsPath,
-    ensureTrailingDirectorySeparator,
-    getDirectoryPath,
-    getFileExtension,
-    getFileName,
-    getFileSystemEntriesFromDirEntries,
-    getPathComponents,
-    getRelativePathComponentsFromDirectory,
-    isDirectory,
-    isDiskPathRoot,
-    isFile,
-    normalizePath,
-    realCasePath,
-    resolvePaths,
-    stripFileExtension,
-    stripTrailingDirectorySeparator,
-    tryRealpath,
-    tryStat,
-} from '../common/pathUtils';
+import { stripFileExtension } from '../common/pathUtils';
 import { PythonVersion, versionFromString } from '../common/pythonVersion';
 import { ServiceProvider } from '../common/serviceProvider';
 import { ServiceKeys } from '../common/serviceProviderExtensions';
 import * as StringUtils from '../common/stringUtils';
 import { equateStringsCaseInsensitive } from '../common/stringUtils';
+import { Uri } from '../common/uri/uri';
+import { getFileSystemEntriesFromDirEntries, isDirectory, isFile, tryRealpath, tryStat } from '../common/uri/uriUtils';
 import { isIdentifierChar, isIdentifierStartChar } from '../parser/characters';
 import { ImplicitImport, ImportResult, ImportType } from './importResult';
 import { getDirectoryLeadingDotsPointsTo } from './importStatementUtils';
@@ -114,16 +94,18 @@ export const supportedFileExtensions = [...supportedSourceFileExtensions, ...sup
 const allowPartialResolutionForThirdPartyPackages = false;
 
 export class ImportResolver {
-    private _cachedPythonSearchPaths: { paths: string[]; failureInfo: string[] } | undefined;
+    private _cachedPythonSearchPaths: { paths: Uri[]; failureInfo: string[] } | undefined;
     private _cachedImportResults = new Map<string | undefined, CachedImportResults>();
     private _cachedModuleNameResults = new Map<string, Map<string, ModuleImportInfo>>();
-    private _cachedTypeshedRoot: string | undefined;
-    private _cachedTypeshedStdLibPath: string | undefined;
+    private _cachedTypeshedRoot: Uri | undefined;
+    private _cachedTypeshedStdLibPath: Uri | undefined;
     private _cachedTypeshedStdLibModuleVersions: Map<string, SupportedVersionRange> | undefined;
-    private _cachedTypeshedThirdPartyPath: string | undefined;
-    private _cachedTypeshedThirdPartyPackagePaths: Map<string, string[]> | undefined;
-    private _cachedTypeshedThirdPartyPackageRoots: string[] | undefined;
+    private _cachedTypeshedThirdPartyPath: Uri | undefined;
+    private _cachedTypeshedThirdPartyPackagePaths: Map<string, Uri[]> | undefined;
+    private _cachedTypeshedThirdPartyPackageRoots: Uri[] | undefined;
     private _cachedEntriesForPath = new Map<string, Dirent[]>();
+    private _cachedFilesForPath = new Map<string, Uri[]>();
+    private _cachedDirExistenceForRoot = new Map<string, boolean>();
     private _stdlibModules: Set<string> | undefined;
     protected cachedParentImportResults: ParentDirectoryCache;
 
@@ -135,17 +117,21 @@ export class ImportResolver {
         return this.serviceProvider.fs();
     }
 
+    get tmp() {
+        return this.serviceProvider.tmp();
+    }
+
     get partialStubs() {
         return this.serviceProvider.tryGet(ServiceKeys.partialStubs);
     }
 
-    static isSupportedImportSourceFile(path: string) {
-        const fileExtension = getFileExtension(path).toLowerCase();
+    static isSupportedImportSourceFile(uri: Uri) {
+        const fileExtension = uri.lastExtension.toLowerCase();
         return supportedSourceFileExtensions.some((ext) => fileExtension === ext);
     }
 
-    static isSupportedImportFile(path: string) {
-        const fileExtension = getFileExtension(path).toLowerCase();
+    static isSupportedImportFile(uri: Uri) {
+        const fileExtension = uri.lastExtension.toLowerCase();
         return supportedFileExtensions.some((ext) => fileExtension === ext);
     }
 
@@ -163,34 +149,34 @@ export class ImportResolver {
     // Resolves the import and returns the path if it exists, otherwise
     // returns undefined.
     resolveImport(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor
     ): ImportResult {
         // Wrap internal call to resolveImportInternal() to prevent calling any
         // child class version of resolveImport().
-        return this.resolveImportInternal(sourceFilePath, execEnv, moduleDescriptor);
+        return this.resolveImportInternal(sourceFileUri, execEnv, moduleDescriptor);
     }
 
     getCompletionSuggestions(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor
     ) {
-        const suggestions = this._getCompletionSuggestionsStrict(sourceFilePath, execEnv, moduleDescriptor);
+        const suggestions = this._getCompletionSuggestionsStrict(sourceFileUri, execEnv, moduleDescriptor);
 
         // We only do parent import resolution for absolute path.
         if (moduleDescriptor.leadingDots > 0) {
             return suggestions;
         }
 
-        const root = this.getParentImportResolutionRoot(sourceFilePath, execEnv.root);
-        const origin = ensureTrailingDirectorySeparator(getDirectoryPath(sourceFilePath));
+        const root = this.getParentImportResolutionRoot(sourceFileUri, execEnv.root);
+        const origin = sourceFileUri.getDirectory();
 
-        let current = origin;
-        while (this._shouldWalkUp(current, root, execEnv)) {
+        let current: Uri | undefined = origin;
+        while (this._shouldWalkUp(current, root, execEnv) && current) {
             this._getCompletionSuggestionsAbsolute(
-                sourceFilePath,
+                sourceFileUri,
                 execEnv,
                 current,
                 moduleDescriptor,
@@ -198,11 +184,7 @@ export class ImportResolver {
                 /* strictOnly */ false
             );
 
-            let success;
-            [success, current] = this._tryWalkUp(current);
-            if (!success) {
-                break;
-            }
+            current = this._tryWalkUp(current);
         }
 
         return suggestions;
@@ -218,8 +200,8 @@ export class ImportResolver {
     }
 
     // Returns the implementation file(s) for the given stub file.
-    getSourceFilesFromStub(stubFilePath: string, execEnv: ExecutionEnvironment, _mapCompiled: boolean): string[] {
-        const sourceFilePaths: string[] = [];
+    getSourceFilesFromStub(stubFileUri: Uri, execEnv: ExecutionEnvironment, _mapCompiled: boolean): Uri[] {
+        const sourceFileUris: Uri[] = [];
 
         // When ImportResolver resolves an import to a stub file, a second resolve is done
         // ignoring stub files, which gives us an approximation of where the implementation
@@ -227,17 +209,17 @@ export class ImportResolver {
         this._cachedImportResults.forEach((map) => {
             map.forEach((result) => {
                 if (result.isStubFile && result.isImportFound && result.nonStubImportResult) {
-                    if (result.resolvedPaths[result.resolvedPaths.length - 1] === stubFilePath) {
+                    if (result.resolvedUris[result.resolvedUris.length - 1].equals(stubFileUri)) {
                         if (result.nonStubImportResult.isImportFound) {
-                            const nonEmptyPath =
-                                result.nonStubImportResult.resolvedPaths[
-                                    result.nonStubImportResult.resolvedPaths.length - 1
+                            const nonEmptyUri =
+                                result.nonStubImportResult.resolvedUris[
+                                    result.nonStubImportResult.resolvedUris.length - 1
                                 ];
 
-                            if (nonEmptyPath.endsWith('.py') || nonEmptyPath.endsWith('.pyi')) {
+                            if (nonEmptyUri.pathEndsWith('.py') || nonEmptyUri.pathEndsWith('.pyi')) {
                                 // We allow pyi in case there are multiple pyi for a compiled module such as
                                 // numpy.random.mtrand
-                                sourceFilePaths.push(nonEmptyPath);
+                                sourceFileUris.push(nonEmptyUri);
                             }
                         }
                     }
@@ -247,15 +229,15 @@ export class ImportResolver {
 
         // We haven't seen an import of that stub, attempt to find the source
         // in some other ways.
-        if (sourceFilePaths.length === 0) {
+        if (sourceFileUris.length === 0) {
             // Simple case where the stub and source files are next to each other.
-            const sourceFilePath = changeAnyExtension(stubFilePath, '.py');
-            if (this.dirExistsCached(sourceFilePath)) {
-                sourceFilePaths.push(sourceFilePath);
+            const sourceFileUri = stubFileUri.replaceExtension('.py');
+            if (this.dirExistsCached(sourceFileUri)) {
+                sourceFileUris.push(sourceFileUri);
             }
         }
 
-        if (sourceFilePaths.length === 0) {
+        if (sourceFileUris.length === 0) {
             // The stub and the source file may have the same name, but be located
             // in different folder hierarchies.
             // Example:
@@ -264,53 +246,48 @@ export class ImportResolver {
             // We get the relative path(s) of the stub to its import root(s),
             // in theory there can be more than one, then look for source
             // files in all the import roots using the same relative path(s).
-            const importRootPaths = this.getImportRoots(execEnv);
+            const importRoots = this.getImportRoots(execEnv);
 
             const relativeStubPaths: string[] = [];
-            for (const importRootPath of importRootPaths) {
-                if (containsPath(importRootPath, stubFilePath, true)) {
-                    const parts = getRelativePathComponentsFromDirectory(importRootPath, stubFilePath, true);
+            for (const importRootUri of importRoots) {
+                if (stubFileUri.isChild(importRootUri)) {
+                    const parts = Array.from(importRootUri.getRelativePathComponents(stubFileUri));
 
-                    // Note that relative paths have an empty parts[0]
-                    if (parts.length > 1) {
+                    if (parts.length >= 1) {
                         // Handle the case where the symbol was resolved to a stubs package
                         // rather than the real package. We'll strip off the "-stubs" suffix
                         // in this case.
-                        if (parts[1].endsWith(stubsSuffix)) {
-                            parts[1] = parts[1].substr(0, parts[1].length - stubsSuffix.length);
+                        if (parts[0].endsWith(stubsSuffix)) {
+                            parts[0] = parts[0].slice(0, parts[0].length - stubsSuffix.length);
                         }
 
-                        const relativeStubPath = combinePathComponents(parts);
-                        if (relativeStubPath) {
-                            relativeStubPaths.push(relativeStubPath);
-                        }
+                        relativeStubPaths.push(parts.join('/'));
                     }
                 }
             }
 
             for (const relativeStubPath of relativeStubPaths) {
-                for (const importRootPath of importRootPaths) {
-                    const absoluteStubPath = resolvePaths(importRootPath, relativeStubPath);
-                    let absoluteSourcePath = changeAnyExtension(absoluteStubPath, '.py');
+                for (const importRootUri of importRoots) {
+                    const absoluteStubPath = importRootUri.combinePaths(relativeStubPath);
+                    let absoluteSourcePath = absoluteStubPath.replaceExtension('.py');
                     if (this.fileExistsCached(absoluteSourcePath)) {
-                        sourceFilePaths.push(absoluteSourcePath);
+                        sourceFileUris.push(absoluteSourcePath);
                     } else {
-                        const filePathWithoutExtension = stripFileExtension(absoluteSourcePath);
+                        const filePathWithoutExtension = absoluteSourcePath.stripExtension();
 
-                        if (filePathWithoutExtension.endsWith('__init__')) {
+                        if (filePathWithoutExtension.pathEndsWith('__init__')) {
                             // Did not match: <root>/package/__init__.py
                             // Try equivalent: <root>/package.py
-                            absoluteSourcePath =
-                                filePathWithoutExtension.substr(0, filePathWithoutExtension.length - 9) + '.py';
+                            absoluteSourcePath = filePathWithoutExtension.getDirectory().packageUri;
                             if (this.fileExistsCached(absoluteSourcePath)) {
-                                sourceFilePaths.push(absoluteSourcePath);
+                                sourceFileUris.push(absoluteSourcePath);
                             }
                         } else {
                             // Did not match: <root>/package.py
                             // Try equivalent: <root>/package/__init__.py
-                            absoluteSourcePath = combinePaths(filePathWithoutExtension, '__init__.py');
+                            absoluteSourcePath = filePathWithoutExtension.initPyUri;
                             if (this.fileExistsCached(absoluteSourcePath)) {
-                                sourceFilePaths.push(absoluteSourcePath);
+                                sourceFileUris.push(absoluteSourcePath);
                             }
                         }
                     }
@@ -318,23 +295,27 @@ export class ImportResolver {
             }
         }
 
-        return sourceFilePaths;
+        return sourceFileUris;
     }
 
     // Returns the module name (of the form X.Y.Z) that needs to be imported
     // from the current context to access the module with the specified file path.
     // In a sense, it's performing the inverse of resolveImport.
     getModuleNameForImport(
-        filePath: string,
+        fileUri: Uri,
         execEnv: ExecutionEnvironment,
         allowInvalidModuleName = false,
         detectPyTyped = false
     ) {
         // Cache results of the reverse of resolveImport as we cache resolveImport.
-        const cache = getOrAdd(this._cachedModuleNameResults, execEnv.root, () => new Map<string, ModuleImportInfo>());
-        const key = `${allowInvalidModuleName}.${detectPyTyped}.${filePath}`;
+        const cache = getOrAdd(
+            this._cachedModuleNameResults,
+            execEnv.root?.key,
+            () => new Map<string, ModuleImportInfo>()
+        );
+        const key = `${allowInvalidModuleName}.${detectPyTyped}.${fileUri.key}`;
         return getOrAdd(cache, key, () =>
-            this._getModuleNameForImport(filePath, execEnv, allowInvalidModuleName, detectPyTyped)
+            this._getModuleNameForImport(fileUri, execEnv, allowInvalidModuleName, detectPyTyped)
         );
     }
 
@@ -386,7 +367,7 @@ export class ImportResolver {
             // is where the third party folder is in the roots.
             const thirdPartyRoot = this._getThirdPartyTypeshedPath(this._configOptions.typeshedPath, importFailureInfo);
             if (thirdPartyRoot) {
-                roots.push(combinePaths(thirdPartyRoot, '...'));
+                roots.push(thirdPartyRoot.combinePaths('...'));
             }
         } else {
             const thirdPartyPaths = this._getThirdPartyTypeshedPackageRoots(importFailureInfo);
@@ -417,12 +398,12 @@ export class ImportResolver {
 
         const ps = this.partialStubs;
         const ignored: string[] = [];
-        const paths: string[] = [];
+        const paths: Uri[] = [];
         const typeshedPathEx = this.getTypeshedPathEx(execEnv, ignored);
 
         // Add paths to search stub packages.
         addPaths(this._configOptions.stubPath);
-        addPaths(execEnv.root);
+        addPaths(execEnv.root ?? this._configOptions.projectRoot);
         execEnv.extraPaths.forEach((p) => addPaths(p));
         addPaths(typeshedPathEx);
         this.getPythonSearchPaths(ignored).forEach((p) => addPaths(p));
@@ -431,7 +412,7 @@ export class ImportResolver {
         this._invalidateFileSystemCache();
         return true;
 
-        function addPaths(path?: string) {
+        function addPaths(path?: Uri) {
             if (!path || ps.isPathScanned(path)) {
                 return;
             }
@@ -440,7 +421,7 @@ export class ImportResolver {
         }
     }
 
-    getPythonSearchPaths(importFailureInfo: string[]) {
+    getPythonSearchPaths(importFailureInfo: string[]): Uri[] {
         // Find the site packages for the configured virtual environment.
         if (!this._cachedPythonSearchPaths) {
             const info: string[] = [];
@@ -457,10 +438,10 @@ export class ImportResolver {
         return this._cachedPythonSearchPaths.paths;
     }
 
-    getTypeshedStdlibExcludeList(customTypeshedPath: string, pythonVersion: PythonVersion): string[] {
+    getTypeshedStdlibExcludeList(customTypeshedPath: Uri, pythonVersion: PythonVersion): Uri[] {
         const unused: string[] = [];
         const typeshedStdlibPath = this._getStdlibTypeshedPath(customTypeshedPath, pythonVersion, unused);
-        const excludes: string[] = [];
+        const excludes: Uri[] = [];
 
         if (!typeshedStdlibPath) {
             return excludes;
@@ -474,10 +455,10 @@ export class ImportResolver {
             if (versionRange.max !== undefined && pythonVersion > versionRange.max) {
                 // Add excludes for both the ".pyi" file and the directory that contains it
                 // (in case it's using a "__init__.pyi" file).
-                const moduleDirPath = combinePaths(typeshedStdlibPath, ...moduleName.split('.'));
+                const moduleDirPath = typeshedStdlibPath.combinePaths(...moduleName.split('.'));
                 excludes.push(moduleDirPath);
 
-                const moduleFilePath = moduleDirPath + '.pyi';
+                const moduleFilePath = moduleDirPath.replaceExtension('.pyi');
                 excludes.push(moduleFilePath);
             }
         });
@@ -485,28 +466,28 @@ export class ImportResolver {
         return excludes;
     }
 
-    protected readdirEntriesCached(path: string): Dirent[] {
-        const cachedValue = this._cachedEntriesForPath.get(path);
+    protected readdirEntriesCached(uri: Uri): Dirent[] {
+        const cachedValue = this._cachedEntriesForPath.get(uri.key);
         if (cachedValue) {
             return cachedValue;
         }
 
         let newCacheValue: Dirent[];
         try {
-            newCacheValue = this.fileSystem.readdirEntriesSync(path);
+            newCacheValue = this.fileSystem.readdirEntriesSync(uri);
         } catch {
             newCacheValue = [];
         }
 
         // Populate cache for next time.
-        this._cachedEntriesForPath.set(path, newCacheValue);
+        this._cachedEntriesForPath.set(uri.key, newCacheValue);
         return newCacheValue;
     }
 
     // Resolves the import and returns the path if it exists, otherwise
     // returns undefined.
     protected resolveImportInternal(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor
     ): ImportResult {
@@ -514,7 +495,7 @@ export class ImportResolver {
         const importFailureInfo: string[] = [];
         const importResult = this._resolveImportStrict(
             importName,
-            sourceFilePath,
+            sourceFileUri,
             execEnv,
             moduleDescriptor,
             importFailureInfo
@@ -527,8 +508,7 @@ export class ImportResolver {
         // If the import is absolute and no other method works, try resolving the
         // absolute in the importing file's directory, then the parent directory,
         // and so on, until the import root is reached.
-        sourceFilePath = realCasePath(normalizePath(sourceFilePath), this.fileSystem);
-        const origin = ensureTrailingDirectorySeparator(getDirectoryPath(sourceFilePath));
+        const origin = sourceFileUri.getDirectory();
 
         const result = this.cachedParentImportResults.getImportResult(origin, importName, importResult);
         if (result) {
@@ -537,18 +517,18 @@ export class ImportResolver {
         }
 
         // Check whether the given file is in the parent directory import resolution cache.
-        const root = this.getParentImportResolutionRoot(sourceFilePath, execEnv.root);
-        if (!this.cachedParentImportResults.checkValidPath(this.fileSystem, sourceFilePath, root)) {
+        const root = this.getParentImportResolutionRoot(sourceFileUri, execEnv.root);
+        if (!this.cachedParentImportResults.checkValidPath(this.fileSystem, sourceFileUri, root)) {
             return importResult;
         }
 
         const importPath: ImportPath = { importPath: undefined };
 
         // Going up the given folder one by one until we can resolve the import.
-        let current = origin;
-        while (this._shouldWalkUp(current, root, execEnv)) {
+        let current: Uri | undefined = origin;
+        while (this._shouldWalkUp(current, root, execEnv) && current) {
             const result = this.resolveAbsoluteImport(
-                sourceFilePath,
+                sourceFileUri,
                 current,
                 execEnv,
                 moduleDescriptor,
@@ -560,7 +540,7 @@ export class ImportResolver {
                 /* allowPyi */ true
             );
 
-            this.cachedParentImportResults.checked(current, importName, importPath);
+            this.cachedParentImportResults.checked(current!, importName, importPath);
 
             if (result.isImportFound) {
                 // This will make cache to point to actual path that contains the module we found
@@ -575,35 +555,30 @@ export class ImportResolver {
                 return this.filterImplicitImports(result, moduleDescriptor.importedSymbols);
             }
 
-            let success;
-            [success, current] = this._tryWalkUp(current);
-            if (!success) {
-                break;
-            }
+            current = this._tryWalkUp(current);
         }
 
-        this.cachedParentImportResults.checked(current, importName, importPath);
+        if (current) {
+            this.cachedParentImportResults.checked(current, importName, importPath);
+        }
         return importResult;
     }
 
-    protected fileExistsCached(path: string): boolean {
-        const splitPath = this._splitPath(path);
-
-        if (!splitPath[0] || !splitPath[1]) {
-            if (!this.fileSystem.existsSync(path)) {
-                return false;
-            }
-            return tryStat(this.fileSystem, path)?.isFile() ?? false;
+    protected fileExistsCached(uri: Uri): boolean {
+        const directory = uri.getDirectory();
+        if (directory.equals(uri)) {
+            // Started at root, so this can't be a file.
+            return false;
         }
-
-        const entries = this.readdirEntriesCached(splitPath[0]);
-        const entry = entries.find((entry) => entry.name === splitPath[1]);
+        const fileName = uri.fileName;
+        const entries = this.readdirEntriesCached(directory);
+        const entry = entries.find((entry) => entry.name === fileName);
         if (entry?.isFile()) {
             return true;
         }
 
         if (entry?.isSymbolicLink()) {
-            const realPath = tryRealpath(this.fileSystem, path);
+            const realPath = tryRealpath(this.fileSystem, uri);
             if (realPath && this.fileSystem.existsSync(realPath) && isFile(this.fileSystem, realPath)) {
                 return true;
             }
@@ -612,24 +587,30 @@ export class ImportResolver {
         return false;
     }
 
-    protected dirExistsCached(path: string): boolean {
-        const splitPath = this._splitPath(path);
-
-        if (!splitPath[0] || !splitPath[1]) {
-            if (!this.fileSystem.existsSync(path)) {
-                return false;
+    protected dirExistsCached(uri: Uri): boolean {
+        const parent = uri.getDirectory();
+        if (parent.equals(uri)) {
+            // Started at root. No entries to read, so have to check ourselves.
+            let cachedExistence = this._cachedDirExistenceForRoot.get(uri.key);
+            // Check if the value was in the cache or not. Undefined means it wasn't.
+            if (cachedExistence === undefined) {
+                cachedExistence = tryStat(this.fileSystem, uri)?.isDirectory() ?? false;
+                this._cachedDirExistenceForRoot.set(uri.key, cachedExistence);
             }
-            return tryStat(this.fileSystem, path)?.isDirectory() ?? false;
+            return cachedExistence;
         }
 
-        const entries = this.readdirEntriesCached(splitPath[0]);
-        const entry = entries.find((entry) => entry.name === splitPath[1]);
+        // Otherwise not a root, so read the entries we have cached to see if
+        // the directory exists or not.
+        const directoryName = uri.fileName;
+        const entries = this.readdirEntriesCached(parent);
+        const entry = entries.find((entry) => entry.name === directoryName);
         if (entry?.isDirectory()) {
             return true;
         }
 
         if (entry?.isSymbolicLink()) {
-            const realPath = tryRealpath(this.fileSystem, path);
+            const realPath = tryRealpath(this.fileSystem, uri);
             if (realPath && this.fileSystem.existsSync(realPath) && isDirectory(this.fileSystem, realPath)) {
                 return true;
             }
@@ -639,7 +620,7 @@ export class ImportResolver {
     }
 
     protected addResultsToCache(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         importName: string,
         importResult: ImportResult,
@@ -647,10 +628,10 @@ export class ImportResolver {
         fromUserFile: boolean
     ) {
         // If the import is relative, include the source file path in the key.
-        const relativeSourceFilePath = moduleDescriptor && moduleDescriptor.leadingDots > 0 ? sourceFilePath : '';
+        const relativeSourceFileUri = moduleDescriptor && moduleDescriptor.leadingDots > 0 ? sourceFileUri : undefined;
 
-        getOrAdd(this._cachedImportResults, execEnv.root, () => new Map<string, ImportResult>()).set(
-            this._getImportCacheKey(relativeSourceFilePath, importName, fromUserFile),
+        getOrAdd(this._cachedImportResults, execEnv.root?.key, () => new Map<string, ImportResult>()).set(
+            this._getImportCacheKey(relativeSourceFileUri, importName, fromUserFile),
             importResult
         );
 
@@ -660,8 +641,8 @@ export class ImportResolver {
     // Follows import resolution algorithm defined in PEP-420:
     // https://www.python.org/dev/peps/pep-0420/
     protected resolveAbsoluteImport(
-        sourceFilePath: string | undefined,
-        rootPath: string,
+        sourceFileUri: Uri | undefined,
+        rootPath: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
         importName: string,
@@ -715,7 +696,7 @@ export class ImportResolver {
 
     // Intended to be overridden by subclasses to provide additional stub
     // path capabilities. Return undefined if no extra stub path were found.
-    protected getTypeshedPathEx(execEnv: ExecutionEnvironment, importFailureInfo: string[]): string | undefined {
+    protected getTypeshedPathEx(execEnv: ExecutionEnvironment, importFailureInfo: string[]): Uri | undefined {
         return undefined;
     }
 
@@ -723,7 +704,7 @@ export class ImportResolver {
     // resolving capabilities. Return undefined if no stubs were found for
     // this import.
     protected resolveImportEx(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
         importName: string,
@@ -737,27 +718,27 @@ export class ImportResolver {
     // resolving capabilities for native (compiled) modules. Returns undefined
     // if no stubs were found for this import.
     protected resolveNativeImportEx(
-        libraryFilePath: string,
+        libraryFileUri: Uri,
         importName: string,
         importFailureInfo: string[] = []
-    ): string | undefined {
+    ): Uri | undefined {
         return undefined;
     }
 
-    protected getNativeModuleName(fileName: string): string | undefined {
-        const fileExtension = getFileExtension(fileName, /* multiDotExtension */ false).toLowerCase();
+    protected getNativeModuleName(uri: Uri): string | undefined {
+        const fileExtension = uri.lastExtension.toLowerCase();
         if (this._isNativeModuleFileExtension(fileExtension)) {
-            return stripFileExtension(stripFileExtension(fileName));
+            return stripFileExtension(uri.fileName, /* multiDotExtension */ true);
         }
         return undefined;
     }
 
     protected getModuleNameFromPath(
-        containerPath: string,
-        filePath: string,
+        containerPath: Uri,
+        fileUri: Uri,
         stripTopContainerDir = false
     ): string | undefined {
-        const moduleNameInfo = this.getModuleNameInfoFromPath(containerPath, filePath, stripTopContainerDir);
+        const moduleNameInfo = this.getModuleNameInfoFromPath(containerPath, fileUri, stripTopContainerDir);
         if (!moduleNameInfo || moduleNameInfo.containsInvalidCharacters) {
             return undefined;
         }
@@ -766,30 +747,27 @@ export class ImportResolver {
     }
 
     protected getModuleNameInfoFromPath(
-        containerPath: string,
-        filePath: string,
+        containerPath: Uri,
+        fileUri: Uri,
         stripTopContainerDir = false
     ): ModuleNameInfoFromPath | undefined {
-        containerPath = ensureTrailingDirectorySeparator(containerPath);
-        let filePathWithoutExtension = stripFileExtension(filePath);
+        let fileUriWithoutExtension = fileUri.stripExtension();
 
         // If module is native, strip platform part, such as 'cp36-win_amd64' in 'mtrand.cp36-win_amd64'.
-        if (this._isNativeModuleFileExtension(getFileExtension(filePath))) {
-            filePathWithoutExtension = stripFileExtension(filePathWithoutExtension);
+        if (this._isNativeModuleFileExtension(fileUri.lastExtension)) {
+            fileUriWithoutExtension = fileUriWithoutExtension.stripExtension();
         }
 
-        if (!filePathWithoutExtension.startsWith(containerPath)) {
+        if (!fileUriWithoutExtension.startsWith(containerPath)) {
             return undefined;
         }
 
         // Strip off the '/__init__' if it's present.
-        if (filePathWithoutExtension.endsWith('__init__')) {
-            filePathWithoutExtension = filePathWithoutExtension.substr(0, filePathWithoutExtension.length - 9);
+        if (fileUriWithoutExtension.pathEndsWith('__init__')) {
+            fileUriWithoutExtension = fileUriWithoutExtension.getDirectory();
         }
 
-        const relativeFilePath = filePathWithoutExtension.substr(containerPath.length);
-        const parts = getPathComponents(relativeFilePath);
-        parts.shift();
+        const parts = Array.from(containerPath.getRelativePathComponents(fileUriWithoutExtension));
         if (stripTopContainerDir) {
             if (parts.length === 0) {
                 return undefined;
@@ -857,22 +835,22 @@ export class ImportResolver {
         return '.'.repeat(moduleDescriptor.leadingDots) + moduleDescriptor.nameParts.join('.');
     }
 
-    protected getParentImportResolutionRoot(sourceFilePath: string, executionRoot: string | undefined) {
+    protected getParentImportResolutionRoot(sourceFileUri: Uri, executionRoot: Uri | undefined) {
         if (executionRoot) {
-            return ensureTrailingDirectorySeparator(realCasePath(normalizePath(executionRoot), this.fileSystem));
+            return this.fileSystem.realCasePath(executionRoot);
         }
 
-        return ensureTrailingDirectorySeparator(getDirectoryPath(sourceFilePath));
+        return sourceFileUri.getDirectory();
     }
 
     private _resolveImportStrict(
         importName: string,
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
         importFailureInfo: string[]
     ) {
-        const fromUserFile = matchFileSpecs(this._configOptions, sourceFilePath);
+        const fromUserFile = matchFileSpecs(this._configOptions, sourceFileUri);
         const notFoundResult: ImportResult = {
             importName,
             isRelative: false,
@@ -882,7 +860,7 @@ export class ImportResolver {
             isInitFilePresent: false,
             isStubPackage: false,
             importFailureInfo,
-            resolvedPaths: [],
+            resolvedUris: [],
             importType: ImportType.Local,
             isStubFile: false,
             isNativeLib: false,
@@ -896,7 +874,7 @@ export class ImportResolver {
         // Is it a relative import?
         if (moduleDescriptor.leadingDots > 0) {
             const cachedResults = this._lookUpResultsInCache(
-                sourceFilePath,
+                sourceFileUri,
                 execEnv,
                 importName,
                 moduleDescriptor,
@@ -908,7 +886,7 @@ export class ImportResolver {
             }
 
             const relativeImport = this._resolveRelativeImport(
-                sourceFilePath,
+                sourceFileUri,
                 execEnv,
                 moduleDescriptor,
                 importName,
@@ -919,7 +897,7 @@ export class ImportResolver {
                 relativeImport.isRelative = true;
 
                 return this.addResultsToCache(
-                    sourceFilePath,
+                    sourceFileUri,
                     execEnv,
                     importName,
                     relativeImport,
@@ -929,7 +907,7 @@ export class ImportResolver {
             }
         } else {
             const cachedResults = this._lookUpResultsInCache(
-                sourceFilePath,
+                sourceFileUri,
                 execEnv,
                 importName,
                 moduleDescriptor,
@@ -953,7 +931,7 @@ export class ImportResolver {
             }
 
             const bestImport = this._resolveBestAbsoluteImport(
-                sourceFilePath,
+                sourceFileUri,
                 execEnv,
                 moduleDescriptor,
                 /* allowPyi */ true
@@ -963,7 +941,7 @@ export class ImportResolver {
                 if (bestImport.isStubFile) {
                     bestImport.nonStubImportResult =
                         this._resolveBestAbsoluteImport(
-                            sourceFilePath,
+                            sourceFileUri,
                             execEnv,
                             moduleDescriptor,
                             /* allowPyi */ false
@@ -971,7 +949,7 @@ export class ImportResolver {
                 }
 
                 return this.addResultsToCache(
-                    sourceFilePath,
+                    sourceFileUri,
                     execEnv,
                     importName,
                     bestImport,
@@ -982,7 +960,7 @@ export class ImportResolver {
         }
 
         return this.addResultsToCache(
-            sourceFilePath,
+            sourceFileUri,
             execEnv,
             importName,
             notFoundResult,
@@ -992,32 +970,26 @@ export class ImportResolver {
     }
 
     private _getCompletionSuggestionsStrict(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor
-    ): Map<string, string> {
+    ): Map<string, Uri> {
         const importFailureInfo: string[] = [];
-        const suggestions = new Map<string, string>();
+        const suggestions = new Map<string, Uri>();
 
         // Is it a relative import?
         if (moduleDescriptor.leadingDots > 0) {
-            this._getCompletionSuggestionsRelative(sourceFilePath, execEnv, moduleDescriptor, suggestions);
+            this._getCompletionSuggestionsRelative(sourceFileUri, execEnv, moduleDescriptor, suggestions);
         } else {
             // First check for a typeshed file.
             if (moduleDescriptor.nameParts.length > 0) {
-                this._getCompletionSuggestionsTypeshedPath(
-                    sourceFilePath,
-                    execEnv,
-                    moduleDescriptor,
-                    true,
-                    suggestions
-                );
+                this._getCompletionSuggestionsTypeshedPath(sourceFileUri, execEnv, moduleDescriptor, true, suggestions);
             }
 
             // Look for it in the root directory of the execution environment.
             if (execEnv.root) {
                 this._getCompletionSuggestionsAbsolute(
-                    sourceFilePath,
+                    sourceFileUri,
                     execEnv,
                     execEnv.root,
                     moduleDescriptor,
@@ -1027,7 +999,7 @@ export class ImportResolver {
 
             for (const extraPath of execEnv.extraPaths) {
                 this._getCompletionSuggestionsAbsolute(
-                    sourceFilePath,
+                    sourceFileUri,
                     execEnv,
                     extraPath,
                     moduleDescriptor,
@@ -1038,7 +1010,7 @@ export class ImportResolver {
             // Check for a typings file.
             if (this._configOptions.stubPath) {
                 this._getCompletionSuggestionsAbsolute(
-                    sourceFilePath,
+                    sourceFileUri,
                     execEnv,
                     this._configOptions.stubPath,
                     moduleDescriptor,
@@ -1047,13 +1019,13 @@ export class ImportResolver {
             }
 
             // Check for a typeshed file.
-            this._getCompletionSuggestionsTypeshedPath(sourceFilePath, execEnv, moduleDescriptor, false, suggestions);
+            this._getCompletionSuggestionsTypeshedPath(sourceFileUri, execEnv, moduleDescriptor, false, suggestions);
 
             // Look for the import in the list of third-party packages.
             const pythonSearchPaths = this.getPythonSearchPaths(importFailureInfo);
             for (const searchPath of pythonSearchPaths) {
                 this._getCompletionSuggestionsAbsolute(
-                    sourceFilePath,
+                    sourceFileUri,
                     execEnv,
                     searchPath,
                     moduleDescriptor,
@@ -1066,7 +1038,7 @@ export class ImportResolver {
     }
 
     private _getModuleNameForImport(
-        filePath: string,
+        fileUri: Uri,
         execEnv: ExecutionEnvironment,
         allowInvalidModuleName: boolean,
         detectPyTyped: boolean
@@ -1093,7 +1065,7 @@ export class ImportResolver {
         );
 
         if (stdLibTypeshedPath) {
-            moduleName = this.getModuleNameFromPath(stdLibTypeshedPath, filePath);
+            moduleName = this.getModuleNameFromPath(stdLibTypeshedPath, fileUri);
             if (moduleName) {
                 const moduleDescriptor: ImportedModuleDescriptor = {
                     leadingDots: 0,
@@ -1122,7 +1094,7 @@ export class ImportResolver {
 
         // Look for it in the root directory of the execution environment.
         if (execEnv.root) {
-            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(execEnv.root, filePath);
+            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(execEnv.root, fileUri);
 
             if (candidateModuleNameInfo) {
                 if (candidateModuleNameInfo.containsInvalidCharacters) {
@@ -1136,7 +1108,7 @@ export class ImportResolver {
         }
 
         for (const extraPath of execEnv.extraPaths) {
-            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(extraPath, filePath);
+            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(extraPath, fileUri);
 
             if (candidateModuleNameInfo) {
                 if (candidateModuleNameInfo.containsInvalidCharacters) {
@@ -1155,7 +1127,7 @@ export class ImportResolver {
 
         // Check for a typings file.
         if (this._configOptions.stubPath) {
-            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(this._configOptions.stubPath, filePath);
+            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(this._configOptions.stubPath, fileUri);
 
             if (candidateModuleNameInfo) {
                 if (candidateModuleNameInfo.containsInvalidCharacters) {
@@ -1184,7 +1156,7 @@ export class ImportResolver {
         if (thirdPartyTypeshedPath) {
             const candidateModuleName = this.getModuleNameFromPath(
                 thirdPartyTypeshedPath,
-                filePath,
+                fileUri,
                 /* stripTopContainerDir */ true
             );
 
@@ -1199,7 +1171,7 @@ export class ImportResolver {
 
         const thirdPartyTypeshedPathEx = this.getTypeshedPathEx(execEnv, importFailureInfo);
         if (thirdPartyTypeshedPathEx) {
-            const candidateModuleName = this.getModuleNameFromPath(thirdPartyTypeshedPathEx, filePath);
+            const candidateModuleName = this.getModuleNameFromPath(thirdPartyTypeshedPathEx, fileUri);
 
             // Does this candidate look better than the previous best module name?
             // We'll always try to use the shortest version.
@@ -1214,7 +1186,7 @@ export class ImportResolver {
         const pythonSearchPaths = this.getPythonSearchPaths(importFailureInfo);
 
         for (const searchPath of pythonSearchPaths) {
-            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(searchPath, filePath);
+            const candidateModuleNameInfo = this.getModuleNameInfoFromPath(searchPath, fileUri);
 
             if (candidateModuleNameInfo) {
                 if (candidateModuleNameInfo.containsInvalidCharacters) {
@@ -1233,24 +1205,18 @@ export class ImportResolver {
         }
 
         if (detectPyTyped && importType === ImportType.ThirdParty) {
-            const root = this.getParentImportResolutionRoot(filePath, execEnv.root);
+            const root = this.getParentImportResolutionRoot(fileUri, execEnv.root);
 
             // Go up directories one by one looking for a py.typed file.
-            let current = ensureTrailingDirectorySeparator(getDirectoryPath(filePath));
+            let current: Uri | undefined = fileUri.getDirectory();
             while (this._shouldWalkUp(current, root, execEnv)) {
-                if (this.fileExistsCached(combinePaths(current, 'py.typed'))) {
-                    const pyTypedInfo = getPyTypedInfo(this.fileSystem, current);
-                    if (pyTypedInfo && !pyTypedInfo.isPartiallyTyped) {
-                        isThirdPartyPyTypedPresent = true;
-                    }
-                    break;
+                const pyTypedInfo = this._getPyTypedInfo(current!);
+                if (pyTypedInfo && !pyTypedInfo.isPartiallyTyped) {
+                    isThirdPartyPyTypedPresent = true;
                 }
+                break;
 
-                let success;
-                [success, current] = this._tryWalkUp(current);
-                if (!success) {
-                    break;
-                }
+                current = this._tryWalkUp(current);
             }
         }
 
@@ -1280,24 +1246,12 @@ export class ImportResolver {
 
     private _invalidateFileSystemCache() {
         this._cachedEntriesForPath.clear();
-    }
-
-    // Splits a path into the name of the containing directory and
-    // a file or dir within that containing directory.
-    private _splitPath(path: string): [string, string] {
-        const pathComponents = getPathComponents(path);
-        if (pathComponents.length <= 1) {
-            return [path, ''];
-        }
-
-        const containingPath = combinePathComponents(pathComponents.slice(0, -1));
-        const fileOrDirName = pathComponents[pathComponents.length - 1];
-
-        return [containingPath, fileOrDirName];
+        this._cachedFilesForPath.clear();
+        this._cachedDirExistenceForRoot.clear();
     }
 
     private _resolveAbsoluteImport(
-        rootPath: string,
+        rootPath: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
         importName: string,
@@ -1316,7 +1270,7 @@ export class ImportResolver {
 
         // Starting at the specified path, walk the file system to find the
         // specified module.
-        const resolvedPaths: string[] = [];
+        const resolvedPaths: Uri[] = [];
         let dirPath = rootPath;
         let isNamespacePackage = false;
         let isInitFilePresent = false;
@@ -1324,14 +1278,13 @@ export class ImportResolver {
         let isStubFile = false;
         let isNativeLib = false;
         let implicitImports = new Map<string, ImplicitImport>();
-        let packageDirectory: string | undefined;
+        let packageDirectory: Uri | undefined;
         let pyTypedInfo: PyTypedInfo | undefined;
 
         // Handle the "from . import XXX" case.
         if (moduleDescriptor.nameParts.length === 0) {
-            const fileNameWithoutExtension = '__init__';
-            const pyFilePath = combinePaths(dirPath, fileNameWithoutExtension + '.py');
-            const pyiFilePath = combinePaths(dirPath, fileNameWithoutExtension + '.pyi');
+            const pyFilePath = dirPath.initPyUri;
+            const pyiFilePath = dirPath.initPyiUri;
 
             if (allowPyi && this.fileExistsCached(pyiFilePath)) {
                 importFailureInfo.push(`Resolved import with file '${pyiFilePath}'`);
@@ -1342,7 +1295,7 @@ export class ImportResolver {
                 resolvedPaths.push(pyFilePath);
             } else {
                 importFailureInfo.push(`Partially resolved import with directory '${dirPath}'`);
-                resolvedPaths.push('');
+                resolvedPaths.push(Uri.empty());
                 isNamespacePackage = true;
             }
 
@@ -1351,10 +1304,10 @@ export class ImportResolver {
             for (let i = 0; i < moduleDescriptor.nameParts.length; i++) {
                 const isFirstPart = i === 0;
                 const isLastPart = i === moduleDescriptor.nameParts.length - 1;
-                dirPath = combinePaths(dirPath, moduleDescriptor.nameParts[i]);
+                dirPath = dirPath.combinePaths(moduleDescriptor.nameParts[i]);
 
                 if (useStubPackage && isFirstPart) {
-                    dirPath += stubsSuffix;
+                    dirPath = dirPath.addPath(stubsSuffix);
                     isStubPackage = true;
                 }
 
@@ -1366,9 +1319,8 @@ export class ImportResolver {
                     }
 
                     // See if we can find an __init__.py[i] in this directory.
-                    const fileNameWithoutExtension = '__init__';
-                    const pyFilePath = combinePaths(dirPath, fileNameWithoutExtension + '.py');
-                    const pyiFilePath = combinePaths(dirPath, fileNameWithoutExtension + '.pyi');
+                    const pyFilePath = dirPath.initPyUri;
+                    const pyiFilePath = dirPath.initPyiUri;
                     isInitFilePresent = false;
 
                     if (allowPyi && this.fileExistsCached(pyiFilePath)) {
@@ -1385,16 +1337,14 @@ export class ImportResolver {
                     }
 
                     if (!pyTypedInfo && lookForPyTyped) {
-                        if (this.fileExistsCached(combinePaths(dirPath, 'py.typed'))) {
-                            pyTypedInfo = getPyTypedInfo(this.fileSystem, dirPath);
-                        }
+                        pyTypedInfo = this._getPyTypedInfo(dirPath);
                     }
 
                     if (!isLastPart) {
                         // We are not at the last part, and we found a directory,
                         // so continue to look for the next part.
                         if (!isInitFilePresent) {
-                            resolvedPaths.push('');
+                            resolvedPaths.push(Uri.empty());
                             isNamespacePackage = true;
                             pyTypedInfo = undefined;
                         }
@@ -1413,11 +1363,9 @@ export class ImportResolver {
                 // We weren't able to find a directory or we found a directory with
                 // no __init__.py[i] file. See if we can find a ".py" or ".pyi" file
                 // with this name.
-                let fileDirectory = stripTrailingDirectorySeparator(dirPath);
-                const fileNameWithoutExtension = getFileName(fileDirectory);
-                fileDirectory = getDirectoryPath(fileDirectory);
-                const pyFilePath = combinePaths(fileDirectory, fileNameWithoutExtension + '.py');
-                const pyiFilePath = combinePaths(fileDirectory, fileNameWithoutExtension + '.pyi');
+                const pyFilePath = dirPath.packageUri;
+                const pyiFilePath = dirPath.packageStubUri;
+                const fileDirectory = dirPath.getDirectory();
 
                 if (allowPyi && this.fileExistsCached(pyiFilePath)) {
                     importFailureInfo.push(`Resolved import with file '${pyiFilePath}'`);
@@ -1431,11 +1379,9 @@ export class ImportResolver {
                 } else {
                     if (allowNativeLib && this.dirExistsCached(fileDirectory)) {
                         const filesInDir = this._getFilesInDirectory(fileDirectory);
-                        const nativeLibFileName = filesInDir.find((f) =>
-                            this._isNativeModuleFileName(fileNameWithoutExtension, f)
-                        );
-                        if (nativeLibFileName) {
-                            const nativeLibPath = combinePaths(fileDirectory, nativeLibFileName);
+                        const dirName = dirPath.fileName;
+                        const nativeLibPath = filesInDir.find((f) => this._isNativeModuleFileName(dirName, f));
+                        if (nativeLibPath) {
                             // Try resolving native library to a custom stub.
                             isNativeLib = this._resolveNativeModuleStub(
                                 nativeLibPath,
@@ -1450,7 +1396,7 @@ export class ImportResolver {
 
                     if (!isNativeLib && foundDirectory) {
                         importFailureInfo.push(`Partially resolved import with directory '${dirPath}'`);
-                        resolvedPaths.push('');
+                        resolvedPaths.push(Uri.empty());
                         if (isLastPart) {
                             implicitImports = this._findImplicitImports(importName, dirPath, [pyFilePath, pyiFilePath]);
                             isNamespacePackage = true;
@@ -1461,9 +1407,7 @@ export class ImportResolver {
                 }
 
                 if (!pyTypedInfo && lookForPyTyped) {
-                    if (this.fileExistsCached(combinePaths(fileDirectory, 'py.typed'))) {
-                        pyTypedInfo = getPyTypedInfo(this.fileSystem, fileDirectory);
-                    }
+                    pyTypedInfo = this._getPyTypedInfo(fileDirectory);
                 }
                 break;
             }
@@ -1487,7 +1431,7 @@ export class ImportResolver {
             isPartlyResolved,
             importFailureInfo,
             importType: ImportType.Local,
-            resolvedPaths,
+            resolvedUris: resolvedPaths,
             searchPath: rootPath,
             isStubFile,
             isNativeLib,
@@ -1498,27 +1442,27 @@ export class ImportResolver {
         };
     }
 
-    private _getImportCacheKey(sourceFilePath: string, importName: string, fromUserFile: boolean) {
-        return `${sourceFilePath}-${importName}-${fromUserFile}`;
+    private _getImportCacheKey(sourceFileUri: Uri | undefined, importName: string, fromUserFile: boolean) {
+        return `${sourceFileUri?.key ?? ''}-${importName}-${fromUserFile}`;
     }
 
     private _lookUpResultsInCache(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         importName: string,
         moduleDescriptor: ImportedModuleDescriptor,
         fromUserFile: boolean
     ) {
-        const cacheForExecEnv = this._cachedImportResults.get(execEnv.root);
+        const cacheForExecEnv = this._cachedImportResults.get(execEnv.root?.key ?? '');
         if (!cacheForExecEnv) {
             return undefined;
         }
 
         // If the import is relative, include the source file path in the key.
-        const relativeSourceFilePath = moduleDescriptor.leadingDots > 0 ? sourceFilePath : '';
+        const relativeSourceFileUri = moduleDescriptor.leadingDots > 0 ? sourceFileUri : undefined;
 
         const cachedEntry = cacheForExecEnv.get(
-            this._getImportCacheKey(relativeSourceFilePath, importName, fromUserFile)
+            this._getImportCacheKey(relativeSourceFileUri, importName, fromUserFile)
         );
 
         if (!cachedEntry) {
@@ -1548,7 +1492,7 @@ export class ImportResolver {
     }
 
     private _resolveBestAbsoluteImport(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
         allowPyi: boolean
@@ -1560,7 +1504,7 @@ export class ImportResolver {
         if (allowPyi && this._configOptions.stubPath) {
             importFailureInfo.push(`Looking in stubPath '${this._configOptions.stubPath}'`);
             const typingsImport = this.resolveAbsoluteImport(
-                sourceFilePath,
+                sourceFileUri,
                 this._configOptions.stubPath,
                 execEnv,
                 moduleDescriptor,
@@ -1583,7 +1527,7 @@ export class ImportResolver {
                 // skip the typings import and continue searching.
                 if (
                     typingsImport.isNamespacePackage &&
-                    !typingsImport.resolvedPaths[typingsImport.resolvedPaths.length - 1]
+                    !typingsImport.resolvedUris[typingsImport.resolvedUris.length - 1]
                 ) {
                     if (this._isNamespacePackageResolved(moduleDescriptor, typingsImport.implicitImports)) {
                         return typingsImport;
@@ -1602,7 +1546,7 @@ export class ImportResolver {
             importFailureInfo.push(`Looking in root directory of execution environment ` + `'${execEnv.root}'`);
 
             localImport = this.resolveAbsoluteImport(
-                sourceFilePath,
+                sourceFileUri,
                 execEnv.root,
                 execEnv,
                 moduleDescriptor,
@@ -1620,7 +1564,7 @@ export class ImportResolver {
         for (const extraPath of execEnv.extraPaths) {
             importFailureInfo.push(`Looking in extraPath '${extraPath}'`);
             localImport = this.resolveAbsoluteImport(
-                sourceFilePath,
+                sourceFileUri,
                 extraPath,
                 execEnv,
                 moduleDescriptor,
@@ -1642,7 +1586,7 @@ export class ImportResolver {
                 importFailureInfo.push(`Looking in python search path '${searchPath}'`);
 
                 const thirdPartyImport = this.resolveAbsoluteImport(
-                    sourceFilePath,
+                    sourceFileUri,
                     searchPath,
                     execEnv,
                     moduleDescriptor,
@@ -1676,7 +1620,7 @@ export class ImportResolver {
 
         // Call the extensibility hook for subclasses.
         const extraResults = this.resolveImportEx(
-            sourceFilePath,
+            sourceFileUri,
             execEnv,
             moduleDescriptor,
             importName,
@@ -1740,8 +1684,8 @@ export class ImportResolver {
 
         if (newImport.isImportFound) {
             // Prefer traditional packages over namespace packages.
-            const soFarIndex = bestImportSoFar.resolvedPaths.findIndex((path) => !!path);
-            const newIndex = newImport.resolvedPaths.findIndex((path) => !!path);
+            const soFarIndex = bestImportSoFar.resolvedUris.findIndex((path) => !path.isEmpty());
+            const newIndex = newImport.resolvedUris.findIndex((path) => !path.isEmpty());
             if (soFarIndex !== newIndex) {
                 if (soFarIndex < 0) {
                     return newImport;
@@ -1798,7 +1742,7 @@ export class ImportResolver {
             }
 
             // All else equal, prefer shorter resolution paths.
-            if (bestImportSoFar.resolvedPaths.length > newImport.resolvedPaths.length) {
+            if (bestImportSoFar.resolvedUris.length > newImport.resolvedUris.length) {
                 return newImport;
             }
         } else if (newImport.isPartlyResolved) {
@@ -1811,8 +1755,8 @@ export class ImportResolver {
             //  bestSoFar: a/~b/~c/~d   new: a      Result: bestSoFar wins
             //  bestSoFar: ~a/~b/~c/~d  new: a      Result: new wins
             //  bestSoFar: a/~b/~c/~d   new: a/b    Result: new wins
-            const soFarIndex = bestImportSoFar.resolvedPaths.findIndex((path) => !!path);
-            const newIndex = newImport.resolvedPaths.findIndex((path) => !!path);
+            const soFarIndex = bestImportSoFar.resolvedUris.findIndex((path) => !path.isEmpty());
+            const newIndex = newImport.resolvedUris.findIndex((path) => !path.isEmpty());
 
             if (soFarIndex !== newIndex) {
                 if (soFarIndex < 0) {
@@ -1850,7 +1794,7 @@ export class ImportResolver {
             } path`
         );
 
-        let typeshedPaths: string[] | undefined;
+        let typeshedPaths: Uri[] | undefined;
         if (isStdLib) {
             const path = this._getStdlibTypeshedPath(
                 this._configOptions.typeshedPath,
@@ -1891,14 +1835,14 @@ export class ImportResolver {
     }
 
     // Finds all of the stdlib modules and returns a Set containing all of their names.
-    private _buildStdlibCache(stdlibRoot: string | undefined): Set<string> {
+    private _buildStdlibCache(stdlibRoot: Uri | undefined): Set<string> {
         const cache = new Set<string>();
 
         if (stdlibRoot) {
-            const readDir = (root: string, prefix: string | undefined) => {
+            const readDir = (root: Uri, prefix: string | undefined) => {
                 this.readdirEntriesCached(root).forEach((entry) => {
                     if (entry.isDirectory()) {
-                        const dirRoot = combinePaths(root, entry.name);
+                        const dirRoot = root.combinePaths(entry.name);
                         readDir(dirRoot, prefix ? `${prefix}.${entry.name}` : entry.name);
                     } else if (entry.name.includes('.py')) {
                         const stripped = stripFileExtension(entry.name);
@@ -1920,13 +1864,13 @@ export class ImportResolver {
     // the pypi-registered name of the package and an inner directory contains
     // the name of the package as it is referenced by import statements. These
     // don't always match.
-    private _buildTypeshedThirdPartyPackageMap(thirdPartyDir: string | undefined) {
-        this._cachedTypeshedThirdPartyPackagePaths = new Map<string, string[]>();
+    private _buildTypeshedThirdPartyPackageMap(thirdPartyDir: Uri | undefined) {
+        this._cachedTypeshedThirdPartyPackagePaths = new Map<string, Uri[]>();
 
         if (thirdPartyDir) {
             this.readdirEntriesCached(thirdPartyDir).forEach((outerEntry) => {
                 if (outerEntry.isDirectory()) {
-                    const innerDirPath = combinePaths(thirdPartyDir, outerEntry.name);
+                    const innerDirPath = thirdPartyDir.combinePaths(outerEntry.name);
 
                     this.readdirEntriesCached(innerDirPath).forEach((innerEntry) => {
                         if (innerEntry.name === '@python2') {
@@ -1961,15 +1905,15 @@ export class ImportResolver {
     }
 
     private _getCompletionSuggestionsTypeshedPath(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
         isStdLib: boolean,
-        suggestions: Map<string, string>
+        suggestions: Map<string, Uri>
     ) {
         const importFailureInfo: string[] = [];
 
-        let typeshedPaths: string[] | undefined;
+        let typeshedPaths: Uri[] | undefined;
         if (isStdLib) {
             const path = this._getStdlibTypeshedPath(
                 this._configOptions.typeshedPath,
@@ -2001,7 +1945,7 @@ export class ImportResolver {
         typeshedPaths.forEach((typeshedPath) => {
             if (this.dirExistsCached(typeshedPath)) {
                 this._getCompletionSuggestionsAbsolute(
-                    sourceFilePath,
+                    sourceFileUri,
                     execEnv,
                     typeshedPath,
                     moduleDescriptor,
@@ -2015,7 +1959,7 @@ export class ImportResolver {
     // If moduleDescriptor is provided, it is filtered based on the VERSIONS
     // file in the typeshed stubs.
     private _getStdlibTypeshedPath(
-        customTypeshedPath: string | undefined,
+        customTypeshedPath: Uri | undefined,
         pythonVersion: PythonVersion,
         importFailureInfo: string[],
         moduleDescriptor?: ImportedModuleDescriptor
@@ -2037,13 +1981,13 @@ export class ImportResolver {
         return subdirectory;
     }
 
-    private _getThirdPartyTypeshedPath(customTypeshedPath: string | undefined, importFailureInfo: string[]) {
+    private _getThirdPartyTypeshedPath(customTypeshedPath: Uri | undefined, importFailureInfo: string[]) {
         return this._getTypeshedSubdirectory(/* isStdLib */ false, customTypeshedPath, importFailureInfo);
     }
 
     private _isStdlibTypeshedStubValidForVersion(
         moduleDescriptor: ImportedModuleDescriptor,
-        customTypeshedPath: string | undefined,
+        customTypeshedPath: Uri | undefined,
         pythonVersion: PythonVersion,
         importFailureInfo: string[]
     ) {
@@ -2074,7 +2018,7 @@ export class ImportResolver {
     }
 
     private _readTypeshedStdLibVersions(
-        customTypeshedPath: string | undefined,
+        customTypeshedPath: Uri | undefined,
         importFailureInfo: string[]
     ): Map<string, SupportedVersionRange> {
         const versionRangeMap = new Map<string, SupportedVersionRange>();
@@ -2087,7 +2031,7 @@ export class ImportResolver {
         );
 
         if (typeshedStdLibPath) {
-            const versionsFilePath = combinePaths(typeshedStdLibPath, 'VERSIONS');
+            const versionsFilePath = typeshedStdLibPath.combinePaths('VERSIONS');
             try {
                 const fileStats = this.fileSystem.statSync(versionsFilePath);
                 if (fileStats.size > 0 && fileStats.size < 256 * 1024) {
@@ -2141,7 +2085,7 @@ export class ImportResolver {
         moduleDescriptor: ImportedModuleDescriptor,
         importFailureInfo: string[],
         includeMatchOnly = true
-    ): string[] | undefined {
+    ): Uri[] | undefined {
         const typeshedPath = this._getThirdPartyTypeshedPath(this._configOptions.typeshedPath, importFailureInfo);
 
         if (!this._cachedTypeshedThirdPartyPackagePaths) {
@@ -2172,12 +2116,12 @@ export class ImportResolver {
         return this._cachedTypeshedThirdPartyPackageRoots!;
     }
 
-    private _getTypeshedRoot(customTypeshedPath: string | undefined, importFailureInfo: string[]) {
+    private _getTypeshedRoot(customTypeshedPath: Uri | undefined, importFailureInfo: string[]) {
         if (this._cachedTypeshedRoot !== undefined) {
             return this._cachedTypeshedRoot;
         }
 
-        let typeshedPath = '';
+        let typeshedPath = undefined;
 
         // Did the user specify a typeshed path? If not, we'll look in the
         // python search paths, then in the typeshed-fallback directory.
@@ -2189,7 +2133,7 @@ export class ImportResolver {
 
         // If typeshed directory wasn't found in other locations, use the fallback.
         if (!typeshedPath) {
-            typeshedPath = PythonPathUtils.getTypeShedFallbackPath(this.fileSystem) || '';
+            typeshedPath = PythonPathUtils.getTypeShedFallbackPath(this.fileSystem) ?? Uri.empty();
         }
 
         this._cachedTypeshedRoot = typeshedPath;
@@ -2198,7 +2142,7 @@ export class ImportResolver {
 
     private _getTypeshedSubdirectory(
         isStdLib: boolean,
-        customTypeshedPath: string | undefined,
+        customTypeshedPath: Uri | undefined,
         importFailureInfo: string[]
     ) {
         // See if we have it cached.
@@ -2230,7 +2174,7 @@ export class ImportResolver {
     }
 
     private _resolveRelativeImport(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
         importName: string,
@@ -2239,10 +2183,7 @@ export class ImportResolver {
         importFailureInfo.push('Attempting to resolve relative import');
 
         // Determine which search path this file is part of.
-        const directory = getDirectoryLeadingDotsPointsTo(
-            getDirectoryPath(sourceFilePath),
-            moduleDescriptor.leadingDots
-        );
+        const directory = getDirectoryLeadingDotsPointsTo(sourceFileUri.getDirectory(), moduleDescriptor.leadingDots);
         if (!directory) {
             importFailureInfo.push(`Invalid relative path '${importName}'`);
             return undefined;
@@ -2250,7 +2191,7 @@ export class ImportResolver {
 
         // Now try to match the module parts from the current directory location.
         const absImport = this.resolveAbsoluteImport(
-            sourceFilePath,
+            sourceFileUri,
             directory,
             execEnv,
             moduleDescriptor,
@@ -2265,7 +2206,7 @@ export class ImportResolver {
             // the same folder for the real module. Otherwise, it will
             // error out on runtime.
             absImport.nonStubImportResult = this.resolveAbsoluteImport(
-                sourceFilePath,
+                sourceFileUri,
                 directory,
                 execEnv,
                 moduleDescriptor,
@@ -2283,7 +2224,7 @@ export class ImportResolver {
                 isNamespacePackage: false,
                 isStubPackage: false,
                 importFailureInfo,
-                resolvedPaths: [],
+                resolvedUris: [],
                 importType: ImportType.Local,
                 isStubFile: false,
                 isNativeLib: false,
@@ -2297,45 +2238,54 @@ export class ImportResolver {
     }
 
     private _getCompletionSuggestionsRelative(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         moduleDescriptor: ImportedModuleDescriptor,
-        suggestions: Map<string, string>
+        suggestions: Map<string, Uri>
     ) {
         // Determine which search path this file is part of.
-        const directory = getDirectoryLeadingDotsPointsTo(
-            getDirectoryPath(sourceFilePath),
-            moduleDescriptor.leadingDots
-        );
+        const directory = getDirectoryLeadingDotsPointsTo(sourceFileUri.getDirectory(), moduleDescriptor.leadingDots);
         if (!directory) {
             return;
         }
 
         // Now try to match the module parts from the current directory location.
-        this._getCompletionSuggestionsAbsolute(sourceFilePath, execEnv, directory, moduleDescriptor, suggestions);
+        this._getCompletionSuggestionsAbsolute(sourceFileUri, execEnv, directory, moduleDescriptor, suggestions);
     }
 
-    private _getFilesInDirectory(dirPath: string): string[] {
-        const entriesInDir = this.readdirEntriesCached(dirPath);
-        const filesInDir = entriesInDir.filter((f) => f.isFile()).map((f) => f.name);
+    private _getFilesInDirectory(dirPath: Uri): Uri[] {
+        const cachedValue = this._cachedFilesForPath.get(dirPath.key);
+        if (cachedValue) {
+            return cachedValue;
+        }
 
-        // Add any symbolic links that point to files.
-        entriesInDir.forEach((f) => {
-            const linkPath = combinePaths(dirPath, f.name);
-            if (f.isSymbolicLink() && tryStat(this.fileSystem, linkPath)?.isFile()) {
-                filesInDir.push(f.name);
-            }
-        });
+        let newCacheValue: Uri[] = [];
+        try {
+            const entriesInDir = this.readdirEntriesCached(dirPath);
+            const filesInDir = entriesInDir.filter((f) => f.isFile());
 
-        return filesInDir;
+            // Add any symbolic links that point to files.
+            entriesInDir.forEach((f) => {
+                if (f.isSymbolicLink() && tryStat(this.fileSystem, dirPath.combinePaths(f.name))?.isFile()) {
+                    filesInDir.push(f);
+                }
+            });
+
+            newCacheValue = filesInDir.map((f) => dirPath.combinePaths(f.name));
+        } catch {
+            newCacheValue = [];
+        }
+
+        this._cachedFilesForPath.set(dirPath.key, newCacheValue);
+        return newCacheValue;
     }
 
     private _getCompletionSuggestionsAbsolute(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
-        rootPath: string,
+        rootPath: Uri,
         moduleDescriptor: ImportedModuleDescriptor,
-        suggestions: Map<string, string>,
+        suggestions: Map<string, Uri>,
         strictOnly = true
     ) {
         // Starting at the specified path, walk the file system to find the
@@ -2358,7 +2308,7 @@ export class ImportResolver {
         // dot (or multiple) in a relative path.
         if (nameParts.length === 0) {
             this._addFilteredSuggestionsAbsolute(
-                sourceFilePath,
+                sourceFileUri,
                 execEnv,
                 dirPath,
                 '',
@@ -2373,7 +2323,7 @@ export class ImportResolver {
                 // of the name.
                 if (i === nameParts.length - 1) {
                     this._addFilteredSuggestionsAbsolute(
-                        sourceFilePath,
+                        sourceFileUri,
                         execEnv,
                         dirPath,
                         nameParts[i],
@@ -2384,7 +2334,7 @@ export class ImportResolver {
                     );
                 }
 
-                dirPath = combinePaths(dirPath, nameParts[i]);
+                dirPath = dirPath.combinePaths(nameParts[i]);
                 if (!this.dirExistsCached(dirPath)) {
                     break;
                 }
@@ -2393,11 +2343,11 @@ export class ImportResolver {
     }
 
     private _addFilteredSuggestionsAbsolute(
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
-        currentPath: string,
+        currentPath: Uri,
         filter: string,
-        suggestions: Map<string, string>,
+        suggestions: Map<string, Uri>,
         leadingDots: number,
         parentNameParts: string[],
         strictOnly: boolean
@@ -2412,7 +2362,7 @@ export class ImportResolver {
         entries.files.forEach((file) => {
             // Strip multi-dot extensions to handle file names like "foo.cpython-32m.so". We want
             // to detect the ".so" but strip off the entire ".cpython-32m.so" extension.
-            const fileWithoutExtension = stripFileExtension(file, /* multiDotExtension */ true);
+            const fileWithoutExtension = file.stripAllExtensions().fileName;
 
             if (ImportResolver.isSupportedImportFile(file)) {
                 if (fileWithoutExtension === '__init__') {
@@ -2429,7 +2379,7 @@ export class ImportResolver {
                         fileWithoutExtension,
                         leadingDots,
                         parentNameParts,
-                        sourceFilePath,
+                        sourceFileUri,
                         execEnv,
                         strictOnly
                     )
@@ -2437,36 +2387,44 @@ export class ImportResolver {
                     return;
                 }
 
-                suggestions.set(fileWithoutExtension, combinePaths(currentPath, file));
+                suggestions.set(fileWithoutExtension, file);
             }
         });
 
         entries.directories.forEach((dir) => {
-            if (filter && !dir.startsWith(filter)) {
+            const dirSuggestion = dir.fileName;
+            if (filter && !dirSuggestion.startsWith(filter)) {
                 return;
             }
 
             if (
-                !this._isUniqueValidSuggestion(dir, suggestions) ||
-                !this._isResolvableSuggestion(dir, leadingDots, parentNameParts, sourceFilePath, execEnv, strictOnly)
+                !this._isUniqueValidSuggestion(dirSuggestion, suggestions) ||
+                !this._isResolvableSuggestion(
+                    dirSuggestion,
+                    leadingDots,
+                    parentNameParts,
+                    sourceFileUri,
+                    execEnv,
+                    strictOnly
+                )
             ) {
                 return;
             }
 
-            const initPyiPath = combinePaths(currentPath, dir, '__init__.pyi');
+            const initPyiPath = dir.initPyiUri;
             if (this.fileExistsCached(initPyiPath)) {
-                suggestions.set(dir, initPyiPath);
+                suggestions.set(dirSuggestion, initPyiPath);
                 return;
             }
 
-            const initPyPath = combinePaths(currentPath, dir, '__init__.py');
+            const initPyPath = dir.initPyUri;
             if (this.fileExistsCached(initPyPath)) {
-                suggestions.set(dir, initPyPath);
+                suggestions.set(dirSuggestion, initPyPath);
                 return;
             }
 
             // It is a namespace package. there is no corresponding module path.
-            suggestions.set(dir, '');
+            suggestions.set(dirSuggestion, Uri.empty());
         });
     }
 
@@ -2476,11 +2434,11 @@ export class ImportResolver {
         name: string,
         leadingDots: number,
         parentNameParts: string[],
-        sourceFilePath: string,
+        sourceFileUri: Uri,
         execEnv: ExecutionEnvironment,
         strictOnly: boolean
     ) {
-        // We always resolve names based on sourceFilePath.
+        // We always resolve names based on sourceFileUri.
         const moduleDescriptor: ImportedModuleDescriptor = {
             leadingDots: leadingDots,
             nameParts: [...parentNameParts, name],
@@ -2495,13 +2453,13 @@ export class ImportResolver {
 
             importResult = this._resolveImportStrict(
                 importName,
-                sourceFilePath,
+                sourceFileUri,
                 execEnv,
                 moduleDescriptor,
                 importFailureInfo
             );
         } else {
-            importResult = this.resolveImportInternal(sourceFilePath, execEnv, moduleDescriptor);
+            importResult = this.resolveImportInternal(sourceFileUri, execEnv, moduleDescriptor);
         }
 
         if (importResult && importResult.isImportFound) {
@@ -2514,7 +2472,7 @@ export class ImportResolver {
         return false;
     }
 
-    private _isUniqueValidSuggestion(suggestionToAdd: string, suggestions: Map<string, string>) {
+    private _isUniqueValidSuggestion(suggestionToAdd: string, suggestions: Map<string, Uri>) {
         if (suggestions.has(suggestionToAdd)) {
             return false;
         }
@@ -2534,8 +2492,8 @@ export class ImportResolver {
 
     private _findImplicitImports(
         importingModuleName: string,
-        dirPath: string,
-        exclusions: string[]
+        dirPath: Uri,
+        exclusions: Uri[]
     ): Map<string, ImplicitImport> {
         const implicitImportMap = new Map<string, ImplicitImport>();
 
@@ -2547,32 +2505,31 @@ export class ImportResolver {
         );
 
         // Add implicit file-based modules.
-        for (const fileName of entries.files) {
-            const fileExt = getFileExtension(fileName);
+        for (const filePath of entries.files) {
+            const fileExt = filePath.lastExtension;
             let strippedFileName: string;
             let isNativeLib = false;
 
             if (fileExt === '.py' || fileExt === '.pyi') {
-                strippedFileName = stripFileExtension(fileName);
+                strippedFileName = stripFileExtension(filePath.fileName);
             } else if (
                 this._isNativeModuleFileExtension(fileExt) &&
-                !this.fileExistsCached(`${fileName}.py`) &&
-                !this.fileExistsCached(`${fileName}.pyi`)
+                !this.fileExistsCached(filePath.packageUri) &&
+                !this.fileExistsCached(filePath.packageStubUri)
             ) {
                 // Native module.
-                strippedFileName = fileName.substr(0, fileName.indexOf('.'));
+                strippedFileName = filePath.stripAllExtensions().fileName;
                 isNativeLib = true;
             } else {
                 continue;
             }
 
-            const filePath = combinePaths(dirPath, fileName);
-            if (!exclusions.find((exclusion) => exclusion === filePath)) {
+            if (!exclusions.find((exclusion) => exclusion.equals(filePath))) {
                 const implicitImport: ImplicitImport = {
-                    isStubFile: fileName.endsWith('.pyi'),
+                    isStubFile: filePath.hasExtension('.pyi'),
                     isNativeLib,
                     name: strippedFileName,
-                    path: filePath,
+                    uri: filePath,
                 };
 
                 // Always prefer stub files over non-stub files.
@@ -2580,14 +2537,14 @@ export class ImportResolver {
                 if (!entry || !entry.isStubFile) {
                     // Try resolving resolving native lib to a custom stub.
                     if (isNativeLib) {
-                        const nativeLibPath = combinePaths(dirPath, fileName);
+                        const nativeLibPath = filePath;
                         const nativeStubPath = this.resolveNativeImportEx(
                             nativeLibPath,
                             `${importingModuleName}.${strippedFileName}`,
                             []
                         );
                         if (nativeStubPath) {
-                            implicitImport.path = nativeStubPath;
+                            implicitImport.uri = nativeStubPath;
                             implicitImport.isNativeLib = false;
                         }
                     }
@@ -2597,11 +2554,11 @@ export class ImportResolver {
         }
 
         // Add implicit directory-based modules.
-        for (const dirName of entries.directories) {
-            const pyFilePath = combinePaths(dirPath, dirName, '__init__.py');
-            const pyiFilePath = pyFilePath + 'i';
+        for (const dirPath of entries.directories) {
+            const pyFilePath = dirPath.initPyUri;
+            const pyiFilePath = dirPath.initPyiUri;
             let isStubFile = false;
-            let path = '';
+            let path: Uri | undefined;
 
             if (this.fileExistsCached(pyiFilePath)) {
                 isStubFile = true;
@@ -2611,13 +2568,13 @@ export class ImportResolver {
             }
 
             if (path) {
-                if (!exclusions.find((exclusion) => exclusion === path)) {
+                if (!exclusions.find((exclusion) => exclusion.equals(path))) {
                     const implicitImport: ImplicitImport = {
                         isStubFile,
                         isNativeLib: false,
-                        name: dirName,
-                        path,
-                        pyTypedInfo: getPyTypedInfo(this.fileSystem, combinePaths(dirPath, dirName)),
+                        name: dirPath.fileName,
+                        uri: path,
+                        pyTypedInfo: this._getPyTypedInfo(dirPath),
                     };
 
                     implicitImportMap.set(implicitImport.name, implicitImport);
@@ -2628,13 +2585,22 @@ export class ImportResolver {
         return implicitImportMap;
     }
 
+    // Retrieves the pytyped info for a directory if it exists. This is a small perf optimization
+    // that allows skipping the search when the pytyped file doesn't exist.
+    private _getPyTypedInfo(filePath: Uri): PyTypedInfo | undefined {
+        if (!this.fileExistsCached(filePath.pytypedUri)) {
+            return undefined;
+        }
+        return getPyTypedInfo(this.fileSystem, filePath);
+    }
+
     private _resolveNativeModuleStub(
-        nativeLibPath: string,
+        nativeLibPath: Uri,
         execEnv: ExecutionEnvironment,
         importName: string,
         moduleDescriptor: ImportedModuleDescriptor,
         importFailureInfo: string[],
-        resolvedPaths: string[]
+        resolvedPaths: Uri[]
     ): boolean {
         let moduleFullName = importName;
 
@@ -2656,12 +2622,12 @@ export class ImportResolver {
         return true;
     }
 
-    private _isNativeModuleFileName(moduleName: string, fileName: string): boolean {
+    private _isNativeModuleFileName(moduleName: string, fileUri: Uri): boolean {
         // Strip off the final file extension and the part of the file name
         // that excludes all (multi-part) file extensions. This allows us to
         // handle file names like "foo.cpython-32m.so".
-        const fileExtension = getFileExtension(fileName, /* multiDotExtension */ false).toLowerCase();
-        const withoutExtension = stripFileExtension(fileName, /* multiDotExtension */ true);
+        const fileExtension = fileUri.lastExtension.toLowerCase();
+        const withoutExtension = stripFileExtension(fileUri.fileName, /* multiDotExtension */ true);
         return (
             this._isNativeModuleFileExtension(fileExtension) &&
             equateStringsCaseInsensitive(moduleName, withoutExtension)
@@ -2672,21 +2638,21 @@ export class ImportResolver {
         return supportedNativeLibExtensions.some((ext) => ext === fileExtension);
     }
 
-    private _tryWalkUp(current: string): [success: boolean, path: string] {
-        if (isDiskPathRoot(current)) {
-            return [false, ''];
+    private _tryWalkUp(current: Uri | undefined): Uri | undefined {
+        if (!current || current.isEmpty() || current.isRoot()) {
+            return undefined;
         }
 
-        // Ensure we don't go around forever even if isDiskPathRoot returns false.
-        const next = ensureTrailingDirectorySeparator(normalizePath(combinePaths(current, '..')));
-        if (next === current) {
-            return [false, ''];
+        // Ensure we don't go around forever even if isRoot returns false.
+        const next = current.combinePaths('..');
+        if (next.equals(current)) {
+            return undefined;
         }
-        return [true, next];
+        return next;
     }
 
-    private _shouldWalkUp(current: string, root: string, execEnv: ExecutionEnvironment) {
-        return current.length > root.length || (current === root && !execEnv.root);
+    private _shouldWalkUp(current: Uri | undefined, root: Uri, execEnv: ExecutionEnvironment) {
+        return current && (current.isChild(root) || (current.equals(root) && !execEnv.root));
     }
 }
 
diff --git a/packages/pyright-internal/src/analyzer/importResult.ts b/packages/pyright-internal/src/analyzer/importResult.ts
index 2a01c5242..7f1bbcb0d 100644
--- a/packages/pyright-internal/src/analyzer/importResult.ts
+++ b/packages/pyright-internal/src/analyzer/importResult.ts
@@ -7,6 +7,7 @@
  * Interface that describes the output of the import resolver.
  */
 
+import { Uri } from '../common/uri/uri';
 import { PyTypedInfo } from './pyTypedUtils';
 
 export const enum ImportType {
@@ -19,7 +20,7 @@ export interface ImplicitImport {
     isStubFile: boolean;
     isNativeLib: boolean;
     name: string;
-    path: string;
+    uri: Uri;
     pyTypedInfo?: PyTypedInfo | undefined;
 }
 
@@ -62,11 +63,11 @@ export interface ImportResult {
     // The resolved absolute paths for each of the files in the module name.
     // Parts that have no files (e.g. directories within a namespace
     // package) have empty strings for a resolvedPath.
-    resolvedPaths: string[];
+    resolvedUris: Uri[];
 
     // For absolute imports, the search path that was used to resolve
     // (or partially resolve) the module.
-    searchPath?: string;
+    searchPath?: Uri;
 
     // True if resolved file is a type hint (.pyi) file rather than
     // a python (.py) file.
@@ -103,5 +104,5 @@ export interface ImportResult {
     pyTypedInfo?: PyTypedInfo | undefined;
 
     // The directory of the package, if found.
-    packageDirectory?: string | undefined;
+    packageDirectory?: Uri | undefined;
 }
diff --git a/packages/pyright-internal/src/analyzer/importStatementUtils.ts b/packages/pyright-internal/src/analyzer/importStatementUtils.ts
index f7d577456..ef2e62458 100644
--- a/packages/pyright-internal/src/analyzer/importStatementUtils.ts
+++ b/packages/pyright-internal/src/analyzer/importStatementUtils.ts
@@ -14,16 +14,11 @@ import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { addIfUnique, appendArray, createMapFromItems } from '../common/collectionUtils';
 import { TextEditAction } from '../common/editAction';
 import { ReadOnlyFileSystem } from '../common/fileSystem';
-import {
-    getDirectoryPath,
-    getFileName,
-    getRelativePathComponentsFromDirectory,
-    isFile,
-    stripFileExtension,
-} from '../common/pathUtils';
 import { convertOffsetToPosition, convertPositionToOffset } from '../common/positionUtils';
 import { compareStringsCaseSensitive } from '../common/stringUtils';
 import { Position, Range, TextRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
+import { isFile } from '../common/uri/uriUtils';
 import {
     ImportAsNode,
     ImportFromAsNode,
@@ -35,18 +30,18 @@ import {
     ParseNodeType,
 } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
+import { TokenType } from '../parser/tokenizerTypes';
 import * as AnalyzerNodeInfo from './analyzerNodeInfo';
 import { ModuleNameAndType } from './importResolver';
 import { ImportResult, ImportType } from './importResult';
-import * as SymbolNameUtils from './symbolNameUtils';
 import { findTokenAfter, getTokenAt } from './parseTreeUtils';
-import { TokenType } from '../parser/tokenizerTypes';
+import * as SymbolNameUtils from './symbolNameUtils';
 
 export interface ImportStatement {
     node: ImportNode | ImportFromNode;
     subnode?: ImportAsNode;
     importResult: ImportResult | undefined;
-    resolvedPath: string | undefined;
+    resolvedPath: Uri | undefined;
     moduleName: string;
     followsNonImportStatement: boolean;
 }
@@ -625,10 +620,10 @@ function _getInsertionEditForAutoImportInsertion(
 function _processImportNode(node: ImportNode, localImports: ImportStatements, followsNonImportStatement: boolean) {
     node.list.forEach((importAsNode) => {
         const importResult = AnalyzerNodeInfo.getImportInfo(importAsNode.module);
-        let resolvedPath: string | undefined;
+        let resolvedPath: Uri | undefined;
 
         if (importResult && importResult.isImportFound) {
-            resolvedPath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+            resolvedPath = importResult.resolvedUris[importResult.resolvedUris.length - 1];
         }
 
         const localImport: ImportStatement = {
@@ -647,8 +642,8 @@ function _processImportNode(node: ImportNode, localImports: ImportStatements, fo
             // Don't overwrite existing import or import from statements
             // because we always want to prefer 'import from' over 'import'
             // in the map.
-            if (!localImports.mapByFilePath.has(resolvedPath)) {
-                localImports.mapByFilePath.set(resolvedPath, localImport);
+            if (!localImports.mapByFilePath.has(resolvedPath.key)) {
+                localImports.mapByFilePath.set(resolvedPath.key, localImport);
             }
         }
     });
@@ -661,10 +656,10 @@ function _processImportFromNode(
     includeImplicitImports: boolean
 ) {
     const importResult = AnalyzerNodeInfo.getImportInfo(node.module);
-    let resolvedPath: string | undefined;
+    let resolvedPath: Uri | undefined;
 
     if (importResult && importResult.isImportFound) {
-        resolvedPath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+        resolvedPath = importResult.resolvedUris[importResult.resolvedUris.length - 1];
     }
 
     if (includeImplicitImports && importResult) {
@@ -673,7 +668,7 @@ function _processImportFromNode(
         for (const implicitImport of importResult.implicitImports.values()) {
             const importFromAs = node.imports.find((i) => i.name.value === implicitImport.name);
             if (importFromAs) {
-                localImports.implicitImports.set(implicitImport.path, importFromAs);
+                localImports.implicitImports.set(implicitImport.uri.key, importFromAs);
             }
         }
     }
@@ -690,7 +685,7 @@ function _processImportFromNode(
 
     // Add it to the map.
     if (resolvedPath) {
-        const prevEntry = localImports.mapByFilePath.get(resolvedPath);
+        const prevEntry = localImports.mapByFilePath.get(resolvedPath.key);
         // Overwrite existing import statements because we always want to prefer
         // 'import from' over 'import'. Also, overwrite existing 'import from' if
         // the module name is shorter.
@@ -699,7 +694,7 @@ function _processImportFromNode(
             prevEntry.node.nodeType === ParseNodeType.Import ||
             prevEntry.moduleName.length > localImport.moduleName.length
         ) {
-            localImports.mapByFilePath.set(resolvedPath, localImport);
+            localImports.mapByFilePath.set(resolvedPath.key, localImport);
         }
     }
 }
@@ -850,23 +845,23 @@ function getConsecutiveNumberPairs(indices: number[]) {
 
 export function getRelativeModuleName(
     fs: ReadOnlyFileSystem,
-    sourcePath: string,
-    targetPath: string,
+    sourcePath: Uri,
+    targetPath: Uri,
     ignoreFolderStructure = false,
     sourceIsFile?: boolean
 ) {
     let srcPath = sourcePath;
     sourceIsFile = sourceIsFile !== undefined ? sourceIsFile : isFile(fs, sourcePath);
     if (sourceIsFile) {
-        srcPath = getDirectoryPath(sourcePath);
+        srcPath = sourcePath.getDirectory();
     }
 
     let symbolName: string | undefined;
     let destPath = targetPath;
     if (sourceIsFile) {
-        destPath = getDirectoryPath(targetPath);
+        destPath = targetPath.getDirectory();
 
-        const fileName = stripFileExtension(getFileName(targetPath));
+        const fileName = targetPath.stripAllExtensions().fileName;
         if (fileName !== '__init__') {
             // ex) src: a.py, dest: b.py -> ".b" will be returned.
             symbolName = fileName;
@@ -875,18 +870,18 @@ export function getRelativeModuleName(
             //     like how it would return for sibling folder.
             //
             // if folder structure is not ignored, ".." will be returned
-            symbolName = getFileName(destPath);
-            destPath = getDirectoryPath(destPath);
+            symbolName = destPath.fileName;
+            destPath = destPath.getDirectory();
         }
     }
 
-    const relativePaths = getRelativePathComponentsFromDirectory(srcPath, destPath, (f) => fs.realCasePath(f));
+    const relativePaths = srcPath.getRelativePathComponents(destPath);
 
     // This assumes both file paths are under the same importing root.
     // So this doesn't handle paths pointing to 2 different import roots.
     // ex) user file A to library file B
     let currentPaths = '.';
-    for (let i = 1; i < relativePaths.length; i++) {
+    for (let i = 0; i < relativePaths.length; i++) {
         const relativePath = relativePaths[i];
         if (relativePath === '..') {
             currentPaths += '.';
@@ -907,25 +902,25 @@ export function getRelativeModuleName(
     return currentPaths;
 }
 
-export function getDirectoryLeadingDotsPointsTo(fromDirectory: string, leadingDots: number) {
+export function getDirectoryLeadingDotsPointsTo(fromDirectory: Uri, leadingDots: number) {
     let currentDirectory = fromDirectory;
     for (let i = 1; i < leadingDots; i++) {
-        if (currentDirectory === '') {
+        if (currentDirectory.isRoot()) {
             return undefined;
         }
 
-        currentDirectory = getDirectoryPath(currentDirectory);
+        currentDirectory = currentDirectory.getDirectory();
     }
 
     return currentDirectory;
 }
 
 export function getResolvedFilePath(importResult: ImportResult | undefined) {
-    if (!importResult || !importResult.isImportFound || importResult.resolvedPaths.length === 0) {
+    if (!importResult || !importResult.isImportFound || importResult.resolvedUris.length === 0) {
         return undefined;
     }
 
-    if (importResult.resolvedPaths.length === 1 && importResult.resolvedPaths[0] === '') {
+    if (importResult.resolvedUris.length === 1 && importResult.resolvedUris[0].equals(Uri.empty())) {
         // Import is resolved to namespace package folder.
         if (importResult.packageDirectory) {
             return importResult.packageDirectory;
@@ -940,7 +935,7 @@ export function getResolvedFilePath(importResult: ImportResult | undefined) {
     }
 
     // Regular case.
-    return importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+    return importResult.resolvedUris[importResult.resolvedUris.length - 1];
 }
 
 export function haveSameParentModule(module1: string[], module2: string[]) {
diff --git a/packages/pyright-internal/src/analyzer/namedTuples.ts b/packages/pyright-internal/src/analyzer/namedTuples.ts
index dde8b9f1e..6cf3f3ab7 100644
--- a/packages/pyright-internal/src/analyzer/namedTuples.ts
+++ b/packages/pyright-internal/src/analyzer/namedTuples.ts
@@ -114,7 +114,7 @@ export function createNamedTupleType(
         className,
         ParseTreeUtils.getClassFullName(errorNode, fileInfo.moduleName, className),
         fileInfo.moduleName,
-        fileInfo.filePath,
+        fileInfo.fileUri,
         ClassTypeFlags.ReadOnlyInstanceVariables,
         ParseTreeUtils.getTypeSourceId(errorNode),
         /* declaredMetaclass */ undefined,
@@ -207,7 +207,7 @@ export function createNamedTupleType(
                             type: DeclarationType.Variable,
                             node: stringNode as StringListNode,
                             isRuntimeTypeExpression: true,
-                            path: fileInfo.filePath,
+                            uri: fileInfo.fileUri,
                             range: convertOffsetsToRange(
                                 stringNode.start,
                                 TextRange.getEnd(stringNode),
@@ -303,7 +303,7 @@ export function createNamedTupleType(
                         const declaration: VariableDeclaration = {
                             type: DeclarationType.Variable,
                             node: entryNameNode,
-                            path: fileInfo.filePath,
+                            uri: fileInfo.fileUri,
                             typeAnnotationNode: entryTypeNode,
                             range: convertOffsetsToRange(
                                 entryNameNode.start,
diff --git a/packages/pyright-internal/src/analyzer/packageTypeReport.ts b/packages/pyright-internal/src/analyzer/packageTypeReport.ts
index 0f08ae003..9301475e8 100644
--- a/packages/pyright-internal/src/analyzer/packageTypeReport.ts
+++ b/packages/pyright-internal/src/analyzer/packageTypeReport.ts
@@ -10,6 +10,7 @@
  */
 
 import { Diagnostic, DiagnosticWithinFile } from '../common/diagnostic';
+import { Uri } from '../common/uri/uri';
 import { ScopeType } from './scope';
 
 export enum SymbolCategory {
@@ -37,7 +38,7 @@ export interface SymbolInfo {
     category: SymbolCategory;
     name: string;
     fullName: string;
-    filePath: string;
+    fileUri: Uri;
     isExported: boolean;
     typeKnownStatus: TypeKnownStatus;
     referenceCount: number;
@@ -47,7 +48,7 @@ export interface SymbolInfo {
 
 export interface ModuleInfo {
     name: string;
-    path: string;
+    uri: Uri;
     isExported: boolean;
 }
 
@@ -57,10 +58,10 @@ export interface PackageTypeReport {
     packageName: string;
     moduleName: string;
     ignoreExternal: boolean;
-    packageRootDirectory: string | undefined;
-    moduleRootDirectory: string | undefined;
+    packageRootDirectoryUri: Uri | undefined;
+    moduleRootDirectoryUri: Uri | undefined;
     isModuleSingleFile: boolean;
-    pyTypedPath: string | undefined;
+    pyTypedPathUri: Uri | undefined;
     missingFunctionDocStringCount: number;
     missingClassDocStringCount: number;
     missingDefaultParamCount: number;
@@ -85,20 +86,20 @@ export interface PackageTypeReport {
 
 export function getEmptyReport(
     packageName: string,
-    packageRootDirectory: string,
+    packageRootUri: Uri,
     moduleName: string,
-    moduleRootDirectory: string,
+    moduleRootUri: Uri,
     isModuleSingleFile: boolean,
     ignoreExternal: boolean
 ) {
     const report: PackageTypeReport = {
         packageName,
         ignoreExternal,
-        packageRootDirectory,
+        packageRootDirectoryUri: packageRootUri,
         moduleName,
-        moduleRootDirectory,
+        moduleRootDirectoryUri: moduleRootUri,
         isModuleSingleFile,
-        pyTypedPath: undefined,
+        pyTypedPathUri: undefined,
         missingFunctionDocStringCount: 0,
         missingClassDocStringCount: 0,
         missingDefaultParamCount: 0,
diff --git a/packages/pyright-internal/src/analyzer/packageTypeVerifier.ts b/packages/pyright-internal/src/analyzer/packageTypeVerifier.ts
index ed6a4f9f5..b4ab7db1f 100644
--- a/packages/pyright-internal/src/analyzer/packageTypeVerifier.ts
+++ b/packages/pyright-internal/src/analyzer/packageTypeVerifier.ts
@@ -14,16 +14,11 @@ import { NullConsole } from '../common/console';
 import { assert } from '../common/debug';
 import { Diagnostic, DiagnosticAddendum, DiagnosticCategory } from '../common/diagnostic';
 import { FullAccessHost } from '../common/fullAccessHost';
-import {
-    combinePaths,
-    getDirectoryPath,
-    getFileExtension,
-    getFileName,
-    stripFileExtension,
-    tryStat,
-} from '../common/pathUtils';
+import { getFileExtension, stripFileExtension } from '../common/pathUtils';
 import { ServiceProvider } from '../common/serviceProvider';
 import { getEmptyRange, Range } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
+import { tryStat } from '../common/uri/uriUtils';
 import { DeclarationType, FunctionDeclaration, VariableDeclaration } from './declaration';
 import { createImportedModuleDescriptor, ImportResolver } from './importResolver';
 import {
@@ -67,7 +62,7 @@ import {
 type PublicSymbolSet = Set<string>;
 
 interface ModuleDirectoryInfo {
-    moduleDirectory: string;
+    moduleDirectory: Uri;
     isModuleSingleFile: boolean;
 }
 
@@ -83,8 +78,8 @@ export class PackageTypeVerifier {
         private _packageName: string,
         private _ignoreExternal = false
     ) {
-        const host = new FullAccessHost(_serviceProvider.fs());
-        this._configOptions = new ConfigOptions('');
+        const host = new FullAccessHost(_serviceProvider);
+        this._configOptions = new ConfigOptions(Uri.empty());
 
         this._configOptions.defaultPythonPlatform = commandLineOptions.pythonPlatform;
         this._configOptions.defaultPythonVersion = commandLineOptions.pythonVersion;
@@ -99,11 +94,11 @@ export class PackageTypeVerifier {
             this._configOptions.evaluateUnknownImportsAsAny = true;
         }
 
-        this._execEnv = this._configOptions.findExecEnvironment('.');
+        this._execEnv = this._configOptions.findExecEnvironment(Uri.file('.', _serviceProvider.fs().isCaseSensitive));
         this._importResolver = new ImportResolver(
             this._serviceProvider,
             this._configOptions,
-            new FullAccessHost(this._serviceProvider.fs())
+            new FullAccessHost(this._serviceProvider)
         );
         this._program = new Program(this._importResolver, this._configOptions, this._serviceProvider);
     }
@@ -117,9 +112,9 @@ export class PackageTypeVerifier {
 
         const report = getEmptyReport(
             moduleNameParts[0],
-            packageDirectoryInfo?.moduleDirectory ?? '',
+            packageDirectoryInfo?.moduleDirectory ?? Uri.empty(),
             trimmedModuleName,
-            moduleDirectoryInfo?.moduleDirectory ?? '',
+            moduleDirectoryInfo?.moduleDirectory ?? Uri.empty(),
             moduleDirectoryInfo?.isModuleSingleFile ?? false,
             this._ignoreExternal
         );
@@ -134,7 +129,7 @@ export class PackageTypeVerifier {
                         getEmptyRange()
                     )
                 );
-            } else if (!report.moduleRootDirectory) {
+            } else if (!report.moduleRootDirectoryUri) {
                 commonDiagnostics.push(
                     new Diagnostic(
                         DiagnosticCategory.Error,
@@ -144,14 +139,14 @@ export class PackageTypeVerifier {
                 );
             } else {
                 let pyTypedInfo: PyTypedInfo | undefined;
-                if (report.moduleRootDirectory) {
-                    pyTypedInfo = this._getDeepestPyTypedInfo(report.moduleRootDirectory, moduleNameParts);
+                if (report.moduleRootDirectoryUri) {
+                    pyTypedInfo = this._getDeepestPyTypedInfo(report.moduleRootDirectoryUri, moduleNameParts);
                 }
 
                 // If we couldn't find any "py.typed" info in the module path, search again
                 // starting at the package root.
-                if (!pyTypedInfo && report.packageRootDirectory) {
-                    pyTypedInfo = this._getDeepestPyTypedInfo(report.packageRootDirectory, moduleNameParts);
+                if (!pyTypedInfo && report.packageRootDirectoryUri) {
+                    pyTypedInfo = this._getDeepestPyTypedInfo(report.packageRootDirectoryUri, moduleNameParts);
                 }
 
                 if (!pyTypedInfo) {
@@ -159,10 +154,10 @@ export class PackageTypeVerifier {
                         new Diagnostic(DiagnosticCategory.Error, 'No py.typed file found', getEmptyRange())
                     );
                 } else {
-                    report.pyTypedPath = pyTypedInfo.pyTypedPath;
+                    report.pyTypedPathUri = pyTypedInfo.pyTypedPath;
 
                     const publicModules = this._getListOfPublicModules(
-                        report.moduleRootDirectory,
+                        report.moduleRootDirectoryUri,
                         report.isModuleSingleFile,
                         trimmedModuleName
                     );
@@ -239,12 +234,12 @@ export class PackageTypeVerifier {
         }
     }
 
-    private _getDeepestPyTypedInfo(rootDirectory: string, packageNameParts: string[]) {
+    private _getDeepestPyTypedInfo(rootDirectory: Uri, packageNameParts: string[]) {
         let subNameParts = Array.from(packageNameParts);
 
         // Find the deepest py.typed file that corresponds to the requested submodule.
         while (subNameParts.length >= 1) {
-            const packageSubdir = combinePaths(rootDirectory, ...subNameParts.slice(1));
+            const packageSubdir = rootDirectory.combinePaths(...subNameParts.slice(1));
             const pyTypedInfo = getPyTypedInfo(this._serviceProvider.fs(), packageSubdir);
             if (pyTypedInfo) {
                 return pyTypedInfo;
@@ -257,7 +252,11 @@ export class PackageTypeVerifier {
     }
 
     private _resolveImport(moduleName: string) {
-        return this._importResolver.resolveImport('', this._execEnv, createImportedModuleDescriptor(moduleName));
+        return this._importResolver.resolveImport(
+            Uri.empty(),
+            this._execEnv,
+            createImportedModuleDescriptor(moduleName)
+        );
     }
 
     private _getPublicSymbolsForModule(
@@ -268,7 +267,7 @@ export class PackageTypeVerifier {
         const importResult = this._resolveImport(moduleName);
 
         if (importResult.isImportFound) {
-            const modulePath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+            const modulePath = importResult.resolvedUris[importResult.resolvedUris.length - 1];
             this._program.addTrackedFiles([modulePath], /* isThirdPartyImport */ true, /* isInPyTypedPackage */ true);
 
             const sourceFile = this._program.getBoundSourceFile(modulePath);
@@ -276,7 +275,7 @@ export class PackageTypeVerifier {
             if (sourceFile) {
                 const module: ModuleInfo = {
                     name: moduleName,
-                    path: modulePath,
+                    uri: modulePath,
                     isExported: true,
                 };
 
@@ -379,15 +378,15 @@ export class PackageTypeVerifier {
                 )
             );
         } else {
-            const modulePath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+            const modulePath = importResult.resolvedUris[importResult.resolvedUris.length - 1];
 
             const module: ModuleInfo = {
                 name: moduleName,
-                path: modulePath,
+                uri: modulePath,
                 isExported: true,
             };
 
-            report.modules.set(modulePath, module);
+            report.modules.set(modulePath.key, module);
             this._program.addTrackedFiles([modulePath], /* isThirdPartyImport */ true, /* isInPyTypedPackage */ true);
 
             const sourceFile = this._program.getBoundSourceFile(modulePath);
@@ -413,9 +412,9 @@ export class PackageTypeVerifier {
 
     // Scans the directory structure for a list of public modules
     // within the package.
-    private _getListOfPublicModules(moduleRootPath: string, isModuleSingleFile: boolean, moduleName: string): string[] {
+    private _getListOfPublicModules(moduleRoot: Uri, isModuleSingleFile: boolean, moduleName: string): string[] {
         const publicModules: string[] = [];
-        this._addPublicModulesRecursive(moduleRootPath, isModuleSingleFile, moduleName, publicModules);
+        this._addPublicModulesRecursive(moduleRoot, isModuleSingleFile, moduleName, publicModules);
 
         // Make sure modules are unique. There may be duplicates if a ".py" and ".pyi"
         // exist for some modules.
@@ -433,7 +432,7 @@ export class PackageTypeVerifier {
     }
 
     private _addPublicModulesRecursive(
-        dirPath: string,
+        dirPath: Uri,
         isModuleSingleFile: boolean,
         modulePath: string,
         publicModules: string[]
@@ -444,7 +443,7 @@ export class PackageTypeVerifier {
             let isFile = entry.isFile();
             let isDirectory = entry.isDirectory();
             if (entry.isSymbolicLink()) {
-                const stat = tryStat(this._serviceProvider.fs(), combinePaths(dirPath, entry.name));
+                const stat = tryStat(this._serviceProvider.fs(), dirPath.combinePaths(entry.name));
                 if (stat) {
                     isFile = stat.isFile();
                     isDirectory = stat.isDirectory();
@@ -477,7 +476,7 @@ export class PackageTypeVerifier {
             } else if (isDirectory) {
                 if (!isPrivateOrProtectedName(entry.name) && this._isLegalModulePartName(entry.name)) {
                     this._addPublicModulesRecursive(
-                        combinePaths(dirPath, entry.name),
+                        dirPath.combinePaths(entry.name),
                         isModuleSingleFile,
                         `${modulePath}.${entry.name}`,
                         publicModules
@@ -572,7 +571,7 @@ export class PackageTypeVerifier {
                     const decls = symbol.getDeclarations();
                     const primaryDecl = decls.length > 0 ? decls[decls.length - 1] : undefined;
                     const declRange = primaryDecl?.range || getEmptyRange();
-                    const declPath = primaryDecl?.path || '';
+                    const declPath = primaryDecl?.uri || Uri.empty();
                     const symbolCategory = this._getSymbolCategory(symbol, symbolType);
                     const isExported = publicSymbols.has(fullName);
 
@@ -590,7 +589,7 @@ export class PackageTypeVerifier {
                         category: symbolCategory,
                         name,
                         fullName,
-                        filePath: module.path,
+                        fileUri: Uri.file(module.path, this._serviceProvider.fs().isCaseSensitive),
                         isExported,
                         typeKnownStatus: TypeKnownStatus.Known,
                         referenceCount: 1,
@@ -616,7 +615,7 @@ export class PackageTypeVerifier {
                     const decls = symbol.getDeclarations();
                     const primaryDecl = decls.length > 0 ? decls[decls.length - 1] : undefined;
                     const declRange = primaryDecl?.range || getEmptyRange();
-                    const declPath = primaryDecl?.path || '';
+                    const declPath = primaryDecl?.uri || Uri.empty();
 
                     const extraInfo = new DiagnosticAddendum();
                     if (baseSymbolType) {
@@ -664,7 +663,7 @@ export class PackageTypeVerifier {
         symbolInfo: SymbolInfo,
         type: Type,
         declRange: Range,
-        declFilePath: string,
+        declFileUri: Uri,
         publicSymbols: PublicSymbolSet,
         skipDocStringCheck = false
     ): TypeKnownStatus {
@@ -677,7 +676,7 @@ export class PackageTypeVerifier {
                         symbolInfo,
                         `Type argument ${index + 1} for type alias "${type.typeAliasInfo!.name}" has unknown type`,
                         declRange,
-                        declFilePath
+                        declFileUri
                     );
                     knownStatus = TypeKnownStatus.Unknown;
                 } else if (isPartlyUnknown(typeArg)) {
@@ -687,7 +686,7 @@ export class PackageTypeVerifier {
                             type.typeAliasInfo!.name
                         }" has partially unknown type`,
                         declRange,
-                        declFilePath
+                        declFileUri
                     );
                     knownStatus = TypeKnownStatus.PartiallyUnknown;
                 }
@@ -702,7 +701,7 @@ export class PackageTypeVerifier {
                 'Type is missing type annotation and could be inferred differently by type checkers' +
                     ambiguousDiag.getString(),
                 declRange,
-                declFilePath
+                declFileUri
             );
             knownStatus = this._updateKnownStatusIfWorse(knownStatus, TypeKnownStatus.Ambiguous);
         }
@@ -721,7 +720,7 @@ export class PackageTypeVerifier {
                         symbolInfo.fullName
                     }"`,
                     declRange,
-                    declFilePath
+                    declFileUri
                 );
                 knownStatus = this._updateKnownStatusIfWorse(knownStatus, TypeKnownStatus.Unknown);
                 break;
@@ -736,7 +735,7 @@ export class PackageTypeVerifier {
                             symbolInfo,
                             subtype,
                             declRange,
-                            declFilePath,
+                            declFileUri,
                             publicSymbols
                         )
                     );
@@ -753,7 +752,7 @@ export class PackageTypeVerifier {
                             symbolInfo,
                             overload,
                             declRange,
-                            declFilePath,
+                            declFileUri,
                             publicSymbols
                         )
                     );
@@ -771,7 +770,7 @@ export class PackageTypeVerifier {
                             publicSymbols,
                             symbolInfo,
                             declRange,
-                            declFilePath,
+                            declFileUri,
                             undefined /* diag */,
                             skipDocStringCheck
                         )
@@ -821,7 +820,7 @@ export class PackageTypeVerifier {
                                 symbolInfo,
                                 accessType,
                                 getEmptyRange(),
-                                '',
+                                Uri.empty(),
                                 publicSymbols,
                                 skipDocStringCheck
                             )
@@ -847,7 +846,7 @@ export class PackageTypeVerifier {
                                 symbolInfo,
                                 `Type argument ${index + 1} for class "${type.details.name}" has unknown type`,
                                 declRange,
-                                declFilePath
+                                declFileUri
                             );
                             knownStatus = this._updateKnownStatusIfWorse(knownStatus, TypeKnownStatus.Unknown);
                         } else if (isPartlyUnknown(typeArg)) {
@@ -859,7 +858,7 @@ export class PackageTypeVerifier {
                                     type.details.name
                                 }" has partially unknown type` + diag.getString(),
                                 declRange,
-                                declFilePath
+                                declFileUri
                             );
                             knownStatus = this._updateKnownStatusIfWorse(knownStatus, TypeKnownStatus.PartiallyUnknown);
                         }
@@ -877,7 +876,7 @@ export class PackageTypeVerifier {
                             symbolInfo,
                             `Module "${moduleSymbol.fullName}" is partially unknown`,
                             declRange,
-                            declFilePath
+                            declFileUri
                         );
                         knownStatus = this._updateKnownStatusIfWorse(knownStatus, moduleSymbol.typeKnownStatus);
                     }
@@ -899,15 +898,15 @@ export class PackageTypeVerifier {
         publicSymbols: PublicSymbolSet,
         symbolInfo?: SymbolInfo,
         declRange?: Range,
-        declFilePath?: string,
+        declFileUri?: Uri,
         diag?: DiagnosticAddendum,
         skipDocStringCheck = false
     ): TypeKnownStatus {
         let knownStatus = TypeKnownStatus.Known;
 
         // If the file path wasn't provided, try to get it from the type.
-        if (type.details.declaration && !declFilePath) {
-            declFilePath = type.details.declaration.path;
+        if (type.details.declaration && !declFileUri) {
+            declFileUri = type.details.declaration.uri;
         }
 
         type.details.parameters.forEach((param, index) => {
@@ -929,7 +928,7 @@ export class PackageTypeVerifier {
                                 symbolInfo,
                                 `Type annotation for parameter "${param.name}" is missing`,
                                 declRange ?? getEmptyRange(),
-                                declFilePath ?? ''
+                                declFileUri ?? Uri.empty()
                             );
                         }
                         diag?.createAddendum().addMessage(`Type annotation for parameter "${param.name}" is missing`);
@@ -941,7 +940,7 @@ export class PackageTypeVerifier {
                             symbolInfo,
                             `Type of parameter "${param.name}" is unknown`,
                             declRange ?? getEmptyRange(),
-                            declFilePath ?? ''
+                            declFileUri ?? Uri.empty()
                         );
                         diag?.createAddendum().addMessage(`Type of parameter "${param.name}" is unknown`);
                     }
@@ -963,7 +962,7 @@ export class PackageTypeVerifier {
                                 symbolInfo,
                                 `Type of parameter "${param.name}" is partially unknown` + extraInfo.getString(),
                                 declRange ?? getEmptyRange(),
-                                declFilePath ?? ''
+                                declFileUri ?? Uri.empty()
                             );
                         }
 
@@ -986,7 +985,7 @@ export class PackageTypeVerifier {
                         symbolInfo,
                         `Return type is unknown`,
                         declRange ?? getEmptyRange(),
-                        declFilePath ?? ''
+                        declFileUri ?? Uri.empty()
                     );
                 }
                 knownStatus = this._updateKnownStatusIfWorse(knownStatus, TypeKnownStatus.Unknown);
@@ -1009,7 +1008,7 @@ export class PackageTypeVerifier {
                             symbolInfo,
                             `Return type is partially unknown` + extraInfo.getString(),
                             declRange ?? getEmptyRange(),
-                            declFilePath ?? ''
+                            declFileUri ?? Uri.empty()
                         );
                     }
 
@@ -1030,7 +1029,7 @@ export class PackageTypeVerifier {
                         symbolInfo,
                         `Return type annotation is missing`,
                         declRange ?? getEmptyRange(),
-                        declFilePath ?? ''
+                        declFileUri ?? Uri.empty()
                     );
                 }
                 diag?.createAddendum().addMessage(`Return type annotation is missing`);
@@ -1060,7 +1059,7 @@ export class PackageTypeVerifier {
                         symbolInfo,
                         `No docstring found for function "${symbolInfo.fullName}"`,
                         declRange ?? getEmptyRange(),
-                        declFilePath ?? ''
+                        declFileUri ?? Uri.empty()
                     );
                 }
 
@@ -1074,7 +1073,7 @@ export class PackageTypeVerifier {
                     symbolInfo,
                     `One or more default values in function "${symbolInfo.fullName}" is specified as "..."`,
                     declRange ?? getEmptyRange(),
-                    declFilePath ?? ''
+                    declFileUri ?? Uri.empty()
                 );
             }
 
@@ -1100,7 +1099,7 @@ export class PackageTypeVerifier {
             category: SymbolCategory.Class,
             name: type.details.name,
             fullName: type.details.fullName,
-            filePath: type.details.filePath,
+            fileUri: type.details.fileUri,
             isExported: publicSymbols.has(type.details.fullName),
             typeKnownStatus: TypeKnownStatus.Known,
             referenceCount: 1,
@@ -1116,7 +1115,7 @@ export class PackageTypeVerifier {
                 symbolInfo,
                 `No docstring found for class "${type.details.fullName}"`,
                 getEmptyRange(),
-                ''
+                Uri.empty()
             );
 
             report.missingClassDocStringCount++;
@@ -1155,7 +1154,7 @@ export class PackageTypeVerifier {
         // Add information for the metaclass.
         if (type.details.effectiveMetaclass) {
             if (!isInstantiableClass(type.details.effectiveMetaclass)) {
-                this._addSymbolError(symbolInfo, `Type of metaclass unknown`, getEmptyRange(), '');
+                this._addSymbolError(symbolInfo, `Type of metaclass unknown`, getEmptyRange(), Uri.empty());
                 symbolInfo.typeKnownStatus = this._updateKnownStatusIfWorse(
                     symbolInfo.typeKnownStatus,
                     TypeKnownStatus.PartiallyUnknown
@@ -1175,7 +1174,7 @@ export class PackageTypeVerifier {
                         `Type of metaclass "${type.details.effectiveMetaclass}" is partially unknown` +
                             diag.getString(),
                         getEmptyRange(),
-                        ''
+                        Uri.empty()
                     );
                     symbolInfo.typeKnownStatus = this._updateKnownStatusIfWorse(
                         symbolInfo.typeKnownStatus,
@@ -1188,7 +1187,7 @@ export class PackageTypeVerifier {
         // Add information for base classes.
         type.details.baseClasses.forEach((baseClass) => {
             if (!isInstantiableClass(baseClass)) {
-                this._addSymbolError(symbolInfo, `Type of base class unknown`, getEmptyRange(), '');
+                this._addSymbolError(symbolInfo, `Type of base class unknown`, getEmptyRange(), Uri.empty());
                 symbolInfo.typeKnownStatus = this._updateKnownStatusIfWorse(
                     symbolInfo.typeKnownStatus,
                     TypeKnownStatus.PartiallyUnknown
@@ -1208,7 +1207,7 @@ export class PackageTypeVerifier {
                         symbolInfo,
                         `Type of base class "${baseClass.details.fullName}" is partially unknown` + diag.getString(),
                         getEmptyRange(),
-                        ''
+                        Uri.empty()
                     );
 
                     symbolInfo.typeKnownStatus = this._updateKnownStatusIfWorse(
@@ -1238,7 +1237,7 @@ export class PackageTypeVerifier {
             category: SymbolCategory.Module,
             name: type.moduleName,
             fullName: type.moduleName,
-            filePath: type.filePath,
+            fileUri: type.fileUri,
             isExported: publicSymbols.has(type.moduleName),
             typeKnownStatus: TypeKnownStatus.Known,
             referenceCount: 1,
@@ -1448,19 +1447,21 @@ export class PackageTypeVerifier {
 
     private _getDirectoryInfoForModule(moduleName: string): ModuleDirectoryInfo | undefined {
         const importResult = this._importResolver.resolveImport(
-            '',
+            Uri.empty(),
             this._execEnv,
             createImportedModuleDescriptor(moduleName)
         );
 
         if (importResult.isImportFound) {
-            const resolvedPath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+            const resolvedPath = importResult.resolvedUris[importResult.resolvedUris.length - 1];
 
             // If it's a namespace package with no __init__.py(i), use the package
             // directory instead.
-            const moduleDirectory = resolvedPath ? getDirectoryPath(resolvedPath) : importResult.packageDirectory ?? '';
+            const moduleDirectory = resolvedPath
+                ? resolvedPath.getDirectory()
+                : importResult.packageDirectory ?? Uri.empty();
             let isModuleSingleFile = false;
-            if (resolvedPath && stripFileExtension(getFileName(resolvedPath)) !== '__init__') {
+            if (resolvedPath && stripFileExtension(resolvedPath.fileName) !== '__init__') {
                 isModuleSingleFile = true;
             }
 
@@ -1508,17 +1509,17 @@ export class PackageTypeVerifier {
         report.symbols.set(symbolInfo.fullName, symbolInfo);
     }
 
-    private _addSymbolError(symbolInfo: SymbolInfo, message: string, declRange: Range, declFilePath: string) {
+    private _addSymbolError(symbolInfo: SymbolInfo, message: string, declRange: Range, declUri: Uri) {
         symbolInfo.diagnostics.push({
             diagnostic: new Diagnostic(DiagnosticCategory.Error, message, declRange),
-            filePath: declFilePath,
+            uri: declUri,
         });
     }
 
-    private _addSymbolWarning(symbolInfo: SymbolInfo, message: string, declRange: Range, declFilePath: string) {
+    private _addSymbolWarning(symbolInfo: SymbolInfo, message: string, declRange: Range, declUri: Uri) {
         symbolInfo.diagnostics.push({
             diagnostic: new Diagnostic(DiagnosticCategory.Warning, message, declRange),
-            filePath: declFilePath,
+            uri: declUri,
         });
     }
 
diff --git a/packages/pyright-internal/src/analyzer/parentDirectoryCache.ts b/packages/pyright-internal/src/analyzer/parentDirectoryCache.ts
index 522b8118b..04e9fd42e 100644
--- a/packages/pyright-internal/src/analyzer/parentDirectoryCache.ts
+++ b/packages/pyright-internal/src/analyzer/parentDirectoryCache.ts
@@ -9,46 +9,46 @@
 
 import { getOrAdd } from '../common/collectionUtils';
 import { FileSystem } from '../common/fileSystem';
-import { ensureTrailingDirectorySeparator, normalizePath, realCasePath } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
 import { ImportResult } from './importResult';
 
-export type ImportPath = { importPath: string | undefined };
+export type ImportPath = { importPath: Uri | undefined };
 
-type CacheEntry = { importResult: ImportResult; path: string; importName: string };
+type CacheEntry = { importResult: ImportResult; path: Uri; importName: string };
 
 export class ParentDirectoryCache {
     private readonly _importChecked = new Map<string, Map<string, ImportPath>>();
     private readonly _cachedResults = new Map<string, Map<string, ImportResult>>();
 
-    private _libPathCache: string[] | undefined = undefined;
+    private _libPathCache: Uri[] | undefined = undefined;
 
-    constructor(private _importRootGetter: () => string[]) {
+    constructor(private _importRootGetter: () => Uri[]) {
         // empty
     }
 
-    getImportResult(path: string, importName: string, importResult: ImportResult): ImportResult | undefined {
-        const result = this._cachedResults.get(importName)?.get(path);
+    getImportResult(path: Uri, importName: string, importResult: ImportResult): ImportResult | undefined {
+        const result = this._cachedResults.get(importName)?.get(path.key);
         if (result) {
             // We already checked for the importName at the path.
             // Return the result if succeeded otherwise, return regular import result given.
             return result ?? importResult;
         }
 
-        const checked = this._importChecked.get(importName)?.get(path);
+        const checked = this._importChecked.get(importName)?.get(path.key);
         if (checked) {
             // We already checked for the importName at the path.
             if (!checked.importPath) {
                 return importResult;
             }
 
-            return this._cachedResults.get(importName)?.get(checked.importPath) ?? importResult;
+            return this._cachedResults.get(importName)?.get(checked.importPath.key) ?? importResult;
         }
 
         return undefined;
     }
 
-    checkValidPath(fs: FileSystem, sourceFilePath: string, root: string): boolean {
-        if (!sourceFilePath.startsWith(root)) {
+    checkValidPath(fs: FileSystem, sourceFileUri: Uri, root: Uri): boolean {
+        if (!sourceFileUri.startsWith(root)) {
             // We don't search containing folders for libs.
             return false;
         }
@@ -56,11 +56,11 @@ export class ParentDirectoryCache {
         this._libPathCache =
             this._libPathCache ??
             this._importRootGetter()
-                .map((r) => ensureTrailingDirectorySeparator(realCasePath(normalizePath(r), fs)))
+                .map((r) => fs.realCasePath(r))
                 .filter((r) => r !== root)
                 .filter((r) => r.startsWith(root));
 
-        if (this._libPathCache.some((p) => sourceFilePath.startsWith(p))) {
+        if (this._libPathCache.some((p) => sourceFileUri.startsWith(p))) {
             // Make sure it is not lib folders under user code root.
             // ex) .venv folder
             return false;
@@ -69,13 +69,13 @@ export class ParentDirectoryCache {
         return true;
     }
 
-    checked(path: string, importName: string, importPath: ImportPath) {
-        getOrAdd(this._importChecked, importName, () => new Map<string, ImportPath>()).set(path, importPath);
+    checked(path: Uri, importName: string, importPath: ImportPath) {
+        getOrAdd(this._importChecked, importName, () => new Map<string, ImportPath>()).set(path.key, importPath);
     }
 
     add(result: CacheEntry) {
         getOrAdd(this._cachedResults, result.importName, () => new Map<string, ImportResult>()).set(
-            result.path,
+            result.path.key,
             result.importResult
         );
     }
diff --git a/packages/pyright-internal/src/analyzer/parseTreeUtils.ts b/packages/pyright-internal/src/analyzer/parseTreeUtils.ts
index 956cd59a8..04a4e088b 100644
--- a/packages/pyright-internal/src/analyzer/parseTreeUtils.ts
+++ b/packages/pyright-internal/src/analyzer/parseTreeUtils.ts
@@ -2718,7 +2718,7 @@ export function getScopeIdForNode(node: ParseNode): string {
     }
 
     const fileInfo = AnalyzerNodeInfo.getFileInfo(node);
-    return `${fileInfo.filePath}.${node.start.toString()}-${name}`;
+    return `${fileInfo.fileUri.key}.${node.start.toString()}-${name}`;
 }
 
 // Walks up the parse tree and finds all scopes that can provide
diff --git a/packages/pyright-internal/src/analyzer/program.ts b/packages/pyright-internal/src/analyzer/program.ts
index bb88c7c42..127efbcec 100644
--- a/packages/pyright-internal/src/analyzer/program.ts
+++ b/packages/pyright-internal/src/analyzer/program.ts
@@ -21,21 +21,14 @@ import { FileDiagnostics } from '../common/diagnosticSink';
 import { FileEditAction } from '../common/editAction';
 import { EditableProgram, ProgramView } from '../common/extensibility';
 import { LogTracker } from '../common/logTracker';
-import {
-    combinePaths,
-    getDirectoryPath,
-    getFileName,
-    getRelativePath,
-    makeDirectories,
-    normalizePath,
-    stripFileExtension,
-} from '../common/pathUtils';
 import { convertRangeToTextRange } from '../common/positionUtils';
 import { ServiceProvider } from '../common/serviceProvider';
 import '../common/serviceProviderExtensions';
 import { ServiceKeys } from '../common/serviceProviderExtensions';
 import { Range, doRangesIntersect } from '../common/textRange';
 import { Duration, timingStats } from '../common/timing';
+import { Uri } from '../common/uri/uri';
+import { makeDirectories } from '../common/uri/uriUtils';
 import { ParseResults } from '../parser/parser';
 import { AbsoluteModuleDescriptor, ImportLookupResult, LookupImportOptions } from './analyzerFileInfo';
 import * as AnalyzerNodeInfo from './analyzerNodeInfo';
@@ -73,7 +66,7 @@ export interface MaxAnalysisTime {
 }
 
 interface UpdateImportInfo {
-    path: string;
+    path: Uri;
     isTypeshedFile: boolean;
     isThirdPartyImport: boolean;
     isPyTypedPresent: boolean;
@@ -84,14 +77,13 @@ export type PreCheckCallback = (parseResults: ParseResults, evaluator: TypeEvalu
 export interface ISourceFileFactory {
     createSourceFile(
         serviceProvider: ServiceProvider,
-        filePath: string,
+        fileUri: Uri,
         moduleName: string,
         isThirdPartyImport: boolean,
         isThirdPartyPyTypedPresent: boolean,
         editMode: SourceFileEditMode,
         console?: ConsoleInterface,
         logTracker?: LogTracker,
-        realFilePath?: string,
         ipythonMode?: IPythonMode
     ): SourceFile;
 }
@@ -105,8 +97,7 @@ export namespace ISourceFileFactory {
 export interface OpenFileOptions {
     isTracked: boolean;
     ipythonMode: IPythonMode;
-    chainedFilePath: string | undefined;
-    realFilePath: string | undefined;
+    chainedFileUri: Uri | undefined;
 }
 
 // Track edit mode related information.
@@ -195,7 +186,7 @@ export class Program {
         return this._console;
     }
 
-    get rootPath(): string {
+    get rootPath(): Uri {
         return this._configOptions.projectRoot;
     }
 
@@ -241,7 +232,7 @@ export class Program {
             if (newContents) {
                 // Create a text document so we can compute the edits.
                 const textDocument = TextDocument.create(
-                    fileInfo.sourceFile.getFilePath(),
+                    fileInfo.sourceFile.getUri().toString(),
                     'python',
                     1,
                     fileInfo.sourceFile.getFileContent() || ''
@@ -249,7 +240,7 @@ export class Program {
 
                 // Add an edit action to the list.
                 edits.push({
-                    filePath: fileInfo.sourceFile.getFilePath(),
+                    fileUri: fileInfo.sourceFile.getUri(),
                     range: {
                         start: { line: 0, character: 0 },
                         end: { line: textDocument.lineCount, character: 0 },
@@ -268,7 +259,7 @@ export class Program {
                     // We don't need to care about file diagnostics since in edit mode
                     // checker won't run.
                     v.sourceFile.prepareForClose();
-                    this._removeSourceFileFromListAndMap(v.sourceFile.getFilePath(), i);
+                    this._removeSourceFileFromListAndMap(v.sourceFile.getUri(), i);
                 }
             }
         }
@@ -299,26 +290,26 @@ export class Program {
     }
 
     // Sets the list of tracked files that make up the program.
-    setTrackedFiles(filePaths: string[]): FileDiagnostics[] {
+    setTrackedFiles(fileUris: Uri[]): FileDiagnostics[] {
         if (this._sourceFileList.length > 0) {
             // We need to determine which files to remove from the existing file list.
-            const newFileMap = new Map<string, string>();
-            filePaths.forEach((path) => {
-                newFileMap.set(path, path);
+            const newFileMap = new Map<string, Uri>();
+            fileUris.forEach((path) => {
+                newFileMap.set(path.key, path);
             });
 
             // Files that are not in the tracked file list are
             // marked as no longer tracked.
             this._sourceFileList.forEach((oldFile) => {
-                const filePath = oldFile.sourceFile.getFilePath();
-                if (!newFileMap.has(filePath)) {
+                const fileUri = oldFile.sourceFile.getUri();
+                if (!newFileMap.has(fileUri.key)) {
                     oldFile.isTracked = false;
                 }
             });
         }
 
         // Add the new files. Only the new items will be added.
-        this.addTrackedFiles(filePaths);
+        this.addTrackedFiles(fileUris);
 
         return this._removeUnneededFiles();
     }
@@ -338,25 +329,25 @@ export class Program {
         this._allowedThirdPartyImports = importNames;
     }
 
-    addTrackedFiles(filePaths: string[], isThirdPartyImport = false, isInPyTypedPackage = false) {
-        filePaths.forEach((filePath) => {
-            this.addTrackedFile(filePath, isThirdPartyImport, isInPyTypedPackage);
+    addTrackedFiles(fileUris: Uri[], isThirdPartyImport = false, isInPyTypedPackage = false) {
+        fileUris.forEach((fileUri) => {
+            this.addTrackedFile(fileUri, isThirdPartyImport, isInPyTypedPackage);
         });
     }
 
-    addInterimFile(filePath: string): SourceFileInfo {
+    addInterimFile(fileUri: Uri): SourceFileInfo {
         // Double check not already there.
-        let fileInfo = this.getSourceFileInfo(filePath);
+        let fileInfo = this.getSourceFileInfo(fileUri);
         if (!fileInfo) {
-            fileInfo = this._createInterimFileInfo(filePath);
+            fileInfo = this._createInterimFileInfo(fileUri);
             this._addToSourceFileListAndMap(fileInfo);
         }
         return fileInfo;
     }
 
-    addTrackedFile(filePath: string, isThirdPartyImport = false, isInPyTypedPackage = false): SourceFile {
-        let sourceFileInfo = this.getSourceFileInfo(filePath);
-        const moduleImportInfo = this._getModuleImportInfoForFile(filePath);
+    addTrackedFile(fileUri: Uri, isThirdPartyImport = false, isInPyTypedPackage = false): SourceFile {
+        let sourceFileInfo = this.getSourceFileInfo(fileUri);
+        const moduleImportInfo = this._getModuleImportInfoForFile(fileUri);
         const importName = moduleImportInfo.moduleName;
 
         if (sourceFileInfo) {
@@ -369,7 +360,7 @@ export class Program {
 
         const sourceFile = this._sourceFileFactory.createSourceFile(
             this.serviceProvider,
-            filePath,
+            fileUri,
             importName,
             isThirdPartyImport,
             isInPyTypedPackage,
@@ -391,23 +382,22 @@ export class Program {
         return sourceFile;
     }
 
-    setFileOpened(filePath: string, version: number | null, contents: string, options?: OpenFileOptions) {
-        let sourceFileInfo = this.getSourceFileInfo(filePath);
+    setFileOpened(fileUri: Uri, version: number | null, contents: string, options?: OpenFileOptions) {
+        let sourceFileInfo = this.getSourceFileInfo(fileUri);
         if (!sourceFileInfo) {
-            const moduleImportInfo = this._getModuleImportInfoForFile(filePath);
+            const moduleImportInfo = this._getModuleImportInfoForFile(fileUri);
             const sourceFile = this._sourceFileFactory.createSourceFile(
                 this.serviceProvider,
-                filePath,
+                fileUri,
                 moduleImportInfo.moduleName,
                 /* isThirdPartyImport */ false,
                 moduleImportInfo.isThirdPartyPyTypedPresent,
                 this._editModeTracker,
                 this._console,
                 this._logTracker,
-                options?.realFilePath,
                 options?.ipythonMode ?? IPythonMode.None
             );
-            const chainedFilePath = options?.chainedFilePath;
+            const chainedFilePath = options?.chainedFileUri;
             sourceFileInfo = new SourceFileInfo(
                 sourceFile,
                 /* isTypeshedFile */ false,
@@ -435,26 +425,26 @@ export class Program {
         sourceFileInfo.sourceFile.setClientVersion(version, contents);
     }
 
-    getChainedFilePath(filePath: string): string | undefined {
-        const sourceFileInfo = this.getSourceFileInfo(filePath);
-        return sourceFileInfo?.chainedSourceFile?.sourceFile.getFilePath();
+    getChainedUri(fileUri: Uri): Uri | undefined {
+        const sourceFileInfo = this.getSourceFileInfo(fileUri);
+        return sourceFileInfo?.chainedSourceFile?.sourceFile.getUri();
     }
 
-    updateChainedFilePath(filePath: string, chainedFilePath: string | undefined) {
-        const sourceFileInfo = this.getSourceFileInfo(filePath);
+    updateChainedUri(fileUri: Uri, chainedFileUri: Uri | undefined) {
+        const sourceFileInfo = this.getSourceFileInfo(fileUri);
         if (!sourceFileInfo) {
             return;
         }
 
-        sourceFileInfo.chainedSourceFile = chainedFilePath ? this.getSourceFileInfo(chainedFilePath) : undefined;
+        sourceFileInfo.chainedSourceFile = chainedFileUri ? this.getSourceFileInfo(chainedFileUri) : undefined;
         sourceFileInfo.sourceFile.markDirty();
         this._markFileDirtyRecursive(sourceFileInfo, new Set<string>());
 
         verifyNoCyclesInChainedFiles(this, sourceFileInfo);
     }
 
-    setFileClosed(filePath: string, isTracked?: boolean): FileDiagnostics[] {
-        const sourceFileInfo = this.getSourceFileInfo(filePath);
+    setFileClosed(fileUri: Uri, isTracked?: boolean): FileDiagnostics[] {
+        const sourceFileInfo = this.getSourceFileInfo(fileUri);
         if (sourceFileInfo) {
             sourceFileInfo.isOpenByClient = false;
             sourceFileInfo.isTracked = isTracked ?? sourceFileInfo.isTracked;
@@ -493,12 +483,12 @@ export class Program {
         }
     }
 
-    markFilesDirty(filePaths: string[], evenIfContentsAreSame: boolean) {
+    markFilesDirty(fileUris: Uri[], evenIfContentsAreSame: boolean) {
         const markDirtySet = new Set<string>();
-        filePaths.forEach((filePath) => {
-            const sourceFileInfo = this.getSourceFileInfo(filePath);
+        fileUris.forEach((fileUri) => {
+            const sourceFileInfo = this.getSourceFileInfo(fileUri);
             if (sourceFileInfo) {
-                const fileName = getFileName(filePath);
+                const fileName = fileUri.fileName;
 
                 // Handle builtins and __builtins__ specially. They are implicitly
                 // included by all source files.
@@ -576,9 +566,9 @@ export class Program {
         return this._configOptions.functionSignatureDisplay;
     }
 
-    containsSourceFileIn(folder: string): boolean {
-        for (const normalizedSourceFilePath of this._sourceFileMap.keys()) {
-            if (normalizedSourceFilePath.startsWith(folder)) {
+    containsSourceFileIn(folder: Uri): boolean {
+        for (const normalizedSourceFilePath of this._sourceFileMap.values()) {
+            if (normalizedSourceFilePath.sourceFile.getUri().startsWith(folder)) {
                 return true;
             }
         }
@@ -586,19 +576,19 @@ export class Program {
         return false;
     }
 
-    owns(filePath: string) {
-        const fileInfo = this.getSourceFileInfo(filePath);
+    owns(uri: Uri) {
+        const fileInfo = this.getSourceFileInfo(uri);
         if (fileInfo) {
             // If we already determined whether the file is tracked or not, don't do it again.
             // This will make sure we have consistent look at the state once it is loaded to the memory.
             return fileInfo.isTracked;
         }
 
-        return matchFileSpecs(this._configOptions, filePath);
+        return matchFileSpecs(this._configOptions, uri);
     }
 
-    getSourceFile(filePath: string): SourceFile | undefined {
-        const sourceFileInfo = this.getSourceFileInfo(filePath);
+    getSourceFile(uri: Uri): SourceFile | undefined {
+        const sourceFileInfo = this.getSourceFileInfo(uri);
         if (!sourceFileInfo) {
             return undefined;
         }
@@ -606,20 +596,23 @@ export class Program {
         return sourceFileInfo.sourceFile;
     }
 
-    getBoundSourceFile(filePath: string): SourceFile | undefined {
-        return this.getBoundSourceFileInfo(filePath)?.sourceFile;
+    getBoundSourceFile(uri: Uri): SourceFile | undefined {
+        return this.getBoundSourceFileInfo(uri)?.sourceFile;
     }
 
     getSourceFileInfoList(): readonly SourceFileInfo[] {
         return this._sourceFileList;
     }
 
-    getSourceFileInfo(filePath: string): SourceFileInfo | undefined {
-        return this._sourceFileMap.get(filePath);
+    getSourceFileInfo(uri: Uri): SourceFileInfo | undefined {
+        if (!uri.isEmpty()) {
+            return this._sourceFileMap.get(uri.key);
+        }
+        return undefined;
     }
 
-    getBoundSourceFileInfo(filePath: string, content?: string, force?: boolean): SourceFileInfo | undefined {
-        const sourceFileInfo = this.getSourceFileInfo(filePath);
+    getBoundSourceFileInfo(uri: Uri, content?: string, force?: boolean): SourceFileInfo | undefined {
+        const sourceFileInfo = this.getSourceFileInfo(uri);
         if (!sourceFileInfo) {
             return undefined;
         }
@@ -685,9 +678,9 @@ export class Program {
 
     // Performs parsing and analysis of a single file in the program. If the file is not part of
     // the program returns false to indicate analysis was not performed.
-    analyzeFile(filePath: string, token: CancellationToken = CancellationToken.None): boolean {
+    analyzeFile(fileUri: Uri, token: CancellationToken = CancellationToken.None): boolean {
         return this._runEvaluatorWithCancellationToken(token, () => {
-            const sourceFileInfo = this.getSourceFileInfo(filePath);
+            const sourceFileInfo = this.getSourceFileInfo(fileUri);
             if (sourceFileInfo && this._checkTypes(sourceFileInfo, token)) {
                 return true;
             }
@@ -710,19 +703,19 @@ export class Program {
     }
 
     getSourceMapper(
-        filePath: string,
+        fileUri: Uri,
         token: CancellationToken,
         mapCompiled?: boolean,
         preferStubs?: boolean
     ): SourceMapper {
-        const sourceFileInfo = this.getSourceFileInfo(filePath);
-        const execEnv = this._configOptions.findExecEnvironment(filePath);
+        const sourceFileInfo = this.getSourceFileInfo(fileUri);
+        const execEnv = this._configOptions.findExecEnvironment(fileUri);
         return this._createSourceMapper(execEnv, token, sourceFileInfo, mapCompiled, preferStubs);
     }
 
-    getParseResults(filePath: string): ParseResults | undefined {
+    getParseResults(fileUri: Uri): ParseResults | undefined {
         return this.getBoundSourceFileInfo(
-            filePath,
+            fileUri,
             /* content */ undefined,
             /* force */ true
         )?.sourceFile.getParseResults();
@@ -746,41 +739,39 @@ export class Program {
 
         sortedFiles.forEach((sfInfo) => {
             const checkTimeInMs = sfInfo.sourceFile.getCheckTime()!;
-            this._console.info(`${checkTimeInMs}ms: ${sfInfo.sourceFile.getFilePath()}`);
+            this._console.info(`${checkTimeInMs}ms: ${sfInfo.sourceFile.getUri()}`);
         });
     }
 
     // Prints import dependency information for each of the files in
     // the program, skipping any typeshed files.
-    printDependencies(projectRootDir: string, verbose: boolean) {
+    printDependencies(projectRootDir: Uri, verbose: boolean) {
         const fs = this._importResolver.fileSystem;
         const sortedFiles = this._sourceFileList
             .filter((s) => !s.isTypeshedFile)
             .sort((a, b) => {
-                return fs.getOriginalFilePath(a.sourceFile.getFilePath()) <
-                    fs.getOriginalFilePath(b.sourceFile.getFilePath())
-                    ? 1
-                    : -1;
+                return fs.getOriginalUri(a.sourceFile.getUri()) < fs.getOriginalUri(b.sourceFile.getUri()) ? 1 : -1;
             });
 
         const zeroImportFiles: SourceFile[] = [];
 
         sortedFiles.forEach((sfInfo) => {
             this._console.info('');
-            let filePath = fs.getOriginalFilePath(sfInfo.sourceFile.getFilePath());
-            const relPath = getRelativePath(filePath, projectRootDir);
+            const fileUri = fs.getOriginalUri(sfInfo.sourceFile.getUri());
+            let fileString = fileUri.toString();
+            const relPath = projectRootDir.getRelativePathComponents(fileUri);
             if (relPath) {
-                filePath = relPath;
+                fileString = relPath.join('/');
             }
 
-            this._console.info(`${filePath}`);
+            this._console.info(`${fileString}`);
 
             this._console.info(
                 ` Imports     ${sfInfo.imports.length} ` + `file${sfInfo.imports.length === 1 ? '' : 's'}`
             );
             if (verbose) {
                 sfInfo.imports.forEach((importInfo) => {
-                    this._console.info(`    ${fs.getOriginalFilePath(importInfo.sourceFile.getFilePath())}`);
+                    this._console.info(`    ${fs.getOriginalUri(importInfo.sourceFile.getUri())}`);
                 });
             }
 
@@ -789,7 +780,7 @@ export class Program {
             );
             if (verbose) {
                 sfInfo.importedBy.forEach((importInfo) => {
-                    this._console.info(`    ${fs.getOriginalFilePath(importInfo.sourceFile.getFilePath())}`);
+                    this._console.info(`    ${fs.getOriginalUri(importInfo.sourceFile.getUri())}`);
                 });
             }
 
@@ -804,33 +795,33 @@ export class Program {
                 `${zeroImportFiles.length} file${zeroImportFiles.length === 1 ? '' : 's'}` + ` not explicitly imported`
             );
             zeroImportFiles.forEach((importFile) => {
-                this._console.info(`    ${fs.getOriginalFilePath(importFile.getFilePath())}`);
+                this._console.info(`    ${fs.getOriginalUri(importFile.getUri())}`);
             });
         }
     }
 
-    writeTypeStub(targetImportPath: string, targetIsSingleFile: boolean, stubPath: string, token: CancellationToken) {
+    writeTypeStub(targetImportPath: Uri, targetIsSingleFile: boolean, stubPath: Uri, token: CancellationToken) {
         for (const sourceFileInfo of this._sourceFileList) {
             throwIfCancellationRequested(token);
 
-            const filePath = sourceFileInfo.sourceFile.getFilePath();
+            const fileUri = sourceFileInfo.sourceFile.getUri();
 
             // Generate type stubs only for the files within the target path,
             // not any files that the target module happened to import.
-            const relativePath = getRelativePath(filePath, targetImportPath);
+            const relativePath = targetImportPath.getRelativePath(fileUri);
             if (relativePath !== undefined) {
-                let typeStubPath = normalizePath(combinePaths(stubPath, relativePath));
+                let typeStubPath = stubPath.combinePaths(relativePath);
 
                 // If the target is a single file implementation, as opposed to
                 // a package in a directory, transform the name of the type stub
                 // to __init__.pyi because we're placing it in a directory.
                 if (targetIsSingleFile) {
-                    typeStubPath = combinePaths(getDirectoryPath(typeStubPath), '__init__.pyi');
+                    typeStubPath = typeStubPath.getDirectory().combinePaths('__init__.pyi');
                 } else {
-                    typeStubPath = stripFileExtension(typeStubPath) + '.pyi';
+                    typeStubPath = typeStubPath.replaceExtension('.pyi');
                 }
 
-                const typeStubDir = getDirectoryPath(typeStubPath);
+                const typeStubDir = typeStubPath.getDirectory();
 
                 try {
                     makeDirectories(this.fileSystem, typeStubDir, stubPath);
@@ -867,8 +858,8 @@ export class Program {
         return evaluator.printType(type, options);
     }
 
-    getTextOnRange(filePath: string, range: Range, token: CancellationToken): string | undefined {
-        const sourceFileInfo = this.getSourceFileInfo(filePath);
+    getTextOnRange(fileUri: Uri, range: Range, token: CancellationToken): string | undefined {
+        const sourceFileInfo = this.getSourceFileInfo(fileUri);
         if (!sourceFileInfo) {
             return undefined;
         }
@@ -904,7 +895,7 @@ export class Program {
                 );
                 if (diagnostics !== undefined) {
                     fileDiagnostics.push({
-                        filePath: sourceFileInfo.sourceFile.getFilePath(),
+                        fileUri: sourceFileInfo.sourceFile.getUri(),
                         version: sourceFileInfo.sourceFile.getClientVersion(),
                         diagnostics,
                     });
@@ -921,7 +912,7 @@ export class Program {
                 // This condition occurs when the user switches from workspace to
                 // "open files only" mode. Clear all diagnostics for this file.
                 fileDiagnostics.push({
-                    filePath: sourceFileInfo.sourceFile.getFilePath(),
+                    fileUri: sourceFileInfo.sourceFile.getUri(),
                     version: sourceFileInfo.sourceFile.getClientVersion(),
                     diagnostics: [],
                 });
@@ -932,8 +923,8 @@ export class Program {
         return fileDiagnostics;
     }
 
-    getDiagnosticsForRange(filePath: string, range: Range): Diagnostic[] {
-        const sourceFile = this.getSourceFile(filePath);
+    getDiagnosticsForRange(fileUri: Uri, range: Range): Diagnostic[] {
+        const sourceFile = this.getSourceFile(fileUri);
         if (!sourceFile) {
             return [];
         }
@@ -958,7 +949,7 @@ export class Program {
 
         // Cloned program will use whatever user files the program currently has.
         const userFiles = this.getUserFiles();
-        program.setTrackedFiles(userFiles.map((i) => i.sourceFile.getFilePath()));
+        program.setTrackedFiles(userFiles.map((i) => i.sourceFile.getUri()));
         program.markAllFilesDirty(/* evenIfContentsAreSame */ true);
 
         // Make sure we keep editor content (open file) which could be different than one in the file system.
@@ -969,14 +960,13 @@ export class Program {
             }
 
             program.setFileOpened(
-                fileInfo.sourceFile.getFilePath(),
+                fileInfo.sourceFile.getUri(),
                 version,
                 fileInfo.sourceFile.getOpenFileContents() ?? '',
                 {
-                    chainedFilePath: fileInfo.chainedSourceFile?.sourceFile.getFilePath(),
+                    chainedFileUri: fileInfo.chainedSourceFile?.sourceFile.getUri(),
                     ipythonMode: fileInfo.sourceFile.getIPythonMode(),
                     isTracked: fileInfo.isTracked,
-                    realFilePath: fileInfo.sourceFile.getRealFilePath(),
                 }
             );
         }
@@ -1071,14 +1061,14 @@ export class Program {
                 // Clear only if there are any errors for this file.
                 if (fileInfo.diagnosticsVersion !== undefined) {
                     fileDiagnostics.push({
-                        filePath: fileInfo.sourceFile.getFilePath(),
+                        fileUri: fileInfo.sourceFile.getUri(),
                         version: fileInfo.sourceFile.getClientVersion(),
                         diagnostics: [],
                     });
                 }
 
                 fileInfo.sourceFile.prepareForClose();
-                this._removeSourceFileFromListAndMap(fileInfo.sourceFile.getFilePath(), i);
+                this._removeSourceFileFromListAndMap(fileInfo.sourceFile.getUri(), i);
 
                 // Unlink any imports and remove them from the list if
                 // they are no longer referenced.
@@ -1099,14 +1089,14 @@ export class Program {
                             // Clear if there are any errors for this import.
                             if (importedFile.diagnosticsVersion !== undefined) {
                                 fileDiagnostics.push({
-                                    filePath: importedFile.sourceFile.getFilePath(),
+                                    fileUri: importedFile.sourceFile.getUri(),
                                     version: importedFile.sourceFile.getClientVersion(),
                                     diagnostics: [],
                                 });
                             }
 
                             importedFile.sourceFile.prepareForClose();
-                            this._removeSourceFileFromListAndMap(importedFile.sourceFile.getFilePath(), indexToRemove);
+                            this._removeSourceFileFromListAndMap(importedFile.sourceFile.getUri(), indexToRemove);
                             i--;
                         }
                     }
@@ -1122,7 +1112,7 @@ export class Program {
                 // out the errors for the now-closed file.
                 if (!this._shouldCheckFile(fileInfo) && fileInfo.diagnosticsVersion !== undefined) {
                     fileDiagnostics.push({
-                        filePath: fileInfo.sourceFile.getFilePath(),
+                        fileUri: fileInfo.sourceFile.getUri(),
                         version: fileInfo.sourceFile.getClientVersion(),
                         diagnostics: [],
                     });
@@ -1165,14 +1155,14 @@ export class Program {
             return true;
         }
 
-        const filePath = fileInfo.sourceFile.getFilePath();
+        const fileUri = fileInfo.sourceFile.getUri();
 
         // Avoid infinite recursion.
-        if (recursionSet.has(filePath)) {
+        if (recursionSet.has(fileUri.key)) {
             return false;
         }
 
-        recursionSet.add(filePath);
+        recursionSet.add(fileUri.key);
 
         for (const importerInfo of fileInfo.importedBy) {
             if (this._isImportNeededRecursive(importerInfo, recursionSet)) {
@@ -1194,16 +1184,16 @@ export class Program {
             this._importResolver,
             execEnv,
             this._evaluator!,
-            (stubFilePath: string, implFilePath: string) => {
-                let stubFileInfo = this.getSourceFileInfo(stubFilePath);
+            (stubFileUri: Uri, implFileUri: Uri) => {
+                let stubFileInfo = this.getSourceFileInfo(stubFileUri);
                 if (!stubFileInfo) {
                     // Special case for import statement like "import X.Y". The SourceFile
                     // for X might not be in memory since import `X.Y` only brings in Y.
-                    stubFileInfo = this.addInterimFile(stubFilePath);
+                    stubFileInfo = this.addInterimFile(stubFileUri);
                 }
 
-                this._addShadowedFile(stubFileInfo, implFilePath);
-                return this.getBoundSourceFile(implFilePath);
+                this._addShadowedFile(stubFileInfo, implFileUri);
+                return this.getBoundSourceFile(implFileUri);
             },
             (f) => {
                 let fileInfo = this.getBoundSourceFileInfo(f);
@@ -1296,6 +1286,10 @@ export class Program {
         return true;
     }
 
+    private _getSourceFileInfoFromKey(key: string) {
+        return this._sourceFileMap.get(key);
+    }
+
     private _updateSourceFileImports(sourceFileInfo: SourceFileInfo, options: ConfigOptions): SourceFileInfo[] {
         const filesAdded: SourceFileInfo[] = [];
 
@@ -1338,9 +1332,9 @@ export class Program {
             if (sourceFileInfo.chainedSourceFile.sourceFile.isFileDeleted()) {
                 sourceFileInfo.chainedSourceFile = undefined;
             } else {
-                const filePath = sourceFileInfo.chainedSourceFile.sourceFile.getFilePath();
-                newImportPathMap.set(filePath, {
-                    path: filePath,
+                const fileUri = sourceFileInfo.chainedSourceFile.sourceFile.getUri();
+                newImportPathMap.set(fileUri.key, {
+                    path: fileUri,
                     isTypeshedFile: false,
                     isThirdPartyImport: false,
                     isPyTypedPresent: false,
@@ -1351,12 +1345,12 @@ export class Program {
         imports.forEach((importResult) => {
             if (importResult.isImportFound) {
                 if (this._isImportAllowed(sourceFileInfo, importResult, importResult.isStubFile)) {
-                    if (importResult.resolvedPaths.length > 0) {
-                        const filePath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
-                        if (filePath) {
+                    if (importResult.resolvedUris.length > 0) {
+                        const fileUri = importResult.resolvedUris[importResult.resolvedUris.length - 1];
+                        if (!fileUri.isEmpty()) {
                             const thirdPartyTypeInfo = getThirdPartyImportInfo(importResult);
-                            newImportPathMap.set(filePath, {
-                                path: filePath,
+                            newImportPathMap.set(fileUri.key, {
+                                path: fileUri,
                                 isTypeshedFile:
                                     !!importResult.isStdlibTypeshedFile || !!importResult.isThirdPartyTypeshedFile,
                                 isThirdPartyImport: thirdPartyTypeInfo.isThirdPartyImport,
@@ -1370,8 +1364,8 @@ export class Program {
                     if (this._isImportAllowed(sourceFileInfo, importResult, implicitImport.isStubFile)) {
                         if (!implicitImport.isNativeLib) {
                             const thirdPartyTypeInfo = getThirdPartyImportInfo(importResult);
-                            newImportPathMap.set(implicitImport.path, {
-                                path: implicitImport.path,
+                            newImportPathMap.set(implicitImport.uri.key, {
+                                path: implicitImport.uri,
                                 isTypeshedFile:
                                     !!importResult.isStdlibTypeshedFile || !!importResult.isThirdPartyTypeshedFile,
                                 isThirdPartyImport: thirdPartyTypeInfo.isThirdPartyImport,
@@ -1391,7 +1385,7 @@ export class Program {
                         if (options.verboseOutput) {
                             this._console.info(
                                 `Could not resolve source for '${importResult.importName}' ` +
-                                    `in file '${sourceFileInfo.sourceFile.getFilePath()}'`
+                                    `in file '${sourceFileInfo.sourceFile.getUri().toUserVisibleString()}'`
                             );
 
                             if (importResult.nonStubImportResult.importFailureInfo) {
@@ -1405,7 +1399,7 @@ export class Program {
             } else if (options.verboseOutput) {
                 this._console.info(
                     `Could not import '${importResult.importName}' ` +
-                        `in file '${sourceFileInfo.sourceFile.getFilePath()}'`
+                        `in file '${sourceFileInfo.sourceFile.getUri().toUserVisibleString()}'`
                 );
                 if (importResult.importFailureInfo) {
                     importResult.importFailureInfo.forEach((diag) => {
@@ -1417,17 +1411,17 @@ export class Program {
 
         const updatedImportMap = new Map<string, SourceFileInfo>();
         sourceFileInfo.imports.forEach((importInfo) => {
-            const oldFilePath = importInfo.sourceFile.getFilePath();
+            const oldFilePath = importInfo.sourceFile.getUri();
 
             // A previous import was removed.
-            if (!newImportPathMap.has(oldFilePath)) {
+            if (!newImportPathMap.has(oldFilePath.key)) {
                 importInfo.mutate((s) => {
                     s.importedBy = s.importedBy.filter(
-                        (fi) => fi.sourceFile.getFilePath() !== sourceFileInfo.sourceFile.getFilePath()
+                        (fi) => !fi.sourceFile.getUri().equals(sourceFileInfo.sourceFile.getUri())
                     );
                 });
             } else {
-                updatedImportMap.set(oldFilePath, importInfo);
+                updatedImportMap.set(oldFilePath.key, importInfo);
             }
         });
 
@@ -1469,9 +1463,9 @@ export class Program {
         // Update the imports list. It should now map the set of imports
         // specified by the source file.
         sourceFileInfo.mutate((s) => (s.imports = []));
-        newImportPathMap.forEach((_, path) => {
-            if (this.getSourceFileInfo(path)) {
-                sourceFileInfo.mutate((s) => s.imports.push(this.getSourceFileInfo(path)!));
+        newImportPathMap.forEach((_, key) => {
+            if (this._getSourceFileInfoFromKey(key)) {
+                sourceFileInfo.mutate((s) => s.imports.push(this._getSourceFileInfoFromKey(key)!));
             }
         });
 
@@ -1480,26 +1474,29 @@ export class Program {
         sourceFileInfo.builtinsImport = undefined;
         const builtinsImport = sourceFileInfo.sourceFile.getBuiltinsImport();
         if (builtinsImport && builtinsImport.isImportFound) {
-            const resolvedBuiltinsPath = builtinsImport.resolvedPaths[builtinsImport.resolvedPaths.length - 1];
+            const resolvedBuiltinsPath = builtinsImport.resolvedUris[builtinsImport.resolvedUris.length - 1];
             sourceFileInfo.builtinsImport = this.getSourceFileInfo(resolvedBuiltinsPath);
         }
 
         return filesAdded;
     }
 
-    private _removeSourceFileFromListAndMap(filePath: string, indexToRemove: number) {
-        this._sourceFileMap.delete(filePath);
+    private _removeSourceFileFromListAndMap(fileUri: Uri, indexToRemove: number) {
+        this._sourceFileMap.delete(fileUri.key);
         this._sourceFileList.splice(indexToRemove, 1);
     }
 
     private _addToSourceFileListAndMap(fileInfo: SourceFileInfo) {
-        const filePath = fileInfo.sourceFile.getFilePath();
+        const fileUri = fileInfo.sourceFile.getUri();
 
         // We should never add a file with the same path twice.
-        assert(!this._sourceFileMap.has(filePath));
+        assert(!this._sourceFileMap.has(fileUri.key));
+
+        // We should never have an empty URI for a source file.
+        assert(!fileInfo.sourceFile.getUri().isEmpty());
 
         this._sourceFileList.push(fileInfo);
-        this._sourceFileMap.set(filePath, fileInfo);
+        this._sourceFileMap.set(fileUri.key, fileInfo);
     }
 
     private static _getPrintTypeFlags(configOptions: ConfigOptions): PrintTypeFlags {
@@ -1528,7 +1525,7 @@ export class Program {
         return flags;
     }
 
-    private _getModuleImportInfoForFile(filePath: string) {
+    private _getModuleImportInfoForFile(fileUri: Uri) {
         // We allow illegal module names (e.g. names that include "-" in them)
         // because we want a unique name for each module even if it cannot be
         // imported through an "import" statement. It's important to have a
@@ -1536,7 +1533,7 @@ export class Program {
         // name. The type checker uses the fully-qualified (unique) module name
         // to differentiate between such types.
         const moduleNameAndType = this._importResolver.getModuleNameForImport(
-            filePath,
+            fileUri,
             this._configOptions.getDefaultExecEnvironment(),
             /* allowIllegalModuleName */ true,
             /* detectPyTyped */ true
@@ -1549,7 +1546,7 @@ export class Program {
     // it "shadows" a type stub file for purposes of finding doc strings and definitions.
     // We need to track the relationship so if the original type stub is removed from the
     // program, we can remove the corresponding shadowed file and any files it imports.
-    private _addShadowedFile(stubFile: SourceFileInfo, shadowImplPath: string): SourceFile {
+    private _addShadowedFile(stubFile: SourceFileInfo, shadowImplPath: Uri): SourceFile {
         let shadowFileInfo = this.getSourceFileInfo(shadowImplPath);
 
         if (!shadowFileInfo) {
@@ -1567,11 +1564,11 @@ export class Program {
         return shadowFileInfo.sourceFile;
     }
 
-    private _createInterimFileInfo(filePath: string) {
-        const moduleImportInfo = this._getModuleImportInfoForFile(filePath);
+    private _createInterimFileInfo(fileUri: Uri) {
+        const moduleImportInfo = this._getModuleImportInfoForFile(fileUri);
         const sourceFile = this._sourceFileFactory.createSourceFile(
             this.serviceProvider,
-            filePath,
+            fileUri,
             moduleImportInfo.moduleName,
             /* isThirdPartyImport */ false,
             /* isInPyTypedPackage */ false,
@@ -1673,8 +1670,8 @@ export class Program {
 
         let nextImplicitImport = this._getImplicitImports(fileToAnalyze);
         while (nextImplicitImport) {
-            const implicitPath = nextImplicitImport.sourceFile.getFilePath();
-            if (implicitSet.has(implicitPath)) {
+            const implicitPath = nextImplicitImport.sourceFile.getUri();
+            if (implicitSet.has(implicitPath.key)) {
                 // We've found a cycle. Break out of the loop.
                 debug.fail(
                     this.serviceProvider
@@ -1683,7 +1680,7 @@ export class Program {
                 );
             }
 
-            implicitSet.add(implicitPath);
+            implicitSet.add(implicitPath.key);
             implicitImports.push(nextImplicitImport);
 
             this._parseFile(nextImplicitImport, /* content */ undefined, skipFileNeededCheck);
@@ -1773,27 +1770,27 @@ export class Program {
     }
 
     private _lookUpImport = (
-        filePathOrModule: string | AbsoluteModuleDescriptor,
+        fileUriOrModule: Uri | AbsoluteModuleDescriptor,
         options?: LookupImportOptions
     ): ImportLookupResult | undefined => {
         let sourceFileInfo: SourceFileInfo | undefined;
 
-        if (typeof filePathOrModule === 'string') {
-            sourceFileInfo = this.getSourceFileInfo(filePathOrModule);
+        if (Uri.isUri(fileUriOrModule)) {
+            sourceFileInfo = this.getSourceFileInfo(fileUriOrModule);
         } else {
             // Resolve the import.
             const importResult = this._importResolver.resolveImport(
-                filePathOrModule.importingFilePath,
-                this._configOptions.findExecEnvironment(filePathOrModule.importingFilePath),
+                fileUriOrModule.importingFileUri,
+                this._configOptions.findExecEnvironment(fileUriOrModule.importingFileUri),
                 {
                     leadingDots: 0,
-                    nameParts: filePathOrModule.nameParts,
+                    nameParts: fileUriOrModule.nameParts,
                     importedSymbols: undefined,
                 }
             );
 
-            if (importResult.isImportFound && !importResult.isNativeLib && importResult.resolvedPaths.length > 0) {
-                const resolvedPath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+            if (importResult.isImportFound && !importResult.isNativeLib && importResult.resolvedUris.length > 0) {
+                const resolvedPath = importResult.resolvedUris[importResult.resolvedUris.length - 1];
                 if (resolvedPath) {
                     // See if the source file already exists in the program.
                     sourceFileInfo = this.getSourceFileInfo(resolvedPath);
@@ -1872,7 +1869,7 @@ export class Program {
     }
 
     private _checkTypes(fileToCheck: SourceFileInfo, token: CancellationToken, chainedByList?: SourceFileInfo[]) {
-        return this._logTracker.log(`analyzing: ${fileToCheck.sourceFile.getFilePath()}`, (logState) => {
+        return this._logTracker.log(`analyzing: ${fileToCheck.sourceFile.getUri()}`, (logState) => {
             // If the file isn't needed because it was eliminated from the
             // transitive closure or deleted, skip the file rather than wasting
             // time on it.
@@ -1911,7 +1908,7 @@ export class Program {
                 }
 
                 if (boundFile) {
-                    const execEnv = this._configOptions.findExecEnvironment(fileToCheck.sourceFile.getFilePath());
+                    const execEnv = this._configOptions.findExecEnvironment(fileToCheck.sourceFile.getUri());
                     fileToCheck.sourceFile.check(
                         this.configOptions,
                         this._importResolver,
@@ -2028,8 +2025,8 @@ export class Program {
     ) {
         // If the file is already in the closure map, we found a cyclical
         // dependency. Don't recur further.
-        const filePath = file.sourceFile.getFilePath();
-        if (closureMap.has(filePath)) {
+        const fileUri = file.sourceFile.getUri();
+        if (closureMap.has(fileUri.key)) {
             return;
         }
 
@@ -2041,7 +2038,7 @@ export class Program {
         }
 
         // Add the file to the closure map.
-        closureMap.set(filePath, file);
+        closureMap.set(fileUri.key, file);
 
         // If this file hasn't already been parsed, parse it now. This will
         // discover any files it imports. Skip this if the file is part
@@ -2074,13 +2071,13 @@ export class Program {
             return false;
         }
 
-        const filePath = sourceFileInfo.sourceFile.getFilePath();
+        const fileUri = sourceFileInfo.sourceFile.getUri();
 
-        filesVisited.set(filePath, sourceFileInfo);
+        filesVisited.set(fileUri.key, sourceFileInfo);
 
         let detectedCycle = false;
 
-        if (dependencyMap.has(filePath)) {
+        if (dependencyMap.has(fileUri.key)) {
             // We detect a cycle (partial or full). A full cycle is one that is
             // rooted in the file at the start of our dependency chain. A partial
             // cycle loops back on some other file in the dependency chain. We
@@ -2097,7 +2094,7 @@ export class Program {
         } else {
             // If we've already checked this dependency along
             // some other path, we can skip it.
-            if (dependencyMap.has(filePath)) {
+            if (dependencyMap.has(fileUri.key)) {
                 return false;
             }
 
@@ -2105,7 +2102,7 @@ export class Program {
             // (for ordering information). Set the dependency map
             // entry to true to indicate that we're actively exploring
             // that dependency.
-            dependencyMap.set(filePath, true);
+            dependencyMap.set(fileUri.key, true);
             dependencyChain.push(sourceFileInfo);
 
             for (const imp of sourceFileInfo.imports) {
@@ -2116,7 +2113,7 @@ export class Program {
 
             // Set the dependencyMap entry to false to indicate that we have
             // already explored this file and don't need to explore it again.
-            dependencyMap.set(filePath, false);
+            dependencyMap.set(fileUri.key, false);
             dependencyChain.pop();
         }
 
@@ -2126,7 +2123,7 @@ export class Program {
     private _logImportCycle(dependencyChain: SourceFileInfo[]) {
         const circDep = new CircularDependency();
         dependencyChain.forEach((sourceFileInfo) => {
-            circDep.appendPath(sourceFileInfo.sourceFile.getFilePath());
+            circDep.appendPath(sourceFileInfo.sourceFile.getUri());
         });
 
         circDep.normalizeOrder();
@@ -2137,15 +2134,15 @@ export class Program {
     }
 
     private _markFileDirtyRecursive(sourceFileInfo: SourceFileInfo, markSet: Set<string>, forceRebinding = false) {
-        const filePath = sourceFileInfo.sourceFile.getFilePath();
+        const fileUri = sourceFileInfo.sourceFile.getUri();
 
         // Don't mark it again if it's already been visited.
-        if (markSet.has(filePath)) {
+        if (markSet.has(fileUri.key)) {
             return;
         }
 
         sourceFileInfo.sourceFile.markReanalysisRequired(forceRebinding);
-        markSet.add(filePath);
+        markSet.add(fileUri.key);
 
         sourceFileInfo.importedBy.forEach((dep) => {
             // Changes on chained source file can change symbols in the symbol table and
diff --git a/packages/pyright-internal/src/analyzer/properties.ts b/packages/pyright-internal/src/analyzer/properties.ts
index e4dbaed6f..10e79af39 100644
--- a/packages/pyright-internal/src/analyzer/properties.ts
+++ b/packages/pyright-internal/src/analyzer/properties.ts
@@ -70,7 +70,7 @@ export function createProperty(
         decoratorType.details.name,
         getClassFullName(decoratorNode, fileInfo.moduleName, `__property_${fget.details.name}`),
         fileInfo.moduleName,
-        fileInfo.filePath,
+        fileInfo.fileUri,
         ClassTypeFlags.PropertyClass | ClassTypeFlags.BuiltInClass,
         typeSourceId,
         /* declaredMetaclass */ undefined,
@@ -171,7 +171,7 @@ export function clonePropertyWithSetter(
         classType.details.name,
         classType.details.fullName,
         classType.details.moduleName,
-        getFileInfo(errorNode).filePath,
+        getFileInfo(errorNode).fileUri,
         flagsToClone,
         classType.details.typeSourceId,
         classType.details.declaredMetaclass,
@@ -228,7 +228,7 @@ export function clonePropertyWithDeleter(
         classType.details.name,
         classType.details.fullName,
         classType.details.moduleName,
-        getFileInfo(errorNode).filePath,
+        getFileInfo(errorNode).fileUri,
         classType.details.flags,
         classType.details.typeSourceId,
         classType.details.declaredMetaclass,
diff --git a/packages/pyright-internal/src/analyzer/pyTypedUtils.ts b/packages/pyright-internal/src/analyzer/pyTypedUtils.ts
index 22378333e..f58fb30c8 100644
--- a/packages/pyright-internal/src/analyzer/pyTypedUtils.ts
+++ b/packages/pyright-internal/src/analyzer/pyTypedUtils.ts
@@ -8,24 +8,23 @@
  */
 
 import { FileSystem } from '../common/fileSystem';
-import { combinePaths, isDirectory, isFile } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
+import { isDirectory, isFile } from '../common/uri/uriUtils';
 
 export interface PyTypedInfo {
-    pyTypedPath: string;
+    pyTypedPath: Uri;
     isPartiallyTyped: boolean;
 }
 
-const _pyTypedFileName = 'py.typed';
-
-export function getPyTypedInfo(fileSystem: FileSystem, dirPath: string): PyTypedInfo | undefined {
+export function getPyTypedInfo(fileSystem: FileSystem, dirPath: Uri): PyTypedInfo | undefined {
     if (!fileSystem.existsSync(dirPath) || !isDirectory(fileSystem, dirPath)) {
         return undefined;
     }
 
     let isPartiallyTyped = false;
-    const pyTypedPath = combinePaths(dirPath, _pyTypedFileName);
+    const pyTypedPath = dirPath.pytypedUri;
 
-    if (!fileSystem.existsSync(dirPath) || !isFile(fileSystem, pyTypedPath)) {
+    if (!fileSystem.existsSync(pyTypedPath) || !isFile(fileSystem, pyTypedPath)) {
         return undefined;
     }
 
diff --git a/packages/pyright-internal/src/analyzer/pythonPathUtils.ts b/packages/pyright-internal/src/analyzer/pythonPathUtils.ts
index 51f559603..13bd97e52 100644
--- a/packages/pyright-internal/src/analyzer/pythonPathUtils.ts
+++ b/packages/pyright-internal/src/analyzer/pythonPathUtils.ts
@@ -12,43 +12,32 @@ import { compareComparableValues } from '../common/core';
 import { FileSystem } from '../common/fileSystem';
 import { Host } from '../common/host';
 import * as pathConsts from '../common/pathConsts';
-import {
-    combinePaths,
-    containsPath,
-    ensureTrailingDirectorySeparator,
-    getDirectoryPath,
-    getFileSystemEntries,
-    isDirectory,
-    normalizePath,
-    tryStat,
-} from '../common/pathUtils';
-import { versionToString } from '../common/pythonVersion';
-import { PythonVersion } from '../common/pythonVersion';
+import { PythonVersion, versionToString } from '../common/pythonVersion';
+import { Uri } from '../common/uri/uri';
+import { getFileSystemEntries, isDirectory, tryStat } from '../common/uri/uriUtils';
 
 export interface PythonPathResult {
-    paths: string[];
-    prefix: string;
+    paths: Uri[];
+    prefix: Uri | undefined;
 }
 
 export const stdLibFolderName = 'stdlib';
 export const thirdPartyFolderName = 'stubs';
 
 export function getTypeShedFallbackPath(fs: FileSystem) {
-    let moduleDirectory = fs.getModulePath();
-    if (!moduleDirectory) {
+    const moduleDirectory = fs.getModulePath();
+    if (!moduleDirectory || moduleDirectory.isEmpty()) {
         return undefined;
     }
 
-    moduleDirectory = getDirectoryPath(ensureTrailingDirectorySeparator(normalizePath(moduleDirectory)));
-
-    const typeshedPath = combinePaths(moduleDirectory, pathConsts.typeshedFallback);
+    const typeshedPath = moduleDirectory.combinePaths(pathConsts.typeshedFallback);
     if (fs.existsSync(typeshedPath)) {
         return fs.realCasePath(typeshedPath);
     }
 
     // In the debug version of Pyright, the code is one level
     // deeper, so we need to look one level up for the typeshed fallback.
-    const debugTypeshedPath = combinePaths(getDirectoryPath(moduleDirectory), pathConsts.typeshedFallback);
+    const debugTypeshedPath = moduleDirectory.getDirectory().combinePaths(pathConsts.typeshedFallback);
     if (fs.existsSync(debugTypeshedPath)) {
         return fs.realCasePath(debugTypeshedPath);
     }
@@ -56,8 +45,8 @@ export function getTypeShedFallbackPath(fs: FileSystem) {
     return undefined;
 }
 
-export function getTypeshedSubdirectory(typeshedPath: string, isStdLib: boolean) {
-    return combinePaths(typeshedPath, isStdLib ? stdLibFolderName : thirdPartyFolderName);
+export function getTypeshedSubdirectory(typeshedPath: Uri, isStdLib: boolean) {
+    return typeshedPath.combinePaths(isStdLib ? stdLibFolderName : thirdPartyFolderName);
 }
 
 export function findPythonSearchPaths(
@@ -66,21 +55,21 @@ export function findPythonSearchPaths(
     host: Host,
     importFailureInfo: string[],
     includeWatchPathsOnly?: boolean | undefined,
-    workspaceRoot?: string | undefined
-): string[] | undefined {
+    workspaceRoot?: Uri | undefined
+): Uri[] | undefined {
     importFailureInfo.push('Finding python search paths');
 
     if (configOptions.venvPath !== undefined && configOptions.venv) {
         const venvDir = configOptions.venv;
-        const venvPath = combinePaths(configOptions.venvPath, venvDir);
+        const venvPath = configOptions.venvPath.combinePaths(venvDir);
 
-        const foundPaths: string[] = [];
-        const sitePackagesPaths: string[] = [];
+        const foundPaths: Uri[] = [];
+        const sitePackagesPaths: Uri[] = [];
 
         [pathConsts.lib, pathConsts.lib64, pathConsts.libAlternate].forEach((libPath) => {
             const sitePackagesPath = findSitePackagesPath(
                 fs,
-                combinePaths(venvPath, libPath),
+                venvPath.combinePaths(libPath),
                 configOptions.defaultPythonVersion,
                 importFailureInfo
             );
@@ -115,11 +104,7 @@ export function findPythonSearchPaths(
     const pathResult = host.getPythonSearchPaths(configOptions.pythonPath, importFailureInfo);
     if (includeWatchPathsOnly && workspaceRoot) {
         const paths = pathResult.paths
-            .filter(
-                (p) =>
-                    !containsPath(workspaceRoot, p, /* ignoreCase */ true) ||
-                    containsPath(pathResult.prefix, p, /* ignoreCase */ true)
-            )
+            .filter((p) => !p.startsWith(workspaceRoot) || p.startsWith(pathResult.prefix))
             .map((p) => fs.realCasePath(p));
 
         return paths;
@@ -135,10 +120,10 @@ export function isPythonBinary(p: string): boolean {
 
 function findSitePackagesPath(
     fs: FileSystem,
-    libPath: string,
+    libPath: Uri,
     pythonVersion: PythonVersion | undefined,
     importFailureInfo: string[]
-): string | undefined {
+): Uri | undefined {
     if (fs.existsSync(libPath)) {
         importFailureInfo.push(`Found path '${libPath}'; looking for ${pathConsts.sitePackages}`);
     } else {
@@ -146,7 +131,7 @@ function findSitePackagesPath(
         return undefined;
     }
 
-    const sitePackagesPath = combinePaths(libPath, pathConsts.sitePackages);
+    const sitePackagesPath = libPath.combinePaths(pathConsts.sitePackages);
     if (fs.existsSync(sitePackagesPath)) {
         importFailureInfo.push(`Found path '${sitePackagesPath}'`);
         return sitePackagesPath;
@@ -160,8 +145,8 @@ function findSitePackagesPath(
 
     // Candidate directories start with "python3.".
     const candidateDirs = entries.directories.filter((dirName) => {
-        if (dirName.startsWith('python3.')) {
-            const dirPath = combinePaths(libPath, dirName, pathConsts.sitePackages);
+        if (dirName.fileName.startsWith('python3.')) {
+            const dirPath = dirName.combinePaths(pathConsts.sitePackages);
             return fs.existsSync(dirPath);
         }
         return false;
@@ -170,9 +155,11 @@ function findSitePackagesPath(
     // If there is a python3.X directory (where 3.X matches the configured python
     // version), prefer that over other python directories.
     if (pythonVersion) {
-        const preferredDir = candidateDirs.find((dirName) => dirName === `python${versionToString(pythonVersion)}`);
+        const preferredDir = candidateDirs.find(
+            (dirName) => dirName.fileName === `python${versionToString(pythonVersion)}`
+        );
         if (preferredDir) {
-            const dirPath = combinePaths(libPath, preferredDir, pathConsts.sitePackages);
+            const dirPath = preferredDir.combinePaths(pathConsts.sitePackages);
             importFailureInfo.push(`Found path '${dirPath}'`);
             return dirPath;
         }
@@ -182,7 +169,7 @@ function findSitePackagesPath(
     // first directory that starts with "python". Most of the time, there will be
     // only one.
     if (candidateDirs.length > 0) {
-        const dirPath = combinePaths(libPath, candidateDirs[0], pathConsts.sitePackages);
+        const dirPath = candidateDirs[0].combinePaths(pathConsts.sitePackages);
         importFailureInfo.push(`Found path '${dirPath}'`);
         return dirPath;
     }
@@ -190,8 +177,8 @@ function findSitePackagesPath(
     return undefined;
 }
 
-export function getPathsFromPthFiles(fs: FileSystem, parentDir: string): string[] {
-    const searchPaths: string[] = [];
+export function getPathsFromPthFiles(fs: FileSystem, parentDir: Uri): Uri[] {
+    const searchPaths: Uri[] = [];
 
     // Get a list of all *.pth files within the specified directory.
     const pthFiles = fs
@@ -200,7 +187,7 @@ export function getPathsFromPthFiles(fs: FileSystem, parentDir: string): string[
         .sort((a, b) => compareComparableValues(a.name, b.name));
 
     pthFiles.forEach((pthFile) => {
-        const filePath = fs.realCasePath(combinePaths(parentDir, pthFile.name));
+        const filePath = fs.realCasePath(parentDir.combinePaths(pthFile.name));
         const fileStats = tryStat(fs, filePath);
 
         // Skip all files that are much larger than expected.
@@ -210,7 +197,7 @@ export function getPathsFromPthFiles(fs: FileSystem, parentDir: string): string[
             lines.forEach((line) => {
                 const trimmedLine = line.trim();
                 if (trimmedLine.length > 0 && !trimmedLine.startsWith('#') && !trimmedLine.match(/^import\s/)) {
-                    const pthPath = combinePaths(parentDir, trimmedLine);
+                    const pthPath = parentDir.combinePaths(trimmedLine);
                     if (fs.existsSync(pthPath) && isDirectory(fs, pthPath)) {
                         searchPaths.push(fs.realCasePath(pthPath));
                     }
@@ -222,8 +209,8 @@ export function getPathsFromPthFiles(fs: FileSystem, parentDir: string): string[
     return searchPaths;
 }
 
-function addPathIfUnique(pathList: string[], pathToAdd: string) {
-    if (!pathList.some((path) => path === pathToAdd)) {
+function addPathIfUnique(pathList: Uri[], pathToAdd: Uri) {
+    if (!pathList.some((path) => path.key === pathToAdd.key)) {
         pathList.push(pathToAdd);
         return true;
     }
diff --git a/packages/pyright-internal/src/analyzer/service.ts b/packages/pyright-internal/src/analyzer/service.ts
index a4eb1953a..e531b4a7c 100644
--- a/packages/pyright-internal/src/analyzer/service.ts
+++ b/packages/pyright-internal/src/analyzer/service.ts
@@ -24,32 +24,24 @@ import { FileSystem } from '../common/fileSystem';
 import { FileWatcher, FileWatcherEventType, ignoredWatchEventFunction } from '../common/fileWatcher';
 import { Host, HostFactory, NoAccessHost } from '../common/host';
 import { defaultStubsDirectory } from '../common/pathConsts';
-import {
-    FileSpec,
-    combinePaths,
-    containsPath,
-    forEachAncestorDirectory,
-    getDirectoryPath,
-    getFileName,
-    getFileSpec,
-    getFileSystemEntries,
-    getPathComponents,
-    hasPythonExtension,
-    isDirectory,
-    isFile,
-    isFileSystemCaseSensitive,
-    makeDirectories,
-    normalizePath,
-    normalizeSlashes,
-    realCasePath,
-    stripFileExtension,
-    tryRealpath,
-    tryStat,
-} from '../common/pathUtils';
+import { isRootedDiskPath } from '../common/pathUtils';
 import { ServiceProvider } from '../common/serviceProvider';
 import { ServiceKeys } from '../common/serviceProviderExtensions';
 import { Range } from '../common/textRange';
 import { timingStats } from '../common/timing';
+import { Uri } from '../common/uri/uri';
+import {
+    FileSpec,
+    forEachAncestorDirectory,
+    getFileSpec,
+    getFileSystemEntries,
+    hasPythonExtension,
+    isDirectory,
+    isFile,
+    makeDirectories,
+    tryRealpath,
+    tryStat,
+} from '../common/uri/uriUtils';
 import { AnalysisCompleteCallback } from './analysis';
 import {
     BackgroundAnalysisProgram,
@@ -69,7 +61,7 @@ export const pyprojectTomlName = 'pyproject.toml';
 // the analyzer on any files that have not yet been analyzed?
 const _userActivityBackoffTimeInMs = 250;
 
-const _gitDirectory = normalizeSlashes('/.git/');
+const _gitDirectory = '/.git/';
 
 export interface AnalyzerServiceOptions {
     console?: ConsoleInterface;
@@ -99,16 +91,16 @@ export class AnalyzerService {
     private readonly _backgroundAnalysisProgram: BackgroundAnalysisProgram;
     private readonly _serviceProvider: ServiceProvider;
 
-    private _executionRootPath: string;
-    private _typeStubTargetPath: string | undefined;
+    private _executionRootUri: Uri;
+    private _typeStubTargetUri: Uri | undefined;
     private _typeStubTargetIsSingleFile = false;
     private _sourceFileWatcher: FileWatcher | undefined;
     private _reloadConfigTimer: any;
     private _libraryReanalysisTimer: any;
-    private _configFilePath: string | undefined;
+    private _configFileUri: Uri | undefined;
     private _configFileWatcher: FileWatcher | undefined;
     private _libraryFileWatcher: FileWatcher | undefined;
-    private _librarySearchPathsToWatch: string[] | undefined;
+    private _librarySearchUrisToWatch: Uri[] | undefined;
     private _onCompletionCallback: AnalysisCompleteCallback | undefined;
     private _commandLineOptions: CommandLineOptions | undefined;
     private _analyzeTimer: any;
@@ -122,7 +114,7 @@ export class AnalyzerService {
     constructor(instanceName: string, serviceProvider: ServiceProvider, options: AnalyzerServiceOptions) {
         this._instanceName = instanceName;
 
-        this._executionRootPath = '';
+        this._executionRootUri = Uri.empty();
         this._options = options;
 
         this._options.serviceId = this._options.serviceId ?? getNextServiceId(instanceName);
@@ -143,7 +135,9 @@ export class AnalyzerService {
         this._options.cancellationProvider = options.cancellationProvider ?? new DefaultCancellationProvider();
         this._options.hostFactory = options.hostFactory ?? (() => new NoAccessHost());
 
-        this._options.configOptions = options.configOptions ?? new ConfigOptions(process.cwd());
+        this._options.configOptions =
+            options.configOptions ??
+            new ConfigOptions(Uri.file(process.cwd(), this._serviceProvider.fs().isCaseSensitive));
         const importResolver = this._options.importResolverFactory(
             this._serviceProvider,
             this._options.configOptions,
@@ -183,8 +177,8 @@ export class AnalyzerService {
         return this._options.cancellationProvider!;
     }
 
-    get librarySearchPathsToWatch() {
-        return this._librarySearchPathsToWatch;
+    get librarySearchUrisToWatch() {
+        return this._librarySearchUrisToWatch;
     }
 
     get backgroundAnalysisProgram(): BackgroundAnalysisProgram {
@@ -223,12 +217,11 @@ export class AnalyzerService {
             const version = fileInfo.sourceFile.getClientVersion();
             if (version !== undefined) {
                 service.setFileOpened(
-                    fileInfo.sourceFile.getFilePath(),
+                    fileInfo.sourceFile.getUri(),
                     version,
                     fileInfo.sourceFile.getOpenFileContents()!,
                     fileInfo.sourceFile.getIPythonMode(),
-                    fileInfo.chainedSourceFile?.sourceFile.getFilePath(),
-                    fileInfo.sourceFile.getRealFilePath()
+                    fileInfo.chainedSourceFile?.sourceFile.getUri()
                 );
             }
         }
@@ -288,93 +281,81 @@ export class AnalyzerService {
 
         this._backgroundAnalysisProgram.setConfigOptions(configOptions);
 
-        this._executionRootPath = realCasePath(
-            combinePaths(commandLineOptions.executionRoot, configOptions.projectRoot),
-            this.fs
-        );
+        this._executionRootUri = configOptions.projectRoot;
         this._applyConfigOptions(host);
     }
 
-    hasSourceFile(filePath: string): boolean {
-        return this.backgroundAnalysisProgram.hasSourceFile(filePath);
+    hasSourceFile(uri: Uri): boolean {
+        return this.backgroundAnalysisProgram.hasSourceFile(uri);
     }
 
-    isTracked(filePath: string): boolean {
-        return this._program.owns(filePath);
+    isTracked(uri: Uri): boolean {
+        return this._program.owns(uri);
     }
 
     getUserFiles() {
-        return this._program.getUserFiles().map((i) => i.sourceFile.getFilePath());
+        return this._program.getUserFiles().map((i) => i.sourceFile.getUri());
     }
 
     getOpenFiles() {
-        return this._program.getOpened().map((i) => i.sourceFile.getFilePath());
+        return this._program.getOpened().map((i) => i.sourceFile.getUri());
     }
 
     setFileOpened(
-        path: string,
+        uri: Uri,
         version: number | null,
         contents: string,
         ipythonMode = IPythonMode.None,
-        chainedFilePath?: string,
-        realFilePath?: string
+        chainedFileUri?: Uri
     ) {
         // Open the file. Notebook cells are always tracked as they aren't 3rd party library files.
         // This is how it's worked in the past since each notebook used to have its own
         // workspace and the workspace include setting marked all cells as tracked.
-        this._backgroundAnalysisProgram.setFileOpened(path, version, contents, {
-            isTracked: this.isTracked(path) || ipythonMode !== IPythonMode.None,
+        this._backgroundAnalysisProgram.setFileOpened(uri, version, contents, {
+            isTracked: this.isTracked(uri) || ipythonMode !== IPythonMode.None,
             ipythonMode,
-            chainedFilePath,
-            realFilePath,
+            chainedFileUri: chainedFileUri,
         });
         this._scheduleReanalysis(/* requireTrackedFileUpdate */ false);
     }
 
-    getChainedFilePath(path: string): string | undefined {
-        return this._backgroundAnalysisProgram.getChainedFilePath(path);
+    getChainedUri(uri: Uri): Uri | undefined {
+        return this._backgroundAnalysisProgram.getChainedUri(uri);
     }
 
-    updateChainedFilePath(path: string, chainedFilePath: string | undefined) {
-        this._backgroundAnalysisProgram.updateChainedFilePath(path, chainedFilePath);
+    updateChainedUri(uri: Uri, chainedFileUri: Uri | undefined) {
+        this._backgroundAnalysisProgram.updateChainedUri(uri, chainedFileUri);
         this._scheduleReanalysis(/* requireTrackedFileUpdate */ false);
     }
 
-    updateOpenFileContents(
-        path: string,
-        version: number | null,
-        contents: string,
-        ipythonMode = IPythonMode.None,
-        realFilePath?: string
-    ) {
-        this._backgroundAnalysisProgram.updateOpenFileContents(path, version, contents, {
-            isTracked: this.isTracked(path),
+    updateOpenFileContents(uri: Uri, version: number | null, contents: string, ipythonMode = IPythonMode.None) {
+        this._backgroundAnalysisProgram.updateOpenFileContents(uri, version, contents, {
+            isTracked: this.isTracked(uri),
             ipythonMode,
-            chainedFilePath: undefined,
-            realFilePath,
+            chainedFileUri: undefined,
         });
         this._scheduleReanalysis(/* requireTrackedFileUpdate */ false);
     }
 
-    setFileClosed(path: string, isTracked?: boolean) {
-        this._backgroundAnalysisProgram.setFileClosed(path, isTracked);
+    setFileClosed(uri: Uri, isTracked?: boolean) {
+        this._backgroundAnalysisProgram.setFileClosed(uri, isTracked);
         this._scheduleReanalysis(/* requireTrackedFileUpdate */ false);
     }
 
-    addInterimFile(path: string) {
-        this._backgroundAnalysisProgram.addInterimFile(path);
+    addInterimFile(uri: Uri) {
+        this._backgroundAnalysisProgram.addInterimFile(uri);
     }
 
-    getParseResult(path: string) {
-        return this._program.getParseResults(path);
+    getParseResult(uri: Uri) {
+        return this._program.getParseResults(uri);
     }
 
-    getSourceFile(path: string) {
-        return this._program.getBoundSourceFile(path);
+    getSourceFile(uri: Uri) {
+        return this._program.getBoundSourceFile(uri);
     }
 
-    getTextOnRange(filePath: string, range: Range, token: CancellationToken) {
-        return this._program.getTextOnRange(filePath, range, token);
+    getTextOnRange(fileUri: Uri, range: Range, token: CancellationToken) {
+        return this._program.getTextOnRange(fileUri, range, token);
     }
 
     getEvaluator(): TypeEvaluator | undefined {
@@ -401,15 +382,15 @@ export class AnalyzerService {
     }
 
     printDependencies(verbose: boolean) {
-        this._program.printDependencies(this._executionRootPath, verbose);
+        this._program.printDependencies(this._executionRootUri, verbose);
     }
 
-    analyzeFile(filePath: string, token: CancellationToken): Promise<boolean> {
-        return this._backgroundAnalysisProgram.analyzeFile(filePath, token);
+    analyzeFile(fileUri: Uri, token: CancellationToken): Promise<boolean> {
+        return this._backgroundAnalysisProgram.analyzeFile(fileUri, token);
     }
 
-    getDiagnosticsForRange(filePath: string, range: Range, token: CancellationToken): Promise<Diagnostic[]> {
-        return this._backgroundAnalysisProgram.getDiagnosticsForRange(filePath, range, token);
+    getDiagnosticsForRange(fileUri: Uri, range: Range, token: CancellationToken): Promise<Diagnostic[]> {
+        return this._backgroundAnalysisProgram.getDiagnosticsForRange(fileUri, range, token);
     }
 
     getConfigOptions() {
@@ -434,36 +415,36 @@ export class AnalyzerService {
         return this._getConfigOptions(this._backgroundAnalysisProgram.host, commandLineOptions);
     }
 
-    test_getFileNamesFromFileSpecs(): string[] {
+    test_getFileNamesFromFileSpecs(): Uri[] {
         return this._getFileNamesFromFileSpecs();
     }
 
-    test_shouldHandleSourceFileWatchChanges(path: string, isFile: boolean) {
-        return this._shouldHandleSourceFileWatchChanges(path, isFile);
+    test_shouldHandleSourceFileWatchChanges(uri: Uri, isFile: boolean) {
+        return this._shouldHandleSourceFileWatchChanges(uri, isFile);
     }
 
-    test_shouldHandleLibraryFileWatchChanges(path: string, libSearchPaths: string[]) {
-        return this._shouldHandleLibraryFileWatchChanges(path, libSearchPaths);
+    test_shouldHandleLibraryFileWatchChanges(uri: Uri, libSearchUris: Uri[]) {
+        return this._shouldHandleLibraryFileWatchChanges(uri, libSearchUris);
     }
 
     writeTypeStub(token: CancellationToken): void {
-        const typingsSubdirPath = this._getTypeStubFolder();
+        const typingsSubdirUri = this._getTypeStubFolder();
 
         this._program.writeTypeStub(
-            this._typeStubTargetPath ?? '',
+            this._typeStubTargetUri ?? Uri.empty(),
             this._typeStubTargetIsSingleFile,
-            typingsSubdirPath,
+            typingsSubdirUri,
             token
         );
     }
 
     writeTypeStubInBackground(token: CancellationToken): Promise<any> {
-        const typingsSubdirPath = this._getTypeStubFolder();
+        const typingsSubdirUri = this._getTypeStubFolder();
 
         return this._backgroundAnalysisProgram.writeTypeStub(
-            this._typeStubTargetPath ?? '',
+            this._typeStubTargetUri ?? Uri.empty(),
             this._typeStubTargetIsSingleFile,
-            typingsSubdirPath,
+            typingsSubdirUri,
             token
         );
     }
@@ -527,33 +508,39 @@ export class AnalyzerService {
     // Calculates the effective options based on the command-line options,
     // an optional config file, and default values.
     private _getConfigOptions(host: Host, commandLineOptions: CommandLineOptions): ConfigOptions {
-        let projectRoot = realCasePath(commandLineOptions.executionRoot, this.fs);
-        let configFilePath: string | undefined;
-        let pyprojectFilePath: string | undefined;
+        let projectRoot = this.fs.realCasePath(
+            Uri.file(commandLineOptions.executionRoot, this.fs.isCaseSensitive, /* checkRelative */ true)
+        );
+        const executionRoot = this.fs.realCasePath(
+            Uri.file(commandLineOptions.executionRoot, this.fs.isCaseSensitive, /* checkRelative */ true)
+        );
+        let configFilePath: Uri | undefined;
+        let pyprojectFilePath: Uri | undefined;
 
         if (commandLineOptions.configFilePath) {
             // If the config file path was specified, determine whether it's
             // a directory (in which case the default config file name is assumed)
             // or a file.
-            configFilePath = realCasePath(
-                combinePaths(commandLineOptions.executionRoot, normalizePath(commandLineOptions.configFilePath)),
-                this.fs
+            configFilePath = this.fs.realCasePath(
+                isRootedDiskPath(commandLineOptions.configFilePath)
+                    ? Uri.file(commandLineOptions.configFilePath, this.fs.isCaseSensitive, /* checkRelative */ true)
+                    : projectRoot.combinePaths(commandLineOptions.configFilePath)
             );
             if (!this.fs.existsSync(configFilePath)) {
-                this._console.info(`Configuration file not found at ${configFilePath}.`);
-                configFilePath = realCasePath(commandLineOptions.executionRoot, this.fs);
+                this._console.info(`Configuration file not found at ${configFilePath.toUserVisibleString()}.`);
+                configFilePath = projectRoot;
             } else {
-                if (configFilePath.toLowerCase().endsWith('.json')) {
-                    projectRoot = realCasePath(getDirectoryPath(configFilePath), this.fs);
+                if (configFilePath.lastExtension.endsWith('.json')) {
+                    projectRoot = configFilePath.getDirectory();
                 } else {
                     projectRoot = configFilePath;
                     configFilePath = this._findConfigFile(configFilePath);
                     if (!configFilePath) {
-                        this._console.info(`Configuration file not found at ${projectRoot}.`);
+                        this._console.info(`Configuration file not found at ${projectRoot.toUserVisibleString()}.`);
                     }
                 }
             }
-        } else if (projectRoot) {
+        } else if (commandLineOptions.executionRoot) {
             // In a project-based IDE like VS Code, we should assume that the
             // project root directory contains the config file.
             configFilePath = this._findConfigFile(projectRoot);
@@ -566,7 +553,7 @@ export class AnalyzerService {
             }
 
             if (configFilePath) {
-                projectRoot = getDirectoryPath(configFilePath);
+                projectRoot = configFilePath.getDirectory();
             } else {
                 this._console.log(`No configuration file found.`);
                 configFilePath = undefined;
@@ -582,8 +569,8 @@ export class AnalyzerService {
             }
 
             if (pyprojectFilePath) {
-                projectRoot = getDirectoryPath(pyprojectFilePath);
-                this._console.log(`pyproject.toml file found at ${projectRoot}.`);
+                projectRoot = pyprojectFilePath.getDirectory();
+                this._console.log(`pyproject.toml file found at ${projectRoot.toUserVisibleString()}.`);
             } else {
                 this._console.log(`No pyproject.toml file found.`);
             }
@@ -596,7 +583,9 @@ export class AnalyzerService {
             this._console.info(
                 `Setting pythonPath for service "${this._instanceName}": ` + `"${commandLineOptions.pythonPath}"`
             );
-            (configOptions.pythonPath = commandLineOptions.pythonPath), this.fs;
+            configOptions.pythonPath = this.fs.realCasePath(
+                Uri.file(commandLineOptions.pythonPath, this.fs.isCaseSensitive, /* checkRelative */ true)
+            );
         }
 
         if (commandLineOptions.pythonEnvironmentName) {
@@ -619,19 +608,19 @@ export class AnalyzerService {
 
         if (commandLineOptions.includeFileSpecs.length > 0) {
             commandLineOptions.includeFileSpecs.forEach((fileSpec) => {
-                configOptions.include.push(getFileSpec(this.serviceProvider, projectRoot, fileSpec));
+                configOptions.include.push(getFileSpec(projectRoot, fileSpec));
             });
         }
 
         if (commandLineOptions.excludeFileSpecs.length > 0) {
             commandLineOptions.excludeFileSpecs.forEach((fileSpec) => {
-                configOptions.exclude.push(getFileSpec(this.serviceProvider, projectRoot, fileSpec));
+                configOptions.exclude.push(getFileSpec(projectRoot, fileSpec));
             });
         }
 
         if (commandLineOptions.ignoreFileSpecs.length > 0) {
             commandLineOptions.ignoreFileSpecs.forEach((fileSpec) => {
-                configOptions.ignore.push(getFileSpec(this.serviceProvider, projectRoot, fileSpec));
+                configOptions.ignore.push(getFileSpec(projectRoot, fileSpec));
             });
         }
 
@@ -640,28 +629,26 @@ export class AnalyzerService {
                 // If no config file was found and there are no explicit include
                 // paths specified, assume the caller wants to include all source
                 // files under the execution root path.
-                configOptions.include.push(getFileSpec(this.serviceProvider, commandLineOptions.executionRoot, '.'));
+                configOptions.include.push(getFileSpec(executionRoot, '.'));
             }
 
             if (commandLineOptions.excludeFileSpecs.length === 0) {
                 // Add a few common excludes to avoid long scan times.
                 defaultExcludes.forEach((exclude) => {
-                    configOptions.exclude.push(
-                        getFileSpec(this.serviceProvider, commandLineOptions.executionRoot, exclude)
-                    );
+                    configOptions.exclude.push(getFileSpec(executionRoot, exclude));
                 });
             }
         }
 
-        this._configFilePath = configFilePath || pyprojectFilePath;
+        this._configFileUri = configFilePath || pyprojectFilePath;
 
         // If we found a config file, parse it to compute the effective options.
         let configJsonObj: object | undefined;
         if (configFilePath) {
-            this._console.info(`Loading configuration file at ${configFilePath}`);
+            this._console.info(`Loading configuration file at ${configFilePath.toUserVisibleString()}`);
             configJsonObj = this._parseJsonConfigFile(configFilePath);
         } else if (pyprojectFilePath) {
-            this._console.info(`Loading pyproject.toml file at ${pyprojectFilePath}`);
+            this._console.info(`Loading pyproject.toml file at ${pyprojectFilePath.toUserVisibleString()}`);
             configJsonObj = this._parsePyprojectTomlFile(pyprojectFilePath);
         }
 
@@ -674,20 +661,20 @@ export class AnalyzerService {
                 commandLineOptions.diagnosticSeverityOverrides
             );
 
-            const configFileDir = getDirectoryPath(this._configFilePath!);
+            const configFileDir = this._configFileUri!.getDirectory();
 
             // If no include paths were provided, assume that all files within
             // the project should be included.
             if (configOptions.include.length === 0) {
-                this._console.info(`No include entries specified; assuming ${configFileDir}`);
-                configOptions.include.push(getFileSpec(this.serviceProvider, configFileDir, '.'));
+                this._console.info(`No include entries specified; assuming ${configFileDir.toUserVisibleString()}`);
+                configOptions.include.push(getFileSpec(configFileDir, '.'));
             }
 
             // If there was no explicit set of excludes, add a few common ones to avoid long scan times.
             if (configOptions.exclude.length === 0) {
                 defaultExcludes.forEach((exclude) => {
                     this._console.info(`Auto-excluding ${exclude}`);
-                    configOptions.exclude.push(getFileSpec(this.serviceProvider, configFileDir, exclude));
+                    configOptions.exclude.push(getFileSpec(configFileDir, exclude));
                 });
 
                 if (configOptions.autoExcludeVenv === undefined) {
@@ -709,7 +696,9 @@ export class AnalyzerService {
         if (commandLineOptions.includeFileSpecsOverride) {
             configOptions.include = [];
             commandLineOptions.includeFileSpecsOverride.forEach((include) => {
-                configOptions.include.push(getFileSpec(this.serviceProvider, include, '.'));
+                configOptions.include.push(
+                    getFileSpec(Uri.file(include, this.fs.isCaseSensitive, /* checkRelative */ true), '.')
+                );
             });
         }
 
@@ -729,17 +718,17 @@ export class AnalyzerService {
         // duplicates.
         if (commandLineOptions.venvPath) {
             if (!configOptions.venvPath) {
-                configOptions.venvPath = commandLineOptions.venvPath;
+                configOptions.venvPath = projectRoot.combinePaths(commandLineOptions.venvPath);
             } else {
-                reportDuplicateSetting('venvPath', configOptions.venvPath);
+                reportDuplicateSetting('venvPath', configOptions.venvPath.toUserVisibleString());
             }
         }
 
         if (commandLineOptions.typeshedPath) {
             if (!configOptions.typeshedPath) {
-                configOptions.typeshedPath = realCasePath(commandLineOptions.typeshedPath, this.fs);
+                configOptions.typeshedPath = projectRoot.combinePaths(commandLineOptions.typeshedPath);
             } else {
-                reportDuplicateSetting('typeshedPath', configOptions.typeshedPath);
+                reportDuplicateSetting('typeshedPath', configOptions.typeshedPath.toUserVisibleString());
             }
         }
 
@@ -759,9 +748,7 @@ export class AnalyzerService {
             this._console.info(`Excluding typeshed stdlib stubs according to VERSIONS file:`);
             excludeList.forEach((exclude) => {
                 this._console.info(`    ${exclude}`);
-                configOptions.exclude.push(
-                    getFileSpec(this.serviceProvider, commandLineOptions.executionRoot, exclude)
-                );
+                configOptions.exclude.push(getFileSpec(executionRoot, exclude.getFilePath()));
             });
         }
 
@@ -788,9 +775,9 @@ export class AnalyzerService {
 
         if (commandLineOptions.stubPath) {
             if (!configOptions.stubPath) {
-                configOptions.stubPath = realCasePath(commandLineOptions.stubPath, this.fs);
+                configOptions.stubPath = this.fs.realCasePath(projectRoot.combinePaths(commandLineOptions.stubPath));
             } else {
-                reportDuplicateSetting('stubPath', configOptions.stubPath);
+                reportDuplicateSetting('stubPath', configOptions.stubPath.toUserVisibleString());
             }
         }
 
@@ -801,33 +788,37 @@ export class AnalyzerService {
             }
         } else {
             // If no stub path was specified, use a default path.
-            configOptions.stubPath = normalizePath(combinePaths(configOptions.projectRoot, defaultStubsDirectory));
+            configOptions.stubPath = configOptions.projectRoot.combinePaths(defaultStubsDirectory);
         }
 
         // Do some sanity checks on the specified settings and report missing
         // or inconsistent information.
         if (configOptions.venvPath) {
             if (!this.fs.existsSync(configOptions.venvPath) || !isDirectory(this.fs, configOptions.venvPath)) {
-                this._console.error(`venvPath ${configOptions.venvPath} is not a valid directory.`);
+                this._console.error(
+                    `venvPath ${configOptions.venvPath.toUserVisibleString()} is not a valid directory.`
+                );
             }
 
             // venvPath without venv means it won't do anything while resolveImport.
             // so first, try to set venv from existing configOption if it is null. if both are null,
             // then, resolveImport won't consider venv
             configOptions.venv = configOptions.venv ?? this._configOptions.venv;
-            if (configOptions.venv) {
-                const fullVenvPath = combinePaths(configOptions.venvPath, configOptions.venv);
+            if (configOptions.venv && configOptions.venvPath) {
+                const fullVenvPath = configOptions.venvPath.combinePaths(configOptions.venv);
 
                 if (!this.fs.existsSync(fullVenvPath) || !isDirectory(this.fs, fullVenvPath)) {
                     this._console.error(
-                        `venv ${configOptions.venv} subdirectory not found in venv path ${configOptions.venvPath}.`
+                        `venv ${
+                            configOptions.venv
+                        } subdirectory not found in venv path ${configOptions.venvPath.toUserVisibleString()}.`
                     );
                 } else {
                     const importFailureInfo: string[] = [];
                     if (findPythonSearchPaths(this.fs, configOptions, host, importFailureInfo) === undefined) {
                         this._console.error(
                             `site-packages directory cannot be located for venvPath ` +
-                                `${configOptions.venvPath} and venv ${configOptions.venv}.`
+                                `${configOptions.venvPath.toUserVisibleString()} and venv ${configOptions.venv}.`
                         );
 
                         if (configOptions.verboseOutput) {
@@ -849,7 +840,9 @@ export class AnalyzerService {
 
         if (configOptions.typeshedPath) {
             if (!this.fs.existsSync(configOptions.typeshedPath) || !isDirectory(this.fs, configOptions.typeshedPath)) {
-                this._console.error(`typeshedPath ${configOptions.typeshedPath} is not a valid directory.`);
+                this._console.error(
+                    `typeshedPath ${configOptions.typeshedPath.toUserVisibleString()} is not a valid directory.`
+                );
             }
         }
 
@@ -859,9 +852,9 @@ export class AnalyzerService {
     private _getTypeStubFolder() {
         const stubPath =
             this._configOptions.stubPath ??
-            realCasePath(combinePaths(this._configOptions.projectRoot, defaultStubsDirectory), this.fs);
+            this.fs.realCasePath(this._configOptions.projectRoot.combinePaths(defaultStubsDirectory));
 
-        if (!this._typeStubTargetPath || !this._typeStubTargetImportName) {
+        if (!this._typeStubTargetUri || !this._typeStubTargetImportName) {
             const errMsg = `Import '${this._typeStubTargetImportName}'` + ` could not be resolved`;
             this._console.error(errMsg);
             throw new Error(errMsg);
@@ -882,14 +875,14 @@ export class AnalyzerService {
                 this.fs.mkdirSync(stubPath);
             }
         } catch (e: any) {
-            const errMsg = `Could not create typings directory '${stubPath}'`;
+            const errMsg = `Could not create typings directory '${stubPath.toUserVisibleString()}'`;
             this._console.error(errMsg);
             throw new Error(errMsg);
         }
 
         // Generate a typings subdirectory hierarchy.
-        const typingsSubdirPath = combinePaths(stubPath, typeStubInputTargetParts[0]);
-        const typingsSubdirHierarchy = combinePaths(stubPath, ...typeStubInputTargetParts);
+        const typingsSubdirPath = stubPath.combinePaths(typeStubInputTargetParts[0]);
+        const typingsSubdirHierarchy = stubPath.combinePaths(...typeStubInputTargetParts);
 
         try {
             // Generate a new typings subdirectory if necessary.
@@ -897,7 +890,7 @@ export class AnalyzerService {
                 makeDirectories(this.fs, typingsSubdirHierarchy, stubPath);
             }
         } catch (e: any) {
-            const errMsg = `Could not create typings subdirectory '${typingsSubdirHierarchy}'`;
+            const errMsg = `Could not create typings subdirectory '${typingsSubdirHierarchy.toUserVisibleString()}'`;
             this._console.error(errMsg);
             throw new Error(errMsg);
         }
@@ -905,33 +898,33 @@ export class AnalyzerService {
         return typingsSubdirPath;
     }
 
-    private _findConfigFileHereOrUp(searchPath: string): string | undefined {
+    private _findConfigFileHereOrUp(searchPath: Uri): Uri | undefined {
         return forEachAncestorDirectory(searchPath, (ancestor) => this._findConfigFile(ancestor));
     }
 
-    private _findConfigFile(searchPath: string): string | undefined {
+    private _findConfigFile(searchPath: Uri): Uri | undefined {
         for (const name of configFileNames) {
-            const fileName = combinePaths(searchPath, name);
+            const fileName = searchPath.combinePaths(name);
             if (this.fs.existsSync(fileName)) {
-                return realCasePath(fileName, this.fs);
+                return this.fs.realCasePath(fileName);
             }
         }
         return undefined;
     }
 
-    private _findPyprojectTomlFileHereOrUp(searchPath: string): string | undefined {
+    private _findPyprojectTomlFileHereOrUp(searchPath: Uri): Uri | undefined {
         return forEachAncestorDirectory(searchPath, (ancestor) => this._findPyprojectTomlFile(ancestor));
     }
 
-    private _findPyprojectTomlFile(searchPath: string) {
-        const fileName = combinePaths(searchPath, pyprojectTomlName);
+    private _findPyprojectTomlFile(searchPath: Uri) {
+        const fileName = searchPath.combinePaths(pyprojectTomlName);
         if (this.fs.existsSync(fileName)) {
-            return realCasePath(fileName, this.fs);
+            return this.fs.realCasePath(fileName);
         }
         return undefined;
     }
 
-    private _parseJsonConfigFile(configPath: string): object | undefined {
+    private _parseJsonConfigFile(configPath: Uri): object | undefined {
         return this._attemptParseFile(configPath, (fileContents) => {
             const errors: JSONC.ParseError[] = [];
             const result = JSONC.parse(fileContents, errors, { allowTrailingComma: true });
@@ -943,7 +936,7 @@ export class AnalyzerService {
         });
     }
 
-    private _parsePyprojectTomlFile(pyprojectPath: string): object | undefined {
+    private _parsePyprojectTomlFile(pyprojectPath: Uri): object | undefined {
         return this._attemptParseFile(pyprojectPath, (fileContents, attemptCount) => {
             try {
                 const configObj = TOML.parse(fileContents);
@@ -955,13 +948,15 @@ export class AnalyzerService {
                 throw e;
             }
 
-            this._console.info(`Pyproject file "${pyprojectPath}" has no "[tool.pyright]" section.`);
+            this._console.info(
+                `Pyproject file "${pyprojectPath.toUserVisibleString()}" has no "[tool.pyright]" section.`
+            );
             return undefined;
         });
     }
 
     private _attemptParseFile(
-        filePath: string,
+        fileUri: Uri,
         parseCallback: (contents: string, attempt: number) => object | undefined
     ): object | undefined {
         let fileContents = '';
@@ -970,9 +965,9 @@ export class AnalyzerService {
         while (true) {
             // Attempt to read the file contents.
             try {
-                fileContents = this.fs.readFileSync(filePath, 'utf8');
+                fileContents = this.fs.readFileSync(fileUri, 'utf8');
             } catch {
-                this._console.error(`Config file "${filePath}" could not be read.`);
+                this._console.error(`Config file "${fileUri.toUserVisibleString()}" could not be read.`);
                 this._reportConfigParseError();
                 return undefined;
             }
@@ -993,7 +988,9 @@ export class AnalyzerService {
             // may have been partially written when we read it, resulting in parse
             // errors. We'll give it a little more time and try again.
             if (parseAttemptCount++ >= 5) {
-                this._console.error(`Config file "${filePath}" could not be parsed. Verify that format is correct.`);
+                this._console.error(
+                    `Config file "${fileUri.toUserVisibleString()}" could not be parsed. Verify that format is correct.`
+                );
                 this._reportConfigParseError();
                 return undefined;
             }
@@ -1002,16 +999,16 @@ export class AnalyzerService {
         return undefined;
     }
 
-    private _getFileNamesFromFileSpecs(): string[] {
+    private _getFileNamesFromFileSpecs(): Uri[] {
         // Use a map to generate a list of unique files.
-        const fileMap = new Map<string, string>();
+        const fileMap = new Map<string, Uri>();
 
         // Scan all matching files from file system.
         timingStats.findFilesTime.timeOperation(() => {
             const matchedFiles = this._matchFiles(this._configOptions.include, this._configOptions.exclude);
 
             for (const file of matchedFiles) {
-                fileMap.set(file, file);
+                fileMap.set(file.key, file);
             }
         });
 
@@ -1019,9 +1016,9 @@ export class AnalyzerService {
         // files in file system but only exist in memory (ex, virtual workspace)
         this._backgroundAnalysisProgram.program
             .getOpened()
-            .map((o) => o.sourceFile.getFilePath())
+            .map((o) => o.sourceFile.getUri())
             .filter((f) => matchFileSpecs(this._program.configOptions, f))
-            .forEach((f) => fileMap.set(f, f));
+            .forEach((f) => fileMap.set(f.key, f));
 
         return Array.from(fileMap.values());
     }
@@ -1035,60 +1032,60 @@ export class AnalyzerService {
         // Are we in type stub generation mode? If so, we need to search
         // for a different set of files.
         if (this._typeStubTargetImportName) {
-            const execEnv = this._configOptions.findExecEnvironment(this._executionRootPath);
+            const execEnv = this._configOptions.findExecEnvironment(this._executionRootUri);
             const moduleDescriptor = createImportedModuleDescriptor(this._typeStubTargetImportName);
             const importResult = this._backgroundAnalysisProgram.importResolver.resolveImport(
-                '',
+                Uri.empty(),
                 execEnv,
                 moduleDescriptor
             );
 
             if (importResult.isImportFound) {
-                const filesToImport: string[] = [];
+                const filesToImport: Uri[] = [];
 
                 // Determine the directory that contains the root package.
-                const finalResolvedPath = importResult.resolvedPaths[importResult.resolvedPaths.length - 1];
+                const finalResolvedPath = importResult.resolvedUris[importResult.resolvedUris.length - 1];
                 const isFinalPathFile = isFile(this.fs, finalResolvedPath);
                 const isFinalPathInitFile =
-                    isFinalPathFile && stripFileExtension(getFileName(finalResolvedPath)) === '__init__';
+                    isFinalPathFile && finalResolvedPath.stripAllExtensions().fileName === '__init__';
 
                 let rootPackagePath = finalResolvedPath;
 
                 if (isFinalPathFile) {
                     // If the module is a __init__.pyi? file, use its parent directory instead.
-                    rootPackagePath = getDirectoryPath(rootPackagePath);
+                    rootPackagePath = rootPackagePath.getDirectory();
                 }
 
-                for (let i = importResult.resolvedPaths.length - 2; i >= 0; i--) {
-                    if (importResult.resolvedPaths[i]) {
-                        rootPackagePath = importResult.resolvedPaths[i];
+                for (let i = importResult.resolvedUris.length - 2; i >= 0; i--) {
+                    if (!importResult.resolvedUris[i].isEmpty()) {
+                        rootPackagePath = importResult.resolvedUris[i];
                     } else {
                         // If there was no file corresponding to this portion
                         // of the name path, assume that it's contained
                         // within its parent directory.
-                        rootPackagePath = getDirectoryPath(rootPackagePath);
+                        rootPackagePath = rootPackagePath.getDirectory();
                     }
                 }
 
                 if (isDirectory(this.fs, rootPackagePath)) {
-                    this._typeStubTargetPath = rootPackagePath;
+                    this._typeStubTargetUri = rootPackagePath;
                 } else if (isFile(this.fs, rootPackagePath)) {
                     // This can occur if there is a "dir/__init__.py" at the same level as a
                     // module "dir/module.py" that is specifically targeted for stub generation.
-                    this._typeStubTargetPath = getDirectoryPath(rootPackagePath);
+                    this._typeStubTargetUri = rootPackagePath.getDirectory();
                 }
 
                 if (!finalResolvedPath) {
                     this._typeStubTargetIsSingleFile = false;
                 } else {
                     filesToImport.push(finalResolvedPath);
-                    this._typeStubTargetIsSingleFile = importResult.resolvedPaths.length === 1 && !isFinalPathInitFile;
+                    this._typeStubTargetIsSingleFile = importResult.resolvedUris.length === 1 && !isFinalPathInitFile;
                 }
 
                 // Add the implicit import paths.
                 importResult.filteredImplicitImports.forEach((implicitImport) => {
-                    if (ImportResolver.isSupportedImportSourceFile(implicitImport.path)) {
-                        filesToImport.push(implicitImport.path);
+                    if (ImportResolver.isSupportedImportSourceFile(implicitImport.uri)) {
+                        filesToImport.push(implicitImport.uri);
                     }
                 });
 
@@ -1098,7 +1095,7 @@ export class AnalyzerService {
                 this._console.error(`Import '${this._typeStubTargetImportName}' not found`);
             }
         } else if (!this._options.skipScanningUserFiles) {
-            let fileList: string[] = [];
+            let fileList: Uri[] = [];
             this._console.log(`Searching for source files`);
             fileList = this._getFileNamesFromFileSpecs();
 
@@ -1117,18 +1114,14 @@ export class AnalyzerService {
         this._requireTrackedFileUpdate = false;
     }
 
-    private _matchFiles(include: FileSpec[], exclude: FileSpec[]): string[] {
+    private _matchFiles(include: FileSpec[], exclude: FileSpec[]): Uri[] {
         const envMarkers = [['bin', 'activate'], ['Scripts', 'activate'], ['pyvenv.cfg']];
-        const results: string[] = [];
+        const results: Uri[] = [];
         const startTime = Date.now();
         const longOperationLimitInSec = 10;
         let loggedLongOperationError = false;
 
-        const visitDirectoryUnchecked = (
-            absolutePath: string,
-            includeRegExp: RegExp,
-            hasDirectoryWildcard: boolean
-        ) => {
+        const visitDirectoryUnchecked = (absolutePath: Uri, includeRegExp: RegExp, hasDirectoryWildcard: boolean) => {
             if (!loggedLongOperationError) {
                 const secondsSinceStart = (Date.now() - startTime) * 0.001;
 
@@ -1152,32 +1145,27 @@ export class AnalyzerService {
             }
 
             if (this._configOptions.autoExcludeVenv) {
-                if (envMarkers.some((f) => this.fs.existsSync(combinePaths(absolutePath, ...f)))) {
+                if (envMarkers.some((f) => this.fs.existsSync(absolutePath.combinePaths(...f)))) {
                     // Save auto exclude paths in the configOptions once we found them.
                     if (!FileSpec.isInPath(absolutePath, exclude)) {
-                        exclude.push(
-                            getFileSpec(this.serviceProvider, this._configOptions.projectRoot, `${absolutePath}/**`)
-                        );
+                        exclude.push(getFileSpec(this._configOptions.projectRoot, `${absolutePath}/**`));
                     }
 
-                    this._console.info(`Auto-excluding ${absolutePath}`);
+                    this._console.info(`Auto-excluding ${absolutePath.toUserVisibleString()}`);
                     return;
                 }
             }
 
             const { files, directories } = getFileSystemEntries(this.fs, absolutePath);
 
-            for (const file of files) {
-                const filePath = combinePaths(absolutePath, file);
-
+            for (const filePath of files) {
                 if (FileSpec.matchIncludeFileSpec(includeRegExp, exclude, filePath)) {
                     results.push(filePath);
                 }
             }
 
-            for (const directory of directories) {
-                const dirPath = combinePaths(absolutePath, directory);
-                if (includeRegExp.test(dirPath) || hasDirectoryWildcard) {
+            for (const dirPath of directories) {
+                if (dirPath.matchesRegex(includeRegExp) || hasDirectoryWildcard) {
                     if (!FileSpec.isInPath(dirPath, exclude)) {
                         visitDirectory(dirPath, includeRegExp, hasDirectoryWildcard);
                     }
@@ -1186,23 +1174,23 @@ export class AnalyzerService {
         };
 
         const seenDirs = new Set<string>();
-        const visitDirectory = (absolutePath: string, includeRegExp: RegExp, hasDirectoryWildcard: boolean) => {
+        const visitDirectory = (absolutePath: Uri, includeRegExp: RegExp, hasDirectoryWildcard: boolean) => {
             const realDirPath = tryRealpath(this.fs, absolutePath);
             if (!realDirPath) {
                 this._console.warn(`Skipping broken link "${absolutePath}"`);
                 return;
             }
 
-            if (seenDirs.has(realDirPath)) {
+            if (seenDirs.has(realDirPath.key)) {
                 this._console.warn(`Skipping recursive symlink "${absolutePath}" -> "${realDirPath}"`);
                 return;
             }
-            seenDirs.add(realDirPath);
+            seenDirs.add(realDirPath.key);
 
             try {
                 visitDirectoryUnchecked(absolutePath, includeRegExp, hasDirectoryWildcard);
             } finally {
-                seenDirs.delete(realDirPath);
+                seenDirs.delete(realDirPath.key);
             }
         };
 
@@ -1220,7 +1208,9 @@ export class AnalyzerService {
                 }
 
                 if (!foundFileSpec) {
-                    this._console.error(`File or directory "${includeSpec.wildcardRoot}" does not exist.`);
+                    this._console.error(
+                        `File or directory "${includeSpec.wildcardRoot.toUserVisibleString()}" does not exist.`
+                    );
                 }
             }
         });
@@ -1244,7 +1234,7 @@ export class AnalyzerService {
 
         if (this._configOptions.include.length > 0) {
             const fileList = this._configOptions.include.map((spec) => {
-                return combinePaths(this._executionRootPath, spec.wildcardRoot);
+                return spec.wildcardRoot;
             });
 
             try {
@@ -1252,7 +1242,7 @@ export class AnalyzerService {
                     this._console.info(`Adding fs watcher for directories:\n ${fileList.join('\n')}`);
                 }
 
-                const isIgnored = ignoredWatchEventFunction(fileList);
+                const isIgnored = ignoredWatchEventFunction(fileList.map((f) => f.getFilePath()));
                 this._sourceFileWatcher = this.fs.createFileSystemWatcher(fileList, (event, path) => {
                     if (!path) {
                         return;
@@ -1262,17 +1252,17 @@ export class AnalyzerService {
                         this._console.info(`SourceFile: Received fs event '${event}' for path '${path}'`);
                     }
 
-                    if (isIgnored(path)) {
+                    if (isIgnored(path.getFilePath())) {
                         return;
                     }
 
                     // Wholesale ignore events that appear to be from tmp file / .git modification.
-                    if (path.endsWith('.tmp') || path.endsWith('.git') || path.includes(_gitDirectory)) {
+                    if (path.pathEndsWith('.tmp') || path.pathEndsWith('.git') || path.pathIncludes(_gitDirectory)) {
                         return;
                     }
 
                     // Make sure path is the true case.
-                    path = realCasePath(path, this.fs);
+                    path = this.fs.realCasePath(path);
 
                     const eventInfo = getEventInfo(this.fs, this._console, this._program, event, path);
                     if (!eventInfo) {
@@ -1304,7 +1294,11 @@ export class AnalyzerService {
                     this._scheduleReanalysis(/* requireTrackedFileUpdate */ true);
                 });
             } catch {
-                this._console.error(`Exception caught when installing fs watcher for:\n ${fileList.join('\n')}`);
+                this._console.error(
+                    `Exception caught when installing fs watcher for:\n ${fileList
+                        .map((f) => f.toUserVisibleString())
+                        .join('\n')}`
+                );
             }
         }
 
@@ -1313,7 +1307,7 @@ export class AnalyzerService {
             console: ConsoleInterface,
             program: Program,
             event: FileWatcherEventType,
-            path: string
+            path: Uri
         ) {
             // Due to the way we implemented file watcher, we will only get 2 events; 'add' and 'change'.
             // Here, we will convert those 2 to 3 events. 'add', 'change' and 'unlink';
@@ -1352,7 +1346,7 @@ export class AnalyzerService {
         }
     }
 
-    private _shouldHandleSourceFileWatchChanges(path: string, isFile: boolean) {
+    private _shouldHandleSourceFileWatchChanges(path: Uri, isFile: boolean) {
         if (isFile) {
             if (!hasPythonExtension(path) || isTemporaryFile(path)) {
                 return false;
@@ -1374,11 +1368,11 @@ export class AnalyzerService {
             return false;
         }
 
-        const parentPath = getDirectoryPath(path);
+        const parentPath = path.getDirectory();
         const hasInit =
             parentPath.startsWith(this._configOptions.projectRoot) &&
-            (this.fs.existsSync(combinePaths(parentPath, '__init__.py')) ||
-                this.fs.existsSync(combinePaths(parentPath, '__init__.pyi')));
+            (this.fs.existsSync(parentPath.combinePaths('__init__.py')) ||
+                this.fs.existsSync(parentPath.combinePaths('__init__.pyi')));
 
         // We don't have any file under the given path and its parent folder doesn't have __init__ then this folder change
         // doesn't have any meaning to us.
@@ -1388,13 +1382,13 @@ export class AnalyzerService {
 
         return true;
 
-        function isTemporaryFile(path: string) {
+        function isTemporaryFile(path: Uri) {
             // Determine if this is an add or delete event related to a temporary
             // file. Some tools (like auto-formatters) create temporary files
             // alongside the original file and name them "x.py.<temp-id>.py" where
             // <temp-id> is a 32-character random string of hex digits. We don't
             // want these events to trigger a full reanalysis.
-            const fileName = getFileName(path);
+            const fileName = path.fileName;
             const fileNameSplit = fileName.split('.');
             if (fileNameSplit.length === 4) {
                 if (fileNameSplit[3] === fileNameSplit[1] && fileNameSplit[2].length === 32) {
@@ -1417,28 +1411,28 @@ export class AnalyzerService {
         this._removeLibraryFileWatcher();
 
         if (!this._watchForLibraryChanges) {
-            this._librarySearchPathsToWatch = undefined;
+            this._librarySearchUrisToWatch = undefined;
             return;
         }
 
         // Watch the library paths for package install/uninstall.
         const importFailureInfo: string[] = [];
-        this._librarySearchPathsToWatch = findPythonSearchPaths(
+        this._librarySearchUrisToWatch = findPythonSearchPaths(
             this.fs,
             this._backgroundAnalysisProgram.configOptions,
             this._backgroundAnalysisProgram.host,
             importFailureInfo,
             /* includeWatchPathsOnly */ true,
-            this._executionRootPath
+            this._executionRootUri
         );
 
-        const watchList = this._librarySearchPathsToWatch;
+        const watchList = this._librarySearchUrisToWatch;
         if (watchList && watchList.length > 0) {
             try {
                 if (this._verboseOutput) {
                     this._console.info(`Adding fs watcher for library directories:\n ${watchList.join('\n')}`);
                 }
-                const isIgnored = ignoredWatchEventFunction(watchList);
+                const isIgnored = ignoredWatchEventFunction(watchList.map((f) => f.getFilePath()));
                 this._libraryFileWatcher = this.fs.createFileSystemWatcher(watchList, (event, path) => {
                     if (!path) {
                         return;
@@ -1448,7 +1442,7 @@ export class AnalyzerService {
                         this._console.info(`LibraryFile: Received fs event '${event}' for path '${path}'`);
                     }
 
-                    if (isIgnored(path)) {
+                    if (isIgnored(path.getFilePath())) {
                         return;
                     }
 
@@ -1461,24 +1455,26 @@ export class AnalyzerService {
                     this._scheduleLibraryAnalysis(isChange);
                 });
             } catch {
-                this._console.error(`Exception caught when installing fs watcher for:\n ${watchList.join('\n')}`);
+                this._console.error(
+                    `Exception caught when installing fs watcher for:\n ${watchList
+                        .map((w) => w.toUserVisibleString())
+                        .join('\n')}`
+                );
             }
         }
     }
 
-    private _shouldHandleLibraryFileWatchChanges(path: string, libSearchPaths: string[]) {
+    private _shouldHandleLibraryFileWatchChanges(path: Uri, libSearchPaths: Uri[]) {
         if (this._program.getSourceFileInfo(path)) {
             return true;
         }
 
         // find the innermost matching search path
         let matchingSearchPath;
-        const tempFile = this.serviceProvider.tryGet(ServiceKeys.tempFile);
-        const ignoreCase = !isFileSystemCaseSensitive(this.fs, tempFile);
         for (const libSearchPath of libSearchPaths) {
             if (
-                containsPath(libSearchPath, path, ignoreCase) &&
-                (!matchingSearchPath || matchingSearchPath.length < libSearchPath.length)
+                path.isChild(libSearchPath) &&
+                (!matchingSearchPath || matchingSearchPath.getPathLength() < libSearchPath.getPathLength())
             ) {
                 matchingSearchPath = libSearchPath;
             }
@@ -1488,8 +1484,8 @@ export class AnalyzerService {
             return true;
         }
 
-        const parentComponents = getPathComponents(matchingSearchPath);
-        const childComponents = getPathComponents(path);
+        const parentComponents = matchingSearchPath.getPathComponents();
+        const childComponents = path.getPathComponents();
 
         for (let i = parentComponents.length; i < childComponents.length; i++) {
             if (childComponents[i].startsWith('.')) {
@@ -1559,21 +1555,21 @@ export class AnalyzerService {
             return;
         }
 
-        if (this._configFilePath) {
-            this._configFileWatcher = this.fs.createFileSystemWatcher([this._configFilePath], (event) => {
+        if (this._configFileUri) {
+            this._configFileWatcher = this.fs.createFileSystemWatcher([this._configFileUri], (event) => {
                 if (this._verboseOutput) {
                     this._console.info(`Received fs event '${event}' for config file`);
                 }
                 this._scheduleReloadConfigFile();
             });
-        } else if (this._executionRootPath) {
-            this._configFileWatcher = this.fs.createFileSystemWatcher([this._executionRootPath], (event, path) => {
+        } else if (this._executionRootUri) {
+            this._configFileWatcher = this.fs.createFileSystemWatcher([this._executionRootUri], (event, path) => {
                 if (!path) {
                     return;
                 }
 
                 if (event === 'add' || event === 'change') {
-                    const fileName = getFileName(path);
+                    const fileName = path.fileName;
                     if (fileName && configFileNames.some((name) => name === fileName)) {
                         if (this._verboseOutput) {
                             this._console.info(`Received fs event '${event}' for config file`);
@@ -1610,8 +1606,8 @@ export class AnalyzerService {
     private _reloadConfigFile() {
         this._updateConfigFileWatcher();
 
-        if (this._configFilePath) {
-            this._console.info(`Reloading configuration file at ${this._configFilePath}`);
+        if (this._configFileUri) {
+            this._console.info(`Reloading configuration file at ${this._configFileUri.toUserVisibleString()}`);
 
             const host = this._backgroundAnalysisProgram.host;
 
@@ -1641,7 +1637,7 @@ export class AnalyzerService {
                 log(this._console, logLevel, `Search paths for ${execEnv.root || '<default>'}`);
                 const roots = importResolver.getImportRoots(execEnv, /* forLogging */ true);
                 roots.forEach((path) => {
-                    log(this._console, logLevel, `  ${path}`);
+                    log(this._console, logLevel, `  ${path.toUserVisibleString()}`);
                 });
             }
         }
diff --git a/packages/pyright-internal/src/analyzer/sourceFile.ts b/packages/pyright-internal/src/analyzer/sourceFile.ts
index 36b5c9aae..b6ba5f09e 100644
--- a/packages/pyright-internal/src/analyzer/sourceFile.ts
+++ b/packages/pyright-internal/src/analyzer/sourceFile.ts
@@ -20,13 +20,14 @@ import { DiagnosticSink, TextRangeDiagnosticSink } from '../common/diagnosticSin
 import { ServiceProvider } from '../common/extensibility';
 import { FileSystem } from '../common/fileSystem';
 import { LogTracker, getPathForLogging } from '../common/logTracker';
-import { getFileName, normalizeSlashes, stripFileExtension } from '../common/pathUtils';
+import { stripFileExtension } from '../common/pathUtils';
 import { convertOffsetsToRange, convertTextRangeToRange } from '../common/positionUtils';
 import { ServiceKeys } from '../common/serviceProviderExtensions';
 import * as StringUtils from '../common/stringUtils';
 import { Range, TextRange, getEmptyRange } from '../common/textRange';
 import { TextRangeCollection } from '../common/textRangeCollection';
 import { Duration, timingStats } from '../common/timing';
+import { Uri } from '../common/uri/uri';
 import { Localizer } from '../localization/localize';
 import { ModuleNode } from '../parser/parseNodes';
 import { IParser, ModuleImport, ParseOptions, ParseResults, Parser } from '../parser/parser';
@@ -179,12 +180,9 @@ export class SourceFile {
     // Console interface to use for debugging.
     private _console: ConsoleInterface;
 
-    // File path unique to this file within the workspace. May not represent
+    // Uri unique to this file within the workspace. May not represent
     // a real file on disk.
-    private readonly _filePath: string;
-
-    // File path on disk. May not be unique.
-    private readonly _realFilePath: string;
+    private readonly _uri: Uri;
 
     // Period-delimited import path for the module.
     private _moduleName: string;
@@ -232,46 +230,42 @@ export class SourceFile {
 
     constructor(
         readonly serviceProvider: ServiceProvider,
-        filePath: string,
+        uri: Uri,
         moduleName: string,
         isThirdPartyImport: boolean,
         isThirdPartyPyTypedPresent: boolean,
         editMode: SourceFileEditMode,
         console?: ConsoleInterface,
         logTracker?: LogTracker,
-        realFilePath?: string,
         ipythonMode?: IPythonMode
     ) {
         this.fileSystem = serviceProvider.get(ServiceKeys.fs);
         this._console = console || new StandardConsole();
         this._editMode = editMode;
-        this._filePath = filePath;
-        this._realFilePath = realFilePath ?? filePath;
+        this._uri = uri;
         this._moduleName = moduleName;
-        this._isStubFile = filePath.endsWith('.pyi');
+        this._isStubFile = uri.hasExtension('.pyi');
         this._isThirdPartyImport = isThirdPartyImport;
         this._isThirdPartyPyTypedPresent = isThirdPartyPyTypedPresent;
-        const fileName = getFileName(filePath);
+        const fileName = uri.fileName;
         this._isTypingStubFile =
-            this._isStubFile &&
-            (this._filePath.endsWith(normalizeSlashes('stdlib/typing.pyi')) || fileName === 'typing_extensions.pyi');
+            this._isStubFile && (this._uri.pathEndsWith('stdlib/typing.pyi') || fileName === 'typing_extensions.pyi');
         this._isTypingExtensionsStubFile = this._isStubFile && fileName === 'typing_extensions.pyi';
-        this._isTypeshedStubFile =
-            this._isStubFile && this._filePath.endsWith(normalizeSlashes('stdlib/_typeshed/__init__.pyi'));
+        this._isTypeshedStubFile = this._isStubFile && this._uri.pathEndsWith('stdlib/_typeshed/__init__.pyi');
 
         this._isBuiltInStubFile = false;
         if (this._isStubFile) {
             if (
-                this._filePath.endsWith(normalizeSlashes('stdlib/collections/__init__.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/asyncio/futures.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/asyncio/tasks.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/builtins.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/_importlib_modulespec.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/dataclasses.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/abc.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/enum.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/queue.pyi')) ||
-                this._filePath.endsWith(normalizeSlashes('stdlib/types.pyi'))
+                this._uri.pathEndsWith('stdlib/collections/__init__.pyi') ||
+                this._uri.pathEndsWith('stdlib/asyncio/futures.pyi') ||
+                this._uri.pathEndsWith('stdlib/asyncio/tasks.pyi') ||
+                this._uri.pathEndsWith('stdlib/builtins.pyi') ||
+                this._uri.pathEndsWith('stdlib/_importlib_modulespec.pyi') ||
+                this._uri.pathEndsWith('stdlib/dataclasses.pyi') ||
+                this._uri.pathEndsWith('stdlib/abc.pyi') ||
+                this._uri.pathEndsWith('stdlib/enum.pyi') ||
+                this._uri.pathEndsWith('stdlib/queue.pyi') ||
+                this._uri.pathEndsWith('stdlib/types.pyi')
             ) {
                 this._isBuiltInStubFile = true;
             }
@@ -282,16 +276,12 @@ export class SourceFile {
         this._ipythonMode = ipythonMode ?? IPythonMode.None;
     }
 
-    getRealFilePath(): string {
-        return this._realFilePath;
-    }
-
     getIPythonMode(): IPythonMode {
         return this._ipythonMode;
     }
 
-    getFilePath(): string {
-        return this._filePath;
+    getUri(): Uri {
+        return this._uri;
     }
 
     getModuleName(): string {
@@ -300,7 +290,7 @@ export class SourceFile {
         }
 
         // Synthesize a module name using the file path.
-        return stripFileExtension(getFileName(this._filePath));
+        return stripFileExtension(this._uri.fileName);
     }
 
     setModuleName(name: string) {
@@ -378,8 +368,8 @@ export class SourceFile {
         // that of the previous contents.
         try {
             // Read the file's contents.
-            if (this.fileSystem.existsSync(this._filePath)) {
-                const fileContents = this.fileSystem.readFileSync(this._filePath, 'utf8');
+            if (this.fileSystem.existsSync(this._uri)) {
+                const fileContents = this.fileSystem.readFileSync(this._uri, 'utf8');
 
                 if (fileContents.length !== this._writableData.lastFileContentLength) {
                     return true;
@@ -465,16 +455,16 @@ export class SourceFile {
         // Otherwise, get content from file system.
         try {
             // Check the file's length before attempting to read its full contents.
-            const fileStat = this.fileSystem.statSync(this._filePath);
+            const fileStat = this.fileSystem.statSync(this._uri);
             if (fileStat.size > _maxSourceFileSize) {
                 this._console.error(
-                    `File length of "${this._filePath}" is ${fileStat.size} ` +
+                    `File length of "${this._uri}" is ${fileStat.size} ` +
                         `which exceeds the maximum supported file size of ${_maxSourceFileSize}`
                 );
                 throw new Error('File larger than max');
             }
 
-            return this.fileSystem.readFileSync(this._filePath, 'utf8');
+            return this.fileSystem.readFileSync(this._uri, 'utf8');
         } catch (error) {
             return undefined;
         }
@@ -580,7 +570,7 @@ export class SourceFile {
     // (or at least cancel) prior to calling again. It returns true if a parse
     // was required and false if the parse information was up to date already.
     parse(configOptions: ConfigOptions, importResolver: ImportResolver, content?: string): boolean {
-        return this._logTracker.log(`parsing: ${this._getPathForLogging(this._filePath)}`, (logState) => {
+        return this._logTracker.log(`parsing: ${this._getPathForLogging(this._uri)}`, (logState) => {
             // If the file is already parsed, we can skip.
             if (!this.isParseRequired()) {
                 logState.suppress();
@@ -608,7 +598,7 @@ export class SourceFile {
                     diagSink.addError(`Source file could not be read`, getEmptyRange());
                     fileContents = '';
 
-                    if (!this.fileSystem.existsSync(this._realFilePath)) {
+                    if (!this.fileSystem.existsSync(this._uri)) {
                         this._writableData.isFileDeleted = true;
                     }
                 }
@@ -618,7 +608,7 @@ export class SourceFile {
                 // Parse the token stream, building the abstract syntax tree.
                 const parseResults = this._parseFile(
                     configOptions,
-                    this._filePath,
+                    this._uri,
                     fileContents!,
                     this._ipythonMode,
                     diagSink
@@ -632,7 +622,7 @@ export class SourceFile {
                     this._writableData.parseResults.tokenizerOutput.pyrightIgnoreLines;
 
                 // Resolve imports.
-                const execEnvironment = configOptions.findExecEnvironment(this._filePath);
+                const execEnvironment = configOptions.findExecEnvironment(this._uri);
                 timingStats.resolveImportsTime.timeOperation(() => {
                     const importResult = this._resolveImports(
                         importResolver,
@@ -648,7 +638,7 @@ export class SourceFile {
 
                 // Is this file in a "strict" path?
                 const useStrict =
-                    configOptions.strict.find((strictFileSpec) => strictFileSpec.regExp.test(this._realFilePath)) !==
+                    configOptions.strict.find((strictFileSpec) => this._uri.matchesRegex(strictFileSpec.regExp)) !==
                     undefined;
 
                 const commentDiags: CommentUtils.CommentDiagnostic[] = [];
@@ -680,7 +670,10 @@ export class SourceFile {
                     (typeof e.message === 'string' ? e.message : undefined) ||
                     JSON.stringify(e);
                 this._console.error(
-                    Localizer.Diagnostic.internalParseError().format({ file: this.getFilePath(), message })
+                    Localizer.Diagnostic.internalParseError().format({
+                        file: this.getUri().toUserVisibleString(),
+                        message,
+                    })
                 );
 
                 // Create dummy parse results.
@@ -708,7 +701,10 @@ export class SourceFile {
 
                 const diagSink = this.createDiagnosticSink();
                 diagSink.addError(
-                    Localizer.Diagnostic.internalParseError().format({ file: this.getFilePath(), message }),
+                    Localizer.Diagnostic.internalParseError().format({
+                        file: this.getUri().toUserVisibleString(),
+                        message,
+                    }),
                     getEmptyRange()
                 );
                 this._writableData.parseDiagnostics = diagSink.fetchAndClear();
@@ -740,7 +736,7 @@ export class SourceFile {
         assert(!this._writableData.isBindingInProgress, 'Bind called while binding in progress');
         assert(this._writableData.parseResults !== undefined, 'Parse results not available');
 
-        return this._logTracker.log(`binding: ${this._getPathForLogging(this._filePath)}`, () => {
+        return this._logTracker.log(`binding: ${this._getPathForLogging(this._uri)}`, () => {
             try {
                 // Perform name binding.
                 timingStats.bindTime.timeOperation(() => {
@@ -777,12 +773,18 @@ export class SourceFile {
                     (typeof e.message === 'string' ? e.message : undefined) ||
                     JSON.stringify(e);
                 this._console.error(
-                    Localizer.Diagnostic.internalBindError().format({ file: this.getFilePath(), message })
+                    Localizer.Diagnostic.internalBindError().format({
+                        file: this.getUri().toUserVisibleString(),
+                        message,
+                    })
                 );
 
                 const diagSink = this.createDiagnosticSink();
                 diagSink.addError(
-                    Localizer.Diagnostic.internalBindError().format({ file: this.getFilePath(), message }),
+                    Localizer.Diagnostic.internalBindError().format({
+                        file: this.getUri().toUserVisibleString(),
+                        message,
+                    }),
                     getEmptyRange()
                 );
                 this._writableData.bindDiagnostics = diagSink.fetchAndClear();
@@ -814,7 +816,7 @@ export class SourceFile {
         assert(this.isCheckingRequired(), 'Check called unnecessarily');
         assert(this._writableData.parseResults !== undefined, 'Parse results not available');
 
-        return this._logTracker.log(`checking: ${this._getPathForLogging(this._filePath)}`, () => {
+        return this._logTracker.log(`checking: ${this._getPathForLogging(this._uri)}`, () => {
             try {
                 timingStats.typeCheckerTime.timeOperation(() => {
                     const checkDuration = new Duration();
@@ -840,11 +842,17 @@ export class SourceFile {
                         (typeof e.message === 'string' ? e.message : undefined) ||
                         JSON.stringify(e);
                     this._console.error(
-                        Localizer.Diagnostic.internalTypeCheckingError().format({ file: this.getFilePath(), message })
+                        Localizer.Diagnostic.internalTypeCheckingError().format({
+                            file: this.getUri().toUserVisibleString(),
+                            message,
+                        })
                     );
                     const diagSink = this.createDiagnosticSink();
                     diagSink.addError(
-                        Localizer.Diagnostic.internalTypeCheckingError().format({ file: this.getFilePath(), message }),
+                        Localizer.Diagnostic.internalTypeCheckingError().format({
+                            file: this.getUri().toUserVisibleString(),
+                            message,
+                        }),
                         getEmptyRange()
                     );
 
@@ -1097,7 +1105,7 @@ export class SourceFile {
                         '\n' +
                         cirDep
                             .getPaths()
-                            .map((path) => '  ' + path)
+                            .map((path) => '  ' + path.toUserVisibleString())
                             .join('\n'),
                     getEmptyRange()
                 );
@@ -1120,7 +1128,7 @@ export class SourceFile {
         this._addTaskListDiagnostics(configOptions.taskListTokens, diagList);
 
         // If the file is in the ignore list, clear the diagnostic list.
-        if (configOptions.ignore.find((ignoreFileSpec) => ignoreFileSpec.regExp.test(this._realFilePath))) {
+        if (configOptions.ignore.find((ignoreFileSpec) => this._uri.matchesRegex(ignoreFileSpec.regExp))) {
             diagList = [];
         }
 
@@ -1243,13 +1251,13 @@ export class SourceFile {
             futureImports,
             builtinsScope,
             diagnosticSink: analysisDiagnostics,
-            executionEnvironment: configOptions.findExecEnvironment(this._filePath),
+            executionEnvironment: configOptions.findExecEnvironment(this._uri),
             diagnosticRuleSet: this._diagnosticRuleSet,
             fileContents,
             lines: this._writableData.parseResults!.tokenizerOutput.lines,
             typingSymbolAliases: this._writableData.parseResults!.typingSymbolAliases,
             definedConstants: configOptions.defineConstant,
-            filePath: this._filePath,
+            fileUri: this._uri,
             moduleName: this.getModuleName(),
             isStubFile: this._isStubFile,
             isTypingStubFile: this._isTypingStubFile,
@@ -1281,7 +1289,7 @@ export class SourceFile {
         const imports: ImportResult[] = [];
 
         const resolveAndAddIfNotSelf = (nameParts: string[], skipMissingImport = false) => {
-            const importResult = importResolver.resolveImport(this._filePath, execEnv, {
+            const importResult = importResolver.resolveImport(this._uri, execEnv, {
                 leadingDots: 0,
                 nameParts,
                 importedSymbols: undefined,
@@ -1292,7 +1300,7 @@ export class SourceFile {
             }
 
             // Avoid importing module from the module file itself.
-            if (importResult.resolvedPaths.length === 0 || importResult.resolvedPaths[0] !== this._filePath) {
+            if (importResult.resolvedUris.length === 0 || importResult.resolvedUris[0] !== this._uri) {
                 imports.push(importResult);
                 return importResult;
             }
@@ -1314,7 +1322,7 @@ export class SourceFile {
         }
 
         for (const moduleImport of moduleImports) {
-            const importResult = importResolver.resolveImport(this._filePath, execEnv, {
+            const importResult = importResolver.resolveImport(this._uri, execEnv, {
                 leadingDots: moduleImport.leadingDots,
                 nameParts: moduleImport.nameParts,
                 importedSymbols: moduleImport.importedSymbols,
@@ -1347,24 +1355,24 @@ export class SourceFile {
         };
     }
 
-    private _getPathForLogging(filepath: string) {
-        return getPathForLogging(this.fileSystem, filepath);
+    private _getPathForLogging(fileUri: Uri) {
+        return getPathForLogging(this.fileSystem, fileUri);
     }
 
     private _parseFile(
         configOptions: ConfigOptions,
-        filePath: string,
+        fileUri: Uri,
         fileContents: string,
         ipythonMode: IPythonMode,
         diagSink: DiagnosticSink
     ) {
         // Use the configuration options to determine the environment in which
         // this source file will be executed.
-        const execEnvironment = configOptions.findExecEnvironment(filePath);
+        const execEnvironment = configOptions.findExecEnvironment(fileUri);
 
         const parseOptions = new ParseOptions();
         parseOptions.ipythonMode = ipythonMode;
-        if (filePath.endsWith('pyi')) {
+        if (fileUri.pathEndsWith('pyi')) {
             parseOptions.isStubFile = true;
         }
         parseOptions.pythonVersion = execEnvironment.pythonVersion;
@@ -1378,7 +1386,7 @@ export class SourceFile {
     private _fireFileDirtyEvent() {
         this.serviceProvider.tryGet(ServiceKeys.stateMutationListeners)?.forEach((l) => {
             try {
-                l.fileDirty?.(this._filePath);
+                l.fileDirty?.(this._uri);
             } catch (ex: any) {
                 const console = this.serviceProvider.tryGet(ServiceKeys.console);
                 if (console) {
diff --git a/packages/pyright-internal/src/analyzer/sourceFileInfoUtils.ts b/packages/pyright-internal/src/analyzer/sourceFileInfoUtils.ts
index 1e15f0ff5..141db0d74 100644
--- a/packages/pyright-internal/src/analyzer/sourceFileInfoUtils.ts
+++ b/packages/pyright-internal/src/analyzer/sourceFileInfoUtils.ts
@@ -34,9 +34,9 @@ export function verifyNoCyclesInChainedFiles<T extends SourceFileInfo>(program:
         return;
     }
 
-    const set = new Set<string>([fileInfo.sourceFile.getFilePath()]);
+    const set = new Set<string>([fileInfo.sourceFile.getUri().key]);
     while (nextChainedFile) {
-        const path = nextChainedFile.sourceFile.getFilePath();
+        const path = nextChainedFile.sourceFile.getUri().key;
         if (set.has(path)) {
             // We found a cycle.
             fail(
@@ -90,7 +90,7 @@ function _parseAllOpenCells(program: ProgramView): void {
             continue;
         }
 
-        program.getParseResults(file.sourceFile.getFilePath());
+        program.getParseResults(file.sourceFile.getUri());
         program.handleMemoryHighUsage();
     }
 }
diff --git a/packages/pyright-internal/src/analyzer/sourceMapper.ts b/packages/pyright-internal/src/analyzer/sourceMapper.ts
index d6006a401..05d03d011 100644
--- a/packages/pyright-internal/src/analyzer/sourceMapper.ts
+++ b/packages/pyright-internal/src/analyzer/sourceMapper.ts
@@ -14,31 +14,31 @@ import { appendArray } from '../common/collectionUtils';
 import { ExecutionEnvironment } from '../common/configOptions';
 import { isDefined } from '../common/core';
 import { assertNever } from '../common/debug';
-import { combinePaths, getAnyExtensionFromPath, stripFileExtension } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
 import { ClassNode, ImportFromNode, ModuleNode, ParseNode, ParseNodeType } from '../parser/parseNodes';
 import {
     AliasDeclaration,
     ClassDeclaration,
     Declaration,
     FunctionDeclaration,
+    ParameterDeclaration,
+    SpecialBuiltInClassDeclaration,
+    VariableDeclaration,
     isAliasDeclaration,
     isClassDeclaration,
     isFunctionDeclaration,
     isParameterDeclaration,
     isSpecialBuiltInClassDeclaration,
     isVariableDeclaration,
-    ParameterDeclaration,
-    SpecialBuiltInClassDeclaration,
-    VariableDeclaration,
 } from './declaration';
 import { ImportResolver } from './importResolver';
-import { SourceFileInfo } from './sourceFileInfo';
 import { SourceFile } from './sourceFile';
+import { SourceFileInfo } from './sourceFileInfo';
 import { isUserCode } from './sourceFileInfoUtils';
 import { buildImportTree } from './sourceMapperUtils';
 import { TypeEvaluator } from './typeEvaluatorTypes';
-import { ClassType, isFunction, isInstantiableClass, isOverloadedFunction } from './types';
 import { lookUpClassMember } from './typeUtils';
+import { ClassType, isFunction, isInstantiableClass, isOverloadedFunction } from './types';
 
 type ClassOrFunctionOrVariableDeclaration =
     | ClassDeclaration
@@ -47,8 +47,8 @@ type ClassOrFunctionOrVariableDeclaration =
     | VariableDeclaration;
 
 // Creates and binds a shadowed file within the program.
-export type ShadowFileBinder = (stubFilePath: string, implFilePath: string) => SourceFile | undefined;
-export type BoundSourceGetter = (filePath: string) => SourceFileInfo | undefined;
+export type ShadowFileBinder = (stubFileUri: Uri, implFileUri: Uri) => SourceFile | undefined;
+export type BoundSourceGetter = (fileUri: Uri) => SourceFileInfo | undefined;
 
 export class SourceMapper {
     constructor(
@@ -63,10 +63,10 @@ export class SourceMapper {
         private _cancelToken: CancellationToken
     ) {}
 
-    findModules(stubFilePath: string): ModuleNode[] {
-        const sourceFiles = this._isStubThatShouldBeMappedToImplementation(stubFilePath)
-            ? this._getBoundSourceFilesFromStubFile(stubFilePath)
-            : [this._boundSourceGetter(stubFilePath)?.sourceFile];
+    findModules(stubFileUri: Uri): ModuleNode[] {
+        const sourceFiles = this._isStubThatShouldBeMappedToImplementation(stubFileUri)
+            ? this._getBoundSourceFilesFromStubFile(stubFileUri)
+            : [this._boundSourceGetter(stubFileUri)?.sourceFile];
 
         return sourceFiles
             .filter(isDefined)
@@ -74,8 +74,8 @@ export class SourceMapper {
             .filter(isDefined);
     }
 
-    getModuleNode(filePath: string): ModuleNode | undefined {
-        return this._boundSourceGetter(filePath)?.sourceFile.getParseResults()?.parseTree;
+    getModuleNode(fileUri: Uri): ModuleNode | undefined {
+        return this._boundSourceGetter(fileUri)?.sourceFile.getParseResults()?.parseTree;
     }
 
     findDeclarations(stubDecl: Declaration): Declaration[] {
@@ -94,13 +94,13 @@ export class SourceMapper {
         return [];
     }
 
-    findDeclarationsByType(originatedPath: string, type: ClassType, useTypeAlias = false): Declaration[] {
+    findDeclarationsByType(originatedPath: Uri, type: ClassType, useTypeAlias = false): Declaration[] {
         const result: ClassOrFunctionOrVariableDeclaration[] = [];
         this._addClassTypeDeclarations(originatedPath, type, result, new Set<string>(), useTypeAlias);
         return result;
     }
 
-    findClassDeclarationsByType(originatedPath: string, type: ClassType): ClassDeclaration[] {
+    findClassDeclarationsByType(originatedPath: Uri, type: ClassType): ClassDeclaration[] {
         const result = this.findDeclarationsByType(originatedPath, type);
         return result.filter((r) => isClassDeclaration(r)).map((r) => r as ClassDeclaration);
     }
@@ -111,17 +111,17 @@ export class SourceMapper {
             .map((d) => d as FunctionDeclaration);
     }
 
-    isUserCode(path: string): boolean {
-        return isUserCode(this._boundSourceGetter(path));
+    isUserCode(uri: Uri): boolean {
+        return isUserCode(this._boundSourceGetter(uri));
     }
 
-    getNextFileName(path: string) {
-        const withoutExtension = stripFileExtension(path);
+    getNextFileName(uri: Uri) {
+        const withoutExtension = uri.stripExtension();
         let suffix = 1;
-        let result = `${withoutExtension}_${suffix}.py`;
+        let result = withoutExtension.addExtension(`_${suffix}.py`);
         while (this.isUserCode(result) && suffix < 1000) {
             suffix += 1;
-            result = `${withoutExtension}_${suffix}.py`;
+            result = withoutExtension.addExtension(`_${suffix}.py`);
         }
         return result;
     }
@@ -132,7 +132,7 @@ export class SourceMapper {
     ) {
         if (stubDecl.node.valueExpression.nodeType === ParseNodeType.Name) {
             const className = stubDecl.node.valueExpression.value;
-            const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.path);
+            const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.uri);
 
             return sourceFiles.flatMap((sourceFile) =>
                 this._findClassDeclarationsByName(sourceFile, className, recursiveDeclCache)
@@ -144,7 +144,7 @@ export class SourceMapper {
 
     private _findClassOrTypeAliasDeclarations(stubDecl: ClassDeclaration, recursiveDeclCache = new Set<string>()) {
         const className = this._getFullClassName(stubDecl.node);
-        const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.path);
+        const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.uri);
 
         return sourceFiles.flatMap((sourceFile) =>
             this._findClassDeclarationsByName(sourceFile, className, recursiveDeclCache)
@@ -156,7 +156,7 @@ export class SourceMapper {
         recursiveDeclCache = new Set<string>()
     ): ClassOrFunctionOrVariableDeclaration[] {
         const functionName = stubDecl.node.name.value;
-        const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.path);
+        const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.uri);
 
         if (stubDecl.isMethod) {
             const classNode = ParseTreeUtils.getEnclosingClass(stubDecl.node);
@@ -184,7 +184,7 @@ export class SourceMapper {
         }
 
         const variableName = stubDecl.node.value;
-        const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.path);
+        const sourceFiles = this._getBoundSourceFilesFromStubFile(stubDecl.uri);
         const classNode = ParseTreeUtils.getEnclosingClass(stubDecl.node);
 
         if (classNode) {
@@ -270,7 +270,7 @@ export class SourceMapper {
     ): VariableDeclaration[] {
         let result: VariableDeclaration[] = [];
 
-        const uniqueId = `@${sourceFile.getFilePath()}/c/${className}/v/${variableName}`;
+        const uniqueId = `@${sourceFile.getUri()}/c/${className}/v/${variableName}`;
         if (recursiveDeclCache.has(uniqueId)) {
             return result;
         }
@@ -283,7 +283,7 @@ export class SourceMapper {
             variableName,
             (decl, cache, result) => {
                 if (isVariableDeclaration(decl)) {
-                    if (this._isStubThatShouldBeMappedToImplementation(decl.path)) {
+                    if (this._isStubThatShouldBeMappedToImplementation(decl.uri)) {
                         for (const implDecl of this._findVariableDeclarations(decl, cache)) {
                             if (isVariableDeclaration(implDecl)) {
                                 result.push(implDecl);
@@ -309,7 +309,7 @@ export class SourceMapper {
     ): ClassOrFunctionOrVariableDeclaration[] {
         let result: ClassOrFunctionOrVariableDeclaration[] = [];
 
-        const uniqueId = `@${sourceFile.getFilePath()}/c/${className}/f/${functionName}`;
+        const uniqueId = `@${sourceFile.getUri()}/c/${className}/f/${functionName}`;
         if (recursiveDeclCache.has(uniqueId)) {
             return result;
         }
@@ -322,7 +322,7 @@ export class SourceMapper {
             functionName,
             (decl, cache, result) => {
                 if (isFunctionDeclaration(decl)) {
-                    if (this._isStubThatShouldBeMappedToImplementation(decl.path)) {
+                    if (this._isStubThatShouldBeMappedToImplementation(decl.uri)) {
                         appendArray(result, this._findFunctionOrTypeAliasDeclarations(decl, cache));
                     } else {
                         result.push(decl);
@@ -343,7 +343,7 @@ export class SourceMapper {
     ): ClassOrFunctionOrVariableDeclaration[] {
         const result: ClassOrFunctionOrVariableDeclaration[] = [];
 
-        const uniqueId = `@${sourceFile.getFilePath()}/v/${variableName}`;
+        const uniqueId = `@${sourceFile.getUri()}/v/${variableName}`;
         if (recursiveDeclCache.has(uniqueId)) {
             return result;
         }
@@ -377,7 +377,7 @@ export class SourceMapper {
     ): ClassOrFunctionOrVariableDeclaration[] {
         const result: ClassOrFunctionOrVariableDeclaration[] = [];
 
-        const uniqueId = `@${sourceFile.getFilePath()}/f/${functionName}`;
+        const uniqueId = `@${sourceFile.getUri()}/f/${functionName}`;
         if (recursiveDeclCache.has(uniqueId)) {
             return result;
         }
@@ -438,7 +438,7 @@ export class SourceMapper {
     ): ClassOrFunctionOrVariableDeclaration[] {
         const result: ClassOrFunctionOrVariableDeclaration[] = [];
 
-        const uniqueId = `@${sourceFile.getFilePath()}[${parentNode.start}]${className}`;
+        const uniqueId = `@${sourceFile.getUri()}[${parentNode.start}]${className}`;
         if (recursiveDeclCache.has(uniqueId)) {
             return result;
         }
@@ -464,7 +464,7 @@ export class SourceMapper {
         recursiveDeclCache: Set<string>
     ) {
         if (isVariableDeclaration(decl)) {
-            if (this._isStubThatShouldBeMappedToImplementation(decl.path)) {
+            if (this._isStubThatShouldBeMappedToImplementation(decl.uri)) {
                 appendArray(result, this._findVariableDeclarations(decl, recursiveDeclCache));
             } else {
                 result.push(decl);
@@ -487,7 +487,7 @@ export class SourceMapper {
         recursiveDeclCache: Set<string>
     ) {
         if (isClassDeclaration(decl)) {
-            if (this._isStubThatShouldBeMappedToImplementation(decl.path)) {
+            if (this._isStubThatShouldBeMappedToImplementation(decl.uri)) {
                 appendArray(result, this._findClassOrTypeAliasDeclarations(decl, recursiveDeclCache));
             } else {
                 result.push(decl);
@@ -495,7 +495,7 @@ export class SourceMapper {
         } else if (isSpecialBuiltInClassDeclaration(decl)) {
             result.push(decl);
         } else if (isFunctionDeclaration(decl)) {
-            if (this._isStubThatShouldBeMappedToImplementation(decl.path)) {
+            if (this._isStubThatShouldBeMappedToImplementation(decl.uri)) {
                 appendArray(result, this._findFunctionOrTypeAliasDeclarations(decl, recursiveDeclCache));
             } else {
                 result.push(decl);
@@ -525,7 +525,7 @@ export class SourceMapper {
                     this._addClassOrFunctionDeclarations(overloadDecl, result, recursiveDeclCache);
                 }
             } else if (isInstantiableClass(type)) {
-                this._addClassTypeDeclarations(decl.path, type, result, recursiveDeclCache);
+                this._addClassTypeDeclarations(decl.uri, type, result, recursiveDeclCache);
             }
         }
     }
@@ -541,7 +541,7 @@ export class SourceMapper {
         // and second, clone the given decl and set path to the generated pyi for the
         // builtin module (ex, _io) to make resolveAliasDeclaration to work.
         // once the path is set, our regular code path will work as expected.
-        if (decl.path || !decl.node) {
+        if (!decl.uri.isEmpty() || !decl.node) {
             // If module actually exists, nothing we need to do.
             return decl;
         }
@@ -563,20 +563,19 @@ export class SourceMapper {
 
         // ImportResolver might be able to generate or extract builtin module's info
         // from runtime if we provide right synthesized stub path.
-        const fakeStubPath = combinePaths(
-            stdLibPath,
+        const fakeStubPath = stdLibPath.combinePaths(
             getModuleName()
                 .nameParts.map((n) => n.value)
                 .join('.') + '.pyi'
         );
 
-        const sources = this._getSourceFiles(fakeStubPath, fileInfo.filePath);
+        const sources = this._getSourceFiles(fakeStubPath, fileInfo.fileUri);
         if (sources.length === 0) {
             return decl;
         }
 
         const synthesizedDecl = { ...decl };
-        synthesizedDecl.path = sources[0].getFilePath();
+        synthesizedDecl.uri = sources[0].getUri();
 
         return synthesizedDecl;
 
@@ -595,14 +594,14 @@ export class SourceMapper {
     }
 
     private _addClassTypeDeclarations(
-        originated: string,
+        originated: Uri,
         type: ClassType,
         result: ClassOrFunctionOrVariableDeclaration[],
         recursiveDeclCache: Set<string>,
         useTypeAlias = false
     ) {
-        const filePath = type.details.filePath;
-        const sourceFiles = this._getSourceFiles(filePath, /* stubToShadow */ undefined, originated);
+        const fileUri = type.details.fileUri;
+        const sourceFiles = this._getSourceFiles(fileUri, /* stubToShadow */ undefined, originated);
 
         const fullName = useTypeAlias && type.typeAliasInfo ? type.typeAliasInfo.fullName : type.details.fullName;
         const fullClassName = fullName.substring(type.details.moduleName.length + 1 /* +1 for trailing dot */);
@@ -612,13 +611,13 @@ export class SourceMapper {
         }
     }
 
-    private _getSourceFiles(filePath: string, stubToShadow?: string, originated?: string) {
+    private _getSourceFiles(fileUri: Uri, stubToShadow?: Uri, originated?: Uri) {
         const sourceFiles: SourceFile[] = [];
 
-        if (this._isStubThatShouldBeMappedToImplementation(filePath)) {
-            appendArray(sourceFiles, this._getBoundSourceFilesFromStubFile(filePath, stubToShadow, originated));
+        if (this._isStubThatShouldBeMappedToImplementation(fileUri)) {
+            appendArray(sourceFiles, this._getBoundSourceFilesFromStubFile(fileUri, stubToShadow, originated));
         } else {
-            const sourceFileInfo = this._boundSourceGetter(filePath);
+            const sourceFileInfo = this._boundSourceGetter(fileUri);
             if (sourceFileInfo) {
                 sourceFiles.push(sourceFileInfo.sourceFile);
             }
@@ -645,14 +644,14 @@ export class SourceMapper {
             for (const decl of symbol.getDeclarations()) {
                 if (
                     !isAliasDeclaration(decl) ||
-                    !decl.path ||
+                    decl.uri.isEmpty() ||
                     decl.node.nodeType !== ParseNodeType.ImportFrom ||
                     !decl.node.isWildcardImport
                 ) {
                     continue;
                 }
 
-                const uniqueId = `@${decl.path}/l/${symbolName}`;
+                const uniqueId = `@${decl.uri.key}/l/${symbolName}`;
                 if (recursiveDeclCache.has(uniqueId)) {
                     continue;
                 }
@@ -667,7 +666,7 @@ export class SourceMapper {
                 // function.
                 recursiveDeclCache.add(uniqueId);
 
-                const sourceFiles = this._getSourceFiles(decl.path);
+                const sourceFiles = this._getSourceFiles(decl.uri);
                 for (const sourceFile of sourceFiles) {
                     const moduleNode = sourceFile.getParseResults()?.parseTree;
                     if (!moduleNode) {
@@ -728,28 +727,21 @@ export class SourceMapper {
         return fullName.reverse().join('.');
     }
 
-    private _getBoundSourceFilesFromStubFile(
-        stubFilePath: string,
-        stubToShadow?: string,
-        originated?: string
-    ): SourceFile[] {
-        const paths = this._getSourcePathsFromStub(
-            stubFilePath,
-            originated ?? this._fromFile?.sourceFile.getFilePath()
-        );
-        return paths.map((fp) => this._fileBinder(stubToShadow ?? stubFilePath, fp)).filter(isDefined);
+    private _getBoundSourceFilesFromStubFile(stubFileUri: Uri, stubToShadow?: Uri, originated?: Uri): SourceFile[] {
+        const paths = this._getSourcePathsFromStub(stubFileUri, originated ?? this._fromFile?.sourceFile.getUri());
+        return paths.map((fp) => this._fileBinder(stubToShadow ?? stubFileUri, fp)).filter(isDefined);
     }
 
-    private _getSourcePathsFromStub(stubFilePath: string, fromFile: string | undefined): string[] {
-        // Attempt our stubFilePath to see if we can resolve it as a source file path
-        let results = this._importResolver.getSourceFilesFromStub(stubFilePath, this._execEnv, this._mapCompiled);
+    private _getSourcePathsFromStub(stubFileUri: Uri, fromFile: Uri | undefined): Uri[] {
+        // Attempt our stubFileUri to see if we can resolve it as a source file path
+        let results = this._importResolver.getSourceFilesFromStub(stubFileUri, this._execEnv, this._mapCompiled);
         if (results.length > 0) {
             return results;
         }
 
         // If that didn't work, try looking through the graph up to our fromFile.
         // One of them should be able to resolve to an actual file.
-        const stubFileImportTree = this._getStubFileImportTree(stubFilePath, fromFile);
+        const stubFileImportTree = this._getStubFileImportTree(stubFileUri, fromFile);
 
         // Go through the items in this tree until we find at least one path.
         for (let i = 0; i < stubFileImportTree.length; i++) {
@@ -766,43 +758,41 @@ export class SourceMapper {
         return [];
     }
 
-    private _getStubFileImportTree(stubFilePath: string, fromFile: string | undefined): string[] {
-        if (!fromFile || !this._isStubThatShouldBeMappedToImplementation(stubFilePath)) {
+    private _getStubFileImportTree(stubFileUri: Uri, fromFile: Uri | undefined): Uri[] {
+        if (!fromFile || !this._isStubThatShouldBeMappedToImplementation(stubFileUri)) {
             // No path to search, just return the starting point.
-            return [stubFilePath];
+            return [stubFileUri];
         } else {
             // Otherwise recurse through the importedBy list up to our 'fromFile'.
             return buildImportTree(
                 fromFile,
-                stubFilePath,
+                stubFileUri,
                 (p) => {
                     const boundSourceInfo = this._boundSourceGetter(p);
-                    return boundSourceInfo
-                        ? boundSourceInfo.importedBy.map((info) => info.sourceFile.getFilePath())
-                        : [];
+                    return boundSourceInfo ? boundSourceInfo.importedBy.map((info) => info.sourceFile.getUri()) : [];
                 },
                 this._cancelToken
             ).filter((p) => this._isStubThatShouldBeMappedToImplementation(p));
         }
     }
 
-    private _isStubThatShouldBeMappedToImplementation(filePath: string): boolean {
+    private _isStubThatShouldBeMappedToImplementation(fileUri: Uri): boolean {
         if (this._preferStubs) {
             return false;
         }
 
-        const stub = isStubFile(filePath);
+        const stub = isStubFile(fileUri);
         if (!stub) {
             return false;
         }
 
         // If we get the same file as a source file, then we treat the file as a regular file even if it has "pyi" extension.
         return this._importResolver
-            .getSourceFilesFromStub(filePath, this._execEnv, this._mapCompiled)
-            .every((f) => f !== filePath);
+            .getSourceFilesFromStub(fileUri, this._execEnv, this._mapCompiled)
+            .every((f) => f !== fileUri);
     }
 }
 
-export function isStubFile(filePath: string): boolean {
-    return getAnyExtensionFromPath(filePath, ['.pyi'], /* ignoreCase */ false) === '.pyi';
+export function isStubFile(uri: Uri): boolean {
+    return uri.lastExtension === '.pyi';
 }
diff --git a/packages/pyright-internal/src/analyzer/sourceMapperUtils.ts b/packages/pyright-internal/src/analyzer/sourceMapperUtils.ts
index 3d9abeca2..8f407908e 100644
--- a/packages/pyright-internal/src/analyzer/sourceMapperUtils.ts
+++ b/packages/pyright-internal/src/analyzer/sourceMapperUtils.ts
@@ -5,6 +5,7 @@
  */
 
 import { CancellationToken } from 'vscode-jsonrpc';
+import { Uri } from '../common/uri/uri';
 
 const MAX_TREE_SEARCH_COUNT = 1000;
 
@@ -15,12 +16,7 @@ class NumberReference {
 // Builds an array of imports from the 'from' to the 'to' entry where 'from'
 // is on the front of the array and the item just before 'to' is on the
 // back of the array.
-export function buildImportTree(
-    to: string,
-    from: string,
-    next: (from: string) => string[],
-    token: CancellationToken
-): string[] {
+export function buildImportTree(to: Uri, from: Uri, next: (from: Uri) => Uri[], token: CancellationToken): Uri[] {
     const totalCountRef = new NumberReference();
     const results = _buildImportTreeImpl(to, from, next, [], totalCountRef, token);
 
@@ -29,25 +25,25 @@ export function buildImportTree(
 }
 
 function _buildImportTreeImpl(
-    to: string,
-    from: string,
-    next: (from: string) => string[],
-    previous: string[],
+    to: Uri,
+    from: Uri,
+    next: (from: Uri) => Uri[],
+    previous: Uri[],
     totalSearched: NumberReference,
     token: CancellationToken
-): string[] {
+): Uri[] {
     // Exit early if cancellation is requested or we've exceeded max count
     if (totalSearched.value > MAX_TREE_SEARCH_COUNT || token.isCancellationRequested) {
         return [];
     }
     totalSearched.value += 1;
 
-    if (from === to) {
+    if (from.equals(to)) {
         // At the top, previous should have our way into this recursion.
         return previous.length ? previous : [from];
     }
 
-    if (previous.length > 1 && previous.find((s) => s === from)) {
+    if (previous.length > 1 && previous.find((s) => s.equals(from))) {
         // Fail the search, we're stuck in a loop.
         return [];
     }
diff --git a/packages/pyright-internal/src/analyzer/tracePrinter.ts b/packages/pyright-internal/src/analyzer/tracePrinter.ts
index 979e8f344..9e4fd6479 100644
--- a/packages/pyright-internal/src/analyzer/tracePrinter.ts
+++ b/packages/pyright-internal/src/analyzer/tracePrinter.ts
@@ -8,8 +8,9 @@
 
 import { isNumber, isString } from '../common/core';
 import { assertNever } from '../common/debug';
-import { ensureTrailingDirectorySeparator, stripFileExtension } from '../common/pathUtils';
+import { stripFileExtension } from '../common/pathUtils';
 import { convertOffsetToPosition } from '../common/positionUtils';
+import { Uri } from '../common/uri/uri';
 import { ParseNode, ParseNodeType, isExpressionNode } from '../parser/parseNodes';
 import { AbsoluteModuleDescriptor } from './analyzerFileInfo';
 import * as AnalyzerNodeInfo from './analyzerNodeInfo';
@@ -22,10 +23,10 @@ export type PrintableType = ParseNode | Declaration | Symbol | Type | undefined;
 
 export interface TracePrinter {
     print(o: PrintableType): string;
-    printFileOrModuleName(filePathOrModule: string | AbsoluteModuleDescriptor): string;
+    printFileOrModuleName(fileUriOrModule: Uri | AbsoluteModuleDescriptor): string;
 }
 
-export function createTracePrinter(roots: string[]): TracePrinter {
+export function createTracePrinter(roots: Uri[]): TracePrinter {
     function wrap(value: string | undefined, ch = "'") {
         return value ? `${ch}${value}${ch}` : '';
     }
@@ -33,25 +34,22 @@ export function createTracePrinter(roots: string[]): TracePrinter {
     // Sort roots in desc order so that we compare longer path first
     // when getting relative path.
     // ex) d:/root/.env/lib/site-packages, d:/root/.env
-    roots = roots
-        .map((r) => ensureTrailingDirectorySeparator(r))
-        .sort((a, b) => a.localeCompare(b))
-        .reverse();
+    roots = roots.sort((a, b) => a.key.localeCompare(b.key)).reverse();
 
     const separatorRegExp = /[\\/]/g;
-    function printFileOrModuleName(filePathOrModule: string | AbsoluteModuleDescriptor | undefined) {
-        if (filePathOrModule) {
-            if (typeof filePathOrModule === 'string') {
+    function printFileOrModuleName(fileUriOrModule: Uri | AbsoluteModuleDescriptor | undefined) {
+        if (fileUriOrModule) {
+            if (Uri.isUri(fileUriOrModule)) {
                 for (const root of roots) {
-                    if (filePathOrModule.startsWith(root)) {
-                        const subFile = filePathOrModule.substring(root.length);
-                        return stripFileExtension(subFile).replace(separatorRegExp, '.');
+                    if (fileUriOrModule.isChild(root)) {
+                        const subFile = root.getRelativePath(fileUriOrModule);
+                        return stripFileExtension(subFile!).replace(separatorRegExp, '.');
                     }
                 }
 
-                return filePathOrModule;
-            } else if (filePathOrModule.nameParts) {
-                return filePathOrModule.nameParts.join('.');
+                return fileUriOrModule.toUserVisibleString();
+            } else if (fileUriOrModule.nameParts) {
+                return fileUriOrModule.nameParts.join('.');
             }
         }
         return '';
@@ -117,33 +115,33 @@ export function createTracePrinter(roots: string[]): TracePrinter {
         if (decl) {
             switch (decl.type) {
                 case DeclarationType.Alias:
-                    return `Alias, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `Alias, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 case DeclarationType.Class:
-                    return `Class, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `Class, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 case DeclarationType.Function:
-                    return `Function, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `Function, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 case DeclarationType.Intrinsic:
                     return `Intrinsic, ${printNode(decl.node)} ${decl.intrinsicType} (${printFileOrModuleName(
-                        decl.path
+                        decl.uri
                     )})`;
 
                 case DeclarationType.Parameter:
-                    return `Parameter, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `Parameter, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 case DeclarationType.TypeParameter:
-                    return `TypeParameter, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `TypeParameter, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 case DeclarationType.SpecialBuiltInClass:
-                    return `SpecialBuiltInClass, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `SpecialBuiltInClass, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 case DeclarationType.Variable:
-                    return `Variable, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `Variable, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 case DeclarationType.TypeAlias:
-                    return `TypeAlias, ${printNode(decl.node)} (${printFileOrModuleName(decl.path)})`;
+                    return `TypeAlias, ${printNode(decl.node)} (${printFileOrModuleName(decl.uri)})`;
 
                 default:
                     assertNever(decl);
@@ -174,7 +172,7 @@ export function createTracePrinter(roots: string[]): TracePrinter {
             return '';
         }
 
-        let path = printPath ? `(${printFileOrModuleName(getFileInfo(node)?.filePath)})` : '';
+        let path = printPath ? `(${printFileOrModuleName(getFileInfo(node)?.fileUri)})` : '';
 
         const fileInfo = getFileInfo(node);
         if (fileInfo?.lines) {
@@ -228,7 +226,7 @@ export function createTracePrinter(roots: string[]): TracePrinter {
 
     function isDeclaration(o: any): o is Declaration {
         const d = o as Declaration;
-        return d && isNumber(d.type) && isString(d.path) && isString(d.moduleName);
+        return d && isNumber(d.type) && Uri.isUri(d.uri) && isString(d.moduleName);
     }
 
     function isType(o: any): o is Type {
diff --git a/packages/pyright-internal/src/analyzer/typeDocStringUtils.ts b/packages/pyright-internal/src/analyzer/typeDocStringUtils.ts
index 7ea90d937..b29129ca2 100644
--- a/packages/pyright-internal/src/analyzer/typeDocStringUtils.ts
+++ b/packages/pyright-internal/src/analyzer/typeDocStringUtils.ts
@@ -33,6 +33,7 @@ import {
     TypeCategory,
 } from '../analyzer/types';
 import { addIfNotNull, appendArray } from '../common/collectionUtils';
+import { Uri } from '../common/uri/uri';
 import { ModuleNode, ParseNodeType } from '../parser/parseNodes';
 import { TypeEvaluator } from './typeEvaluatorTypes';
 import {
@@ -160,7 +161,7 @@ export function getPropertyDocStringInherited(
 
 export function getVariableInStubFileDocStrings(decl: VariableDeclaration, sourceMapper: SourceMapper) {
     const docStrings: string[] = [];
-    if (!isStubFile(decl.path)) {
+    if (!isStubFile(decl.uri)) {
         return docStrings;
     }
 
@@ -193,14 +194,14 @@ export function getModuleDocStringFromModuleNodes(modules: ModuleNode[]): string
     return undefined;
 }
 
-export function getModuleDocStringFromPaths(filePaths: string[], sourceMapper: SourceMapper) {
+export function getModuleDocStringFromUris(uris: Uri[], sourceMapper: SourceMapper) {
     const modules: ModuleNode[] = [];
-    for (const filePath of filePaths) {
-        if (isStubFile(filePath)) {
-            addIfNotNull(modules, sourceMapper.getModuleNode(filePath));
+    for (const uri of uris) {
+        if (isStubFile(uri)) {
+            addIfNotNull(modules, sourceMapper.getModuleNode(uri));
         }
 
-        appendArray(modules, sourceMapper.findModules(filePath));
+        appendArray(modules, sourceMapper.findModules(uri));
     }
 
     return getModuleDocStringFromModuleNodes(modules);
@@ -213,8 +214,8 @@ export function getModuleDocString(
 ) {
     let docString = type.docString;
     if (!docString) {
-        const filePath = resolvedDecl?.path ?? type.filePath;
-        docString = getModuleDocStringFromPaths([filePath], sourceMapper);
+        const uri = resolvedDecl?.uri ?? type.fileUri;
+        docString = getModuleDocStringFromUris([uri], sourceMapper);
     }
 
     return docString;
@@ -228,12 +229,7 @@ export function getClassDocString(
     let docString = classType.details.docString;
     if (!docString && resolvedDecl && isClassDeclaration(resolvedDecl)) {
         docString = _getFunctionOrClassDeclsDocString([resolvedDecl]);
-        if (
-            !docString &&
-            resolvedDecl &&
-            isStubFile(resolvedDecl.path) &&
-            resolvedDecl.type === DeclarationType.Class
-        ) {
+        if (!docString && resolvedDecl && isStubFile(resolvedDecl.uri) && resolvedDecl.type === DeclarationType.Class) {
             for (const implDecl of sourceMapper.findDeclarations(resolvedDecl)) {
                 if (isVariableDeclaration(implDecl) && !!implDecl.docString) {
                     docString = implDecl.docString;
@@ -249,7 +245,7 @@ export function getClassDocString(
     }
 
     if (!docString && resolvedDecl) {
-        const implDecls = sourceMapper.findClassDeclarationsByType(resolvedDecl.path, classType);
+        const implDecls = sourceMapper.findClassDeclarationsByType(resolvedDecl.uri, classType);
         if (implDecls) {
             const classDecls = implDecls.filter((d) => isClassDeclaration(d)).map((d) => d);
             docString = _getFunctionOrClassDeclsDocString(classDecls);
@@ -294,7 +290,7 @@ function _getOverloadedFunctionDocStrings(
                 docStrings.push(overload.details.docString);
             }
         });
-    } else if (resolvedDecl && isStubFile(resolvedDecl.path) && isFunctionDeclaration(resolvedDecl)) {
+    } else if (resolvedDecl && isStubFile(resolvedDecl.uri) && isFunctionDeclaration(resolvedDecl)) {
         const implDecls = sourceMapper.findFunctionDeclarations(resolvedDecl);
         const docString = _getFunctionOrClassDeclsDocString(implDecls);
         if (docString) {
@@ -372,7 +368,7 @@ function _getFunctionDocString(type: Type, resolvedDecl: FunctionDeclaration | u
 
 function _getFunctionDocStringFromDeclaration(resolvedDecl: FunctionDeclaration, sourceMapper: SourceMapper) {
     let docString = _getFunctionOrClassDeclsDocString([resolvedDecl]);
-    if (!docString && isStubFile(resolvedDecl.path)) {
+    if (!docString && isStubFile(resolvedDecl.uri)) {
         const implDecls = sourceMapper.findFunctionDeclarations(resolvedDecl);
         docString = _getFunctionOrClassDeclsDocString(implDecls);
     }
diff --git a/packages/pyright-internal/src/analyzer/typeEvaluator.ts b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
index 2657f1484..228d150c1 100644
--- a/packages/pyright-internal/src/analyzer/typeEvaluator.ts
+++ b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
@@ -26,6 +26,7 @@ import { DiagnosticRule } from '../common/diagnosticRules';
 import { convertOffsetToPosition, convertOffsetsToRange } from '../common/positionUtils';
 import { PythonVersion } from '../common/pythonVersion';
 import { TextRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { Localizer, ParameterizedString } from '../localization/localize';
 import {
     ArgumentCategory,
@@ -665,7 +666,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                         `Type cache flag mismatch for node type ${node.nodeType} ` +
                         `(parent ${node.parent?.nodeType ?? 'none'}): ` +
                         `cached flags = ${expectedFlags}, access flags = ${flags}, ` +
-                        `file = {${fileInfo.filePath} [${position.line + 1}:${position.character + 1}]}`;
+                        `file = {${fileInfo.fileUri} [${position.line + 1}:${position.character + 1}]}`;
                     if (evaluatorOptions.verifyTypeCacheEvaluatorFlags) {
                         fail(message);
                     } else {
@@ -2895,7 +2896,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
 
     function getTypeOfModule(node: ParseNode, symbolName: string, nameParts: string[]) {
         const fileInfo = AnalyzerNodeInfo.getFileInfo(node);
-        const lookupResult = importLookup({ nameParts, importingFilePath: fileInfo.filePath });
+        const lookupResult = importLookup({ nameParts, importingFileUri: fileInfo.fileUri });
 
         if (!lookupResult) {
             return undefined;
@@ -5355,9 +5356,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                         if (getAttrSymbol) {
                             const isModuleGetAttrSupported =
                                 fileInfo.executionEnvironment.pythonVersion >= PythonVersion.V3_7 ||
-                                getAttrSymbol
-                                    .getDeclarations()
-                                    .some((decl) => decl.path.toLowerCase().endsWith('.pyi'));
+                                getAttrSymbol.getDeclarations().some((decl) => decl.uri.hasExtension('.pyi'));
 
                             if (isModuleGetAttrSupported) {
                                 const getAttrTypeResult = getEffectiveTypeOfSymbolForUsage(getAttrSymbol);
@@ -8904,7 +8903,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                 if (diagnostic && overrideDecl) {
                     diagnostic.addRelatedInfo(
                         Localizer.DiagnosticAddendum.overloadIndex().format({ index: bestMatch.overloadIndex + 1 }),
-                        overrideDecl.path,
+                        overrideDecl.uri,
                         overrideDecl.range
                     );
                 }
@@ -9717,7 +9716,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                 newClassName,
                 '',
                 '',
-                AnalyzerNodeInfo.getFileInfo(errorNode).filePath,
+                AnalyzerNodeInfo.getFileInfo(errorNode).fileUri,
                 ClassTypeFlags.None,
                 ParseTreeUtils.getTypeSourceId(errorNode),
                 ClassType.cloneAsInstantiable(returnType),
@@ -12628,7 +12627,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
             className,
             ParseTreeUtils.getClassFullName(errorNode, fileInfo.moduleName, className),
             fileInfo.moduleName,
-            fileInfo.filePath,
+            fileInfo.fileUri,
             classFlags,
             ParseTreeUtils.getTypeSourceId(errorNode),
             /* declaredMetaclass */ undefined,
@@ -12689,7 +12688,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
             className,
             ParseTreeUtils.getClassFullName(errorNode, fileInfo.moduleName, className),
             fileInfo.moduleName,
-            fileInfo.filePath,
+            fileInfo.fileUri,
             ClassTypeFlags.None,
             ParseTreeUtils.getTypeSourceId(errorNode),
             /* declaredMetaclass */ undefined,
@@ -15269,7 +15268,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
             assignedName,
             ParseTreeUtils.getClassFullName(node, fileInfo.moduleName, assignedName),
             fileInfo.moduleName,
-            fileInfo.filePath,
+            fileInfo.fileUri,
             ClassTypeFlags.BuiltInClass | ClassTypeFlags.SpecialBuiltIn,
             /* typeSourceId */ 0,
             /* declaredMetaclass */ undefined,
@@ -15835,7 +15834,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
             node.name.value,
             ParseTreeUtils.getClassFullName(node, fileInfo.moduleName, node.name.value),
             fileInfo.moduleName,
-            fileInfo.filePath,
+            fileInfo.fileUri,
             classFlags,
             /* typeSourceId */ 0,
             /* declaredMetaclass */ undefined,
@@ -16615,7 +16614,16 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
         );
         const updatedClassType = ClassType.cloneWithNewTypeParameters(classType, updatedTypeParams);
 
-        const dummyTypeObject = ClassType.createInstantiable('__varianceDummy', '', '', '', 0, 0, undefined, undefined);
+        const dummyTypeObject = ClassType.createInstantiable(
+            '__varianceDummy',
+            '',
+            '',
+            Uri.empty(),
+            0,
+            0,
+            undefined,
+            undefined
+        );
 
         updatedTypeParams.forEach((param, paramIndex) => {
             // Skip variadics and ParamSpecs.
@@ -16999,7 +17007,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                                 Localizer.DiagnosticAddendum.initSubclassLocation().format({
                                     name: printType(convertToInstance(initSubclassMethodInfo.classType)),
                                 }),
-                                initSubclassDecl.path,
+                                initSubclassDecl.uri,
                                 initSubclassDecl.range
                             );
                         }
@@ -18381,7 +18389,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
 
             const importInfo = AnalyzerNodeInfo.getImportInfo(parentNode.module);
             if (importInfo && importInfo.isImportFound && !importInfo.isNativeLib) {
-                const resolvedPath = importInfo.resolvedPaths[importInfo.resolvedPaths.length - 1];
+                const resolvedPath = importInfo.resolvedUris[importInfo.resolvedUris.length - 1];
 
                 const importLookupInfo = importLookup(resolvedPath);
                 let reportError = false;
@@ -18403,7 +18411,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                             }
                         }
                     }
-                } else if (!resolvedPath) {
+                } else if (resolvedPath.isEmpty()) {
                     // This corresponds to the "from . import a" form.
                     reportError = true;
                 }
@@ -20207,15 +20215,15 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                 namePartIndex >= 0 &&
                 importInfo &&
                 !importInfo.isNativeLib &&
-                namePartIndex < importInfo.resolvedPaths.length
+                namePartIndex < importInfo.resolvedUris.length
             ) {
-                if (importInfo.resolvedPaths[namePartIndex]) {
+                if (importInfo.resolvedUris[namePartIndex]) {
                     evaluateTypesForStatement(node);
 
                     // Synthesize an alias declaration for this name part. The only
                     // time this case is used is for IDE services such as
                     // the find all references, hover provider and etc.
-                    declarations.push(createSynthesizedAliasDeclaration(importInfo.resolvedPaths[namePartIndex]));
+                    declarations.push(createSynthesizedAliasDeclaration(importInfo.resolvedUris[namePartIndex]));
                 }
             }
         } else if (node.parent && node.parent.nodeType === ParseNodeType.Argument && node === node.parent.name) {
@@ -20634,8 +20642,8 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
             loaderActions: ModuleLoaderActions,
             importLookup: ImportLookup
         ): Type {
-            if (loaderActions.path && loaderActions.loadSymbolsFromPath) {
-                const lookupResults = importLookup(loaderActions.path);
+            if (!loaderActions.uri.isEmpty() && loaderActions.loadSymbolsFromPath) {
+                const lookupResults = importLookup(loaderActions.uri);
                 if (lookupResults) {
                     moduleType.fields = lookupResults.symbolTable;
                     moduleType.docString = lookupResults.docString;
@@ -20658,7 +20666,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
                         symbolType = UnknownType.create();
                     } else {
                         const moduleName = moduleType.moduleName ? moduleType.moduleName + '.' + name : '';
-                        const importedModuleType = ModuleType.create(moduleName, implicitImport.path);
+                        const importedModuleType = ModuleType.create(moduleName, implicitImport.uri);
                         symbolType = applyLoaderActionsToModuleType(importedModuleType, implicitImport, importLookup);
                     }
 
@@ -20676,7 +20684,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
         if (resolvedDecl.type === DeclarationType.Alias) {
             // Build a module type that corresponds to the declaration and
             // its associated loader actions.
-            const moduleType = ModuleType.create(resolvedDecl.moduleName, resolvedDecl.path);
+            const moduleType = ModuleType.create(resolvedDecl.moduleName, resolvedDecl.uri);
             if (resolvedDecl.symbolName && resolvedDecl.submoduleFallback) {
                 return applyLoaderActionsToModuleType(moduleType, resolvedDecl.submoduleFallback, importLookup);
             } else {
diff --git a/packages/pyright-internal/src/analyzer/typeGuards.ts b/packages/pyright-internal/src/analyzer/typeGuards.ts
index ede5d65b9..5da99df58 100644
--- a/packages/pyright-internal/src/analyzer/typeGuards.ts
+++ b/packages/pyright-internal/src/analyzer/typeGuards.ts
@@ -1480,7 +1480,7 @@ function narrowTypeForIsInstance(
                             className,
                             ParseTreeUtils.getClassFullName(errorNode, fileInfo.moduleName, className),
                             fileInfo.moduleName,
-                            fileInfo.filePath,
+                            fileInfo.fileUri,
                             ClassTypeFlags.None,
                             ParseTreeUtils.getTypeSourceId(errorNode),
                             /* declaredMetaclass */ undefined,
@@ -2545,7 +2545,7 @@ function narrowTypeForCallable(
                             className,
                             ParseTreeUtils.getClassFullName(errorNode, fileInfo.moduleName, className),
                             fileInfo.moduleName,
-                            fileInfo.filePath,
+                            fileInfo.fileUri,
                             ClassTypeFlags.None,
                             ParseTreeUtils.getTypeSourceId(errorNode),
                             /* declaredMetaclass */ undefined,
diff --git a/packages/pyright-internal/src/analyzer/typeStubWriter.ts b/packages/pyright-internal/src/analyzer/typeStubWriter.ts
index 1bbeee9a7..a79bf2d54 100644
--- a/packages/pyright-internal/src/analyzer/typeStubWriter.ts
+++ b/packages/pyright-internal/src/analyzer/typeStubWriter.ts
@@ -8,6 +8,7 @@
  * and analyzed python source file.
  */
 
+import { Uri } from '../common/uri/uri';
 import {
     ArgumentCategory,
     AssignmentNode,
@@ -158,13 +159,13 @@ export class TypeStubWriter extends ParseTreeWalker {
     private _trackedImportFrom = new Map<string, TrackedImportFrom>();
     private _accessedImportedSymbols = new Set<string>();
 
-    constructor(private _stubPath: string, private _sourceFile: SourceFile, private _evaluator: TypeEvaluator) {
+    constructor(private _stubPath: Uri, private _sourceFile: SourceFile, private _evaluator: TypeEvaluator) {
         super();
 
         // As a heuristic, we'll include all of the import statements
         // in "__init__.pyi" files even if they're not locally referenced
         // because these are often used as ways to re-export symbols.
-        if (this._stubPath.endsWith('__init__.pyi')) {
+        if (this._stubPath.fileName === '__init__.pyi') {
             this._includeAllImports = true;
         }
     }
diff --git a/packages/pyright-internal/src/analyzer/typedDicts.ts b/packages/pyright-internal/src/analyzer/typedDicts.ts
index 80b04c6f0..063c78aef 100644
--- a/packages/pyright-internal/src/analyzer/typedDicts.ts
+++ b/packages/pyright-internal/src/analyzer/typedDicts.ts
@@ -97,7 +97,7 @@ export function createTypedDictType(
         className,
         ParseTreeUtils.getClassFullName(errorNode, fileInfo.moduleName, className),
         fileInfo.moduleName,
-        fileInfo.filePath,
+        fileInfo.fileUri,
         ClassTypeFlags.TypedDictClass,
         ParseTreeUtils.getTypeSourceId(errorNode),
         /* declaredMetaclass */ undefined,
@@ -147,7 +147,7 @@ export function createTypedDictType(
                 const declaration: VariableDeclaration = {
                     type: DeclarationType.Variable,
                     node: entry.name,
-                    path: fileInfo.filePath,
+                    uri: fileInfo.fileUri,
                     typeAnnotationNode: entry.valueExpression,
                     isRuntimeTypeExpression: true,
                     range: convertOffsetsToRange(
@@ -209,7 +209,7 @@ export function createTypedDictTypeInlined(
         className,
         ParseTreeUtils.getClassFullName(dictNode, fileInfo.moduleName, className),
         fileInfo.moduleName,
-        fileInfo.filePath,
+        fileInfo.fileUri,
         ClassTypeFlags.TypedDictClass,
         ParseTreeUtils.getTypeSourceId(dictNode),
         /* declaredMetaclass */ undefined,
@@ -773,7 +773,7 @@ function getTypedDictFieldsFromDictSyntax(
         const declaration: VariableDeclaration = {
             type: DeclarationType.Variable,
             node: entry.keyExpression,
-            path: fileInfo.filePath,
+            uri: fileInfo.fileUri,
             typeAnnotationNode: entry.valueExpression,
             isRuntimeTypeExpression: !isInline,
             range: convertOffsetsToRange(
diff --git a/packages/pyright-internal/src/analyzer/types.ts b/packages/pyright-internal/src/analyzer/types.ts
index c485e076b..873f121b0 100644
--- a/packages/pyright-internal/src/analyzer/types.ts
+++ b/packages/pyright-internal/src/analyzer/types.ts
@@ -8,6 +8,7 @@
  */
 
 import { assert } from '../common/debug';
+import { Uri } from '../common/uri/uri';
 import { ArgumentNode, ExpressionNode, NameNode, ParameterCategory } from '../parser/parseNodes';
 import { FunctionDeclaration } from './declaration';
 import { Symbol, SymbolTable } from './symbol';
@@ -383,18 +384,18 @@ export interface ModuleType extends TypeBase {
     // The period-delimited import name of this module.
     moduleName: string;
 
-    filePath: string;
+    fileUri: Uri;
 }
 
 export namespace ModuleType {
-    export function create(moduleName: string, filePath: string, symbolTable?: SymbolTable) {
+    export function create(moduleName: string, fileUri: Uri, symbolTable?: SymbolTable) {
         const newModuleType: ModuleType = {
             category: TypeCategory.Module,
             fields: symbolTable || new Map<string, Symbol>(),
             loaderFields: new Map<string, Symbol>(),
             flags: TypeFlags.Instantiable | TypeFlags.Instantiable,
             moduleName,
-            filePath,
+            fileUri,
         };
         return newModuleType;
     }
@@ -561,7 +562,7 @@ interface ClassDetails {
     name: string;
     fullName: string;
     moduleName: string;
-    filePath: string;
+    fileUri: Uri;
     flags: ClassTypeFlags;
     typeSourceId: TypeSourceId;
     baseClasses: Type[];
@@ -709,7 +710,7 @@ export namespace ClassType {
         name: string,
         fullName: string,
         moduleName: string,
-        filePath: string,
+        fileUri: Uri,
         flags: ClassTypeFlags,
         typeSourceId: TypeSourceId,
         declaredMetaclass: ClassType | UnknownType | undefined,
@@ -722,7 +723,7 @@ export namespace ClassType {
                 name,
                 fullName,
                 moduleName,
-                filePath,
+                fileUri,
                 flags,
                 typeSourceId,
                 baseClasses: [],
diff --git a/packages/pyright-internal/src/backgroundAnalysis.ts b/packages/pyright-internal/src/backgroundAnalysis.ts
index 7db49ebef..aafa1b159 100644
--- a/packages/pyright-internal/src/backgroundAnalysis.ts
+++ b/packages/pyright-internal/src/backgroundAnalysis.ts
@@ -13,17 +13,17 @@ import { BackgroundAnalysisBase, BackgroundAnalysisRunnerBase } from './backgrou
 import { InitializationData } from './backgroundThreadBase';
 import { getCancellationFolderName } from './common/cancellationUtils';
 import { ConfigOptions } from './common/configOptions';
-import { ConsoleInterface } from './common/console';
 import { FullAccessHost } from './common/fullAccessHost';
 import { Host } from './common/host';
 import { ServiceProvider } from './common/serviceProvider';
+import { getRootUri } from './common/uri/uriUtils';
 
 export class BackgroundAnalysis extends BackgroundAnalysisBase {
-    constructor(console: ConsoleInterface) {
-        super(console);
+    constructor(serviceProvider: ServiceProvider) {
+        super(serviceProvider.console());
 
         const initialData: InitializationData = {
-            rootDirectory: (global as any).__rootDirectory as string,
+            rootUri: getRootUri(serviceProvider.fs().isCaseSensitive)?.toString() ?? '',
             cancellationFolderName: getCancellationFolderName(),
             runner: undefined,
         };
@@ -40,7 +40,7 @@ export class BackgroundAnalysisRunner extends BackgroundAnalysisRunnerBase {
     }
 
     protected override createHost(): Host {
-        return new FullAccessHost(this.fs);
+        return new FullAccessHost(this.getServiceProvider());
     }
 
     protected override createImportResolver(
diff --git a/packages/pyright-internal/src/backgroundAnalysisBase.ts b/packages/pyright-internal/src/backgroundAnalysisBase.ts
index a2fcc9151..43b621626 100644
--- a/packages/pyright-internal/src/backgroundAnalysisBase.ts
+++ b/packages/pyright-internal/src/backgroundAnalysisBase.ts
@@ -10,6 +10,7 @@ import { CancellationToken } from 'vscode-languageserver';
 import { MessageChannel, MessagePort, Worker, parentPort, threadId, workerData } from 'worker_threads';
 
 import { AnalysisCompleteCallback, AnalysisResults, analyzeProgram, nullCallback } from './analyzer/analysis';
+import { BackgroundAnalysisProgram, InvalidatedReason } from './analyzer/backgroundAnalysisProgram';
 import { ImportResolver } from './analyzer/importResolver';
 import { OpenFileOptions, Program } from './analyzer/program';
 import {
@@ -33,9 +34,9 @@ import { FileDiagnostics } from './common/diagnosticSink';
 import { disposeCancellationToken, getCancellationTokenFromId } from './common/fileBasedCancellationUtils';
 import { Host, HostKind } from './common/host';
 import { LogTracker } from './common/logTracker';
-import { Range } from './common/textRange';
-import { BackgroundAnalysisProgram, InvalidatedReason } from './analyzer/backgroundAnalysisProgram';
 import { ServiceProvider } from './common/serviceProvider';
+import { Range } from './common/textRange';
+import { Uri } from './common/uri/uri';
 
 export class BackgroundAnalysisBase {
     private _worker: Worker | undefined;
@@ -57,8 +58,8 @@ export class BackgroundAnalysisBase {
         this.enqueueRequest({ requestType: 'setConfigOptions', data: configOptions });
     }
 
-    setTrackedFiles(filePaths: string[]) {
-        this.enqueueRequest({ requestType: 'setTrackedFiles', data: filePaths });
+    setTrackedFiles(fileUris: Uri[]) {
+        this.enqueueRequest({ requestType: 'setTrackedFiles', data: fileUris.map((f) => f.toString()) });
     }
 
     setAllowedThirdPartyImports(importNames: string[]) {
@@ -69,36 +70,36 @@ export class BackgroundAnalysisBase {
         this.enqueueRequest({ requestType: 'ensurePartialStubPackages', data: { executionRoot } });
     }
 
-    setFileOpened(filePath: string, version: number | null, contents: string, options: OpenFileOptions) {
+    setFileOpened(fileUri: Uri, version: number | null, contents: string, options: OpenFileOptions) {
         this.enqueueRequest({
             requestType: 'setFileOpened',
-            data: { filePath, version, contents, options },
+            data: { fileUri: fileUri.toString(), version, contents, options },
         });
     }
 
-    updateChainedFilePath(filePath: string, chainedFilePath: string | undefined) {
+    updateChainedUri(fileUri: Uri, chainedUri: Uri | undefined) {
         this.enqueueRequest({
-            requestType: 'updateChainedFilePath',
-            data: { filePath, chainedFilePath },
+            requestType: 'updateChainedFileUri',
+            data: { fileUri: fileUri.toString(), chainedUri: chainedUri?.toString() },
         });
     }
 
-    setFileClosed(filePath: string, isTracked?: boolean) {
-        this.enqueueRequest({ requestType: 'setFileClosed', data: { filePath, isTracked } });
+    setFileClosed(fileUri: Uri, isTracked?: boolean) {
+        this.enqueueRequest({ requestType: 'setFileClosed', data: { fileUri, isTracked } });
     }
 
-    addInterimFile(filePath: string) {
-        this.enqueueRequest({ requestType: 'addInterimFile', data: { filePath } });
+    addInterimFile(fileUri: Uri) {
+        this.enqueueRequest({ requestType: 'addInterimFile', data: { fileUri: fileUri.toString() } });
     }
 
     markAllFilesDirty(evenIfContentsAreSame: boolean) {
         this.enqueueRequest({ requestType: 'markAllFilesDirty', data: { evenIfContentsAreSame } });
     }
 
-    markFilesDirty(filePaths: string[], evenIfContentsAreSame: boolean) {
+    markFilesDirty(fileUris: Uri[], evenIfContentsAreSame: boolean) {
         this.enqueueRequest({
             requestType: 'markFilesDirty',
-            data: { filePaths, evenIfContentsAreSame },
+            data: { fileUris: fileUris.map((f) => f.toString()), evenIfContentsAreSame },
         });
     }
 
@@ -106,7 +107,7 @@ export class BackgroundAnalysisBase {
         this._startOrResumeAnalysis('analyze', program, token);
     }
 
-    async analyzeFile(filePath: string, token: CancellationToken): Promise<boolean> {
+    async analyzeFile(fileUri: Uri, token: CancellationToken): Promise<boolean> {
         throwIfCancellationRequested(token);
 
         const { port1, port2 } = new MessageChannel();
@@ -115,7 +116,7 @@ export class BackgroundAnalysisBase {
         const cancellationId = getCancellationTokenId(token);
         this.enqueueRequest({
             requestType: 'analyzeFile',
-            data: { filePath, cancellationId },
+            data: { fileUri: fileUri.toString(), cancellationId },
             port: port2,
         });
 
@@ -127,7 +128,7 @@ export class BackgroundAnalysisBase {
         return result;
     }
 
-    async getDiagnosticsForRange(filePath: string, range: Range, token: CancellationToken): Promise<Diagnostic[]> {
+    async getDiagnosticsForRange(fileUri: Uri, range: Range, token: CancellationToken): Promise<Diagnostic[]> {
         throwIfCancellationRequested(token);
 
         const { port1, port2 } = new MessageChannel();
@@ -136,7 +137,7 @@ export class BackgroundAnalysisBase {
         const cancellationId = getCancellationTokenId(token);
         this.enqueueRequest({
             requestType: 'getDiagnosticsForRange',
-            data: { filePath, range, cancellationId },
+            data: { fileUri: fileUri.toString(), range, cancellationId },
             port: port2,
         });
 
@@ -149,9 +150,9 @@ export class BackgroundAnalysisBase {
     }
 
     async writeTypeStub(
-        targetImportPath: string,
+        targetImportPath: Uri,
         targetIsSingleFile: boolean,
-        stubPath: string,
+        stubPath: Uri,
         token: CancellationToken
     ): Promise<any> {
         throwIfCancellationRequested(token);
@@ -162,7 +163,12 @@ export class BackgroundAnalysisBase {
         const cancellationId = getCancellationTokenId(token);
         this.enqueueRequest({
             requestType: 'writeTypeStub',
-            data: { targetImportPath, targetIsSingleFile, stubPath, cancellationId },
+            data: {
+                targetImportPath: targetImportPath.toString(),
+                targetIsSingleFile,
+                stubPath: stubPath.toString(),
+                cancellationId,
+            },
             port: port2,
         });
 
@@ -283,15 +289,15 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
 
     protected importResolver: ImportResolver;
     protected logTracker: LogTracker;
+    protected isCaseSensitive = true;
 
     protected constructor(serviceProvider: ServiceProvider) {
         super(workerData as InitializationData, serviceProvider);
 
         // Stash the base directory into a global variable.
         const data = workerData as InitializationData;
-        this.log(LogLevel.Info, `Background analysis(${threadId}) root directory: ${data.rootDirectory}`);
-
-        this._configOptions = new ConfigOptions(data.rootDirectory);
+        this.log(LogLevel.Info, `Background analysis(${threadId}) root directory: ${data.rootUri}`);
+        this._configOptions = new ConfigOptions(Uri.parse(data.rootUri, serviceProvider.fs().isCaseSensitive));
         this.importResolver = this.createImportResolver(serviceProvider, this._configOptions, this.createHost());
 
         const console = this.getConsole();
@@ -339,20 +345,20 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
 
             case 'analyzeFile': {
                 run(() => {
-                    const { filePath, cancellationId } = msg.data;
+                    const { fileUri, cancellationId } = msg.data;
                     const token = getCancellationTokenFromId(cancellationId);
 
-                    return this.handleAnalyzeFile(filePath, token);
+                    return this.handleAnalyzeFile(fileUri, token);
                 }, msg.port!);
                 break;
             }
 
             case 'getDiagnosticsForRange': {
                 run(() => {
-                    const { filePath, range, cancellationId } = msg.data;
+                    const { fileUri, range, cancellationId } = msg.data;
                     const token = getCancellationTokenFromId(cancellationId);
 
-                    return this.handleGetDiagnosticsForRange(filePath, range, token);
+                    return this.handleGetDiagnosticsForRange(fileUri, range, token);
                 }, msg.port!);
                 break;
             }
@@ -394,26 +400,26 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
             }
 
             case 'setFileOpened': {
-                const { filePath, version, contents, options } = msg.data;
-                this.handleSetFileOpened(filePath, version, contents, options);
+                const { fileUri, version, contents, options } = msg.data;
+                this.handleSetFileOpened(fileUri, version, contents, options);
                 break;
             }
 
-            case 'updateChainedFilePath': {
-                const { filePath, chainedFilePath } = msg.data;
-                this.handleUpdateChainedFilePath(filePath, chainedFilePath);
+            case 'updateChainedFileUri': {
+                const { fileUri, chainedUri } = msg.data;
+                this.handleUpdateChainedfileUri(fileUri, chainedUri);
                 break;
             }
 
             case 'setFileClosed': {
-                const { filePath, isTracked } = msg.data;
-                this.handleSetFileClosed(filePath, isTracked);
+                const { fileUri, isTracked } = msg.data;
+                this.handleSetFileClosed(fileUri, isTracked);
                 break;
             }
 
             case 'addInterimFile': {
-                const { filePath } = msg.data;
-                this.handleAddInterimFile(filePath);
+                const { fileUri } = msg.data;
+                this.handleAddInterimFile(fileUri);
                 break;
             }
 
@@ -424,8 +430,8 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
             }
 
             case 'markFilesDirty': {
-                const { filePaths, evenIfContentsAreSame } = msg.data;
-                this.handleMarkFilesDirty(filePaths, evenIfContentsAreSame);
+                const { fileUris, evenIfContentsAreSame } = msg.data;
+                this.handleMarkFilesDirty(fileUris, evenIfContentsAreSame);
                 break;
             }
 
@@ -499,14 +505,14 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
         }
     }
 
-    protected handleAnalyzeFile(filePath: string, token: CancellationToken) {
+    protected handleAnalyzeFile(fileUri: string, token: CancellationToken) {
         throwIfCancellationRequested(token);
-        return this.program.analyzeFile(filePath, token);
+        return this.program.analyzeFile(Uri.parse(fileUri, this.isCaseSensitive), token);
     }
 
-    protected handleGetDiagnosticsForRange(filePath: string, range: Range, token: CancellationToken) {
+    protected handleGetDiagnosticsForRange(fileUri: string, range: Range, token: CancellationToken) {
         throwIfCancellationRequested(token);
-        return this.program.getDiagnosticsForRange(filePath, range);
+        return this.program.getDiagnosticsForRange(Uri.parse(fileUri, this.isCaseSensitive), range);
     }
 
     protected handleWriteTypeStub(
@@ -524,7 +530,12 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
             token
         );
 
-        this.program.writeTypeStub(targetImportPath, targetIsSingleFile, stubPath, token);
+        this.program.writeTypeStub(
+            Uri.parse(targetImportPath, this.isCaseSensitive),
+            targetIsSingleFile,
+            Uri.parse(stubPath, this.isCaseSensitive),
+            token
+        );
     }
 
     protected handleSetImportResolver(hostKind: HostKind) {
@@ -548,8 +559,8 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
         this.program.setImportResolver(this.importResolver);
     }
 
-    protected handleSetTrackedFiles(filePaths: string[]) {
-        const diagnostics = this.program.setTrackedFiles(filePaths);
+    protected handleSetTrackedFiles(fileUris: string[]) {
+        const diagnostics = this.program.setTrackedFiles(fileUris.map((f) => Uri.parse(f, this.isCaseSensitive)));
         this._reportDiagnostics(diagnostics, this.program.getFilesToAnalyzeCount(), 0);
     }
 
@@ -565,29 +576,35 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
     }
 
     protected handleSetFileOpened(
-        filePath: string,
+        fileUri: string,
         version: number | null,
         contents: string,
         options: OpenFileOptions | undefined
     ) {
-        this.program.setFileOpened(filePath, version, contents, options);
+        this.program.setFileOpened(Uri.parse(fileUri, this.isCaseSensitive), version, contents, options);
     }
 
-    protected handleUpdateChainedFilePath(filePath: string, chainedFilePath: string | undefined) {
-        this.program.updateChainedFilePath(filePath, chainedFilePath);
+    protected handleUpdateChainedfileUri(fileUri: string, chainedfileUri: string | undefined) {
+        this.program.updateChainedUri(
+            Uri.parse(fileUri, this.isCaseSensitive),
+            chainedfileUri ? Uri.parse(chainedfileUri, this.isCaseSensitive) : undefined
+        );
     }
 
-    protected handleSetFileClosed(filePath: string, isTracked: boolean | undefined) {
-        const diagnostics = this.program.setFileClosed(filePath, isTracked);
+    protected handleSetFileClosed(fileUri: string, isTracked: boolean | undefined) {
+        const diagnostics = this.program.setFileClosed(Uri.parse(fileUri, this.isCaseSensitive), isTracked);
         this._reportDiagnostics(diagnostics, this.program.getFilesToAnalyzeCount(), 0);
     }
 
-    protected handleAddInterimFile(filePath: string) {
-        this.program.addInterimFile(filePath);
+    protected handleAddInterimFile(fileUri: string) {
+        this.program.addInterimFile(Uri.parse(fileUri, this.isCaseSensitive));
     }
 
-    protected handleMarkFilesDirty(filePaths: string[], evenIfContentsAreSame: boolean) {
-        this.program.markFilesDirty(filePaths, evenIfContentsAreSame);
+    protected handleMarkFilesDirty(fileUris: string[], evenIfContentsAreSame: boolean) {
+        this.program.markFilesDirty(
+            fileUris.map((f) => Uri.parse(f, this.isCaseSensitive)),
+            evenIfContentsAreSame
+        );
     }
 
     protected handleMarkAllFilesDirty(evenIfContentsAreSame: boolean) {
@@ -666,7 +683,7 @@ export abstract class BackgroundAnalysisRunnerBase extends BackgroundThreadBase
 function convertAnalysisResults(result: AnalysisResults): AnalysisResults {
     result.diagnostics = result.diagnostics.map((f: FileDiagnostics) => {
         return {
-            filePath: f.filePath,
+            fileUri: f.fileUri,
             version: f.version,
             diagnostics: convertDiagnostics(f.diagnostics),
         };
@@ -692,7 +709,7 @@ function convertDiagnostics(diagnostics: Diagnostic[]) {
 
         if (d._relatedInfo) {
             for (const info of d._relatedInfo) {
-                diag.addRelatedInfo(info.message, info.filePath, info.range);
+                diag.addRelatedInfo(info.message, info.fileUri, info.range);
             }
         }
 
@@ -708,7 +725,7 @@ export type AnalysisRequestKind =
     | 'setAllowedThirdPartyImports'
     | 'ensurePartialStubPackages'
     | 'setFileOpened'
-    | 'updateChainedFilePath'
+    | 'updateChainedFileUri'
     | 'setFileClosed'
     | 'markAllFilesDirty'
     | 'markFilesDirty'
diff --git a/packages/pyright-internal/src/backgroundThreadBase.ts b/packages/pyright-internal/src/backgroundThreadBase.ts
index 425507f0d..ecf8f4523 100644
--- a/packages/pyright-internal/src/backgroundThreadBase.ts
+++ b/packages/pyright-internal/src/backgroundThreadBase.ts
@@ -12,11 +12,12 @@ import { OperationCanceledException, setCancellationFolderName } from './common/
 import { ConfigOptions } from './common/configOptions';
 import { ConsoleInterface, LogLevel } from './common/console';
 import * as debug from './common/debug';
-import { FileSpec } from './common/pathUtils';
 import { createFromRealFileSystem, RealTempFile } from './common/realFileSystem';
 import { ServiceProvider } from './common/serviceProvider';
 import './common/serviceProviderExtensions';
 import { ServiceKeys } from './common/serviceProviderExtensions';
+import { Uri } from './common/uri/uri';
+import { FileSpec } from './common/uri/uriUtils';
 
 export class BackgroundConsole implements ConsoleInterface {
     // We always generate logs in the background. For the foreground,
@@ -48,9 +49,6 @@ export class BackgroundThreadBase {
     protected constructor(data: InitializationData, serviceProvider?: ServiceProvider) {
         setCancellationFolderName(data.cancellationFolderName);
 
-        // Stash the base directory into a global variable.
-        (global as any).__rootDirectory = data.rootDirectory;
-
         // Make sure there's a file system and a console interface.
         this._serviceProvider = serviceProvider ?? new ServiceProvider();
         if (!this._serviceProvider.tryGet(ServiceKeys.console)) {
@@ -60,8 +58,17 @@ export class BackgroundThreadBase {
             this._serviceProvider.add(ServiceKeys.fs, createFromRealFileSystem(this.getConsole()));
         }
         if (!this._serviceProvider.tryGet(ServiceKeys.tempFile)) {
-            this._serviceProvider.add(ServiceKeys.tempFile, new RealTempFile());
+            this._serviceProvider.add(
+                ServiceKeys.tempFile,
+                new RealTempFile(this._serviceProvider.fs().isCaseSensitive)
+            );
         }
+
+        // Stash the base directory into a global variable.
+        (global as any).__rootDirectory = Uri.parse(
+            data.rootUri,
+            this._serviceProvider.fs().isCaseSensitive
+        ).getFilePath();
     }
 
     protected get fs() {
@@ -170,7 +177,7 @@ export function getBackgroundWaiter<T>(port: MessagePort): Promise<T> {
 }
 
 export interface InitializationData {
-    rootDirectory: string;
+    rootUri: string;
     cancellationFolderName: string | undefined;
     runner: string | undefined;
     title?: string;
diff --git a/packages/pyright-internal/src/commands/createTypeStub.ts b/packages/pyright-internal/src/commands/createTypeStub.ts
index 94e72b3f6..78ce575f3 100644
--- a/packages/pyright-internal/src/commands/createTypeStub.ts
+++ b/packages/pyright-internal/src/commands/createTypeStub.ts
@@ -9,6 +9,7 @@
 import { CancellationToken, ExecuteCommandParams } from 'vscode-languageserver';
 
 import { OperationCanceledException } from '../common/cancellationUtils';
+import { Uri } from '../common/uri/uri';
 import { LanguageServerInterface } from '../languageServerBase';
 import { AnalyzerServiceExecutor } from '../languageService/analyzerServiceExecutor';
 import { ServerCommand } from './commandController';
@@ -18,9 +19,9 @@ export class CreateTypeStubCommand implements ServerCommand {
 
     async execute(cmdParams: ExecuteCommandParams, token: CancellationToken): Promise<any> {
         if (cmdParams.arguments && cmdParams.arguments.length >= 2) {
-            const workspaceRoot = cmdParams.arguments[0] as string;
+            const workspaceRoot = Uri.parse(cmdParams.arguments[0] as string, this._ls.rootUri.isCaseSensitive);
             const importName = cmdParams.arguments[1] as string;
-            const callingFile = cmdParams.arguments[2] as string;
+            const callingFile = Uri.parse(cmdParams.arguments[2] as string, this._ls.rootUri.isCaseSensitive);
 
             const service = await AnalyzerServiceExecutor.cloneService(
                 this._ls,
diff --git a/packages/pyright-internal/src/commands/dumpFileDebugInfoCommand.ts b/packages/pyright-internal/src/commands/dumpFileDebugInfoCommand.ts
index c400648d7..171408edd 100644
--- a/packages/pyright-internal/src/commands/dumpFileDebugInfoCommand.ts
+++ b/packages/pyright-internal/src/commands/dumpFileDebugInfoCommand.ts
@@ -29,6 +29,7 @@ import { isNumber, isString } from '../common/core';
 import { convertOffsetToPosition, convertOffsetsToRange } from '../common/positionUtils';
 import { TextRange } from '../common/textRange';
 import { TextRangeCollection } from '../common/textRangeCollection';
+import { Uri } from '../common/uri/uri';
 import { LanguageServerInterface } from '../languageServerBase';
 import {
     ArgumentCategory,
@@ -132,11 +133,11 @@ export class DumpFileDebugInfoCommand implements ServerCommand {
             return [];
         }
 
-        const filePath = params.arguments[0] as string;
+        const fileUri = Uri.parse(params.arguments[0] as string, this._ls.rootUri.isCaseSensitive);
         const kind = params.arguments[1];
 
-        const workspace = await this._ls.getWorkspaceForFile(filePath);
-        const parseResults = workspace.service.getParseResult(workspace.service.fs.realCasePath(filePath));
+        const workspace = await this._ls.getWorkspaceForFile(fileUri);
+        const parseResults = workspace.service.getParseResult(workspace.service.fs.realCasePath(fileUri));
         if (!parseResults) {
             return [];
         }
@@ -157,7 +158,7 @@ export class DumpFileDebugInfoCommand implements ServerCommand {
             },
         };
 
-        collectingConsole.info(`* Dump debug info for '${filePath}'`);
+        collectingConsole.info(`* Dump debug info for '${fileUri.toUserVisibleString()}'`);
 
         switch (kind) {
             case 'tokens': {
@@ -166,7 +167,7 @@ export class DumpFileDebugInfoCommand implements ServerCommand {
                 for (let i = 0; i < parseResults.tokenizerOutput.tokens.count; i++) {
                     const token = parseResults.tokenizerOutput.tokens.getItemAt(i);
                     collectingConsole.info(
-                        `[${i}] ${getTokenString(filePath, token, parseResults.tokenizerOutput.lines)}`
+                        `[${i}] ${getTokenString(fileUri, token, parseResults.tokenizerOutput.lines)}`
                     );
                 }
                 break;
@@ -174,7 +175,7 @@ export class DumpFileDebugInfoCommand implements ServerCommand {
             case 'nodes': {
                 collectingConsole.info(`* Node info`);
 
-                const dumper = new TreeDumper(filePath, parseResults.tokenizerOutput.lines);
+                const dumper = new TreeDumper(fileUri, parseResults.tokenizerOutput.lines);
                 dumper.walk(parseResults.parseTree);
 
                 collectingConsole.info(dumper.output);
@@ -189,7 +190,7 @@ export class DumpFileDebugInfoCommand implements ServerCommand {
                 }
 
                 collectingConsole.info(`* Type info`);
-                collectingConsole.info(`${getTypeEvaluatorString(filePath, evaluator, parseResults, start, end)}`);
+                collectingConsole.info(`${getTypeEvaluatorString(fileUri, evaluator, parseResults, start, end)}`);
                 break;
             }
             case 'cachedtypes': {
@@ -201,9 +202,7 @@ export class DumpFileDebugInfoCommand implements ServerCommand {
                 }
 
                 collectingConsole.info(`* Cached Type info`);
-                collectingConsole.info(
-                    `${getTypeEvaluatorString(filePath, evaluator, parseResults, start, end, true)}`
-                );
+                collectingConsole.info(`${getTypeEvaluatorString(fileUri, evaluator, parseResults, start, end, true)}`);
                 break;
             }
 
@@ -239,14 +238,14 @@ function stringify(value: any, replacer: (this: any, key: string, value: any) =>
 }
 
 function getTypeEvaluatorString(
-    file: string,
+    uri: Uri,
     evaluator: TypeEvaluator,
     results: ParseResults,
     start: number,
     end: number,
     cacheOnly?: boolean
 ) {
-    const dumper = new TreeDumper(file, results.tokenizerOutput.lines);
+    const dumper = new TreeDumper(uri, results.tokenizerOutput.lines);
     const node = findNodeByOffset(results.parseTree, start) ?? findNodeByOffset(results.parseTree, end);
     if (!node) {
         return 'N/A';
@@ -549,7 +548,7 @@ class TreeDumper extends ParseTreeWalker {
     private _indentation = '';
     private _output = '';
 
-    constructor(private _file: string, private _lines: TextRangeCollection<TextRange>) {
+    constructor(private _uri: Uri, private _lines: TextRangeCollection<TextRange>) {
         super();
     }
 
@@ -604,7 +603,7 @@ class TreeDumper extends ParseTreeWalker {
     override visitBinaryOperation(node: BinaryOperationNode) {
         this._log(
             `${this._getPrefix(node)} ${getTokenString(
-                this._file,
+                this._uri,
                 node.operatorToken,
                 this._lines
             )} ${getOperatorTypeString(node.operator)}} parenthesized:(${node.parenthesized})`
@@ -697,7 +696,7 @@ class TreeDumper extends ParseTreeWalker {
             `${this._getPrefix(node)} wildcard import:(${node.isWildcardImport}) paren:(${
                 node.usesParens
             }) wildcard token:(${
-                node.wildcardToken ? getTokenString(this._file, node.wildcardToken, this._lines) : 'N/A'
+                node.wildcardToken ? getTokenString(this._uri, node.wildcardToken, this._lines) : 'N/A'
             }) missing import keyword:(${node.missingImportKeyword})`
         );
         return true;
@@ -784,7 +783,7 @@ class TreeDumper extends ParseTreeWalker {
     }
 
     override visitName(node: NameNode) {
-        this._log(`${this._getPrefix(node)} ${getTokenString(this._file, node.token, this._lines)} ${node.value}`);
+        this._log(`${this._getPrefix(node)} ${getTokenString(this._uri, node.token, this._lines)} ${node.value}`);
         return true;
     }
 
@@ -834,7 +833,7 @@ class TreeDumper extends ParseTreeWalker {
     }
 
     override visitString(node: StringNode) {
-        this._log(`${this._getPrefix(node)} ${getTokenString(this._file, node.token, this._lines)} ${node.value}`);
+        this._log(`${this._getPrefix(node)} ${getTokenString(this._uri, node.token, this._lines)} ${node.value}`);
         return true;
     }
 
@@ -866,7 +865,7 @@ class TreeDumper extends ParseTreeWalker {
     override visitUnaryOperation(node: UnaryOperationNode) {
         this._log(
             `${this._getPrefix(node)} ${getTokenString(
-                this._file,
+                this._uri,
                 node.operatorToken,
                 this._lines
             )} ${getOperatorTypeString(node.operator)}`
@@ -988,7 +987,7 @@ class TreeDumper extends ParseTreeWalker {
     private _getPrefix(node: ParseNode) {
         const pos = convertOffsetToPosition(node.start, this._lines);
         // VS code's output window expects 1 based values, print the line/char with 1 based.
-        return `[${node.id}] '${this._file}:${pos.line + 1}:${pos.character + 1}' => ${printParseNodeType(
+        return `[${node.id}] '${this._uri.toString()}:${pos.line + 1}:${pos.character + 1}' => ${printParseNodeType(
             node.nodeType
         )} ${getTextSpanString(node, this._lines)} =>`;
     }
@@ -1066,9 +1065,9 @@ function getErrorExpressionCategoryString(type: ErrorExpressionCategory) {
     }
 }
 
-function getTokenString(file: string, token: Token, lines: TextRangeCollection<TextRange>) {
+function getTokenString(uri: Uri, token: Token, lines: TextRangeCollection<TextRange>) {
     const pos = convertOffsetToPosition(token.start, lines);
-    let str = `'${file}:${pos.line + 1}:${pos.character + 1}' (`;
+    let str = `'${uri.toUserVisibleString()}:${pos.line + 1}:${pos.character + 1}' (`;
     str += getTokenTypeString(token.type);
     str += getNewLineInfo(token);
     str += getOperatorInfo(token);
diff --git a/packages/pyright-internal/src/commands/quickActionCommand.ts b/packages/pyright-internal/src/commands/quickActionCommand.ts
index 460ba03b5..4db117fd8 100644
--- a/packages/pyright-internal/src/commands/quickActionCommand.ts
+++ b/packages/pyright-internal/src/commands/quickActionCommand.ts
@@ -8,6 +8,7 @@
 
 import { CancellationToken, ExecuteCommandParams } from 'vscode-languageserver';
 
+import { Uri } from '../common/uri/uri';
 import { convertToFileTextEdits, convertToWorkspaceEdit } from '../common/workspaceEditUtils';
 import { LanguageServerInterface } from '../languageServerBase';
 import { performQuickAction } from '../languageService/quickActions';
@@ -19,20 +20,19 @@ export class QuickActionCommand implements ServerCommand {
 
     async execute(params: ExecuteCommandParams, token: CancellationToken): Promise<any> {
         if (params.arguments && params.arguments.length >= 1) {
-            const docUri = params.arguments[0] as string;
+            const docUri = Uri.parse(params.arguments[0] as string, this._ls.rootUri.isCaseSensitive);
             const otherArgs = params.arguments.slice(1);
-            const filePath = this._ls.decodeTextDocumentUri(docUri);
-            const workspace = await this._ls.getWorkspaceForFile(filePath);
+            const workspace = await this._ls.getWorkspaceForFile(docUri);
 
             if (params.command === Commands.orderImports && workspace.disableOrganizeImports) {
                 return [];
             }
 
             const editActions = workspace.service.run((p) => {
-                return performQuickAction(p, filePath, params.command, otherArgs, token);
+                return performQuickAction(p, docUri, params.command, otherArgs, token);
             }, token);
 
-            return convertToWorkspaceEdit(workspace.service.fs, convertToFileTextEdits(filePath, editActions ?? []));
+            return convertToWorkspaceEdit(convertToFileTextEdits(docUri, editActions ?? []));
         }
     }
 }
diff --git a/packages/pyright-internal/src/common/configOptions.ts b/packages/pyright-internal/src/common/configOptions.ts
index a1cc69579..25a9cfaf0 100644
--- a/packages/pyright-internal/src/common/configOptions.ts
+++ b/packages/pyright-internal/src/common/configOptions.ts
@@ -18,19 +18,11 @@ import { TaskListToken } from './diagnostic';
 import { DiagnosticRule } from './diagnosticRules';
 import { FileSystem } from './fileSystem';
 import { Host } from './host';
-import {
-    FileSpec,
-    combinePaths,
-    ensureTrailingDirectorySeparator,
-    getFileSpec,
-    isDirectory,
-    normalizePath,
-    realCasePath,
-    resolvePaths,
-} from './pathUtils';
 import { PythonVersion, latestStablePythonVersion, versionFromString, versionToString } from './pythonVersion';
 import { ServiceProvider } from './serviceProvider';
 import { ServiceKeys } from './serviceProviderExtensions';
+import { Uri } from './uri/uri';
+import { FileSpec, getFileSpec, isDirectory } from './uri/uriUtils';
 
 export enum PythonPlatform {
     Darwin = 'Darwin',
@@ -39,10 +31,9 @@ export enum PythonPlatform {
 }
 
 export class ExecutionEnvironment {
-    // Root directory for execution - absolute or relative to the
-    // project root.
+    // Root directory for execution.
     // Undefined if this is a rootless environment (e.g., open file mode).
-    root?: string;
+    root?: Uri;
 
     // Name of a virtual environment if there is one, otherwise
     // just the path to the python executable.
@@ -55,18 +46,18 @@ export class ExecutionEnvironment {
     pythonPlatform?: string | undefined;
 
     // Default to no extra paths.
-    extraPaths: string[] = [];
+    extraPaths: Uri[] = [];
 
     // Default to "." which indicates every file in the project.
     constructor(
         name: string,
-        root: string,
+        root: Uri,
         defaultPythonVersion: PythonVersion | undefined,
         defaultPythonPlatform: string | undefined,
-        defaultExtraPaths: string[] | undefined
+        defaultExtraPaths: Uri[] | undefined
     ) {
         this.name = name;
-        this.root = root || undefined;
+        this.root = root;
         this.pythonVersion = defaultPythonVersion || latestStablePythonVersion;
         this.pythonPlatform = defaultPythonPlatform;
         this.extraPaths = Array.from(defaultExtraPaths ?? []);
@@ -780,9 +771,9 @@ export function getStrictDiagnosticRuleSet(): DiagnosticRuleSet {
     return diagSettings;
 }
 
-export function matchFileSpecs(configOptions: ConfigOptions, filePath: string, isFile = true) {
+export function matchFileSpecs(configOptions: ConfigOptions, uri: Uri, isFile = true) {
     for (const includeSpec of configOptions.include) {
-        if (FileSpec.matchIncludeFileSpec(includeSpec.regExp, configOptions.exclude, filePath, isFile)) {
+        if (FileSpec.matchIncludeFileSpec(includeSpec.regExp, configOptions.exclude, uri, isFile)) {
             return true;
         }
     }
@@ -795,19 +786,19 @@ export function matchFileSpecs(configOptions: ConfigOptions, filePath: string, i
 export class ConfigOptions {
     // Absolute directory of project. All relative paths in the config
     // are based on this path.
-    projectRoot: string;
+    projectRoot: Uri;
 
     // Path to python interpreter.
-    pythonPath?: string | undefined;
+    pythonPath?: Uri | undefined;
 
     // Name of the python environment.
     pythonEnvironmentName?: string | undefined;
 
     // Path to use for typeshed definitions.
-    typeshedPath?: string | undefined;
+    typeshedPath?: Uri | undefined;
 
     // Path to custom typings (stub) modules.
-    stubPath?: string | undefined;
+    stubPath?: Uri | undefined;
 
     // A list of file specs to include in the analysis. Can contain
     // directories, in which case all "*.py" files within those directories
@@ -887,7 +878,7 @@ export class ConfigOptions {
     // directories. This is used in conjunction with the "venv" name in
     // the config file to identify the python environment used for resolving
     // third-party modules.
-    venvPath?: string | undefined;
+    venvPath?: Uri | undefined;
 
     // Default venv environment.
     venv?: string | undefined;
@@ -899,7 +890,7 @@ export class ConfigOptions {
     defaultPythonPlatform?: string | undefined;
 
     // Default extraPaths. Can be overridden by executionEnvironment.
-    defaultExtraPaths?: string[] | undefined;
+    defaultExtraPaths?: Uri[] | undefined;
 
     //---------------------------------------------------------------
     // Internal-only switches
@@ -917,7 +908,7 @@ export class ConfigOptions {
     // Controls how hover and completion function signatures are displayed.
     functionSignatureDisplay: SignatureDisplayType;
 
-    constructor(projectRoot: string, typeCheckingMode?: string) {
+    constructor(projectRoot: Uri, typeCheckingMode?: string) {
         this.projectRoot = projectRoot;
         this.typeCheckingMode = typeCheckingMode;
         this.diagnosticRuleSet = ConfigOptions.getDiagnosticRuleSet(typeCheckingMode);
@@ -950,17 +941,15 @@ export class ConfigOptions {
         );
     }
 
-    // Finds the best execution environment for a given file path. The
+    // Finds the best execution environment for a given file uri. The
     // specified file path should be absolute.
     // If no matching execution environment can be found, a default
     // execution environment is used.
-    findExecEnvironment(filePath: string): ExecutionEnvironment {
+    findExecEnvironment(file: Uri): ExecutionEnvironment {
         return (
             this.executionEnvironments.find((env) => {
-                const envRoot = ensureTrailingDirectorySeparator(
-                    normalizePath(combinePaths(this.projectRoot, env.root))
-                );
-                return filePath.startsWith(envRoot);
+                const envRoot = Uri.isUri(env.root) ? env.root : this.projectRoot.combinePaths(env.root || '');
+                return file.startsWith(envRoot);
             }) ?? this.getDefaultExecEnvironment()
         );
     }
@@ -997,7 +986,7 @@ export class ConfigOptions {
                     } else if (isAbsolute(fileSpec)) {
                         console.error(`Ignoring path "${fileSpec}" in "include" array because it is not relative.`);
                     } else {
-                        this.include.push(getFileSpec(serviceProvider, this.projectRoot, fileSpec));
+                        this.include.push(getFileSpec(this.projectRoot, fileSpec));
                     }
                 });
             }
@@ -1016,7 +1005,7 @@ export class ConfigOptions {
                     } else if (isAbsolute(fileSpec)) {
                         console.error(`Ignoring path "${fileSpec}" in "exclude" array because it is not relative.`);
                     } else {
-                        this.exclude.push(getFileSpec(serviceProvider, this.projectRoot, fileSpec));
+                        this.exclude.push(getFileSpec(this.projectRoot, fileSpec));
                     }
                 });
             }
@@ -1035,7 +1024,7 @@ export class ConfigOptions {
                     } else if (isAbsolute(fileSpec)) {
                         console.error(`Ignoring path "${fileSpec}" in "ignore" array because it is not relative.`);
                     } else {
-                        this.ignore.push(getFileSpec(serviceProvider, this.projectRoot, fileSpec));
+                        this.ignore.push(getFileSpec(this.projectRoot, fileSpec));
                     }
                 });
             }
@@ -1054,7 +1043,7 @@ export class ConfigOptions {
                     } else if (isAbsolute(fileSpec)) {
                         console.error(`Ignoring path "${fileSpec}" in "strict" array because it is not relative.`);
                     } else {
-                        this.strict.push(getFileSpec(serviceProvider, this.projectRoot, fileSpec));
+                        this.strict.push(getFileSpec(this.projectRoot, fileSpec));
                     }
                 });
             }
@@ -1116,7 +1105,7 @@ export class ConfigOptions {
             if (typeof configObj.venvPath !== 'string') {
                 console.error(`Config "venvPath" field must contain a string.`);
             } else {
-                this.venvPath = normalizePath(combinePaths(this.projectRoot, configObj.venvPath));
+                this.venvPath = this.projectRoot.combinePaths(configObj.venvPath);
             }
         }
 
@@ -1141,7 +1130,7 @@ export class ConfigOptions {
                     if (typeof path !== 'string') {
                         console.error(`Config "extraPaths" field ${pathIndex} must be a string.`);
                     } else {
-                        this.defaultExtraPaths!.push(normalizePath(combinePaths(this.projectRoot, path)));
+                        this.defaultExtraPaths!.push(this.projectRoot.combinePaths(path));
                     }
                 });
             }
@@ -1181,8 +1170,8 @@ export class ConfigOptions {
                 console.error(`Config "typeshedPath" field must contain a string.`);
             } else {
                 this.typeshedPath = configObj.typeshedPath
-                    ? normalizePath(combinePaths(this.projectRoot, configObj.typeshedPath))
-                    : '';
+                    ? this.projectRoot.combinePaths(configObj.typeshedPath)
+                    : undefined;
             }
         }
 
@@ -1195,7 +1184,7 @@ export class ConfigOptions {
                 console.error(`Config "typingsPath" field must contain a string.`);
             } else {
                 console.error(`Config "typingsPath" is now deprecated. Please, use stubPath instead.`);
-                this.stubPath = normalizePath(combinePaths(this.projectRoot, configObj.typingsPath));
+                this.stubPath = this.projectRoot.combinePaths(configObj.typingsPath);
             }
         }
 
@@ -1203,7 +1192,7 @@ export class ConfigOptions {
             if (typeof configObj.stubPath !== 'string') {
                 console.error(`Config "stubPath" field must contain a string.`);
             } else {
-                this.stubPath = normalizePath(combinePaths(this.projectRoot, configObj.stubPath));
+                this.stubPath = this.projectRoot.combinePaths(configObj.stubPath);
             }
         }
 
@@ -1345,20 +1334,20 @@ export class ConfigOptions {
     }
 
     ensureDefaultExtraPaths(fs: FileSystem, autoSearchPaths: boolean, extraPaths: string[] | undefined) {
-        const paths: string[] = [];
+        const paths: Uri[] = [];
 
         if (autoSearchPaths) {
             // Auto-detect the common scenario where the sources are under the src folder
-            const srcPath = resolvePaths(this.projectRoot, pathConsts.src);
-            if (fs.existsSync(srcPath) && !fs.existsSync(resolvePaths(srcPath, '__init__.py'))) {
-                paths.push(realCasePath(srcPath, fs));
+            const srcPath = this.projectRoot.combinePaths(pathConsts.src);
+            if (fs.existsSync(srcPath) && !fs.existsSync(srcPath.combinePaths('__init__.py'))) {
+                paths.push(fs.realCasePath(srcPath));
             }
         }
 
         if (extraPaths && extraPaths.length > 0) {
             for (const p of extraPaths) {
-                const path = resolvePaths(this.projectRoot, p);
-                paths.push(realCasePath(path, fs));
+                const path = this.projectRoot.combinePaths(p);
+                paths.push(fs.realCasePath(path));
                 if (isDirectory(fs, path)) {
                     appendArray(paths, getPathsFromPthFiles(fs, path));
                 }
@@ -1384,7 +1373,7 @@ export class ConfigOptions {
     }
 
     private _getEnvironmentName(): string {
-        return this.pythonEnvironmentName || this.pythonPath || 'python';
+        return this.pythonEnvironmentName || this.pythonPath?.toString() || 'python';
     }
 
     private _convertBoolean(value: any, fieldName: string, defaultValue: boolean): boolean {
@@ -1429,7 +1418,7 @@ export class ConfigOptions {
 
             // Validate the root.
             if (envObj.root && typeof envObj.root === 'string') {
-                newExecEnv.root = normalizePath(combinePaths(this.projectRoot, envObj.root));
+                newExecEnv.root = this.projectRoot.combinePaths(envObj.root);
             } else {
                 console.error(`Config executionEnvironments index ${index}: missing root value.`);
             }
@@ -1449,7 +1438,7 @@ export class ConfigOptions {
                                     ` extraPaths field ${pathIndex} must be a string.`
                             );
                         } else {
-                            newExecEnv.extraPaths.push(normalizePath(combinePaths(this.projectRoot, path)));
+                            newExecEnv.extraPaths.push(this.projectRoot.combinePaths(path));
                         }
                     });
                 }
diff --git a/packages/pyright-internal/src/common/diagnostic.ts b/packages/pyright-internal/src/common/diagnostic.ts
index 7f6216999..4d8f528e4 100644
--- a/packages/pyright-internal/src/common/diagnostic.ts
+++ b/packages/pyright-internal/src/common/diagnostic.ts
@@ -11,6 +11,7 @@ import { Commands } from '../commands/commands';
 import { appendArray } from './collectionUtils';
 import { DiagnosticLevel } from './configOptions';
 import { Range, TextRange } from './textRange';
+import { Uri } from './uri/uri';
 
 const defaultMaxDepth = 5;
 const defaultMaxLineCount = 8;
@@ -63,7 +64,7 @@ export interface DiagnosticAction {
 }
 
 export interface DiagnosticWithinFile {
-    filePath: string;
+    uri: Uri;
     diagnostic: Diagnostic;
 }
 
@@ -74,13 +75,13 @@ export interface CreateTypeStubFileAction extends DiagnosticAction {
 
 export interface RenameShadowedFileAction extends DiagnosticAction {
     action: ActionKind.RenameShadowedFileAction;
-    oldFile: string;
-    newFile: string;
+    oldUri: Uri;
+    newUri: Uri;
 }
 
 export interface DiagnosticRelatedInfo {
     message: string;
-    filePath: string;
+    uri: Uri;
     range: Range;
     priority: TaskListPriority;
 }
@@ -118,13 +119,8 @@ export class Diagnostic {
         return this._rule;
     }
 
-    addRelatedInfo(
-        message: string,
-        filePath: string,
-        range: Range,
-        priority: TaskListPriority = TaskListPriority.Normal
-    ) {
-        this._relatedInfo.push({ filePath, message, range, priority });
+    addRelatedInfo(message: string, fileUri: Uri, range: Range, priority: TaskListPriority = TaskListPriority.Normal) {
+        this._relatedInfo.push({ uri: fileUri, message, range, priority });
     }
 
     getRelatedInfo() {
diff --git a/packages/pyright-internal/src/common/diagnosticSink.ts b/packages/pyright-internal/src/common/diagnosticSink.ts
index b1949371f..37307b2c8 100644
--- a/packages/pyright-internal/src/common/diagnosticSink.ts
+++ b/packages/pyright-internal/src/common/diagnosticSink.ts
@@ -14,10 +14,11 @@ import { convertOffsetsToRange } from './positionUtils';
 import { hashString } from './stringUtils';
 import { Range, TextRange } from './textRange';
 import { TextRangeCollection } from './textRangeCollection';
+import { Uri } from './uri/uri';
 
 // Represents a collection of diagnostics within a file.
 export interface FileDiagnostics {
-    filePath: string;
+    fileUri: Uri;
     version: number | undefined;
     diagnostics: Diagnostic[];
 }
diff --git a/packages/pyright-internal/src/common/editAction.ts b/packages/pyright-internal/src/common/editAction.ts
index c496941da..0736fea6a 100644
--- a/packages/pyright-internal/src/common/editAction.ts
+++ b/packages/pyright-internal/src/common/editAction.ts
@@ -8,6 +8,7 @@
  */
 
 import { Range, rangesAreEqual } from './textRange';
+import { Uri } from './uri/uri';
 
 export interface TextEditAction {
     range: Range;
@@ -15,7 +16,7 @@ export interface TextEditAction {
 }
 
 export interface FileEditAction extends TextEditAction {
-    filePath: string;
+    fileUri: Uri;
 }
 
 export interface FileEditActions {
@@ -31,18 +32,18 @@ export interface FileOperation {
 
 export interface RenameFileOperation extends FileOperation {
     kind: 'rename';
-    oldFilePath: string;
-    newFilePath: string;
+    oldFileUri: Uri;
+    newFileUri: Uri;
 }
 
 export interface CreateFileOperation extends FileOperation {
     kind: 'create';
-    filePath: string;
+    fileUri: Uri;
 }
 
 export interface DeleteFileOperation extends FileOperation {
     kind: 'delete';
-    filePath: string;
+    fileUri: Uri;
 }
 
 export namespace TextEditAction {
@@ -53,13 +54,13 @@ export namespace TextEditAction {
 
 export namespace FileEditAction {
     export function is(value: any): value is FileEditAction {
-        return value.filePath !== undefined && TextEditAction.is(value);
+        return value.fileUri !== undefined && TextEditAction.is(value);
     }
 
     export function areEqual(e1: FileEditAction, e2: FileEditAction) {
         return (
             e1 === e2 ||
-            (e1.filePath === e2.filePath &&
+            (e1.fileUri.equals(e2.fileUri) &&
                 rangesAreEqual(e1.range, e2.range) &&
                 e1.replacementText === e2.replacementText)
         );
diff --git a/packages/pyright-internal/src/common/envVarUtils.ts b/packages/pyright-internal/src/common/envVarUtils.ts
index 3d9e50417..324017499 100644
--- a/packages/pyright-internal/src/common/envVarUtils.ts
+++ b/packages/pyright-internal/src/common/envVarUtils.ts
@@ -8,43 +8,35 @@
 
 import * as os from 'os';
 
-import {
-    combinePaths,
-    ensureTrailingDirectorySeparator,
-    getPathComponents,
-    hasTrailingDirectorySeparator,
-} from './pathUtils';
+import { Uri } from './uri/uri';
 
 // Expands certain predefined variables supported within VS Code settings.
 // Ideally, VS Code would provide an API for doing this expansion, but
 // it doesn't. We'll handle the most common variables here as a convenience.
-export function expandPathVariables(rootPath: string, path: string): string {
-    const pathParts = getPathComponents(path);
+export function expandPathVariables(rootPath: Uri, path: string): string {
+    // Make sure the pathStr looks like a URI path.
+    let pathStr = path.replace(/\\/g, '/');
 
-    const expandedParts: string[] = [];
-    for (const part of pathParts) {
-        const trimmedPart = part.trim();
+    // Make sure all replacements look like URI paths too.
+    const replace = (match: RegExp, replaceValue: string) => {
+        pathStr = pathStr.replace(match, replaceValue.replace(/\\/g, '/'));
+    };
 
-        if (trimmedPart === '${workspaceFolder}') {
-            expandedParts.push(rootPath);
-        } else if (trimmedPart === '${env:HOME}' && process.env.HOME !== undefined) {
-            expandedParts.push(process.env.HOME);
-        } else if (trimmedPart === '${env:USERNAME}' && process.env.USERNAME !== undefined) {
-            expandedParts.push(process.env.USERNAME);
-        } else if (trimmedPart === '${env:VIRTUAL_ENV}' && process.env.VIRTUAL_ENV !== undefined) {
-            expandedParts.push(process.env.VIRTUAL_ENV);
-        } else if (trimmedPart === '~' && os.homedir) {
-            expandedParts.push(os.homedir() || process.env.HOME || process.env.USERPROFILE || '~');
-        } else {
-            expandedParts.push(part);
-        }
+    // Replace everything inline.
+    pathStr = pathStr.replace(/\$\{workspaceFolder\}/g, rootPath.getPath());
+    if (process.env.HOME !== undefined) {
+        replace(/\$\{env:HOME\}/g, process.env.HOME || '');
+    }
+    if (process.env.USERNAME !== undefined) {
+        replace(/\$\{env:USERNAME\}/g, process.env.USERNAME || '');
+    }
+    if (process.env.VIRTUAL_ENV !== undefined) {
+        replace(/\$\{env:VIRTUAL_ENV\}/g, process.env.VIRTUAL_ENV || '');
+    }
+    if (os.homedir) {
+        replace(/\/~/g, os.homedir() || process.env.HOME || process.env.USERPROFILE || '~');
+        replace(/^~/g, os.homedir() || process.env.HOME || process.env.USERPROFILE || '~');
     }
 
-    if (expandedParts.length === 0) {
-        return path;
-    }
-
-    const root = expandedParts.shift()!;
-    const expandedPath = combinePaths(root, ...expandedParts);
-    return hasTrailingDirectorySeparator(path) ? ensureTrailingDirectorySeparator(expandedPath) : expandedPath;
+    return pathStr;
 }
diff --git a/packages/pyright-internal/src/common/extensibility.ts b/packages/pyright-internal/src/common/extensibility.ts
index b29923a44..51a11a99d 100644
--- a/packages/pyright-internal/src/common/extensibility.ts
+++ b/packages/pyright-internal/src/common/extensibility.ts
@@ -11,19 +11,20 @@ import { CancellationToken } from 'vscode-languageserver';
 import { Declaration } from '../analyzer/declaration';
 import { ImportResolver } from '../analyzer/importResolver';
 import * as prog from '../analyzer/program';
+import { IPythonMode } from '../analyzer/sourceFile';
 import { SourceMapper } from '../analyzer/sourceMapper';
+import { SymbolTable } from '../analyzer/symbol';
 import { TypeEvaluator } from '../analyzer/typeEvaluatorTypes';
+import { Diagnostic } from '../common/diagnostic';
 import { ServerSettings } from '../languageServerBase';
 import { ParseNode } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
 import { ConfigOptions } from './configOptions';
 import { ConsoleInterface } from './console';
 import { ReadOnlyFileSystem } from './fileSystem';
-import { Range } from './textRange';
-import { SymbolTable } from '../analyzer/symbol';
-import { Diagnostic } from '../common/diagnostic';
-import { IPythonMode } from '../analyzer/sourceFile';
 import { GroupServiceKey, ServiceKey } from './serviceProvider';
+import { Range } from './textRange';
+import { Uri } from './uri/uri';
 
 export interface SourceFile {
     // See whether we can convert these to regular properties.
@@ -31,9 +32,8 @@ export interface SourceFile {
     isThirdPartyPyTypedPresent(): boolean;
 
     getIPythonMode(): IPythonMode;
-    getFilePath(): string;
+    getUri(): Uri;
     getFileContent(): string | undefined;
-    getRealFilePath(): string | undefined;
     getClientVersion(): number | undefined;
     getOpenFileContents(): string | undefined;
     getModuleSymbolTable(): SymbolTable | undefined;
@@ -73,7 +73,7 @@ export interface ServiceProvider {
 // Readonly wrapper around a Program. Makes sure it doesn't mutate the program.
 export interface ProgramView {
     readonly id: string;
-    readonly rootPath: string;
+    readonly rootPath: Uri;
     readonly console: ConsoleInterface;
     readonly evaluator: TypeEvaluator | undefined;
     readonly configOptions: ConfigOptions;
@@ -81,21 +81,16 @@ export interface ProgramView {
     readonly fileSystem: ReadOnlyFileSystem;
     readonly serviceProvider: ServiceProvider;
 
-    owns(file: string): boolean;
+    owns(uri: Uri): boolean;
     getSourceFileInfoList(): readonly SourceFileInfo[];
-    getParseResults(filePath: string): ParseResults | undefined;
-    getSourceFileInfo(filePath: string): SourceFileInfo | undefined;
-    getChainedFilePath(filePath: string): string | undefined;
-    getSourceMapper(
-        filePath: string,
-        token: CancellationToken,
-        mapCompiled?: boolean,
-        preferStubs?: boolean
-    ): SourceMapper;
+    getParseResults(fileUri: Uri): ParseResults | undefined;
+    getSourceFileInfo(fileUri: Uri): SourceFileInfo | undefined;
+    getChainedUri(fileUri: Uri): Uri | undefined;
+    getSourceMapper(fileUri: Uri, token: CancellationToken, mapCompiled?: boolean, preferStubs?: boolean): SourceMapper;
 
     // Consider getDiagnosticsForRange to call `analyzeFile` automatically if the file is not analyzed.
-    analyzeFile(filePath: string, token: CancellationToken): boolean;
-    getDiagnosticsForRange(filePath: string, range: Range): Diagnostic[];
+    analyzeFile(fileUri: Uri, token: CancellationToken): boolean;
+    getDiagnosticsForRange(fileUri: Uri, range: Range): Diagnostic[];
 
     // See whether we can get rid of these methods
     handleMemoryHighUsage(): void;
@@ -106,9 +101,9 @@ export interface ProgramView {
 // and doesn't forward the request to the BG thread.
 // One can use this when edits are temporary such as `runEditMode` or `test`
 export interface EditableProgram extends ProgramView {
-    addInterimFile(file: string): void;
-    setFileOpened(filePath: string, version: number | null, contents: string, options?: prog.OpenFileOptions): void;
-    updateChainedFilePath(filePath: string, chainedFilePath: string | undefined): void;
+    addInterimFile(uri: Uri): void;
+    setFileOpened(fileUri: Uri, version: number | null, contents: string, options?: prog.OpenFileOptions): void;
+    updateChainedUri(fileUri: Uri, chainedUri: Uri | undefined): void;
 }
 
 // Mutable wrapper around a program. Allows the FG thread to forward this request to the BG thread
@@ -116,7 +111,7 @@ export interface EditableProgram extends ProgramView {
 export interface ProgramMutator {
     addInterimFile(file: string): void;
     setFileOpened(
-        filePath: string,
+        fileUri: Uri,
         version: number | null,
         contents: string,
         ipythonMode: IPythonMode,
@@ -162,7 +157,7 @@ export interface SymbolUsageProvider {
 }
 
 export interface StatusMutationListener {
-    fileDirty?: (filePath: string) => void;
+    fileDirty?: (fileUri: Uri) => void;
     clearCache?: () => void;
     updateSettings?: <T extends ServerSettings>(settings: T) => void;
 }
diff --git a/packages/pyright-internal/src/common/fileSystem.ts b/packages/pyright-internal/src/common/fileSystem.ts
index 8ffa3ef9f..f03f454f1 100644
--- a/packages/pyright-internal/src/common/fileSystem.ts
+++ b/packages/pyright-internal/src/common/fileSystem.ts
@@ -11,6 +11,7 @@
 // * NOTE * except tests, this should be only file that import "fs"
 import type * as fs from 'fs';
 import { FileWatcher, FileWatcherEventHandler } from './fileWatcher';
+import { Uri } from './uri/uri';
 
 export interface Stats {
     size: number;
@@ -33,48 +34,47 @@ export interface MkDirOptions {
 }
 
 export interface ReadOnlyFileSystem {
-    existsSync(path: string): boolean;
-    chdir(path: string): void;
-    readdirEntriesSync(path: string): fs.Dirent[];
-    readdirSync(path: string): string[];
-    readFileSync(path: string, encoding?: null): Buffer;
-    readFileSync(path: string, encoding: BufferEncoding): string;
-    readFileSync(path: string, encoding?: BufferEncoding | null): string | Buffer;
+    readonly isCaseSensitive: boolean;
+    existsSync(uri: Uri): boolean;
+    chdir(uri: Uri): void;
+    readdirEntriesSync(uri: Uri): fs.Dirent[];
+    readdirSync(uri: Uri): string[];
+    readFileSync(uri: Uri, encoding?: null): Buffer;
+    readFileSync(uri: Uri, encoding: BufferEncoding): string;
+    readFileSync(uri: Uri, encoding?: BufferEncoding | null): string | Buffer;
 
-    statSync(path: string): Stats;
-    realpathSync(path: string): string;
-    getModulePath(): string;
+    statSync(uri: Uri): Stats;
+    realpathSync(uri: Uri): Uri;
+    getModulePath(): Uri;
     // Async I/O
-    readFile(path: string): Promise<Buffer>;
-    readFileText(path: string, encoding?: BufferEncoding): Promise<string>;
+    readFile(uri: Uri): Promise<Buffer>;
+    readFileText(uri: Uri, encoding?: BufferEncoding): Promise<string>;
     // Return path in casing on OS.
-    realCasePath(path: string): string;
+    realCasePath(uri: Uri): Uri;
 
     // See whether the file is mapped to another location.
-    isMappedFilePath(filepath: string): boolean;
+    isMappedUri(uri: Uri): boolean;
 
-    // Get original filepath if the given filepath is mapped.
-    getOriginalFilePath(mappedFilePath: string): string;
+    // Get original uri if the given uri is mapped.
+    getOriginalUri(mappedUri: Uri): Uri;
 
-    // Get mapped filepath if the given filepath is mapped.
-    getMappedFilePath(originalFilepath: string): string;
+    // Get mapped uri if the given uri is mapped.
+    getMappedUri(originalUri: Uri): Uri;
 
-    getUri(path: string): string;
-
-    isInZip(path: string): boolean;
+    isInZip(uri: Uri): boolean;
 }
 
 export interface FileSystem extends ReadOnlyFileSystem {
-    mkdirSync(path: string, options?: MkDirOptions): void;
-    writeFileSync(path: string, data: string | Buffer, encoding: BufferEncoding | null): void;
+    mkdirSync(uri: Uri, options?: MkDirOptions): void;
+    writeFileSync(uri: Uri, data: string | Buffer, encoding: BufferEncoding | null): void;
 
-    unlinkSync(path: string): void;
-    rmdirSync(path: string): void;
+    unlinkSync(uri: Uri): void;
+    rmdirSync(uri: Uri): void;
 
-    createFileSystemWatcher(paths: string[], listener: FileWatcherEventHandler): FileWatcher;
-    createReadStream(path: string): fs.ReadStream;
-    createWriteStream(path: string): fs.WriteStream;
-    copyFileSync(src: string, dst: string): void;
+    createFileSystemWatcher(uris: Uri[], listener: FileWatcherEventHandler): FileWatcher;
+    createReadStream(uri: Uri): fs.ReadStream;
+    createWriteStream(uri: Uri): fs.WriteStream;
+    copyFileSync(uri: Uri, dst: Uri): void;
 }
 
 export interface TmpfileOptions {
@@ -84,8 +84,8 @@ export interface TmpfileOptions {
 
 export interface TempFile {
     // The directory returned by tmpdir must exist and be the same each time tmpdir is called.
-    tmpdir(): string;
-    tmpfile(options?: TmpfileOptions): string;
+    tmpdir(): Uri;
+    tmpfile(options?: TmpfileOptions): Uri;
     dispose(): void;
 }
 
diff --git a/packages/pyright-internal/src/common/fileWatcher.ts b/packages/pyright-internal/src/common/fileWatcher.ts
index bc635904e..c385eda16 100644
--- a/packages/pyright-internal/src/common/fileWatcher.ts
+++ b/packages/pyright-internal/src/common/fileWatcher.ts
@@ -6,16 +6,17 @@
  * file watcher related functionality.
  */
 import { Stats } from './fileSystem';
+import { Uri } from './uri/uri';
 
 export type FileWatcherEventType = 'add' | 'addDir' | 'change' | 'unlink' | 'unlinkDir';
-export type FileWatcherEventHandler = (eventName: FileWatcherEventType, path: string, stats?: Stats) => void;
+export type FileWatcherEventHandler = (eventName: FileWatcherEventType, uri: Uri, stats?: Stats) => void;
 
 export interface FileWatcher {
     close(): void;
 }
 
 export interface FileWatcherHandler {
-    onFileChange(eventType: FileWatcherEventType, path: string): void;
+    onFileChange(eventType: FileWatcherEventType, uri: Uri): void;
 }
 
 export interface FileWatcherProvider {
@@ -23,7 +24,7 @@ export interface FileWatcherProvider {
 }
 
 export const nullFileWatcherHandler: FileWatcherHandler = {
-    onFileChange(_1: FileWatcherEventType, _2: string): void {
+    onFileChange(_1: FileWatcherEventType, _2: Uri): void {
         // do nothing
     },
 };
diff --git a/packages/pyright-internal/src/common/fullAccessHost.ts b/packages/pyright-internal/src/common/fullAccessHost.ts
index 0429e3f63..de3a59610 100644
--- a/packages/pyright-internal/src/common/fullAccessHost.ts
+++ b/packages/pyright-internal/src/common/fullAccessHost.ts
@@ -13,10 +13,12 @@ import { PythonPathResult } from '../analyzer/pythonPathUtils';
 import { OperationCanceledException, throwIfCancellationRequested } from './cancellationUtils';
 import { PythonPlatform } from './configOptions';
 import { assertNever } from './debug';
-import { FileSystem } from './fileSystem';
 import { HostKind, NoAccessHost, ScriptOutput } from './host';
-import { isDirectory, normalizePath } from './pathUtils';
+import { normalizePath } from './pathUtils';
 import { PythonVersion, versionFromMajorMinor } from './pythonVersion';
+import { ServiceProvider } from './serviceProvider';
+import { Uri } from './uri/uri';
+import { isDirectory } from './uri/uriUtils';
 
 // preventLocalImports removes the working directory from sys.path.
 // The -c flag adds it automatically, which can allow some stdlib
@@ -60,7 +62,7 @@ export class LimitedAccessHost extends NoAccessHost {
 }
 
 export class FullAccessHost extends LimitedAccessHost {
-    constructor(protected fs: FileSystem) {
+    constructor(protected serviceProvider: ServiceProvider) {
         super();
     }
 
@@ -68,29 +70,29 @@ export class FullAccessHost extends LimitedAccessHost {
         return HostKind.FullAccess;
     }
 
-    static createHost(kind: HostKind, fs: FileSystem) {
+    static createHost(kind: HostKind, serviceProvider: ServiceProvider) {
         switch (kind) {
             case HostKind.NoAccess:
                 return new NoAccessHost();
             case HostKind.LimitedAccess:
                 return new LimitedAccessHost();
             case HostKind.FullAccess:
-                return new FullAccessHost(fs);
+                return new FullAccessHost(serviceProvider);
             default:
                 assertNever(kind);
         }
     }
 
-    override getPythonSearchPaths(pythonPath?: string, logInfo?: string[]): PythonPathResult {
+    override getPythonSearchPaths(pythonPath?: Uri, logInfo?: string[]): PythonPathResult {
         const importFailureInfo = logInfo ?? [];
-        let result = this._executePythonInterpreter(pythonPath, (p) =>
-            this._getSearchPathResultFromInterpreter(this.fs, p, importFailureInfo)
+        let result = this._executePythonInterpreter(pythonPath?.getFilePath(), (p) =>
+            this._getSearchPathResultFromInterpreter(p, importFailureInfo)
         );
 
         if (!result) {
             result = {
                 paths: [],
-                prefix: '',
+                prefix: undefined,
             };
         }
 
@@ -102,12 +104,12 @@ export class FullAccessHost extends LimitedAccessHost {
         return result;
     }
 
-    override getPythonVersion(pythonPath?: string, logInfo?: string[]): PythonVersion | undefined {
+    override getPythonVersion(pythonPath?: Uri, logInfo?: string[]): PythonVersion | undefined {
         const importFailureInfo = logInfo ?? [];
 
         try {
             const commandLineArgs: string[] = ['-c', extractVersion];
-            const execOutput = this._executePythonInterpreter(pythonPath, (p) =>
+            const execOutput = this._executePythonInterpreter(pythonPath?.getFilePath(), (p) =>
                 child_process.execFileSync(p, commandLineArgs, { encoding: 'utf8' })
             );
 
@@ -128,8 +130,8 @@ export class FullAccessHost extends LimitedAccessHost {
     }
 
     override runScript(
-        pythonPath: string | undefined,
-        script: string,
+        pythonPath: Uri | undefined,
+        script: Uri,
         args: string[],
         cwd: string,
         token: CancellationToken
@@ -141,9 +143,9 @@ export class FullAccessHost extends LimitedAccessHost {
         return new Promise<{ stdout: string; stderr: string }>((resolve, reject) => {
             let stdout = '';
             let stderr = '';
-            const commandLineArgs = [script, ...args];
+            const commandLineArgs = [script.getFilePath(), ...args];
 
-            const child = this._executePythonInterpreter(pythonPath, (p) =>
+            const child = this._executePythonInterpreter(pythonPath?.getFilePath(), (p) =>
                 child_process.spawn(p, commandLineArgs, { cwd })
             );
             const tokenWatch = token.onCancellationRequested(() => {
@@ -210,20 +212,19 @@ export class FullAccessHost extends LimitedAccessHost {
     }
 
     private _getSearchPathResultFromInterpreter(
-        fs: FileSystem,
-        interpreter: string,
+        interpreterPath: string,
         importFailureInfo: string[]
     ): PythonPathResult | undefined {
         const result: PythonPathResult = {
             paths: [],
-            prefix: '',
+            prefix: undefined,
         };
 
         try {
             const commandLineArgs: string[] = ['-c', extractSys];
-
-            importFailureInfo.push(`Executing interpreter: '${interpreter}'`);
-            const execOutput = child_process.execFileSync(interpreter, commandLineArgs, { encoding: 'utf8' });
+            importFailureInfo.push(`Executing interpreter: '${interpreterPath}'`);
+            const execOutput = child_process.execFileSync(interpreterPath, commandLineArgs, { encoding: 'utf8' });
+            const isCaseSensitive = this.serviceProvider.fs().isCaseSensitive;
 
             // Parse the execOutput. It should be a JSON-encoded array of paths.
             try {
@@ -232,16 +233,20 @@ export class FullAccessHost extends LimitedAccessHost {
                     execSplitEntry = execSplitEntry.trim();
                     if (execSplitEntry) {
                         const normalizedPath = normalizePath(execSplitEntry);
+                        const normalizedUri = Uri.file(normalizedPath, isCaseSensitive);
                         // Skip non-existent paths and broken zips/eggs.
-                        if (fs.existsSync(normalizedPath) && isDirectory(fs, normalizedPath)) {
-                            result.paths.push(normalizedPath);
+                        if (
+                            this.serviceProvider.fs().existsSync(normalizedUri) &&
+                            isDirectory(this.serviceProvider.fs(), normalizedUri)
+                        ) {
+                            result.paths.push(normalizedUri);
                         } else {
                             importFailureInfo.push(`Skipping '${normalizedPath}' because it is not a valid directory`);
                         }
                     }
                 }
 
-                result.prefix = execSplit.prefix;
+                result.prefix = Uri.file(execSplit.prefix, isCaseSensitive);
 
                 if (result.paths.length === 0) {
                     importFailureInfo.push(`Found no valid directories`);
diff --git a/packages/pyright-internal/src/common/host.ts b/packages/pyright-internal/src/common/host.ts
index 133c67c33..ffb70ea06 100644
--- a/packages/pyright-internal/src/common/host.ts
+++ b/packages/pyright-internal/src/common/host.ts
@@ -11,6 +11,7 @@ import { CancellationToken } from 'vscode-languageserver';
 import { PythonPathResult } from '../analyzer/pythonPathUtils';
 import { PythonPlatform } from './configOptions';
 import { PythonVersion } from './pythonVersion';
+import { Uri } from './uri/uri';
 
 export const enum HostKind {
     FullAccess,
@@ -25,12 +26,12 @@ export interface ScriptOutput {
 
 export interface Host {
     readonly kind: HostKind;
-    getPythonSearchPaths(pythonPath?: string, logInfo?: string[]): PythonPathResult;
-    getPythonVersion(pythonPath?: string, logInfo?: string[]): PythonVersion | undefined;
+    getPythonSearchPaths(pythonPath?: Uri, logInfo?: string[]): PythonPathResult;
+    getPythonVersion(pythonPath?: Uri, logInfo?: string[]): PythonVersion | undefined;
     getPythonPlatform(logInfo?: string[]): PythonPlatform | undefined;
     runScript(
-        pythonPath: string | undefined,
-        script: string,
+        pythonPath: Uri | undefined,
+        script: Uri,
         args: string[],
         cwd: string,
         token: CancellationToken
@@ -42,16 +43,16 @@ export class NoAccessHost implements Host {
         return HostKind.NoAccess;
     }
 
-    getPythonSearchPaths(pythonPath?: string, logInfo?: string[]): PythonPathResult {
+    getPythonSearchPaths(pythonPath?: Uri, logInfo?: string[]): PythonPathResult {
         logInfo?.push('No access to python executable.');
 
         return {
             paths: [],
-            prefix: '',
+            prefix: undefined,
         };
     }
 
-    getPythonVersion(pythonPath?: string, logInfo?: string[]): PythonVersion | undefined {
+    getPythonVersion(pythonPath?: Uri, logInfo?: string[]): PythonVersion | undefined {
         return undefined;
     }
 
@@ -60,8 +61,8 @@ export class NoAccessHost implements Host {
     }
 
     async runScript(
-        pythonPath: string | undefined,
-        scriptPath: string,
+        pythonPath: Uri | undefined,
+        scriptPath: Uri,
         args: string[],
         cwd: string,
         token: CancellationToken
diff --git a/packages/pyright-internal/src/common/logTracker.ts b/packages/pyright-internal/src/common/logTracker.ts
index dfcf181ce..24801cee2 100644
--- a/packages/pyright-internal/src/common/logTracker.ts
+++ b/packages/pyright-internal/src/common/logTracker.ts
@@ -9,16 +9,17 @@
 import { ConsoleInterface, LogLevel } from './console';
 import { ReadOnlyFileSystem } from './fileSystem';
 import { Duration, timingStats } from './timing';
+import { Uri } from './uri/uri';
 
 // Consider an operation "long running" if it goes longer than this.
 const durationThresholdForInfoInMs = 2000;
 
-export function getPathForLogging(fs: ReadOnlyFileSystem, filepath: string) {
-    if (fs.isMappedFilePath(filepath)) {
-        return fs.getOriginalFilePath(filepath);
+export function getPathForLogging(fs: ReadOnlyFileSystem, fileUri: Uri) {
+    if (fs.isMappedUri(fileUri)) {
+        return fs.getOriginalUri(fileUri);
     }
 
-    return filepath;
+    return fileUri;
 }
 
 export class LogTracker {
diff --git a/packages/pyright-internal/src/common/pathUtils.ts b/packages/pyright-internal/src/common/pathUtils.ts
index 5b78735e1..142d4f9cb 100644
--- a/packages/pyright-internal/src/common/pathUtils.ts
+++ b/packages/pyright-internal/src/common/pathUtils.ts
@@ -7,24 +7,14 @@
  * Pathname utility functions.
  */
 
-import type { Dirent } from 'fs';
 import * as path from 'path';
-import { URI, Utils } from 'vscode-uri';
 
 import { Char } from './charCodes';
 import { some } from './collectionUtils';
 import { GetCanonicalFileName, identity } from './core';
-import { randomBytesHex } from './crypto';
 import * as debug from './debug';
-import { ServiceProvider } from './extensibility';
-import { FileSystem, ReadOnlyFileSystem, Stats, TempFile } from './fileSystem';
-import { ServiceKeys } from './serviceProviderExtensions';
 import { equateStringsCaseInsensitive, equateStringsCaseSensitive } from './stringUtils';
 
-let _fsCaseSensitivity: boolean | undefined = undefined;
-let _underTest: boolean = false;
-const _uriSchemePattern = /^\w[\w\d+.-]*$/;
-
 export interface FileSpec {
     // File specs can contain wildcard characters (**, *, ?). This
     // specifies the first portion of the file spec that contains
@@ -72,52 +62,26 @@ export interface FileSystemEntries {
     directories: string[];
 }
 
-export function forEachAncestorDirectory(
-    directory: string,
-    callback: (directory: string) => string | undefined
-): string | undefined {
-    while (true) {
-        const result = callback(directory);
-        if (result !== undefined) {
-            return result;
-        }
-
-        const parentPath = getDirectoryPath(directory);
-        if (parentPath === directory) {
-            return undefined;
-        }
-
-        directory = parentPath;
-    }
-}
-
 export function getDirectoryPath(pathString: string): string {
-    if (isUri(pathString)) {
-        return Utils.dirname(URI.parse(pathString).with({ fragment: '', query: '' })).toString();
-    }
     return pathString.substr(0, Math.max(getRootLength(pathString), pathString.lastIndexOf(path.sep)));
 }
 
-export function isUri(pathString: string) {
-    return pathString.indexOf(':') > 1 && _uriSchemePattern.test(pathString.split(':')[0]);
-}
-
 /**
  * Returns length of the root part of a path or URL (i.e. length of "/", "x:/", "//server/").
  */
-export function getRootLength(pathString: string, checkUri = true): number {
-    if (pathString.charAt(0) === path.sep) {
-        if (pathString.charAt(1) !== path.sep) {
+export function getRootLength(pathString: string, sep = path.sep): number {
+    if (pathString.charAt(0) === sep) {
+        if (pathString.charAt(1) !== sep) {
             return 1; // POSIX: "/" (or non-normalized "\")
         }
-        const p1 = pathString.indexOf(path.sep, 2);
+        const p1 = pathString.indexOf(sep, 2);
         if (p1 < 0) {
             return pathString.length; // UNC: "//server" or "\\server"
         }
         return p1 + 1; // UNC: "//server/" or "\\server\"
     }
     if (pathString.charAt(1) === ':') {
-        if (pathString.charAt(2) === path.sep) {
+        if (pathString.charAt(2) === sep) {
             return 3; // DOS: "c:/" or "c:\"
         }
         if (pathString.length === 2) {
@@ -125,25 +89,16 @@ export function getRootLength(pathString: string, checkUri = true): number {
         }
     }
 
-    if (checkUri && isUri(pathString)) {
-        const uri = URI.parse(pathString);
-        if (uri.authority) {
-            return uri.scheme.length + 3; // URI: "file://"
-        } else {
-            return uri.scheme.length + 1; // URI: "untitled:"
-        }
-    }
-
     return 0;
 }
 
 export function getPathSeparator(pathString: string) {
-    return isUri(pathString) ? '/' : path.sep;
+    return path.sep;
 }
 
 export function getPathComponents(pathString: string) {
     const normalizedPath = normalizeSlashes(pathString);
-    const rootLength = getRootLength(normalizedPath, /* checkUri */ isUri(normalizedPath));
+    const rootLength = getRootLength(normalizedPath);
     const root = normalizedPath.substring(0, rootLength);
     const sep = getPathSeparator(pathString);
     const rest = normalizedPath.substring(rootLength).split(sep);
@@ -211,47 +166,11 @@ export function getRelativePath(dirPath: string, relativeTo: string) {
     return relativePath;
 }
 
-// Creates a directory hierarchy for a path, starting from some ancestor path.
-export function makeDirectories(fs: FileSystem, dirPath: string, startingFromDirPath: string) {
-    if (!dirPath.startsWith(startingFromDirPath)) {
-        return;
-    }
-
-    const pathComponents = getPathComponents(dirPath);
-    const relativeToComponents = getPathComponents(startingFromDirPath);
-    let curPath = startingFromDirPath;
-
-    for (let i = relativeToComponents.length; i < pathComponents.length; i++) {
-        curPath = combinePaths(curPath, pathComponents[i]);
-        if (!fs.existsSync(curPath)) {
-            fs.mkdirSync(curPath);
-        }
-    }
-}
-
-export function getFileSize(fs: ReadOnlyFileSystem, path: string) {
-    const stat = tryStat(fs, path);
-    if (stat?.isFile()) {
-        return stat.size;
-    }
-    return 0;
-}
-
-export function fileExists(fs: ReadOnlyFileSystem, path: string): boolean {
-    return fileSystemEntryExists(fs, path, FileSystemEntryKind.File);
-}
-
-export function directoryExists(fs: ReadOnlyFileSystem, path: string): boolean {
-    return fileSystemEntryExists(fs, path, FileSystemEntryKind.Directory);
-}
-
 const getInvalidSeparator = (sep: string) => (sep === '/' ? '\\' : '/');
 export function normalizeSlashes(pathString: string, sep = path.sep): string {
-    if (!isUri(pathString)) {
-        if (pathString.includes(getInvalidSeparator(sep))) {
-            const separatorRegExp = /[\\/]/g;
-            return pathString.replace(separatorRegExp, sep);
-        }
+    if (pathString.includes(getInvalidSeparator(sep))) {
+        const separatorRegExp = /[\\/]/g;
+        return pathString.replace(separatorRegExp, sep);
     }
 
     return pathString;
@@ -271,7 +190,7 @@ export function resolvePaths(path: string, ...paths: (string | undefined)[]): st
     return normalizePath(some(paths) ? combinePaths(path, ...paths) : normalizeSlashes(path));
 }
 
-function combineFilePaths(pathString: string, ...paths: (string | undefined)[]): string {
+export function combinePaths(pathString: string, ...paths: (string | undefined)[]): string {
     if (pathString) {
         pathString = normalizeSlashes(pathString);
     }
@@ -283,7 +202,7 @@ function combineFilePaths(pathString: string, ...paths: (string | undefined)[]):
 
         relativePath = normalizeSlashes(relativePath);
 
-        if (!pathString || getRootLength(relativePath, /* checkUri */ false) !== 0) {
+        if (!pathString || getRootLength(relativePath) !== 0) {
             pathString = relativePath;
         } else {
             pathString = ensureTrailingDirectorySeparator(pathString) + relativePath;
@@ -293,29 +212,6 @@ function combineFilePaths(pathString: string, ...paths: (string | undefined)[]):
     return pathString;
 }
 
-export function combinePaths(pathString: string, ...paths: (string | undefined)[]): string {
-    if (!isUri(pathString)) {
-        // Not a URI, or a URI with a single letter scheme.
-        return combineFilePaths(pathString, ...paths);
-    }
-
-    // Go through the paths to see if any are rooted. If so, treat as
-    // a file path. On linux this might be wrong if a path starts with '/'.
-    if (some(paths, (p) => !!p && getRootLength(p, /* checkUri */ false) !== 0)) {
-        return combineFilePaths(pathString, ...paths);
-    }
-
-    // Otherwise this is a URI
-    const nonEmptyPaths = paths.filter((p) => !!p) as string[];
-    const uri = URI.parse(pathString);
-
-    // Make sure we have a path to append to.
-    if (uri.path === '' || uri.path === undefined) {
-        nonEmptyPaths.unshift('/');
-    }
-    return Utils.joinPath(uri.with({ fragment: '', query: '' }), ...nonEmptyPaths).toString();
-}
-
 /**
  * Determines whether a `parent` path contains a `child` path using the provide case sensitivity.
  */
@@ -485,9 +381,7 @@ export function getBaseFileName(pathString: string, extensions?: string | readon
     // return the trailing portion of the path starting after the last (non-terminal) directory
     // separator but not including any trailing directory separator.
     pathString = stripTrailingDirectorySeparator(pathString);
-    const name = isUri(pathString)
-        ? Utils.basename(URI.parse(pathString).with({ fragment: '', query: '' }))
-        : pathString.slice(Math.max(getRootLength(pathString), pathString.lastIndexOf(path.sep) + 1));
+    const name = pathString.slice(Math.max(getRootLength(pathString), pathString.lastIndexOf(path.sep) + 1));
     const extension =
         extensions !== undefined && ignoreCase !== undefined
             ? getAnyExtensionFromPath(name, extensions, ignoreCase)
@@ -561,7 +455,7 @@ export function stripTrailingDirectorySeparator(pathString: string) {
     if (!hasTrailingDirectorySeparator(pathString)) {
         return pathString;
     }
-    return pathString.substr(0, pathString.length - 1);
+    return pathString.slice(0, pathString.length - 1);
 }
 
 export function getFileExtension(fileName: string, multiDotExtension = false) {
@@ -571,7 +465,7 @@ export function getFileExtension(fileName: string, multiDotExtension = false) {
 
     fileName = getFileName(fileName);
     const firstDotIndex = fileName.indexOf('.');
-    return fileName.substr(firstDotIndex);
+    return fileName.slice(firstDotIndex);
 }
 
 export function getFileName(pathString: string) {
@@ -592,102 +486,8 @@ export function stripFileExtension(fileName: string, multiDotExtension = false)
     return fileName.substr(0, fileName.length - ext.length);
 }
 
-export function realCasePath(pathString: string, fileSystem: ReadOnlyFileSystem): string {
-    return isUri(pathString) ? pathString : fileSystem.realCasePath(pathString);
-}
-
 export function normalizePath(pathString: string): string {
-    if (!isUri(pathString)) {
-        return normalizeSlashes(path.normalize(pathString));
-    }
-
-    // Must be a URI, already normalized.
-    return pathString;
-}
-
-export function isDirectory(fs: ReadOnlyFileSystem, path: string): boolean {
-    return tryStat(fs, path)?.isDirectory() ?? false;
-}
-
-export function isFile(fs: ReadOnlyFileSystem, path: string, treatZipDirectoryAsFile = false): boolean {
-    const stats = tryStat(fs, path);
-    if (stats?.isFile()) {
-        return true;
-    }
-
-    if (!treatZipDirectoryAsFile) {
-        return false;
-    }
-
-    return stats?.isZipDirectory?.() ?? false;
-}
-
-export function tryStat(fs: ReadOnlyFileSystem, path: string): Stats | undefined {
-    try {
-        if (fs.existsSync(path)) {
-            return fs.statSync(path);
-        }
-    } catch (e: any) {
-        return undefined;
-    }
-    return undefined;
-}
-
-export function tryRealpath(fs: ReadOnlyFileSystem, path: string): string | undefined {
-    try {
-        return fs.realCasePath(path);
-    } catch (e: any) {
-        return undefined;
-    }
-}
-
-export function getFileSystemEntries(fs: ReadOnlyFileSystem, path: string): FileSystemEntries {
-    try {
-        return getFileSystemEntriesFromDirEntries(fs.readdirEntriesSync(path || '.'), fs, path);
-    } catch (e: any) {
-        return { files: [], directories: [] };
-    }
-}
-
-// Sorts the entires into files and directories, including any symbolic links.
-export function getFileSystemEntriesFromDirEntries(
-    dirEntries: Dirent[],
-    fs: ReadOnlyFileSystem,
-    path: string
-): FileSystemEntries {
-    const entries = dirEntries.sort((a, b) => {
-        if (a.name < b.name) {
-            return -1;
-        } else if (a.name > b.name) {
-            return 1;
-        } else {
-            return 0;
-        }
-    });
-    const files: string[] = [];
-    const directories: string[] = [];
-    for (const entry of entries) {
-        // This is necessary because on some file system node fails to exclude
-        // "." and "..". See https://github.com/nodejs/node/issues/4002
-        if (entry.name === '.' || entry.name === '..') {
-            continue;
-        }
-
-        if (entry.isFile()) {
-            files.push(entry.name);
-        } else if (entry.isDirectory()) {
-            directories.push(entry.name);
-        } else if (entry.isSymbolicLink()) {
-            const entryPath = combinePaths(path, entry.name);
-            const stat = tryStat(fs, entryPath);
-            if (stat?.isFile()) {
-                files.push(entry.name);
-            } else if (stat?.isDirectory()) {
-                directories.push(entry.name);
-            }
-        }
-    }
-    return { files, directories };
+    return normalizeSlashes(path.normalize(pathString));
 }
 
 // Transforms a relative file spec (one that potentially contains
@@ -803,25 +603,6 @@ export function hasPythonExtension(path: string) {
     return path.endsWith('.py') || path.endsWith('.pyi');
 }
 
-export function getFileSpec(sp: ServiceProvider, rootPath: string, fileSpec: string): FileSpec {
-    let regExPattern = getWildcardRegexPattern(rootPath, fileSpec);
-    const escapedSeparator = getRegexEscapedSeparator(getPathSeparator(rootPath));
-    regExPattern = `^(${regExPattern})($|${escapedSeparator})`;
-
-    const fs = sp.get(ServiceKeys.fs);
-    const tmp = sp.tryGet(ServiceKeys.tempFile);
-
-    const regExp = new RegExp(regExPattern, isFileSystemCaseSensitive(fs, tmp) ? undefined : 'i');
-    const wildcardRoot = getWildcardRoot(rootPath, fileSpec);
-    const hasDirectoryWildcard = isDirectoryWildcardPatternPresent(fileSpec);
-
-    return {
-        wildcardRoot,
-        regExp,
-        hasDirectoryWildcard,
-    };
-}
-
 export function getRegexEscapedSeparator(pathSep: string = path.sep) {
     // we don't need to escape "/" in typescript regular expression
     return pathSep === '/' ? '/' : '\\\\';
@@ -908,168 +689,3 @@ function getPathComponentsRelativeTo(
     }
     return ['', ...relative, ...components];
 }
-
-const enum FileSystemEntryKind {
-    File,
-    Directory,
-}
-
-function fileSystemEntryExists(fs: ReadOnlyFileSystem, path: string, entryKind: FileSystemEntryKind): boolean {
-    try {
-        const stat = fs.statSync(path);
-        switch (entryKind) {
-            case FileSystemEntryKind.File:
-                return stat.isFile();
-            case FileSystemEntryKind.Directory:
-                return stat.isDirectory();
-            default:
-                return false;
-        }
-    } catch (e: any) {
-        return false;
-    }
-}
-
-export function convertUriToPath(fs: ReadOnlyFileSystem, uriString: string): string {
-    return realCasePath(fs.getMappedFilePath(extractPathFromUri(uriString)), fs);
-}
-
-export function extractPathFromUri(uriString: string) {
-    const uri = URI.parse(uriString);
-
-    // Only for file scheme do we actually modify anything. All other uri strings
-    // maintain the same value they started with.
-    if (uri.scheme === 'file' && !uri.fragment) {
-        // When schema is "file", we use fsPath so that we can handle things like UNC paths.
-        let convertedPath = normalizePath(uri.fsPath);
-
-        // If this is a DOS-style path with a drive letter, remove
-        // the leading slash.
-        if (convertedPath.match(/^\\[a-zA-Z]:\\/)) {
-            convertedPath = convertedPath.slice(1);
-        }
-
-        return convertedPath;
-    }
-
-    return uriString;
-}
-
-export function convertPathToUri(fs: ReadOnlyFileSystem, path: string): string {
-    return fs.getUri(fs.getOriginalFilePath(path));
-}
-
-export function setTestingMode(underTest: boolean) {
-    _underTest = underTest;
-}
-
-const isFileSystemCaseSensitiveMap = new WeakMap<FileSystem, boolean>();
-
-export function isFileSystemCaseSensitive(fs: FileSystem, tmp?: TempFile) {
-    if (!tmp) {
-        return false;
-    }
-
-    if (!_underTest && _fsCaseSensitivity !== undefined) {
-        return _fsCaseSensitivity;
-    }
-
-    if (!isFileSystemCaseSensitiveMap.has(fs)) {
-        _fsCaseSensitivity = isFileSystemCaseSensitiveInternal(fs, tmp);
-        isFileSystemCaseSensitiveMap.set(fs, _fsCaseSensitivity);
-    }
-    return !!isFileSystemCaseSensitiveMap.get(fs);
-}
-
-export function isFileSystemCaseSensitiveInternal(fs: FileSystem, tmp: TempFile) {
-    let filePath: string | undefined = undefined;
-    try {
-        // Make unique file name.
-        let name: string;
-        let mangledFilePath: string;
-        do {
-            name = `${randomBytesHex(21)}-a`;
-            filePath = path.join(tmp.tmpdir(), name);
-            mangledFilePath = path.join(tmp.tmpdir(), name.toUpperCase());
-        } while (fs.existsSync(filePath) || fs.existsSync(mangledFilePath));
-
-        fs.writeFileSync(filePath, '', 'utf8');
-
-        // If file exists, then it is insensitive.
-        return !fs.existsSync(mangledFilePath);
-    } catch (e: any) {
-        return false;
-    } finally {
-        if (filePath) {
-            // remove temp file created
-            try {
-                fs.unlinkSync(filePath);
-            } catch (e: any) {
-                /* ignored */
-            }
-        }
-    }
-}
-
-export function getLibraryPathWithoutExtension(libraryFilePath: string) {
-    let filePathWithoutExtension = stripFileExtension(libraryFilePath);
-
-    // Strip off the '/__init__' if it's present.
-    if (filePathWithoutExtension.endsWith('__init__')) {
-        filePathWithoutExtension = filePathWithoutExtension.substr(0, filePathWithoutExtension.length - 9);
-    }
-
-    return filePathWithoutExtension;
-}
-
-export function getDirectoryChangeKind(
-    fs: ReadOnlyFileSystem,
-    oldDirectory: string,
-    newDirectory: string
-): 'Same' | 'Renamed' | 'Moved' {
-    if (fs.realCasePath(oldDirectory) === fs.realCasePath(newDirectory)) {
-        return 'Same';
-    }
-
-    const relativePaths = getRelativePathComponentsFromDirectory(oldDirectory, newDirectory, (f) => fs.realCasePath(f));
-
-    // 3 means only last folder name has changed.
-    if (relativePaths.length === 3 && relativePaths[1] === '..' && relativePaths[2] !== '..') {
-        return 'Renamed';
-    }
-
-    return 'Moved';
-}
-
-export function deduplicateFolders(listOfFolders: string[][]): string[] {
-    const foldersToWatch = new Set<string>();
-
-    listOfFolders.forEach((folders) => {
-        folders.forEach((p) => {
-            if (foldersToWatch.has(p)) {
-                // Bail out on exact match.
-                return;
-            }
-
-            for (const existing of foldersToWatch) {
-                // ex) p: "/user/test" existing: "/user"
-                if (p.startsWith(existing)) {
-                    // We already have the parent folder in the watch list
-                    return;
-                }
-
-                // ex) p: "/user" folderToWatch: "/user/test"
-                if (existing.startsWith(p)) {
-                    // We found better one to watch. replace.
-                    foldersToWatch.delete(existing);
-                    foldersToWatch.add(p);
-                    return;
-                }
-            }
-
-            foldersToWatch.add(p);
-        });
-    });
-
-    return [...foldersToWatch];
-}
diff --git a/packages/pyright-internal/src/common/realFileSystem.ts b/packages/pyright-internal/src/common/realFileSystem.ts
index 5659f438e..d122fdd7e 100644
--- a/packages/pyright-internal/src/common/realFileSystem.ts
+++ b/packages/pyright-internal/src/common/realFileSystem.ts
@@ -8,7 +8,6 @@ import { FakeFS, NativePath, PortablePath, PosixFS, ppath, VirtualFS, ZipFS, Zip
 import { getLibzipSync } from '@yarnpkg/libzip';
 import * as fs from 'fs';
 import * as tmp from 'tmp';
-import { URI } from 'vscode-uri';
 import { isMainThread } from 'worker_threads';
 
 import { ConsoleInterface, NullConsole } from './console';
@@ -21,7 +20,9 @@ import {
     FileWatcherProvider,
     nullFileWatcherProvider,
 } from './fileWatcher';
-import { combinePaths, getRootLength, isUri } from './pathUtils';
+import { getRootLength } from './pathUtils';
+import { Uri } from './uri/uri';
+import { getRootUri, isFileSystemCaseSensitive } from './uri/uriUtils';
 
 // Automatically remove files created by tmp at process exit.
 tmp.setGracefulCleanup();
@@ -208,9 +209,19 @@ class YarnFS extends PosixFS {
 const yarnFS = new YarnFS();
 
 class RealFileSystem implements FileSystem {
-    constructor(private _fileWatcherProvider: FileWatcherProvider, private _console: ConsoleInterface) {}
+    private _isCaseSensitive = true;
+    constructor(private _fileWatcherProvider: FileWatcherProvider, private _console: ConsoleInterface) {
+        this._isCaseSensitive = isFileSystemCaseSensitive(this, new RealTempFile(/* isCaseSensitive */ true));
+    }
 
-    existsSync(path: string) {
+    get isCaseSensitive(): boolean {
+        return this._isCaseSensitive;
+    }
+    existsSync(uri: Uri) {
+        if (uri.isEmpty()) {
+            return false;
+        }
+        const path = uri.getFilePath();
         try {
             // Catch zip open errors. existsSync is assumed to never throw by callers.
             return yarnFS.existsSync(path);
@@ -219,11 +230,13 @@ class RealFileSystem implements FileSystem {
         }
     }
 
-    mkdirSync(path: string, options?: MkDirOptions) {
+    mkdirSync(uri: Uri, options?: MkDirOptions) {
+        const path = uri.getFilePath();
         yarnFS.mkdirSync(path, options);
     }
 
-    chdir(path: string) {
+    chdir(uri: Uri) {
+        const path = uri.getFilePath();
         // If this file system happens to be running in a worker thread,
         // then we can't call 'chdir'.
         if (isMainThread) {
@@ -231,11 +244,13 @@ class RealFileSystem implements FileSystem {
         }
     }
 
-    readdirSync(path: string): string[] {
+    readdirSync(uri: Uri): string[] {
+        const path = uri.getFilePath();
         return yarnFS.readdirSync(path);
     }
 
-    readdirEntriesSync(path: string): fs.Dirent[] {
+    readdirEntriesSync(uri: Uri): fs.Dirent[] {
+        const path = uri.getFilePath();
         return yarnFS.readdirSync(path, { withFileTypes: true }).map((entry): fs.Dirent => {
             // Treat zip/egg files as directories.
             // See: https://github.com/yarnpkg/berry/blob/master/packages/vscode-zipfs/sources/ZipFSProvider.ts
@@ -257,21 +272,24 @@ class RealFileSystem implements FileSystem {
         });
     }
 
-    readFileSync(path: string, encoding?: null): Buffer;
-    readFileSync(path: string, encoding: BufferEncoding): string;
-    readFileSync(path: string, encoding?: BufferEncoding | null): Buffer | string;
-    readFileSync(path: string, encoding: BufferEncoding | null = null) {
+    readFileSync(uri: Uri, encoding?: null): Buffer;
+    readFileSync(uri: Uri, encoding: BufferEncoding): string;
+    readFileSync(uri: Uri, encoding?: BufferEncoding | null): Buffer | string;
+    readFileSync(uri: Uri, encoding: BufferEncoding | null = null) {
+        const path = uri.getFilePath();
         if (encoding === 'utf8' || encoding === 'utf-8') {
             return yarnFS.readFileSync(path, 'utf8');
         }
         return yarnFS.readFileSync(path);
     }
 
-    writeFileSync(path: string, data: string | Buffer, encoding: BufferEncoding | null) {
+    writeFileSync(uri: Uri, data: string | Buffer, encoding: BufferEncoding | null) {
+        const path = uri.getFilePath();
         yarnFS.writeFileSync(path, data, encoding || undefined);
     }
 
-    statSync(path: string) {
+    statSync(uri: Uri) {
+        const path = uri.getFilePath();
         const stat = yarnFS.statSync(path);
         // Treat zip/egg files as directories.
         // See: https://github.com/yarnpkg/berry/blob/master/packages/vscode-zipfs/sources/ZipFSProvider.ts
@@ -286,53 +304,62 @@ class RealFileSystem implements FileSystem {
         return stat;
     }
 
-    rmdirSync(path: string): void {
+    rmdirSync(uri: Uri): void {
+        const path = uri.getFilePath();
         yarnFS.rmdirSync(path);
     }
 
-    unlinkSync(path: string) {
+    unlinkSync(uri: Uri) {
+        const path = uri.getFilePath();
         yarnFS.unlinkSync(path);
     }
 
-    realpathSync(path: string) {
+    realpathSync(uri: Uri) {
         try {
-            return yarnFS.realpathSync(path);
+            const path = uri.getFilePath();
+            return Uri.file(yarnFS.realpathSync(path), this._isCaseSensitive);
         } catch (e: any) {
-            return path;
+            return uri;
         }
     }
 
-    getModulePath(): string {
+    getModulePath(): Uri {
         // The entry point to the tool should have set the __rootDirectory
         // global variable to point to the directory that contains the
         // typeshed-fallback directory.
-        return (global as any).__rootDirectory;
+        return getRootUri(this._isCaseSensitive) || Uri.empty();
     }
 
-    createFileSystemWatcher(paths: string[], listener: FileWatcherEventHandler): FileWatcher {
+    createFileSystemWatcher(paths: Uri[], listener: FileWatcherEventHandler): FileWatcher {
         return this._fileWatcherProvider.createFileWatcher(
-            paths.map((p) => this.realCasePath(p)),
+            paths.map((p) => p.getFilePath()),
             listener
         );
     }
 
-    createReadStream(path: string): fs.ReadStream {
+    createReadStream(uri: Uri): fs.ReadStream {
+        const path = uri.getFilePath();
         return yarnFS.createReadStream(path);
     }
 
-    createWriteStream(path: string): fs.WriteStream {
+    createWriteStream(uri: Uri): fs.WriteStream {
+        const path = uri.getFilePath();
         return yarnFS.createWriteStream(path);
     }
 
-    copyFileSync(src: string, dst: string): void {
-        yarnFS.copyFileSync(src, dst);
+    copyFileSync(src: Uri, dst: Uri): void {
+        const srcPath = src.getFilePath();
+        const destPath = dst.getFilePath();
+        yarnFS.copyFileSync(srcPath, destPath);
     }
 
-    readFile(path: string): Promise<Buffer> {
+    readFile(uri: Uri): Promise<Buffer> {
+        const path = uri.getFilePath();
         return yarnFS.readFilePromise(path);
     }
 
-    async readFileText(path: string, encoding: BufferEncoding): Promise<string> {
+    async readFileText(uri: Uri, encoding: BufferEncoding): Promise<string> {
+        const path = uri.getFilePath();
         if (encoding === 'utf8' || encoding === 'utf-8') {
             return yarnFS.readFilePromise(path, 'utf8');
         }
@@ -340,17 +367,18 @@ class RealFileSystem implements FileSystem {
         return buffer.toString(encoding);
     }
 
-    realCasePath(path: string): string {
+    realCasePath(uri: Uri): Uri {
         try {
             // If it doesn't exist in the real FS, then just use this path.
-            if (!this.existsSync(path)) {
-                return this._getNormalizedPath(path);
+            if (!this.existsSync(uri)) {
+                return uri;
             }
 
             // If it does exist, skip this for symlinks.
+            const path = uri.getFilePath();
             const stat = fs.lstatSync(path);
             if (stat.isSymbolicLink()) {
-                return this._getNormalizedPath(path);
+                return uri;
             }
 
             // realpathSync.native will return casing as in OS rather than
@@ -359,53 +387,34 @@ class RealFileSystem implements FileSystem {
 
             // On UNC mapped drives we want to keep the original drive letter.
             if (getRootLength(realCase) !== getRootLength(path)) {
-                return path;
+                return uri;
             }
 
-            return realCase;
+            return Uri.file(realCase, this._isCaseSensitive);
         } catch (e: any) {
             // Return as it is, if anything failed.
-            this._console.log(`Failed to get real file system casing for ${path}: ${e}`);
+            this._console.log(`Failed to get real file system casing for ${uri}: ${e}`);
 
-            return path;
+            return uri;
         }
     }
 
-    isMappedFilePath(filepath: string): boolean {
+    isMappedUri(uri: Uri): boolean {
         return false;
     }
 
-    getOriginalFilePath(mappedFilePath: string) {
-        return mappedFilePath;
+    getOriginalUri(mappedUri: Uri) {
+        return mappedUri;
     }
 
-    getMappedFilePath(originalFilepath: string) {
-        return originalFilepath;
+    getMappedUri(originalUri: Uri) {
+        return originalUri;
     }
 
-    getUri(path: string): string {
-        // If this is not a file path, just return the original path.
-        if (isUri(path)) {
-            return path;
-        }
-        return URI.file(path).toString();
-    }
-
-    isInZip(path: string): boolean {
+    isInZip(uri: Uri): boolean {
+        const path = uri.getFilePath();
         return /[^\\/]\.(?:egg|zip|jar)[\\/]/.test(path) && yarnFS.isZip(path);
     }
-
-    private _getNormalizedPath(path: string) {
-        const driveLength = getRootLength(path);
-
-        if (driveLength === 0) {
-            return path;
-        }
-
-        // `vscode` sometimes uses different casing for drive letter.
-        // Make sure we normalize at least drive letter.
-        return combinePaths(fs.realpathSync.native(path.substring(0, driveLength)), path.substring(driveLength));
-    }
 }
 
 interface WorkspaceFileWatcher extends FileWatcher {
@@ -436,15 +445,15 @@ export class WorkspaceFileWatcherProvider implements FileWatcherProvider, FileWa
         return fileWatcher;
     }
 
-    onFileChange(eventType: FileWatcherEventType, filePath: string): void {
+    onFileChange(eventType: FileWatcherEventType, fileUri: Uri): void {
         // Since file watcher is a server wide service, we don't know which watcher is
         // for which workspace (for multi workspace case), also, we don't know which watcher
         // is for source or library. so we need to solely rely on paths that can cause us
         // to raise events both for source and library if .venv is inside of workspace root
         // for a file change. It is event handler's job to filter those out.
         this._fileWatchers.forEach((watcher) => {
-            if (watcher.workspacePaths.some((dirPath) => filePath.startsWith(dirPath))) {
-                watcher.eventHandler(eventType, filePath);
+            if (watcher.workspacePaths.some((dirPath) => fileUri.pathStartsWith(dirPath))) {
+                watcher.eventHandler(eventType, fileUri);
             }
         });
     }
@@ -453,17 +462,15 @@ export class WorkspaceFileWatcherProvider implements FileWatcherProvider, FileWa
 export class RealTempFile implements TempFile {
     private _tmpdir?: tmp.DirResult;
 
-    tmpdir() {
-        if (!this._tmpdir) {
-            this._tmpdir = tmp.dirSync({ prefix: 'pyright' });
-        }
+    constructor(private readonly _isCaseSensitive: boolean) {}
 
-        return this._tmpdir.name;
+    tmpdir(): Uri {
+        return Uri.file(this._getTmpDir().name, this._isCaseSensitive);
     }
 
-    tmpfile(options?: TmpfileOptions): string {
-        const f = tmp.fileSync({ dir: this.tmpdir(), discardDescriptor: true, ...options });
-        return f.name;
+    tmpfile(options?: TmpfileOptions): Uri {
+        const f = tmp.fileSync({ dir: this._getTmpDir().name, discardDescriptor: true, ...options });
+        return Uri.file(f.name, this._isCaseSensitive);
     }
 
     dispose(): void {
@@ -474,4 +481,12 @@ export class RealTempFile implements TempFile {
             // ignore
         }
     }
+
+    private _getTmpDir(): tmp.DirResult {
+        if (!this._tmpdir) {
+            this._tmpdir = tmp.dirSync({ prefix: 'pyright' });
+        }
+
+        return this._tmpdir;
+    }
 }
diff --git a/packages/pyright-internal/src/common/serviceProviderExtensions.ts b/packages/pyright-internal/src/common/serviceProviderExtensions.ts
index 61e437071..0f4a99094 100644
--- a/packages/pyright-internal/src/common/serviceProviderExtensions.ts
+++ b/packages/pyright-internal/src/common/serviceProviderExtensions.ts
@@ -11,20 +11,22 @@ import { IPythonMode, SourceFile, SourceFileEditMode } from '../analyzer/sourceF
 import { SupportPartialStubs } from '../pyrightFileSystem';
 import { ConsoleInterface } from './console';
 import {
-    StatusMutationListener,
+    DebugInfoInspector,
     ServiceProvider as ReadOnlyServiceProvider,
+    StatusMutationListener,
     SymbolDefinitionProvider,
     SymbolUsageProviderFactory,
-    DebugInfoInspector,
 } from './extensibility';
 import { FileSystem, TempFile } from './fileSystem';
 import { LogTracker } from './logTracker';
 import { GroupServiceKey, ServiceKey, ServiceProvider } from './serviceProvider';
+import { Uri } from './uri/uri';
 
 declare module './serviceProvider' {
     interface ServiceProvider {
         fs(): FileSystem;
         console(): ConsoleInterface;
+        tmp(): TempFile | undefined;
         sourceFileFactory(): ISourceFileFactory;
         partialStubs(): SupportPartialStubs;
     }
@@ -79,6 +81,9 @@ ServiceProvider.prototype.console = function () {
 ServiceProvider.prototype.partialStubs = function () {
     return this.get(ServiceKeys.partialStubs);
 };
+ServiceProvider.prototype.tmp = function () {
+    return this.tryGet(ServiceKeys.tempFile);
+};
 ServiceProvider.prototype.sourceFileFactory = function () {
     const result = this.tryGet(ServiceKeys.sourceFileFactory);
     return result || DefaultSourceFileFactory;
@@ -87,26 +92,24 @@ ServiceProvider.prototype.sourceFileFactory = function () {
 const DefaultSourceFileFactory: ISourceFileFactory = {
     createSourceFile(
         serviceProvider: ReadOnlyServiceProvider,
-        filePath: string,
+        fileUri: Uri,
         moduleName: string,
         isThirdPartyImport: boolean,
         isThirdPartyPyTypedPresent: boolean,
         editMode: SourceFileEditMode,
         console?: ConsoleInterface,
         logTracker?: LogTracker,
-        realFilePath?: string,
         ipythonMode?: IPythonMode
     ) {
         return new SourceFile(
             serviceProvider,
-            filePath,
+            fileUri,
             moduleName,
             isThirdPartyImport,
             isThirdPartyPyTypedPresent,
             editMode,
             console,
             logTracker,
-            realFilePath,
             ipythonMode
         );
     },
diff --git a/packages/pyright-internal/src/common/textEditTracker.ts b/packages/pyright-internal/src/common/textEditTracker.ts
index 8b8040812..637818845 100644
--- a/packages/pyright-internal/src/common/textEditTracker.ts
+++ b/packages/pyright-internal/src/common/textEditTracker.ts
@@ -32,11 +32,11 @@ import {
 } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
 import { appendArray, getOrAdd, removeArrayElements } from './collectionUtils';
-import { isString } from './core';
 import * as debug from './debug';
 import { FileEditAction } from './editAction';
 import { convertOffsetToPosition, convertTextRangeToRange } from './positionUtils';
 import { doesRangeContain, doRangesIntersect, extendRange, Range, TextRange } from './textRange';
+import { Uri } from './uri/uri';
 
 export class TextEditTracker {
     private readonly _nodesRemoved: Map<ParseNode, ParseResults> = new Map<ParseNode, ParseResults>();
@@ -49,11 +49,11 @@ export class TextEditTracker {
     }
 
     addEdits(...edits: FileEditAction[]) {
-        edits.forEach((e) => this.addEdit(e.filePath, e.range, e.replacementText));
+        edits.forEach((e) => this.addEdit(e.fileUri, e.range, e.replacementText));
     }
 
-    addEdit(filePath: string, range: Range, replacementText: string) {
-        const edits = getOrAdd(this._results, filePath, () => []);
+    addEdit(fileUri: Uri, range: Range, replacementText: string) {
+        const edits = getOrAdd(this._results, fileUri.key, () => []);
 
         // If there is any overlapping edit, see whether we can merge edits.
         // We can merge edits, if one of them is 'deletion' or 2 edits has the same
@@ -70,11 +70,11 @@ export class TextEditTracker {
             );
         }
 
-        edits.push({ filePath, range, replacementText });
+        edits.push({ fileUri: fileUri, range, replacementText });
     }
 
     addEditWithTextRange(parseResults: ParseResults, range: TextRange, replacementText: string) {
-        const filePath = getFileInfo(parseResults.parseTree).filePath;
+        const filePath = getFileInfo(parseResults.parseTree).fileUri;
 
         const existing = parseResults.text.substr(range.start, range.length);
         if (existing === replacementText) {
@@ -93,7 +93,7 @@ export class TextEditTracker {
                 ? (importToDelete.parent as ImportNode).list
                 : (importToDelete.parent as ImportFromNode).imports;
 
-        const filePath = getFileInfo(parseResults.parseTree).filePath;
+        const filePath = getFileInfo(parseResults.parseTree).fileUri;
         const ranges = getTextRangeForImportNameDeletion(
             parseResults,
             imports,
@@ -183,7 +183,7 @@ export class TextEditTracker {
         importGroup: ImportGroup,
         importNameInfo?: ImportNameInfo[]
     ) {
-        const filePath = getFileInfo(parseResults.parseTree).filePath;
+        const fileUri = getFileInfo(parseResults.parseTree).fileUri;
 
         this.addEdits(
             ...getTextEditsForAutoImportInsertion(
@@ -193,7 +193,7 @@ export class TextEditTracker {
                 importGroup,
                 parseResults,
                 convertOffsetToPosition(parseResults.parseTree.length, parseResults.tokenizerOutput.lines)
-            ).map((e) => ({ filePath, range: e.range, replacementText: e.replacementText }))
+            ).map((e) => ({ fileUri, range: e.range, replacementText: e.replacementText }))
         );
     }
 
@@ -220,7 +220,7 @@ export class TextEditTracker {
             return false;
         }
 
-        const filePath = getFileInfo(parseResults.parseTree).filePath;
+        const fileUri = getFileInfo(parseResults.parseTree).fileUri;
 
         const edits = getTextEditsForAutoImportSymbolAddition(importNameInfo, imported, parseResults);
         if (imported.node !== updateOptions.currentFromImport) {
@@ -228,7 +228,7 @@ export class TextEditTracker {
             // node we are working on.
             // ex) from xxx import yyy <= we are working on here.
             //     from xxx import zzz <= but we found this.
-            this.addEdits(...edits.map((e) => ({ filePath, range: e.range, replacementText: e.replacementText })));
+            this.addEdits(...edits.map((e) => ({ fileUri, range: e.range, replacementText: e.replacementText })));
             return true;
         }
 
@@ -247,9 +247,9 @@ export class TextEditTracker {
             return false;
         }
 
-        const deletions = this._getDeletionsForSpan(filePath, edits[0].range);
+        const deletions = this._getDeletionsForSpan(fileUri, edits[0].range);
         if (deletions.length === 0) {
-            this.addEdit(filePath, edits[0].range, edits[0].replacementText);
+            this.addEdit(fileUri, edits[0].range, edits[0].replacementText);
             return true;
         }
 
@@ -265,13 +265,13 @@ export class TextEditTracker {
             return false;
         }
 
-        this._removeEdits(filePath, deletions);
+        this._removeEdits(fileUri, deletions);
         if (importName.alias) {
             this._nodesRemoved.delete(importName.alias);
         }
 
         this.addEdit(
-            filePath,
+            fileUri,
             convertTextRangeToRange(importName.name, parseResults.tokenizerOutput.lines),
             newLastModuleName
         );
@@ -279,17 +279,17 @@ export class TextEditTracker {
         return true;
     }
 
-    private _getDeletionsForSpan(filePathOrEdit: string | FileEditAction[], range: Range) {
-        const edits = this._getOverlappingForSpan(filePathOrEdit, range);
+    private _getDeletionsForSpan(fileUriOrEdit: Uri | FileEditAction[], range: Range) {
+        const edits = this._getOverlappingForSpan(fileUriOrEdit, range);
         return edits.filter((e) => e.replacementText === '');
     }
 
-    private _removeEdits(filePathOrEdit: string | FileEditAction[], edits: FileEditAction[]) {
-        if (isString(filePathOrEdit)) {
-            filePathOrEdit = this._results.get(filePathOrEdit) ?? [];
+    private _removeEdits(fileUriOrEdit: Uri | FileEditAction[], edits: FileEditAction[]) {
+        if (Uri.isUri(fileUriOrEdit)) {
+            fileUriOrEdit = this._results.get(fileUriOrEdit.key) ?? [];
         }
 
-        removeArrayElements(filePathOrEdit, (f) => edits.some((e) => FileEditAction.areEqual(f, e)));
+        removeArrayElements(fileUriOrEdit, (f) => edits.some((e) => FileEditAction.areEqual(f, e)));
     }
 
     private _getEditsToMerge(edits: FileEditAction[], range: Range, replacementText: string) {
@@ -319,12 +319,12 @@ export class TextEditTracker {
         );
     }
 
-    private _getOverlappingForSpan(filePathOrEdit: string | FileEditAction[], range: Range) {
-        if (isString(filePathOrEdit)) {
-            filePathOrEdit = this._results.get(filePathOrEdit) ?? [];
+    private _getOverlappingForSpan(fileUriOrEdit: Uri | FileEditAction[], range: Range) {
+        if (Uri.isUri(fileUriOrEdit)) {
+            fileUriOrEdit = this._results.get(fileUriOrEdit.key) ?? [];
         }
 
-        return filePathOrEdit.filter((e) => doRangesIntersect(e.range, range));
+        return fileUriOrEdit.filter((e) => doRangesIntersect(e.range, range));
     }
 
     private _processNodeRemoved(token: CancellationToken) {
@@ -343,7 +343,7 @@ export class TextEditTracker {
                 this._pendingNodeToRemove.pop();
 
                 const info = getFileInfo(peekNodeToRemove.parseResults.parseTree);
-                this.addEdit(info.filePath, convertTextRangeToRange(peekNodeToRemove.node, info.lines), '');
+                this.addEdit(info.fileUri, convertTextRangeToRange(peekNodeToRemove.node, info.lines), '');
             }
         }
     }
@@ -370,11 +370,7 @@ export class TextEditTracker {
         );
 
         if (nameNodes.length === nodesRemoved.length) {
-            this.addEdit(
-                info.filePath,
-                ParseTreeUtils.getFullStatementRange(importNode, nodeToRemove.parseResults),
-                ''
-            );
+            this.addEdit(info.fileUri, ParseTreeUtils.getFullStatementRange(importNode, nodeToRemove.parseResults), '');
 
             // Remove nodes that are handled from queue.
             this._removeNodesHandled(nodesRemoved);
@@ -397,7 +393,7 @@ export class TextEditTracker {
         }
 
         const editSpans = getTextRangeForImportNameDeletion(nodeToRemove.parseResults, nameNodes, ...indices);
-        editSpans.forEach((e) => this.addEdit(info.filePath, convertTextRangeToRange(e, info.lines), ''));
+        editSpans.forEach((e) => this.addEdit(info.fileUri, convertTextRangeToRange(e, info.lines), ''));
 
         this._removeNodesHandled(nodesRemoved);
         return true;
diff --git a/packages/pyright-internal/src/common/textRange.ts b/packages/pyright-internal/src/common/textRange.ts
index 1f8547f0c..9f4b5c9ea 100644
--- a/packages/pyright-internal/src/common/textRange.ts
+++ b/packages/pyright-internal/src/common/textRange.ts
@@ -7,6 +7,8 @@
  * Specifies the range of text within a larger string.
  */
 
+import { Uri } from './uri/uri';
+
 export interface TextRange {
     readonly start: number;
     readonly length: number;
@@ -131,7 +133,7 @@ export namespace Range {
 
 // Represents a range within a particular document.
 export interface DocumentRange {
-    path: string;
+    uri: Uri;
     range: Range;
 }
 
diff --git a/packages/pyright-internal/src/common/uri/baseUri.ts b/packages/pyright-internal/src/common/uri/baseUri.ts
new file mode 100644
index 000000000..197703f6f
--- /dev/null
+++ b/packages/pyright-internal/src/common/uri/baseUri.ts
@@ -0,0 +1,269 @@
+/*
+ * baseUri.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ *
+ * Base URI class for storing and manipulating URIs.
+ */
+
+import { some } from '../collectionUtils';
+import { getShortenedFileName, normalizeSlashes } from '../pathUtils';
+import { Uri } from './uri';
+
+export abstract class BaseUri implements Uri {
+    protected constructor(private readonly _key: string) {}
+
+    // Unique key for storing in maps.
+    get key() {
+        return this._key;
+    }
+
+    // Returns the scheme of the URI.
+    abstract get scheme(): string;
+
+    // Returns whether the underlying file system is case sensitive or not.
+    abstract get isCaseSensitive(): boolean;
+
+    // Returns the last segment of the URI, similar to the UNIX basename command.
+    abstract get fileName(): string;
+
+    // Returns just the fileName without any extensions
+    get fileNameWithoutExtension(): string {
+        const fileName = this.fileName;
+        const index = fileName.lastIndexOf('.');
+        if (index > 0) {
+            return fileName.slice(0, index);
+        } else {
+            return fileName;
+        }
+    }
+
+    // Returns the extension of the URI, similar to the UNIX extname command.
+    abstract get lastExtension(): string;
+
+    // Returns a URI where the path just contains the root folder.
+    abstract get root(): Uri;
+
+    // Returns a URI where the path contains the path with .py appended.
+    get packageUri(): Uri {
+        // This is assuming that the current path is a file already.
+        return this.addExtension('.py');
+    }
+
+    // Returns a URI where the path contains the path with .pyi appended.
+    get packageStubUri(): Uri {
+        // This is assuming that the current path is a file already.
+        return this.addExtension('.pyi');
+    }
+
+    // Returns a URI where the path has __init__.py appended.
+    get initPyUri(): Uri {
+        // This is assuming that the current path is a directory already.
+        return this.combinePaths('__init__.py');
+    }
+
+    // Returns a URI where the path has __init__.pyi appended.
+    get initPyiUri(): Uri {
+        // This is assuming that the current path is a directory already.
+        return this.combinePaths('__init__.pyi');
+    }
+
+    // Returns a URI where the path has py.typed appended.
+    get pytypedUri(): Uri {
+        // This is assuming that the current path is a directory already.
+        return this.combinePaths('py.typed');
+    }
+
+    isEmpty(): boolean {
+        return false;
+    }
+
+    abstract toString(): string;
+
+    abstract toUserVisibleString(): string;
+
+    abstract matchesRegex(regex: RegExp): boolean;
+
+    replaceExtension(ext: string): Uri {
+        const dir = this.getDirectory();
+        const base = this.fileName;
+        const newBase = base.slice(0, base.length - this.lastExtension.length) + ext;
+        return dir.combinePaths(newBase);
+    }
+
+    addExtension(ext: string): Uri {
+        return this.addPath(ext);
+    }
+
+    hasExtension(ext: string): boolean {
+        return this.isCaseSensitive
+            ? this.lastExtension === ext
+            : this.lastExtension.toLowerCase() === ext.toLowerCase();
+    }
+
+    abstract addPath(extra: string): Uri;
+
+    // Returns a URI where the path is the directory name of the original URI, similar to the UNIX dirname command.
+    abstract getDirectory(): Uri;
+
+    getRootPathLength(): number {
+        return this.getRootPath().length;
+    }
+
+    // Determines whether a path consists only of a path root.
+    abstract isRoot(): boolean;
+
+    // Determines whether a Uri is a child of some parent Uri.
+    abstract isChild(parent: Uri, ignoreCase?: boolean): boolean;
+
+    abstract isLocal(): boolean;
+
+    isUntitled(): boolean {
+        return this.scheme === 'untitled';
+    }
+
+    equals(other: Uri | undefined): boolean {
+        return this.key === other?.key;
+    }
+
+    abstract startsWith(other: Uri | undefined, ignoreCase?: boolean): boolean;
+
+    pathStartsWith(name: string): boolean {
+        // ignore path separators.
+        name = normalizeSlashes(name);
+        return this.getComparablePath().startsWith(name);
+    }
+
+    pathEndsWith(name: string): boolean {
+        // ignore path separators.
+        name = normalizeSlashes(name);
+        return this.getComparablePath().endsWith(name);
+    }
+
+    pathIncludes(include: string): boolean {
+        // ignore path separators.
+        include = normalizeSlashes(include);
+        return this.getComparablePath().includes(include);
+    }
+
+    // How long the path for this Uri is.
+    abstract getPathLength(): number;
+
+    // Combines paths to create a new Uri. Any '..' or '.' path components will be normalized.
+    abstract combinePaths(...paths: string[]): Uri;
+
+    getRelativePath(child: Uri): string | undefined {
+        if (this.scheme !== child.scheme) {
+            return undefined;
+        }
+
+        // Unlike getRelativePathComponents, this function should not return relative path
+        // markers for non children.
+        if (child.isChild(this)) {
+            const relativeToComponents = this.getRelativePathComponents(child);
+            if (relativeToComponents.length > 0) {
+                return ['.', ...relativeToComponents].join('/');
+            }
+        }
+        return undefined;
+    }
+
+    getPathComponents(): readonly string[] {
+        // Make sure to freeze the result so that it can't be modified.
+        return Object.freeze(this.getPathComponentsImpl());
+    }
+
+    abstract getPath(): string;
+
+    abstract getFilePath(): string;
+
+    getRelativePathComponents(to: Uri): readonly string[] {
+        const fromComponents = this.getPathComponents();
+        const toComponents = to.getPathComponents();
+
+        let start: number;
+        for (start = 0; start < fromComponents.length && start < toComponents.length; start++) {
+            const fromComponent = fromComponents[start];
+            const toComponent = toComponents[start];
+            if (fromComponent !== toComponent) {
+                break;
+            }
+        }
+
+        if (start === 0) {
+            return toComponents;
+        }
+
+        const components = toComponents.slice(start);
+        const relative: string[] = [];
+        for (; start < fromComponents.length; start++) {
+            relative.push('..');
+        }
+        return [...relative, ...components];
+    }
+
+    getShortenedFileName(maxDirLength: number = 15): string {
+        return getShortenedFileName(this.getPath(), maxDirLength);
+    }
+
+    stripExtension(): Uri {
+        const base = this.fileName;
+        const index = base.lastIndexOf('.');
+        if (index > 0) {
+            const stripped = base.slice(0, index);
+            return this.getDirectory().combinePaths(stripped);
+        } else {
+            return this;
+        }
+    }
+
+    stripAllExtensions(): Uri {
+        const base = this.fileName;
+        const stripped = base.split('.')[0];
+        if (stripped === base) {
+            return this;
+        } else {
+            return this.getDirectory().combinePaths(stripped);
+        }
+    }
+
+    protected abstract getRootPath(): string;
+
+    protected normalizeSlashes(path: string): string {
+        return path.replace(/\\/g, '/');
+    }
+
+    protected reducePathComponents(components: string[]): string[] {
+        if (!some(components)) {
+            return [];
+        }
+
+        // Reduce the path components by eliminating
+        // any '.' or '..'. We start at 1 because the first component is
+        // always the root.
+        const reduced = [components[0]];
+        for (let i = 1; i < components.length; i++) {
+            const component = components[i];
+            if (!component || component === '.') {
+                continue;
+            }
+
+            if (component === '..') {
+                if (reduced.length > 1) {
+                    if (reduced[reduced.length - 1] !== '..') {
+                        reduced.pop();
+                        continue;
+                    }
+                } else if (reduced[0]) {
+                    continue;
+                }
+            }
+            reduced.push(component);
+        }
+
+        return reduced;
+    }
+
+    protected abstract getComparablePath(): string;
+    protected abstract getPathComponentsImpl(): string[];
+}
diff --git a/packages/pyright-internal/src/common/uri/emptyUri.ts b/packages/pyright-internal/src/common/uri/emptyUri.ts
new file mode 100644
index 000000000..ad76d61aa
--- /dev/null
+++ b/packages/pyright-internal/src/common/uri/emptyUri.ts
@@ -0,0 +1,123 @@
+/*
+ * emptyUri.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ *
+ * URI class that represents an empty URI.
+ */
+
+import * as debug from '../debug';
+import { BaseUri } from './baseUri';
+import { Uri } from './uri';
+
+const EmptyKey = '<empty>';
+
+export class EmptyUri extends BaseUri {
+    private static _instance = new EmptyUri();
+    private constructor() {
+        super(EmptyKey);
+    }
+
+    static get instance() {
+        return EmptyUri._instance;
+    }
+
+    override get scheme(): string {
+        return '';
+    }
+
+    override get fileName(): string {
+        return '';
+    }
+
+    override get lastExtension(): string {
+        return '';
+    }
+
+    override get root(): Uri {
+        return this;
+    }
+
+    get isCaseSensitive(): boolean {
+        return true;
+    }
+
+    override isEmpty(): boolean {
+        return true;
+    }
+
+    override isLocal(): boolean {
+        return false;
+    }
+
+    override getPath(): string {
+        return '';
+    }
+
+    override getFilePath(): string {
+        debug.fail(`EmptyUri.getFilePath() should not be called.`);
+    }
+
+    override toString(): string {
+        return '';
+    }
+
+    override toUserVisibleString(): string {
+        return '';
+    }
+
+    override matchesRegex(regex: RegExp): boolean {
+        return false;
+    }
+
+    override replaceExtension(ext: string): Uri {
+        return this;
+    }
+    override addPath(extra: string): Uri {
+        return this;
+    }
+
+    override getDirectory(): Uri {
+        return this;
+    }
+
+    override isRoot(): boolean {
+        return true;
+    }
+
+    override isChild(parent: Uri): boolean {
+        return false;
+    }
+
+    override startsWith(other: Uri | undefined): boolean {
+        return false;
+    }
+
+    override getPathLength(): number {
+        return 0;
+    }
+
+    override combinePaths(...paths: string[]): Uri {
+        return this;
+    }
+
+    override getShortenedFileName(maxDirLength: number): string {
+        return '';
+    }
+
+    override stripExtension(): Uri {
+        return this;
+    }
+
+    protected override getPathComponentsImpl(): string[] {
+        return [];
+    }
+
+    protected override getRootPath(): string {
+        return '';
+    }
+
+    protected override getComparablePath(): string {
+        return '';
+    }
+}
diff --git a/packages/pyright-internal/src/common/uri/fileUri.ts b/packages/pyright-internal/src/common/uri/fileUri.ts
new file mode 100644
index 000000000..ba44bf9cd
--- /dev/null
+++ b/packages/pyright-internal/src/common/uri/fileUri.ts
@@ -0,0 +1,203 @@
+/*
+ * fileUri.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ *
+ * URI class that represents a file path. These URIs are always 'file' schemed.
+ */
+
+import { URI } from 'vscode-uri';
+import {
+    ensureTrailingDirectorySeparator,
+    getDirectoryPath,
+    getFileExtension,
+    getFileName,
+    getPathComponents,
+    getRootLength,
+    hasTrailingDirectorySeparator,
+    isDiskPathRoot,
+    normalizeSlashes,
+    resolvePaths,
+} from '../pathUtils';
+import { BaseUri } from './baseUri';
+import { cacheMethodWithNoArgs, cacheProperty, cacheStaticFunc } from './memoization';
+import { Uri } from './uri';
+
+export class FileUri extends BaseUri {
+    private _formattedString: string | undefined;
+    private constructor(
+        key: string,
+        private readonly _filePath: string,
+        private readonly _query: string,
+        private readonly _fragment: string,
+        private readonly _originalString: string | undefined,
+        private readonly _isCaseSensitive: boolean
+    ) {
+        super(_isCaseSensitive ? key : key.toLowerCase());
+    }
+
+    override get scheme(): string {
+        return 'file';
+    }
+
+    @cacheProperty()
+    override get fileName(): string {
+        return getFileName(this._filePath);
+    }
+
+    @cacheProperty()
+    override get lastExtension(): string {
+        return getFileExtension(this._filePath);
+    }
+
+    @cacheProperty()
+    override get root(): Uri {
+        const rootPath = this.getRootPath();
+        if (rootPath !== this._filePath) {
+            return FileUri.createFileUri(rootPath, '', '', undefined, this._isCaseSensitive);
+        }
+        return this;
+    }
+
+    get isCaseSensitive(): boolean {
+        return this._isCaseSensitive;
+    }
+
+    @cacheStaticFunc()
+    static createFileUri(
+        filePath: string,
+        query: string,
+        fragment: string,
+        originalString: string | undefined,
+        isCaseSensitive: boolean
+    ): FileUri {
+        const key = FileUri._createKey(filePath, query, fragment);
+        return new FileUri(key, filePath, query, fragment, originalString, isCaseSensitive);
+    }
+
+    static isFileUri(uri: Uri): uri is FileUri {
+        return uri.scheme === 'file' && (uri as any)._filePath !== undefined;
+    }
+
+    override matchesRegex(regex: RegExp): boolean {
+        // Compare the regex to our path but normalize it for comparison.
+        // The regex assumes it's comparing itself to a URI path.
+        const path = this.normalizeSlashes(this._filePath);
+        return regex.test(path);
+    }
+
+    override toString(): string {
+        if (!this._formattedString) {
+            this._formattedString =
+                this._originalString ||
+                URI.file(this._filePath).with({ query: this._query, fragment: this._fragment }).toString();
+        }
+        return this._formattedString;
+    }
+
+    override toUserVisibleString(): string {
+        return this._filePath;
+    }
+
+    override addPath(extra: string): Uri {
+        return FileUri.createFileUri(this._filePath + extra, '', '', undefined, this._isCaseSensitive);
+    }
+
+    override isRoot(): boolean {
+        return isDiskPathRoot(this._filePath);
+    }
+
+    override isChild(parent: Uri): boolean {
+        if (!FileUri.isFileUri(parent)) {
+            return false;
+        }
+
+        return parent._filePath.length < this._filePath.length && this.startsWith(parent);
+    }
+
+    override isLocal(): boolean {
+        return true;
+    }
+
+    override startsWith(other: Uri | undefined): boolean {
+        if (!other || !FileUri.isFileUri(other)) {
+            return false;
+        }
+        if (other.isEmpty() !== this.isEmpty()) {
+            return false;
+        }
+        if (this._filePath.length >= other._filePath.length) {
+            // Make sure the other ends with a / when comparing longer paths, otherwise we might
+            // say that /a/food is a child of /a/foo.
+            const otherPath =
+                this._filePath.length > other._filePath.length && !hasTrailingDirectorySeparator(other._filePath)
+                    ? ensureTrailingDirectorySeparator(other._filePath)
+                    : other._filePath;
+
+            if (!this.isCaseSensitive) {
+                return this._filePath.toLowerCase().startsWith(otherPath.toLowerCase());
+            }
+            return this._filePath.startsWith(otherPath);
+        }
+        return false;
+    }
+    override getPathLength(): number {
+        return this._filePath.length;
+    }
+    override getPath(): string {
+        return this.normalizeSlashes(this._filePath);
+    }
+    override getFilePath(): string {
+        return this._filePath;
+    }
+
+    override combinePaths(...paths: string[]): Uri {
+        // Resolve and combine paths, never want URIs with '..' in the middle.
+        let combined = resolvePaths(this._filePath, ...paths);
+
+        // Make sure to remove any trailing directory chars.
+        if (hasTrailingDirectorySeparator(combined) && combined.length > 1) {
+            combined = combined.slice(0, combined.length - 1);
+        }
+        if (combined !== this._filePath) {
+            return FileUri.createFileUri(combined, '', '', undefined, this._isCaseSensitive);
+        }
+        return this;
+    }
+
+    @cacheMethodWithNoArgs()
+    override getDirectory(): Uri {
+        const filePath = this._filePath;
+        let dir = getDirectoryPath(filePath);
+        if (hasTrailingDirectorySeparator(dir) && dir.length > 1) {
+            dir = dir.slice(0, -1);
+        }
+        if (dir !== filePath) {
+            return FileUri.createFileUri(dir, '', '', undefined, this._isCaseSensitive);
+        } else {
+            return this;
+        }
+    }
+
+    protected override getPathComponentsImpl(): string[] {
+        const components = getPathComponents(this._filePath);
+        // Remove the first one if it's empty. The new algorithm doesn't
+        // expect this to be there.
+        if (components.length > 0 && components[0] === '') {
+            components.shift();
+        }
+        return components.map((component) => this.normalizeSlashes(component));
+    }
+
+    protected override getRootPath(): string {
+        return this._filePath.slice(0, getRootLength(this._filePath));
+    }
+
+    protected override getComparablePath(): string {
+        return normalizeSlashes(this._filePath);
+    }
+
+    private static _createKey(filePath: string, query: string, fragment: string) {
+        return `${filePath}${query ? '?' + query : ''}${fragment ? '#' + fragment : ''}`;
+    }
+}
diff --git a/packages/pyright-internal/src/common/uri/memoization.ts b/packages/pyright-internal/src/common/uri/memoization.ts
new file mode 100644
index 000000000..084395bec
--- /dev/null
+++ b/packages/pyright-internal/src/common/uri/memoization.ts
@@ -0,0 +1,70 @@
+/*
+ * memoization.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ *
+ * Decorators used to memoize the result of a function call.
+ */
+
+// Cache for static method results.
+const staticCache = new Map<string, any>();
+
+// Caches the results of a getter property.
+export function cacheProperty() {
+    return function (target: any, functionName: string, descriptor: PropertyDescriptor) {
+        const originalMethod = descriptor.get;
+        descriptor.get = function (this: any, ...args: any) {
+            // Call the function once to get the result.
+            const result = originalMethod!.apply(this, args);
+
+            // Then we replace the original function with one that just returns the result.
+            Object.defineProperty(this, functionName, {
+                get() {
+                    return result;
+                },
+            });
+            return result;
+        };
+        return descriptor;
+    };
+}
+
+// Caches the results of method that takes no args.
+// This situation can be optimized because the parameters are always the same.
+export function cacheMethodWithNoArgs() {
+    return function (target: any, functionName: string, descriptor: PropertyDescriptor) {
+        const originalMethod = descriptor.value;
+        descriptor.value = function (this: any, ...args: any) {
+            // Call the function once to get the result.
+            const result = originalMethod.apply(this, args);
+
+            // Then we replace the original function with one that just returns the result.
+            this[functionName] = () => {
+                // Note that this poses a risk. The result is passed by reference, so if the caller
+                // modifies the result, it will modify the cached result.
+                return result;
+            };
+            return result;
+        };
+        return descriptor;
+    };
+}
+
+// Create a decorator to cache the results of a static method.
+export function cacheStaticFunc() {
+    return function cacheStaticFunc_Fast(target: any, functionName: string, descriptor: PropertyDescriptor) {
+        const originalMethod = descriptor.value;
+        descriptor.value = function (...args: any) {
+            const key = `${functionName}+${args.map((a: any) => a?.toString()).join(',')}`;
+            let cachedResult: any;
+            if (!staticCache.has(key)) {
+                cachedResult = originalMethod.apply(this, args);
+                staticCache.set(key, cachedResult);
+            } else {
+                cachedResult = staticCache.get(key);
+            }
+            return cachedResult;
+        };
+        return descriptor;
+    };
+}
diff --git a/packages/pyright-internal/src/common/uri/uri.ts b/packages/pyright-internal/src/common/uri/uri.ts
new file mode 100644
index 000000000..64dfc1d3d
--- /dev/null
+++ b/packages/pyright-internal/src/common/uri/uri.ts
@@ -0,0 +1,215 @@
+/*
+ * uri.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ *
+ * URI namespace for storing and manipulating URIs.
+ */
+
+import { URI, Utils } from 'vscode-uri';
+import { combinePaths, isRootedDiskPath } from '../pathUtils';
+import { EmptyUri } from './emptyUri';
+import { FileUri } from './fileUri';
+import { WebUri } from './webUri';
+
+export interface Uri {
+    // Unique key for storing in maps.
+    readonly key: string;
+
+    // Returns the scheme of the URI.
+    readonly scheme: string;
+
+    // Returns the last segment of the URI, similar to the UNIX basename command.
+    readonly fileName: string;
+
+    // Returns the extension of the URI, similar to the UNIX extname command. This includes '.' on the extension.
+    readonly lastExtension: string;
+
+    // Returns a URI where the path just contains the root folder.
+    readonly root: Uri;
+
+    // Returns a URI where the path contains the directory name with .py appended.
+    readonly packageUri: Uri;
+
+    // Returns a URI where the path contains the directory name with .pyi appended.
+    readonly packageStubUri: Uri;
+
+    // Returns a URI where the path has __init__.py appended.
+    readonly initPyUri: Uri;
+
+    // Returns a URI where the path has __init__.pyi appended.
+    readonly initPyiUri: Uri;
+
+    // Returns a URI where the path has py.typed appended.
+    readonly pytypedUri: Uri;
+
+    // Returns the filename without any extensions
+    readonly fileNameWithoutExtension: string;
+
+    // Indicates if the underlying file system for this URI is case sensitive or not.
+    readonly isCaseSensitive: boolean;
+
+    isEmpty(): boolean;
+
+    toString(): string;
+
+    toUserVisibleString(): string;
+
+    // Determines whether a path consists only of a path root.
+    isRoot(): boolean;
+
+    // Determines whether a Uri is a child of some parent Uri.
+    isChild(parent: Uri): boolean;
+
+    isLocal(): boolean;
+
+    isUntitled(): boolean;
+
+    equals(other: Uri | undefined): boolean;
+
+    startsWith(other: Uri | undefined): boolean;
+
+    pathStartsWith(name: string): boolean;
+
+    pathEndsWith(name: string): boolean;
+
+    pathIncludes(include: string): boolean;
+    matchesRegex(regex: RegExp): boolean;
+
+    addPath(extra: string): Uri;
+
+    // Returns a URI where the path is the directory name of the original URI, similar to the UNIX dirname command.
+    getDirectory(): Uri;
+
+    getRootPathLength(): number;
+
+    // How long the path for this Uri is.
+    getPathLength(): number;
+
+    combinePaths(...paths: string[]): Uri;
+
+    getRelativePath(child: Uri): string | undefined;
+
+    getPathComponents(): readonly string[];
+
+    getPath(): string;
+
+    getFilePath(): string;
+
+    getRelativePathComponents(to: Uri): readonly string[];
+    getShortenedFileName(maxDirLength?: number): string;
+
+    stripExtension(): Uri;
+
+    stripAllExtensions(): Uri;
+    replaceExtension(ext: string): Uri;
+
+    addExtension(ext: string): Uri;
+    hasExtension(ext: string): boolean;
+}
+
+// Returns just the fsPath path portion of a vscode URI.
+function getFilePath(uri: URI): string {
+    let filePath: string | undefined;
+
+    // Compute the file path ourselves. The vscode.URI class doesn't
+    // treat UNC shares with a single slash as UNC paths.
+    // https://github.com/microsoft/vscode-uri/blob/53e4ca6263f2e4ddc35f5360c62bc1b1d30f27dd/src/uri.ts#L567
+    if (uri.authority && uri.path[0] === '/' && uri.path.length === 1) {
+        filePath = `//${uri.authority}${uri.path}`;
+    } else {
+        // Otherwise use the vscode.URI version
+        filePath = uri.fsPath;
+    }
+
+    // If this is a DOS-style path with a drive letter, remove
+    // the leading slash.
+    if (filePath.match(/^\/[a-zA-Z]:\//)) {
+        filePath = filePath.slice(1);
+    }
+
+    // vscode.URI normalizes the path to use the correct path separators.
+    // We need to do the same.
+    if (process.platform === 'win32') {
+        filePath = filePath.replace(/\//g, '\\');
+    }
+
+    return filePath;
+}
+
+// Function called to normalize input URIs. This gets rid of '..' and '.' in the path.
+// It also removes any '/' on the end of the path.
+// This is slow but should only be called when the URI is first created.
+function normalizeUri(uri: string | URI): { uri: URI; str: string } {
+    // Make sure the drive letter is lower case. This
+    // is consistent with what VS code does for URIs.
+    let originalString = URI.isUri(uri) ? uri.toString() : uri;
+    const parsed = URI.isUri(uri) ? uri : URI.parse(uri);
+    if (parsed.scheme === 'file') {
+        // The Vscode.URI parser makes sure the drive is lower cased.
+        originalString = parsed.toString();
+    }
+
+    // Original URI may not have resolved all the `..` in the path, so remove them.
+    // Note: this also has the effect of removing any trailing slashes.
+    const finalURI = Utils.resolvePath(parsed);
+    const finalString = finalURI.path.length !== parsed.path.length ? finalURI.toString() : originalString;
+    return { uri: finalURI, str: finalString };
+}
+
+export namespace Uri {
+    export function file(path: string, isCaseSensitive = true, checkRelative = false): Uri {
+        // Fix path if we're checking for relative paths and this is not a rooted path.
+        path = checkRelative && !isRootedDiskPath(path) ? combinePaths(process.cwd(), path) : path;
+
+        // If this already starts with 'file:', then we can
+        // parse it normally. It's actually a uri string. Otherwise parse it as a file path.
+        const normalized = path.startsWith('file:') ? normalizeUri(path) : normalizeUri(URI.file(path));
+
+        // Turn the path into a file URI.
+        return FileUri.createFileUri(
+            getFilePath(normalized.uri),
+            normalized.uri.query,
+            normalized.uri.fragment,
+            normalized.str,
+            isCaseSensitive
+        );
+    }
+
+    export function empty(): Uri {
+        return EmptyUri.instance;
+    }
+
+    export function parse(value: string | undefined, isCaseSensitive: boolean): Uri {
+        if (!value) {
+            return Uri.empty();
+        }
+
+        // Normalize the value here. This gets rid of '..' and '.' in the path. It also removes any
+        // '/' on the end of the path.
+        const normalized = normalizeUri(value);
+        if (normalized.uri.scheme === 'file') {
+            return FileUri.createFileUri(
+                getFilePath(normalized.uri),
+                normalized.uri.query,
+                normalized.uri.fragment,
+                normalized.str,
+                isCaseSensitive
+            );
+        }
+
+        // Web URIs are always case sensitive.
+        return WebUri.createWebUri(
+            normalized.uri.scheme,
+            normalized.uri.authority,
+            normalized.uri.path,
+            normalized.uri.query,
+            normalized.uri.fragment,
+            normalized.str
+        );
+    }
+
+    export function isUri(thing: any): thing is Uri {
+        return !!thing && typeof thing._key === 'string';
+    }
+}
diff --git a/packages/pyright-internal/src/common/uri/uriUtils.ts b/packages/pyright-internal/src/common/uri/uriUtils.ts
new file mode 100644
index 000000000..f3f51a6ce
--- /dev/null
+++ b/packages/pyright-internal/src/common/uri/uriUtils.ts
@@ -0,0 +1,406 @@
+/*
+ * uriUtils.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ *
+ * Utility functions for manipulating URIs.
+ */
+
+import type { Dirent } from 'fs';
+
+import { randomBytesHex } from '../crypto';
+import { FileSystem, ReadOnlyFileSystem, Stats, TempFile } from '../fileSystem';
+import {
+    getRegexEscapedSeparator,
+    isDirectoryWildcardPatternPresent,
+    stripTrailingDirectorySeparator,
+} from '../pathUtils';
+import { Uri } from './uri';
+
+let _fsCaseSensitivity: boolean | undefined = undefined;
+let _underTest: boolean = false;
+
+export interface FileSpec {
+    // File specs can contain wildcard characters (**, *, ?). This
+    // specifies the first portion of the file spec that contains
+    // no wildcards.
+    wildcardRoot: Uri;
+
+    // Regular expression that can be used to match against this
+    // file spec.
+    regExp: RegExp;
+
+    // Indicates whether the file spec has a directory wildcard (**).
+    // When present, the search cannot terminate without exploring to
+    // an arbitrary depth.
+    hasDirectoryWildcard: boolean;
+}
+
+const _includeFileRegex = /\.pyi?$/;
+
+export namespace FileSpec {
+    export function is(value: any): value is FileSpec {
+        const candidate: FileSpec = value as FileSpec;
+        return candidate && !!candidate.wildcardRoot && !!candidate.regExp;
+    }
+    export function isInPath(uri: Uri, paths: FileSpec[]) {
+        return !!paths.find((p) => uri.matchesRegex(p.regExp));
+    }
+
+    export function matchesIncludeFileRegex(uri: Uri, isFile = true) {
+        return isFile ? uri.matchesRegex(_includeFileRegex) : true;
+    }
+
+    export function matchIncludeFileSpec(includeRegExp: RegExp, exclude: FileSpec[], uri: Uri, isFile = true) {
+        if (uri.matchesRegex(includeRegExp)) {
+            if (!FileSpec.isInPath(uri, exclude) && FileSpec.matchesIncludeFileRegex(uri, isFile)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
+
+export interface FileSystemEntries {
+    files: Uri[];
+    directories: Uri[];
+}
+
+export function forEachAncestorDirectory(
+    directory: Uri,
+    callback: (directory: Uri) => Uri | undefined
+): Uri | undefined {
+    while (true) {
+        const result = callback(directory);
+        if (result !== undefined) {
+            return result;
+        }
+
+        const parentPath = directory.getDirectory();
+        if (parentPath.equals(directory)) {
+            return undefined;
+        }
+
+        directory = parentPath;
+    }
+}
+
+// Creates a directory hierarchy for a path, starting from some ancestor path.
+export function makeDirectories(fs: FileSystem, dir: Uri, startingFrom: Uri) {
+    if (!dir.startsWith(startingFrom)) {
+        return;
+    }
+
+    const pathComponents = dir.getPathComponents();
+    const relativeToComponents = startingFrom.getPathComponents();
+    let curPath = startingFrom;
+
+    for (let i = relativeToComponents.length; i < pathComponents.length; i++) {
+        curPath = curPath.combinePaths(pathComponents[i]);
+        if (!fs.existsSync(curPath)) {
+            fs.mkdirSync(curPath);
+        }
+    }
+}
+
+export function getFileSize(fs: ReadOnlyFileSystem, uri: Uri) {
+    const stat = tryStat(fs, uri);
+    if (stat?.isFile()) {
+        return stat.size;
+    }
+    return 0;
+}
+
+export function fileExists(fs: ReadOnlyFileSystem, uri: Uri): boolean {
+    return fileSystemEntryExists(fs, uri, FileSystemEntryKind.File);
+}
+
+export function directoryExists(fs: ReadOnlyFileSystem, uri: Uri): boolean {
+    return fileSystemEntryExists(fs, uri, FileSystemEntryKind.Directory);
+}
+
+export function isDirectory(fs: ReadOnlyFileSystem, uri: Uri): boolean {
+    return tryStat(fs, uri)?.isDirectory() ?? false;
+}
+
+export function isFile(fs: ReadOnlyFileSystem, uri: Uri, treatZipDirectoryAsFile = false): boolean {
+    const stats = tryStat(fs, uri);
+    if (stats?.isFile()) {
+        return true;
+    }
+
+    if (!treatZipDirectoryAsFile) {
+        return false;
+    }
+
+    return stats?.isZipDirectory?.() ?? false;
+}
+
+export function tryStat(fs: ReadOnlyFileSystem, uri: Uri): Stats | undefined {
+    try {
+        if (fs.existsSync(uri)) {
+            return fs.statSync(uri);
+        }
+    } catch (e: any) {
+        return undefined;
+    }
+    return undefined;
+}
+
+export function tryRealpath(fs: ReadOnlyFileSystem, uri: Uri): Uri | undefined {
+    try {
+        return fs.realCasePath(uri);
+    } catch (e: any) {
+        return undefined;
+    }
+}
+
+export function getFileSystemEntries(fs: ReadOnlyFileSystem, uri: Uri): FileSystemEntries {
+    try {
+        return getFileSystemEntriesFromDirEntries(fs.readdirEntriesSync(uri), fs, uri);
+    } catch (e: any) {
+        return { files: [], directories: [] };
+    }
+}
+
+// Sorts the entires into files and directories, including any symbolic links.
+export function getFileSystemEntriesFromDirEntries(
+    dirEntries: Dirent[],
+    fs: ReadOnlyFileSystem,
+    uri: Uri
+): FileSystemEntries {
+    const entries = dirEntries.sort((a, b) => {
+        if (a.name < b.name) {
+            return -1;
+        } else if (a.name > b.name) {
+            return 1;
+        } else {
+            return 0;
+        }
+    });
+    const files: Uri[] = [];
+    const directories: Uri[] = [];
+    for (const entry of entries) {
+        // This is necessary because on some file system node fails to exclude
+        // "." and "..". See https://github.com/nodejs/node/issues/4002
+        if (entry.name === '.' || entry.name === '..') {
+            continue;
+        }
+
+        const entryUri = uri.combinePaths(entry.name);
+        if (entry.isFile()) {
+            files.push(entryUri);
+        } else if (entry.isDirectory()) {
+            directories.push(entryUri);
+        } else if (entry.isSymbolicLink()) {
+            const stat = tryStat(fs, entryUri);
+            if (stat?.isFile()) {
+                files.push(entryUri);
+            } else if (stat?.isDirectory()) {
+                directories.push(entryUri);
+            }
+        }
+    }
+    return { files, directories };
+}
+
+export function setTestingMode(underTest: boolean) {
+    _underTest = underTest;
+}
+
+// Transforms a relative file spec (one that potentially contains
+// escape characters **, * or ?) and returns a regular expression
+// that can be used for matching against.
+export function getWildcardRegexPattern(root: Uri, fileSpec: string): string {
+    const absolutePath = root.combinePaths(fileSpec);
+    const pathComponents = Array.from(absolutePath.getPathComponents());
+    const escapedSeparator = getRegexEscapedSeparator('/');
+    const doubleAsteriskRegexFragment = `(${escapedSeparator}[^${escapedSeparator}][^${escapedSeparator}]*)*?`;
+    const reservedCharacterPattern = new RegExp(`[^\\w\\s${escapedSeparator}]`, 'g');
+
+    // Strip the directory separator from the root component.
+    if (pathComponents.length > 0) {
+        pathComponents[0] = stripTrailingDirectorySeparator(pathComponents[0]);
+    }
+
+    let regExPattern = '';
+    let firstComponent = true;
+
+    for (let component of pathComponents) {
+        if (component === '**') {
+            regExPattern += doubleAsteriskRegexFragment;
+        } else {
+            if (!firstComponent) {
+                component = escapedSeparator + component;
+            }
+
+            regExPattern += component.replace(reservedCharacterPattern, (match) => {
+                if (match === '*') {
+                    return `[^${escapedSeparator}]*`;
+                } else if (match === '?') {
+                    return `[^${escapedSeparator}]`;
+                } else {
+                    // escaping anything that is not reserved characters - word/space/separator
+                    return '\\' + match;
+                }
+            });
+
+            firstComponent = false;
+        }
+    }
+
+    return regExPattern;
+}
+
+// Returns the topmost path that contains no wildcard characters.
+export function getWildcardRoot(root: Uri, fileSpec: string): Uri {
+    const absolutePath = root.combinePaths(fileSpec);
+    // make a copy of the path components so we can modify them.
+    const pathComponents = Array.from(absolutePath.getPathComponents());
+    let wildcardRoot = absolutePath.root;
+
+    // Remove the root component.
+    if (pathComponents.length > 0) {
+        pathComponents.shift();
+    }
+
+    for (const component of pathComponents) {
+        if (component === '**') {
+            break;
+        } else {
+            if (/[*?]/.test(component)) {
+                break;
+            }
+
+            wildcardRoot = wildcardRoot.combinePaths(component);
+        }
+    }
+
+    return wildcardRoot;
+}
+
+export function hasPythonExtension(uri: Uri) {
+    return uri.hasExtension('.py') || uri.hasExtension('.pyi');
+}
+
+export function getFileSpec(root: Uri, fileSpec: string): FileSpec {
+    let regExPattern = getWildcardRegexPattern(root, fileSpec);
+    const escapedSeparator = getRegexEscapedSeparator('/');
+    regExPattern = `^(${regExPattern})($|${escapedSeparator})`;
+
+    const regExp = new RegExp(regExPattern, root.isCaseSensitive ? undefined : 'i');
+    const wildcardRoot = getWildcardRoot(root, fileSpec);
+    const hasDirectoryWildcard = isDirectoryWildcardPatternPresent(fileSpec);
+
+    return {
+        wildcardRoot,
+        regExp,
+        hasDirectoryWildcard,
+    };
+}
+
+const enum FileSystemEntryKind {
+    File,
+    Directory,
+}
+
+function fileSystemEntryExists(fs: ReadOnlyFileSystem, uri: Uri, entryKind: FileSystemEntryKind): boolean {
+    try {
+        const stat = fs.statSync(uri);
+        switch (entryKind) {
+            case FileSystemEntryKind.File:
+                return stat.isFile();
+            case FileSystemEntryKind.Directory:
+                return stat.isDirectory();
+            default:
+                return false;
+        }
+    } catch (e: any) {
+        return false;
+    }
+}
+
+const isFileSystemCaseSensitiveMap = new WeakMap<FileSystem, boolean>();
+
+export function isFileSystemCaseSensitive(fs: FileSystem, tmp: TempFile | undefined) {
+    if (!_underTest && _fsCaseSensitivity !== undefined) {
+        return _fsCaseSensitivity;
+    }
+
+    if (!isFileSystemCaseSensitiveMap.has(fs)) {
+        _fsCaseSensitivity = tmp ? isFileSystemCaseSensitiveInternal(fs, tmp) : false;
+        isFileSystemCaseSensitiveMap.set(fs, _fsCaseSensitivity);
+    }
+    return !!isFileSystemCaseSensitiveMap.get(fs);
+}
+
+export function isFileSystemCaseSensitiveInternal(fs: FileSystem, tmp: TempFile) {
+    let filePath: Uri | undefined = undefined;
+    try {
+        // Make unique file name.
+        let name: string;
+        let mangledFilePath: Uri;
+        do {
+            name = `${randomBytesHex(21)}-a`;
+            filePath = tmp.tmpdir().combinePaths(name);
+            mangledFilePath = tmp.tmpdir().combinePaths(name.toUpperCase());
+        } while (fs.existsSync(filePath) || fs.existsSync(mangledFilePath));
+
+        fs.writeFileSync(filePath, '', 'utf8');
+
+        // If file exists, then it is insensitive.
+        return !fs.existsSync(mangledFilePath);
+    } catch (e: any) {
+        return false;
+    } finally {
+        if (filePath) {
+            // remove temp file created
+            try {
+                fs.unlinkSync(filePath);
+            } catch (e: any) {
+                /* ignored */
+            }
+        }
+    }
+}
+
+export function deduplicateFolders(listOfFolders: Uri[][]): Uri[] {
+    const foldersToWatch = new Map<string, Uri>();
+
+    listOfFolders.forEach((folders) => {
+        folders.forEach((p) => {
+            if (foldersToWatch.has(p.key)) {
+                // Bail out on exact match.
+                return;
+            }
+
+            for (const existing of foldersToWatch) {
+                // ex) p: "/user/test" existing: "/user"
+                if (p.startsWith(existing[1])) {
+                    // We already have the parent folder in the watch list
+                    return;
+                }
+
+                // ex) p: "/user" folderToWatch: "/user/test"
+                if (existing[1].startsWith(p)) {
+                    // We found better one to watch. replace.
+                    foldersToWatch.delete(existing[0]);
+                    foldersToWatch.set(p.key, p);
+                    return;
+                }
+            }
+
+            foldersToWatch.set(p.key, p);
+        });
+    });
+
+    return [...foldersToWatch.values()];
+}
+
+export function getRootUri(isCaseSensitive: boolean): Uri | undefined {
+    if ((global as any).__rootDirectory) {
+        return Uri.file((global as any).__rootDirectory, isCaseSensitive);
+    }
+    return undefined;
+}
diff --git a/packages/pyright-internal/src/common/uri/webUri.ts b/packages/pyright-internal/src/common/uri/webUri.ts
new file mode 100644
index 000000000..d363daad4
--- /dev/null
+++ b/packages/pyright-internal/src/common/uri/webUri.ts
@@ -0,0 +1,207 @@
+/*
+ * webUri.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ *
+ * URI class that represents a URI that isn't 'file' schemed.
+ * This can be URIs like:
+ * - http://www.microsoft.com/file.txt
+ * - untitled:Untitled-1
+ * - vscode:extension/ms-python.python
+ * - vscode-vfs://github.com/microsoft/debugpy/debugpy/launcher/debugAdapter.py
+ */
+
+import * as debug from '../debug';
+import { getRootLength, hasTrailingDirectorySeparator, normalizeSlashes, resolvePaths } from '../pathUtils';
+import { BaseUri } from './baseUri';
+import { cacheMethodWithNoArgs, cacheProperty, cacheStaticFunc } from './memoization';
+import { Uri } from './uri';
+
+export class WebUri extends BaseUri {
+    private constructor(
+        key: string,
+        private readonly _scheme: string,
+        private readonly _authority: string,
+        private readonly _path: string,
+        private readonly _query: string,
+        private readonly _fragment: string,
+        private readonly _originalString: string | undefined
+    ) {
+        super(key);
+    }
+
+    override get scheme(): string {
+        return this._scheme;
+    }
+
+    get isCaseSensitive(): boolean {
+        // Web URIs are always case sensitive
+        return true;
+    }
+
+    @cacheProperty()
+    override get root(): Uri {
+        const rootPath = this.getRootPath();
+        if (rootPath !== this._path) {
+            return WebUri.createWebUri(this._scheme, this._authority, rootPath, '', '', undefined);
+        }
+        return this;
+    }
+
+    @cacheProperty()
+    override get fileName(): string {
+        // Path should already be normalized, just get the last on a split of '/'.
+        const components = this._path.split('/');
+        return components[components.length - 1];
+    }
+
+    @cacheProperty()
+    override get lastExtension(): string {
+        const basename = this.fileName;
+        const index = basename.lastIndexOf('.');
+        if (index >= 0) {
+            return basename.slice(index);
+        }
+        return '';
+    }
+
+    @cacheStaticFunc()
+    static createWebUri(
+        scheme: string,
+        authority: string,
+        path: string,
+        query: string,
+        fragment: string,
+        originalString: string | undefined
+    ): WebUri {
+        const key = WebUri._createKey(scheme, authority, path, query, fragment);
+        return new WebUri(key, scheme, authority, path, query, fragment, originalString);
+    }
+
+    override toString(): string {
+        if (!this._originalString) {
+            return `${this._scheme}://${this._authority}${this._path}${this._query ? '?' + this._query : ''}${
+                this._fragment ? '#' + this._fragment : ''
+            }`;
+        }
+        return this._originalString;
+    }
+    override toUserVisibleString(): string {
+        return this.toString();
+    }
+    static isWebUri(uri: Uri): uri is WebUri {
+        return uri.scheme !== 'file' && (uri as any)._scheme !== undefined;
+    }
+
+    override matchesRegex(regex: RegExp): boolean {
+        return regex.test(this._path);
+    }
+
+    override addPath(extra: string): Uri {
+        const newPath = this._path + extra;
+        return WebUri.createWebUri(this._scheme, this._authority, newPath, this._query, this._fragment, undefined);
+    }
+
+    override isRoot(): boolean {
+        return this._path === this.getRootPath() && this._path.length > 0;
+    }
+
+    override isChild(parent: Uri): boolean {
+        if (!WebUri.isWebUri(parent)) {
+            return false;
+        }
+
+        return parent._path.length < this._path.length && this.startsWith(parent);
+    }
+
+    override isLocal(): boolean {
+        return false;
+    }
+
+    override startsWith(other: Uri | undefined): boolean {
+        if (!other || !WebUri.isWebUri(other)) {
+            return false;
+        }
+        if (other.isEmpty() !== this.isEmpty()) {
+            return false;
+        }
+        if (this.scheme !== other.scheme) {
+            return false;
+        }
+        if (this._path.length >= other._path.length) {
+            // Make sure the other ends with a / when comparing longer paths, otherwise we might
+            // say that /a/food is a child of /a/foo.
+            const otherPath =
+                this._path.length > other._path.length && !hasTrailingDirectorySeparator(other._path)
+                    ? `${other._path}/`
+                    : other._path;
+
+            return this._path.startsWith(otherPath);
+        }
+        return false;
+    }
+    override getPathLength(): number {
+        return this._path.length;
+    }
+
+    override getPath(): string {
+        return this._path;
+    }
+
+    override getFilePath(): string {
+        debug.fail(`${this} is not a file based URI.`);
+    }
+
+    override combinePaths(...paths: string[]): Uri {
+        // Resolve and combine paths, never want URIs with '..' in the middle.
+        let combined = this.normalizeSlashes(resolvePaths(this._path, ...paths));
+
+        // Make sure to remove any trailing directory chars.
+        if (hasTrailingDirectorySeparator(combined) && combined.length > 1) {
+            combined = combined.slice(0, combined.length - 1);
+        }
+        if (combined !== this._path) {
+            return WebUri.createWebUri(this._scheme, this._authority, combined, '', '', undefined);
+        }
+        return this;
+    }
+
+    @cacheMethodWithNoArgs()
+    override getDirectory(): Uri {
+        const index = this._path.lastIndexOf('/');
+        if (index > 0) {
+            return WebUri.createWebUri(
+                this._scheme,
+                this._authority,
+                this._path.slice(0, index),
+                this._query,
+                this._fragment,
+                undefined
+            );
+        } else {
+            return this;
+        }
+    }
+
+    protected override getPathComponentsImpl(): string[] {
+        // Get the root path and the rest of the path components.
+        const rootPath = this.getRootPath();
+        const otherPaths = this._path.slice(rootPath.length).split('/');
+        return this.reducePathComponents([rootPath, ...otherPaths]).map((component) =>
+            this.normalizeSlashes(component)
+        );
+    }
+
+    protected override getRootPath(): string {
+        const rootLength = getRootLength(this._path, '/');
+        return this._path.slice(0, rootLength);
+    }
+
+    protected override getComparablePath(): string {
+        return normalizeSlashes(this._path);
+    }
+
+    private static _createKey(scheme: string, authority: string, path: string, query: string, fragment: string) {
+        return `${scheme}://${authority}${path}${query ? '?' + query : ''}${fragment ? '#' + fragment : ''}`;
+    }
+}
diff --git a/packages/pyright-internal/src/common/uriParser.ts b/packages/pyright-internal/src/common/uriParser.ts
deleted file mode 100644
index 33c3f3f12..000000000
--- a/packages/pyright-internal/src/common/uriParser.ts
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- * uriParser.ts
- * Copyright (c) Microsoft Corporation.
- * Licensed under the MIT license.
- *
- * URI utility functions.
- */
-
-import { Position } from 'vscode-languageserver';
-import { TextDocumentIdentifier } from 'vscode-languageserver-protocol';
-import { URI } from 'vscode-uri';
-
-import { isString } from './core';
-import { FileSystem } from './fileSystem';
-import { convertUriToPath } from './pathUtils';
-
-export interface IUriParser {
-    decodeTextDocumentPosition(
-        textDocument: TextDocumentIdentifier,
-        position: Position
-    ): { filePath: string; position: Position };
-    decodeTextDocumentUri(uriString: string): string;
-    isUntitled(uri: URI | string | undefined): boolean;
-    isLocal(uri: URI | string | undefined): boolean;
-}
-
-export class UriParser implements IUriParser {
-    constructor(protected readonly fs: FileSystem) {}
-
-    decodeTextDocumentPosition(textDocument: TextDocumentIdentifier, position: Position) {
-        const filePath = this.decodeTextDocumentUri(textDocument.uri);
-        return { filePath, position };
-    }
-
-    decodeTextDocumentUri(uriString: string) {
-        return convertUriToPath(this.fs, uriString);
-    }
-
-    isUntitled(uri: URI | string | undefined) {
-        if (!uri) {
-            return false;
-        }
-
-        if (isString(uri)) {
-            uri = URI.parse(uri);
-        }
-
-        return uri.scheme === 'untitled';
-    }
-
-    isLocal(uri: URI | string | undefined) {
-        if (!uri) {
-            return false;
-        }
-
-        if (isString(uri)) {
-            uri = URI.parse(uri);
-        }
-
-        return uri.scheme === 'file';
-    }
-}
diff --git a/packages/pyright-internal/src/common/workspaceEditUtils.ts b/packages/pyright-internal/src/common/workspaceEditUtils.ts
index 02e669910..047be8d8f 100644
--- a/packages/pyright-internal/src/common/workspaceEditUtils.ts
+++ b/packages/pyright-internal/src/common/workspaceEditUtils.ts
@@ -19,15 +19,14 @@ import {
 import { TextDocument } from 'vscode-languageserver-textdocument';
 import { AnalyzerService } from '../analyzer/service';
 import { FileEditAction, FileEditActions, TextEditAction } from '../common/editAction';
-import { convertPathToUri, convertUriToPath } from '../common/pathUtils';
 import { createMapFromItems } from './collectionUtils';
 import { isArray } from './core';
 import { assertNever } from './debug';
 import { EditableProgram, SourceFileInfo } from './extensibility';
-import { ReadOnlyFileSystem } from './fileSystem';
 import { convertRangeToTextRange, convertTextRangeToRange } from './positionUtils';
 import { TextRange } from './textRange';
 import { TextRangeCollection } from './textRangeCollection';
+import { Uri } from './uri/uri';
 
 export function convertToTextEdits(editActions: TextEditAction[]): TextEdit[] {
     return editActions.map((editAction) => ({
@@ -36,14 +35,13 @@ export function convertToTextEdits(editActions: TextEditAction[]): TextEdit[] {
     }));
 }
 
-export function convertToFileTextEdits(filePath: string, editActions: TextEditAction[]): FileEditAction[] {
-    return editActions.map((a) => ({ filePath, ...a }));
+export function convertToFileTextEdits(fileUri: Uri, editActions: TextEditAction[]): FileEditAction[] {
+    return editActions.map((a) => ({ fileUri, ...a }));
 }
 
-export function convertToWorkspaceEdit(fs: ReadOnlyFileSystem, edits: FileEditAction[]): WorkspaceEdit;
-export function convertToWorkspaceEdit(fs: ReadOnlyFileSystem, edits: FileEditActions): WorkspaceEdit;
+export function convertToWorkspaceEdit(edits: FileEditAction[]): WorkspaceEdit;
+export function convertToWorkspaceEdit(edits: FileEditActions): WorkspaceEdit;
 export function convertToWorkspaceEdit(
-    fs: ReadOnlyFileSystem,
     edits: FileEditActions,
     changeAnnotations: {
         [id: string]: ChangeAnnotation;
@@ -51,7 +49,6 @@ export function convertToWorkspaceEdit(
     defaultAnnotationId: string
 ): WorkspaceEdit;
 export function convertToWorkspaceEdit(
-    fs: ReadOnlyFileSystem,
     edits: FileEditActions | FileEditAction[],
     changeAnnotations?: {
         [id: string]: ChangeAnnotation;
@@ -59,17 +56,17 @@ export function convertToWorkspaceEdit(
     defaultAnnotationId = 'default'
 ): WorkspaceEdit {
     if (isArray(edits)) {
-        return _convertToWorkspaceEditWithChanges(fs, edits);
+        return _convertToWorkspaceEditWithChanges(edits);
     }
 
-    return _convertToWorkspaceEditWithDocumentChanges(fs, edits, changeAnnotations, defaultAnnotationId);
+    return _convertToWorkspaceEditWithDocumentChanges(edits, changeAnnotations, defaultAnnotationId);
 }
 
-export function appendToWorkspaceEdit(fs: ReadOnlyFileSystem, edits: FileEditAction[], workspaceEdit: WorkspaceEdit) {
+export function appendToWorkspaceEdit(edits: FileEditAction[], workspaceEdit: WorkspaceEdit) {
     edits.forEach((edit) => {
-        const uri = convertPathToUri(fs, edit.filePath);
-        workspaceEdit.changes![uri] = workspaceEdit.changes![uri] || [];
-        workspaceEdit.changes![uri].push({ range: edit.range, newText: edit.replacementText });
+        const uri = edit.fileUri;
+        workspaceEdit.changes![uri.toString()] = workspaceEdit.changes![uri.toString()] || [];
+        workspaceEdit.changes![uri.toString()].push({ range: edit.range, newText: edit.replacementText });
     });
 }
 
@@ -101,18 +98,18 @@ export function applyTextEditsToString(
     return current;
 }
 
-export function applyWorkspaceEdit(program: EditableProgram, edits: WorkspaceEdit, filesChanged: Set<string>) {
+export function applyWorkspaceEdit(program: EditableProgram, edits: WorkspaceEdit, filesChanged: Map<string, Uri>) {
     if (edits.changes) {
         for (const kv of Object.entries(edits.changes)) {
-            const filePath = convertUriToPath(program.fileSystem, kv[0]);
-            const fileInfo = program.getSourceFileInfo(filePath);
+            const fileUri = Uri.parse(kv[0], program.configOptions.projectRoot.isCaseSensitive);
+            const fileInfo = program.getSourceFileInfo(fileUri);
             if (!fileInfo || !fileInfo.isTracked) {
                 // We don't allow non user file being modified.
                 continue;
             }
 
             applyDocumentChanges(program, fileInfo, kv[1]);
-            filesChanged.add(filePath);
+            filesChanged.set(fileUri.key, fileUri);
         }
     }
 
@@ -120,15 +117,15 @@ export function applyWorkspaceEdit(program: EditableProgram, edits: WorkspaceEdi
     if (edits.documentChanges) {
         for (const change of edits.documentChanges) {
             if (TextDocumentEdit.is(change)) {
-                const filePath = convertUriToPath(program.fileSystem, change.textDocument.uri);
-                const fileInfo = program.getSourceFileInfo(filePath);
+                const fileUri = Uri.parse(change.textDocument.uri, program.configOptions.projectRoot.isCaseSensitive);
+                const fileInfo = program.getSourceFileInfo(fileUri);
                 if (!fileInfo || !fileInfo.isTracked) {
                     // We don't allow non user file being modified.
                     continue;
                 }
 
                 applyDocumentChanges(program, fileInfo, change.edits);
-                filesChanged.add(filePath);
+                filesChanged.set(fileUri.key, fileUri);
             }
 
             // For now, we don't support other kinds of text changes.
@@ -140,30 +137,29 @@ export function applyWorkspaceEdit(program: EditableProgram, edits: WorkspaceEdi
 export function applyDocumentChanges(program: EditableProgram, fileInfo: SourceFileInfo, edits: TextEdit[]) {
     if (!fileInfo.isOpenByClient) {
         const fileContent = fileInfo.sourceFile.getFileContent();
-        program.setFileOpened(fileInfo.sourceFile.getFilePath(), 0, fileContent ?? '', {
+        program.setFileOpened(fileInfo.sourceFile.getUri(), 0, fileContent ?? '', {
             isTracked: fileInfo.isTracked,
             ipythonMode: fileInfo.sourceFile.getIPythonMode(),
-            chainedFilePath: fileInfo.chainedSourceFile?.sourceFile.getFilePath(),
-            realFilePath: fileInfo.sourceFile.getRealFilePath(),
+            chainedFileUri: fileInfo.chainedSourceFile?.sourceFile.getUri(),
         });
     }
 
     const version = fileInfo.sourceFile.getClientVersion() ?? 0;
-    const filePath = fileInfo.sourceFile.getFilePath();
+    const fileUri = fileInfo.sourceFile.getUri();
+    const filePath = fileUri.getFilePath();
     const sourceDoc = TextDocument.create(filePath, 'python', version, fileInfo.sourceFile.getOpenFileContents() ?? '');
 
-    program.setFileOpened(filePath, version + 1, TextDocument.applyEdits(sourceDoc, edits), {
+    program.setFileOpened(fileUri, version + 1, TextDocument.applyEdits(sourceDoc, edits), {
         isTracked: fileInfo.isTracked,
         ipythonMode: fileInfo.sourceFile.getIPythonMode(),
-        chainedFilePath: fileInfo.chainedSourceFile?.sourceFile.getFilePath(),
-        realFilePath: fileInfo.sourceFile.getRealFilePath(),
+        chainedFileUri: fileInfo.chainedSourceFile?.sourceFile.getUri(),
     });
 }
 
 export function generateWorkspaceEdit(
     originalService: AnalyzerService,
     clonedService: AnalyzerService,
-    filesChanged: Set<string>
+    filesChanged: Map<string, Uri>
 ) {
     // For now, we won't do text diff to find out minimal text changes. instead, we will
     // consider whole text of the files are changed. In future, we could consider
@@ -171,9 +167,9 @@ export function generateWorkspaceEdit(
     // to support annotation.
     const edits: WorkspaceEdit = { changes: {} };
 
-    for (const filePath of filesChanged) {
-        const original = originalService.backgroundAnalysisProgram.program.getBoundSourceFile(filePath);
-        const final = clonedService.backgroundAnalysisProgram.program.getBoundSourceFile(filePath);
+    for (const uri of filesChanged.values()) {
+        const original = originalService.backgroundAnalysisProgram.program.getBoundSourceFile(uri);
+        const final = clonedService.backgroundAnalysisProgram.program.getBoundSourceFile(uri);
         if (!original || !final) {
             // Both must exist.
             continue;
@@ -184,7 +180,7 @@ export function generateWorkspaceEdit(
             continue;
         }
 
-        edits.changes![convertPathToUri(originalService.fs, filePath)] = [
+        edits.changes![uri.toString()] = [
             {
                 range: convertTextRangeToRange(parseResults.parseTree, parseResults.tokenizerOutput.lines),
                 newText: final.getFileContent() ?? '',
@@ -195,17 +191,16 @@ export function generateWorkspaceEdit(
     return edits;
 }
 
-function _convertToWorkspaceEditWithChanges(fs: ReadOnlyFileSystem, edits: FileEditAction[]) {
+function _convertToWorkspaceEditWithChanges(edits: FileEditAction[]) {
     const workspaceEdit: WorkspaceEdit = {
         changes: {},
     };
 
-    appendToWorkspaceEdit(fs, edits, workspaceEdit);
+    appendToWorkspaceEdit(edits, workspaceEdit);
     return workspaceEdit;
 }
 
 function _convertToWorkspaceEditWithDocumentChanges(
-    fs: ReadOnlyFileSystem,
     editActions: FileEditActions,
     changeAnnotations?: {
         [id: string]: ChangeAnnotation;
@@ -223,11 +218,7 @@ function _convertToWorkspaceEditWithDocumentChanges(
         switch (operation.kind) {
             case 'create':
                 workspaceEdit.documentChanges!.push(
-                    CreateFile.create(
-                        convertPathToUri(fs, operation.filePath),
-                        /* options */ undefined,
-                        defaultAnnotationId
-                    )
+                    CreateFile.create(operation.fileUri.toString(), /* options */ undefined, defaultAnnotationId)
                 );
                 break;
             case 'rename':
@@ -239,11 +230,11 @@ function _convertToWorkspaceEditWithDocumentChanges(
     }
 
     // Text edit's file path must refer to original file paths unless it is a new file just created.
-    const mapPerFile = createMapFromItems(editActions.edits, (e) => e.filePath);
+    const mapPerFile = createMapFromItems(editActions.edits, (e) => e.fileUri.key);
     for (const [key, value] of mapPerFile) {
         workspaceEdit.documentChanges!.push(
             TextDocumentEdit.create(
-                { uri: convertPathToUri(fs, key), version: null },
+                { uri: key, version: null },
                 Array.from(
                     value.map((v) => ({
                         range: v.range,
@@ -262,8 +253,8 @@ function _convertToWorkspaceEditWithDocumentChanges(
             case 'rename':
                 workspaceEdit.documentChanges!.push(
                     RenameFile.create(
-                        convertPathToUri(fs, operation.oldFilePath),
-                        convertPathToUri(fs, operation.newFilePath),
+                        operation.oldFileUri.toString(),
+                        operation.newFileUri.toString(),
                         /* options */ undefined,
                         defaultAnnotationId
                     )
@@ -271,11 +262,7 @@ function _convertToWorkspaceEditWithDocumentChanges(
                 break;
             case 'delete':
                 workspaceEdit.documentChanges!.push(
-                    DeleteFile.create(
-                        convertPathToUri(fs, operation.filePath),
-                        /* options */ undefined,
-                        defaultAnnotationId
-                    )
+                    DeleteFile.create(operation.fileUri.toString(), /* options */ undefined, defaultAnnotationId)
                 );
                 break;
             default:
diff --git a/packages/pyright-internal/src/languageServerBase.ts b/packages/pyright-internal/src/languageServerBase.ts
index 2570d1051..607da4885 100644
--- a/packages/pyright-internal/src/languageServerBase.ts
+++ b/packages/pyright-internal/src/languageServerBase.ts
@@ -107,18 +107,11 @@ import { FileSystem, ReadOnlyFileSystem } from './common/fileSystem';
 import { FileWatcherEventType, FileWatcherHandler } from './common/fileWatcher';
 import { Host } from './common/host';
 import { fromLSPAny } from './common/lspUtils';
-import {
-    convertPathToUri,
-    convertUriToPath,
-    deduplicateFolders,
-    getDirectoryPath,
-    getFileName,
-    isFile,
-} from './common/pathUtils';
 import { ProgressReportTracker, ProgressReporter } from './common/progressReporter';
 import { ServiceProvider } from './common/serviceProvider';
 import { DocumentRange, Position, Range } from './common/textRange';
-import { UriParser } from './common/uriParser';
+import { Uri } from './common/uri/uri';
+import { deduplicateFolders, isFile } from './common/uri/uriUtils';
 import { AnalyzerServiceExecutor } from './languageService/analyzerServiceExecutor';
 import { CallHierarchyProvider } from './languageService/callHierarchyProvider';
 import { CompletionItemData, CompletionProvider } from './languageService/completionProvider';
@@ -137,17 +130,17 @@ import { ParseResults } from './parser/parser';
 import { InitStatus, WellKnownWorkspaceKinds, Workspace, WorkspaceFactory } from './workspaceFactory';
 
 export interface ServerSettings {
-    venvPath?: string | undefined;
-    pythonPath?: string | undefined;
-    typeshedPath?: string | undefined;
-    stubPath?: string | undefined;
+    venvPath?: Uri | undefined;
+    pythonPath?: Uri | undefined;
+    typeshedPath?: Uri | undefined;
+    stubPath?: Uri | undefined;
     openFilesOnly?: boolean | undefined;
     typeCheckingMode?: string | undefined;
     useLibraryCodeForTypes?: boolean | undefined;
     disableLanguageServices?: boolean | undefined;
     disableOrganizeImports?: boolean | undefined;
     autoSearchPaths?: boolean | undefined;
-    extraPaths?: string[] | undefined;
+    extraPaths?: Uri[] | undefined;
     watchForSourceChanges?: boolean | undefined;
     watchForLibraryChanges?: boolean | undefined;
     watchForConfigChanges?: boolean | undefined;
@@ -181,23 +174,22 @@ export interface WindowInterface {
 }
 
 export interface LanguageServerInterface {
-    readonly rootPath: string;
+    readonly rootUri: Uri;
     readonly console: ConsoleInterface;
     readonly window: WindowInterface;
     readonly supportAdvancedEdits: boolean;
 
     getWorkspaces(): Promise<Workspace[]>;
-    getWorkspaceForFile(filePath: string): Promise<Workspace>;
+    getWorkspaceForFile(fileUri: Uri): Promise<Workspace>;
     getSettings(workspace: Workspace): Promise<ServerSettings>;
     createBackgroundAnalysis(serviceId: string): BackgroundAnalysisBase | undefined;
     reanalyze(): void;
     restart(): void;
-    decodeTextDocumentUri(uriString: string): string;
 }
 
 export interface ServerOptions {
     productName: string;
-    rootDirectory: string;
+    rootDirectory: Uri;
     version: string;
     cancellationProvider: CancellationProvider;
     serviceProvider: ServiceProvider;
@@ -323,7 +315,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     private _workspaceFoldersChangedDisposable: Disposable | undefined;
 
     // Global root path - the basis for all global settings.
-    rootPath = '';
+    rootUri = Uri.empty();
 
     protected client: ClientCapabilities = {
         hasConfigurationCapability: false,
@@ -358,16 +350,10 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     // The URIs for which diagnostics are reported
     protected readonly documentsWithDiagnostics = new Set<string>();
 
-    readonly uriParser: UriParser;
-
-    constructor(
-        protected serverOptions: ServerOptions,
-        protected connection: Connection,
-        uriParserFactory = (fs: FileSystem) => new UriParser(fs)
-    ) {
+    constructor(protected serverOptions: ServerOptions, protected connection: Connection) {
         // Stash the base directory into a global variable.
         // This must happen before fs.getModulePath().
-        (global as any).__rootDirectory = serverOptions.rootDirectory;
+        (global as any).__rootDirectory = serverOptions.rootDirectory.getFilePath();
 
         this.console.info(
             `${serverOptions.productName} language server ${
@@ -379,16 +365,14 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
 
         this.fs = this.serverOptions.serviceProvider.fs();
 
-        this.uriParser = uriParserFactory(this.fs);
-
         this.workspaceFactory = new WorkspaceFactory(
             this.console,
-            this.uriParser,
             /* isWeb */ false,
             this.createAnalyzerServiceForWorkspace.bind(this),
             this.isPythonPathImmutable.bind(this),
             this.onWorkspaceCreated.bind(this),
-            this.onWorkspaceRemoved.bind(this)
+            this.onWorkspaceRemoved.bind(this),
+            this.fs.isCaseSensitive
         );
 
         // Set the working directory to a known location within
@@ -427,11 +411,6 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         this._workspaceFoldersChangedDisposable?.dispose();
     }
 
-    // Convert uri to path
-    decodeTextDocumentUri(uriString: string): string {
-        return this.uriParser.decodeTextDocumentUri(uriString);
-    }
-
     abstract createBackgroundAnalysis(serviceId: string): BackgroundAnalysisBase | undefined;
 
     abstract getSettings(workspace: Workspace): Promise<ServerSettings>;
@@ -472,12 +451,12 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         return workspaces;
     }
 
-    async getWorkspaceForFile(filePath: string, pythonPath?: string): Promise<Workspace> {
-        return this.workspaceFactory.getWorkspaceForFile(filePath, pythonPath);
+    async getWorkspaceForFile(fileUri: Uri, pythonPath?: Uri): Promise<Workspace> {
+        return this.workspaceFactory.getWorkspaceForFile(fileUri, pythonPath);
     }
 
-    async getContainingWorkspacesForFile(filePath: string): Promise<Workspace[]> {
-        return this.workspaceFactory.getContainingWorkspacesForFile(filePath);
+    async getContainingWorkspacesForFile(fileUri: Uri): Promise<Workspace[]> {
+        return this.workspaceFactory.getContainingWorkspacesForFile(fileUri);
     }
 
     reanalyze() {
@@ -521,7 +500,10 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         (this.console as ConsoleWithLogLevel).level = serverSettings.logLevel ?? LogLevel.Info;
 
         // Apply the new path to the workspace (before restarting the service).
-        serverSettings.pythonPath = this.workspaceFactory.applyPythonPath(workspace, serverSettings.pythonPath);
+        serverSettings.pythonPath = this.workspaceFactory.applyPythonPath(
+            workspace,
+            serverSettings.pythonPath ? serverSettings.pythonPath : undefined
+        );
 
         // Then use the updated settings to restart the service.
         this.updateOptionsAndRestartService(workspace, serverSettings);
@@ -540,8 +522,8 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         serverSettings: ServerSettings,
         typeStubTargetImportName?: string
     ) {
-        AnalyzerServiceExecutor.runWithOptions(this.rootPath, workspace, serverSettings, typeStubTargetImportName);
-        workspace.searchPathsToWatch = workspace.service.librarySearchPathsToWatch ?? [];
+        AnalyzerServiceExecutor.runWithOptions(this.rootUri, workspace, serverSettings, typeStubTargetImportName);
+        workspace.searchPathsToWatch = workspace.service.librarySearchUrisToWatch ?? [];
     }
 
     protected abstract executeCommand(params: ExecuteCommandParams, token: CancellationToken): Promise<any>;
@@ -553,18 +535,18 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         token: CancellationToken
     ): Promise<(Command | CodeAction)[] | undefined | null>;
 
-    protected isPythonPathImmutable(filePath: string): boolean {
+    protected isPythonPathImmutable(fileUri: Uri): boolean {
         // This function is called to determine if the file is using
         // a special pythonPath separate from a workspace or not.
         // The default is no.
         return false;
     }
 
-    protected async getConfiguration(scopeUri: string | undefined, section: string) {
+    protected async getConfiguration(scopeUri: Uri | undefined, section: string) {
         if (this.client.hasConfigurationCapability) {
             const item: ConfigurationItem = {};
             if (scopeUri !== undefined) {
-                item.scopeUri = scopeUri;
+                item.scopeUri = scopeUri.toString();
             }
             if (section !== undefined) {
                 item.section = section;
@@ -691,7 +673,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
             setLocaleOverride(params.locale);
         }
 
-        this.rootPath = params.rootPath || '';
+        this.rootUri = params.rootUri ? Uri.parse(params.rootUri, this.fs.isCaseSensitive) : Uri.empty();
 
         const capabilities = params.capabilities;
         this.client.hasConfigurationCapability = !!capabilities.workspace?.configuration;
@@ -862,7 +844,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         filter: DefinitionFilter,
         getDefinitionsFunc: (
             workspace: Workspace,
-            filePath: string,
+            fileUri: Uri,
             position: Position,
             filter: DefinitionFilter,
             token: CancellationToken
@@ -870,20 +852,20 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     ) {
         this.recordUserInteractionTime();
 
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
 
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return undefined;
         }
 
-        const locations = getDefinitionsFunc(workspace, filePath, position, filter, token);
+        const locations = getDefinitionsFunc(workspace, uri, params.position, filter, token);
         if (!locations) {
             return undefined;
         }
         return locations
-            .filter((loc) => this.canNavigateToFile(loc.path, workspace.service.fs))
-            .map((loc) => Location.create(convertPathToUri(workspace.service.fs, loc.path), loc.range));
+            .filter((loc) => this.canNavigateToFile(loc.uri, workspace.service.fs))
+            .map((loc) => Location.create(loc.uri.toString(), loc.range));
     }
 
     protected async onReferences(
@@ -891,7 +873,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         token: CancellationToken,
         workDoneReporter: WorkDoneProgressReporter,
         resultReporter: ResultProgressReporter<Location[]> | undefined,
-        createDocumentRange?: (filePath: string, result: CollectionResult, parseResults: ParseResults) => DocumentRange,
+        createDocumentRange?: (uri: Uri, result: CollectionResult, parseResults: ParseResults) => DocumentRange,
         convertToLocation?: (fs: ReadOnlyFileSystem, ranges: DocumentRange) => Location | undefined
     ): Promise<Location[] | null | undefined> {
         if (this._pendingFindAllRefsCancellationSource) {
@@ -912,12 +894,9 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         this._pendingFindAllRefsCancellationSource = source;
 
         try {
-            const { filePath, position } = this.uriParser.decodeTextDocumentPosition(
-                params.textDocument,
-                params.position
-            );
+            const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
 
-            const workspace = await this.getWorkspaceForFile(filePath);
+            const workspace = await this.getWorkspaceForFile(uri);
             if (workspace.disableLanguageServices) {
                 return;
             }
@@ -928,7 +907,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
                     source.token,
                     createDocumentRange,
                     convertToLocation
-                ).reportReferences(filePath, position, params.context.includeDeclaration, resultReporter);
+                ).reportReferences(uri, params.position, params.context.includeDeclaration, resultReporter);
             }, token);
         } finally {
             progress.reporter.done();
@@ -942,8 +921,8 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     ): Promise<DocumentSymbol[] | SymbolInformation[] | null | undefined> {
         this.recordUserInteractionTime();
 
-        const filePath = this.uriParser.decodeTextDocumentUri(params.textDocument.uri);
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return undefined;
         }
@@ -951,7 +930,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         return workspace.service.run((program) => {
             return new DocumentSymbolProvider(
                 program,
-                filePath,
+                uri,
                 this.client.hasHierarchicalDocumentSymbolCapability,
                 token
             ).getSymbols();
@@ -974,11 +953,11 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     }
 
     protected async onHover(params: HoverParams, token: CancellationToken) {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
+        const workspace = await this.getWorkspaceForFile(uri);
 
         return workspace.service.run((program) => {
-            return new HoverProvider(program, filePath, position, this.client.hoverContentFormat, token).getHover();
+            return new HoverProvider(program, uri, params.position, this.client.hoverContentFormat, token).getHover();
         }, token);
     }
 
@@ -986,11 +965,11 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         params: DocumentHighlightParams,
         token: CancellationToken
     ): Promise<DocumentHighlight[] | null | undefined> {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
+        const workspace = await this.getWorkspaceForFile(uri);
 
         return workspace.service.run((program) => {
-            return new DocumentHighlightProvider(program, filePath, position, token).getDocumentHighlight();
+            return new DocumentHighlightProvider(program, uri, params.position, token).getDocumentHighlight();
         }, token);
     }
 
@@ -998,9 +977,9 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         params: SignatureHelpParams,
         token: CancellationToken
     ): Promise<SignatureHelp | undefined | null> {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
 
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return;
         }
@@ -1008,8 +987,8 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         return workspace.service.run((program) => {
             return new SignatureHelpProvider(
                 program,
-                filePath,
-                position,
+                uri,
+                params.position,
                 this.client.signatureDocFormat,
                 this.client.hasSignatureLabelOffsetCapability,
                 this.client.hasActiveParameterCapability,
@@ -1040,8 +1019,8 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     }
 
     protected async onCompletion(params: CompletionParams, token: CancellationToken): Promise<CompletionList | null> {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return null;
         }
@@ -1049,9 +1028,9 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         return workspace.service.run((program) => {
             const completions = new CompletionProvider(
                 program,
-                workspace.rootPath,
-                filePath,
-                position,
+                workspace.rootUri,
+                uri,
+                params.position,
                 {
                     format: this.client.completionDocFormat,
                     snippet: this.client.completionSupportsSnippet,
@@ -1074,13 +1053,14 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     // cache that result and never call us back.
     protected async onCompletionResolve(params: CompletionItem, token: CancellationToken): Promise<CompletionItem> {
         const completionItemData = fromLSPAny<CompletionItemData>(params.data);
-        if (completionItemData && completionItemData.filePath) {
-            const workspace = await this.getWorkspaceForFile(completionItemData.filePath);
+        if (completionItemData && completionItemData.uri) {
+            const uri = Uri.parse(completionItemData.uri, this.fs.isCaseSensitive);
+            const workspace = await this.getWorkspaceForFile(uri);
             workspace.service.run((program) => {
                 return new CompletionProvider(
                     program,
-                    workspace.rootPath,
-                    completionItemData.filePath,
+                    workspace.rootUri,
+                    uri,
                     completionItemData.position,
                     {
                         format: this.client.completionDocFormat,
@@ -1098,16 +1078,16 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         params: PrepareRenameParams,
         token: CancellationToken
     ): Promise<Range | { range: Range; placeholder: string } | null> {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
-        const isUntitled = this.uriParser.isUntitled(params.textDocument.uri);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
+        const isUntitled = uri.isUntitled();
 
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return null;
         }
 
         return workspace.service.run((program) => {
-            return new RenameProvider(program, filePath, position, token).canRenameSymbol(
+            return new RenameProvider(program, uri, params.position, token).canRenameSymbol(
                 workspace.kinds.includes(WellKnownWorkspaceKinds.Default),
                 isUntitled
             );
@@ -1118,16 +1098,16 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         params: RenameParams,
         token: CancellationToken
     ): Promise<WorkspaceEdit | null | undefined> {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
-        const isUntitled = this.uriParser.isUntitled(params.textDocument.uri);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
+        const isUntitled = uri.isUntitled();
 
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return;
         }
 
         return workspace.service.run((program) => {
-            return new RenameProvider(program, filePath, position, token).renameSymbol(
+            return new RenameProvider(program, uri, params.position, token).renameSymbol(
                 params.newName,
                 workspace.kinds.includes(WellKnownWorkspaceKinds.Default),
                 isUntitled
@@ -1139,28 +1119,28 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         params: CallHierarchyPrepareParams,
         token: CancellationToken
     ): Promise<CallHierarchyItem[] | null> {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.textDocument, params.position);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
 
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return null;
         }
 
         return workspace.service.run((program) => {
-            return new CallHierarchyProvider(program, filePath, position, token).onPrepare();
+            return new CallHierarchyProvider(program, uri, params.position, token).onPrepare();
         }, token);
     }
 
     protected async onCallHierarchyIncomingCalls(params: CallHierarchyIncomingCallsParams, token: CancellationToken) {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.item, params.item.range.start);
+        const uri = Uri.parse(params.item.uri, this.fs.isCaseSensitive);
 
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return null;
         }
 
         return workspace.service.run((program) => {
-            return new CallHierarchyProvider(program, filePath, position, token).getIncomingCalls();
+            return new CallHierarchyProvider(program, uri, params.item.range.start, token).getIncomingCalls();
         }, token);
     }
 
@@ -1168,46 +1148,51 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         params: CallHierarchyOutgoingCallsParams,
         token: CancellationToken
     ): Promise<CallHierarchyOutgoingCall[] | null> {
-        const { filePath, position } = this.uriParser.decodeTextDocumentPosition(params.item, params.item.range.start);
+        const uri = Uri.parse(params.item.uri, this.fs.isCaseSensitive);
 
-        const workspace = await this.getWorkspaceForFile(filePath);
+        const workspace = await this.getWorkspaceForFile(uri);
         if (workspace.disableLanguageServices) {
             return null;
         }
 
         return workspace.service.run((program) => {
-            return new CallHierarchyProvider(program, filePath, position, token).getOutgoingCalls();
+            return new CallHierarchyProvider(program, uri, params.item.range.start, token).getOutgoingCalls();
         }, token);
     }
 
     protected async onDidOpenTextDocument(params: DidOpenTextDocumentParams, ipythonMode = IPythonMode.None) {
-        const filePath = this.uriParser.decodeTextDocumentUri(params.textDocument.uri);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
 
-        let doc = this.openFileMap.get(filePath);
+        let doc = this.openFileMap.get(uri.key);
         if (doc) {
             // We shouldn't get an open text document request for an already-opened doc.
-            this.console.error(`Received redundant open text document command for ${filePath}`);
+            this.console.error(`Received redundant open text document command for ${uri}`);
             TextDocument.update(doc, [{ text: params.textDocument.text }], params.textDocument.version);
         } else {
-            doc = TextDocument.create(filePath, 'python', params.textDocument.version, params.textDocument.text);
+            doc = TextDocument.create(
+                params.textDocument.uri,
+                'python',
+                params.textDocument.version,
+                params.textDocument.text
+            );
         }
-        this.openFileMap.set(filePath, doc);
+        this.openFileMap.set(uri.key, doc);
 
         // Send this open to all the workspaces that might contain this file.
-        const workspaces = await this.getContainingWorkspacesForFile(filePath);
+        const workspaces = await this.getContainingWorkspacesForFile(uri);
         workspaces.forEach((w) => {
-            w.service.setFileOpened(filePath, params.textDocument.version, params.textDocument.text, ipythonMode);
+            w.service.setFileOpened(uri, params.textDocument.version, params.textDocument.text, ipythonMode);
         });
     }
 
     protected async onDidChangeTextDocument(params: DidChangeTextDocumentParams, ipythonMode = IPythonMode.None) {
         this.recordUserInteractionTime();
 
-        const filePath = this.uriParser.decodeTextDocumentUri(params.textDocument.uri);
-        const doc = this.openFileMap.get(filePath);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
+        const doc = this.openFileMap.get(uri.key);
         if (!doc) {
             // We shouldn't get a change text request for a closed doc.
-            this.console.error(`Received change text document command for closed file ${filePath}`);
+            this.console.error(`Received change text document command for closed file ${uri}`);
             return;
         }
 
@@ -1215,27 +1200,27 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         const newContents = doc.getText();
 
         // Send this change to all the workspaces that might contain this file.
-        const workspaces = await this.getContainingWorkspacesForFile(filePath);
+        const workspaces = await this.getContainingWorkspacesForFile(uri);
         workspaces.forEach((w) => {
-            w.service.updateOpenFileContents(filePath, params.textDocument.version, newContents, ipythonMode);
+            w.service.updateOpenFileContents(uri, params.textDocument.version, newContents, ipythonMode);
         });
     }
 
     protected async onDidCloseTextDocument(params: DidCloseTextDocumentParams) {
-        const filePath = this.uriParser.decodeTextDocumentUri(params.textDocument.uri);
+        const uri = Uri.parse(params.textDocument.uri, this.fs.isCaseSensitive);
 
         // Send this close to all the workspaces that might contain this file.
-        const workspaces = await this.getContainingWorkspacesForFile(filePath);
+        const workspaces = await this.getContainingWorkspacesForFile(uri);
         workspaces.forEach((w) => {
-            w.service.setFileClosed(filePath);
+            w.service.setFileClosed(uri);
         });
 
-        this.openFileMap.delete(filePath);
+        this.openFileMap.delete(uri.key);
     }
 
     protected onDidChangeWatchedFiles(params: DidChangeWatchedFilesParams) {
         params.changes.forEach((change) => {
-            const filePath = this.fs.realCasePath(this.uriParser.decodeTextDocumentUri(change.uri));
+            const filePath = this.fs.realCasePath(Uri.parse(change.uri, this.fs.isCaseSensitive));
             const eventType: FileWatcherEventType = change.type === 1 ? 'add' : 'change';
             this.serverOptions.fileWatcherHandler.onFileChange(eventType, filePath);
         });
@@ -1302,7 +1287,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     protected convertDiagnostics(fs: FileSystem, fileDiagnostics: FileDiagnostics): PublishDiagnosticsParams[] {
         return [
             {
-                uri: convertPathToUri(fs, fileDiagnostics.filePath),
+                uri: fileDiagnostics.fileUri.toString(),
                 version: fileDiagnostics.version,
                 diagnostics: this._convertDiagnostics(fs, fileDiagnostics.diagnostics),
             },
@@ -1316,7 +1301,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
     protected onAnalysisCompletedHandler(fs: FileSystem, results: AnalysisResults): void {
         // Send the computed diagnostics to the client.
         results.diagnostics.forEach((fileDiag) => {
-            if (!this.canNavigateToFile(fileDiag.filePath, fs)) {
+            if (!this.canNavigateToFile(fileDiag.fileUri, fs)) {
                 return;
             }
 
@@ -1361,11 +1346,11 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
         const otherWorkspaces = this.workspaceFactory.items().filter((w) => w !== workspace);
 
         for (const uri of documentsWithDiagnosticsList) {
-            const filePath = convertUriToPath(workspace.service.fs, uri);
+            const fileUri = Uri.parse(uri, this.fs.isCaseSensitive);
 
-            if (workspace.service.isTracked(filePath)) {
+            if (workspace.service.isTracked(fileUri)) {
                 // Do not clean up diagnostics for files tracked by multiple workspaces
-                if (otherWorkspaces.some((w) => w.service.isTracked(filePath))) {
+                if (otherWorkspaces.some((w) => w.service.isTracked(fileUri))) {
                     continue;
                 }
                 this.sendDiagnostics([
@@ -1380,8 +1365,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
 
     protected createAnalyzerServiceForWorkspace(
         name: string,
-        _rootPath: string,
-        _uri: string,
+        uri: Uri,
         kinds: string[],
         services?: WorkspaceServices
     ): AnalyzerService {
@@ -1422,7 +1406,7 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
 
     protected abstract createProgressReporter(): ProgressReporter;
 
-    protected canNavigateToFile(path: string, fs: FileSystem): boolean {
+    protected canNavigateToFile(path: Uri, fs: FileSystem): boolean {
         return canNavigateToFile(fs, path);
     }
 
@@ -1481,13 +1465,13 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
             const foldersToWatch = deduplicateFolders(
                 this.workspaceFactory
                     .getNonDefaultWorkspaces()
-                    .map((w) => w.searchPathsToWatch.filter((p) => !p.startsWith(w.rootPath)))
+                    .map((w) => w.searchPathsToWatch.filter((p) => !p.startsWith(w.rootUri)))
             );
 
             foldersToWatch.forEach((p) => {
                 const globPattern = isFile(this.fs, p, /* treatZipDirectoryAsFile */ true)
-                    ? { baseUri: convertPathToUri(this.fs, getDirectoryPath(p)), pattern: getFileName(p) }
-                    : { baseUri: convertPathToUri(this.fs, p), pattern: '**' };
+                    ? { baseUri: p.getDirectory().toString(), pattern: p.fileName }
+                    : { baseUri: p.toString(), pattern: '**' };
 
                 watchers.push({ globPattern, kind: watchKind });
             });
@@ -1582,10 +1566,10 @@ export abstract class LanguageServerBase implements LanguageServerInterface, Dis
             const relatedInfo = diag.getRelatedInfo();
             if (relatedInfo.length > 0) {
                 vsDiag.relatedInformation = relatedInfo
-                    .filter((info) => this.canNavigateToFile(info.filePath, fs))
+                    .filter((info) => this.canNavigateToFile(info.uri, fs))
                     .map((info) =>
                         DiagnosticRelatedInformation.create(
-                            Location.create(convertPathToUri(fs, info.filePath), info.range),
+                            Location.create(info.uri.toString(), info.range),
                             info.message
                         )
                     );
diff --git a/packages/pyright-internal/src/languageService/analyzerServiceExecutor.ts b/packages/pyright-internal/src/languageService/analyzerServiceExecutor.ts
index cab3dffe4..70ae135b5 100644
--- a/packages/pyright-internal/src/languageService/analyzerServiceExecutor.ts
+++ b/packages/pyright-internal/src/languageService/analyzerServiceExecutor.ts
@@ -13,7 +13,7 @@ import { AnalyzerService, getNextServiceId } from '../analyzer/service';
 import { CommandLineOptions } from '../common/commandLineOptions';
 import { LogLevel } from '../common/console';
 import { FileSystem } from '../common/fileSystem';
-import { combinePaths } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
 import { LanguageServerInterface, ServerSettings } from '../languageServerBase';
 import { WellKnownWorkspaceKinds, Workspace, createInitStatus } from '../workspaceFactory';
 
@@ -25,15 +25,15 @@ export interface CloneOptions {
 
 export class AnalyzerServiceExecutor {
     static runWithOptions(
-        languageServiceRootPath: string,
+        languageServiceRootUri: Uri,
         workspace: Workspace,
         serverSettings: ServerSettings,
         typeStubTargetImportName?: string,
         trackFiles = true
     ): void {
         const commandLineOptions = getEffectiveCommandLineOptions(
-            languageServiceRootPath,
-            workspace.rootPath,
+            languageServiceRootUri.getFilePath(),
+            workspace.rootUri.getFilePath(),
             serverSettings,
             trackFiles,
             typeStubTargetImportName,
@@ -58,8 +58,7 @@ export class AnalyzerServiceExecutor {
         const tempWorkspace: Workspace = {
             ...workspace,
             workspaceName: `temp workspace for cloned service`,
-            rootPath: workspace.rootPath,
-            uri: workspace.uri,
+            rootUri: workspace.rootUri,
             pythonPath: workspace.pythonPath,
             pythonPathKind: workspace.pythonPathKind,
             kinds: [...workspace.kinds, WellKnownWorkspaceKinds.Cloned],
@@ -78,7 +77,7 @@ export class AnalyzerServiceExecutor {
 
         const serverSettings = await ls.getSettings(workspace);
         AnalyzerServiceExecutor.runWithOptions(
-            ls.rootPath,
+            ls.rootUri,
             tempWorkspace,
             serverSettings,
             options.typeStubTargetImportName,
@@ -120,21 +119,15 @@ function getEffectiveCommandLineOptions(
     }
 
     if (serverSettings.venvPath) {
-        commandLineOptions.venvPath = combinePaths(
-            workspaceRootPath || languageServiceRootPath,
-            serverSettings.venvPath
-        );
+        commandLineOptions.venvPath = serverSettings.venvPath.getFilePath();
     }
 
     if (serverSettings.pythonPath) {
         // The Python VS Code extension treats the value "python" specially. This means
         // the local python interpreter should be used rather than interpreting the
         // setting value as a path to the interpreter. We'll simply ignore it in this case.
-        if (!isPythonBinary(serverSettings.pythonPath)) {
-            commandLineOptions.pythonPath = combinePaths(
-                workspaceRootPath || languageServiceRootPath,
-                serverSettings.pythonPath
-            );
+        if (!isPythonBinary(serverSettings.pythonPath.getFilePath())) {
+            commandLineOptions.pythonPath = serverSettings.pythonPath.getFilePath();
         }
     }
 
@@ -142,11 +135,11 @@ function getEffectiveCommandLineOptions(
         // Pyright supports only one typeshed path currently, whereas the
         // official VS Code Python extension supports multiple typeshed paths.
         // We'll use the first one specified and ignore the rest.
-        commandLineOptions.typeshedPath = serverSettings.typeshedPath;
+        commandLineOptions.typeshedPath = serverSettings.typeshedPath.getFilePath();
     }
 
     if (serverSettings.stubPath) {
-        commandLineOptions.stubPath = serverSettings.stubPath;
+        commandLineOptions.stubPath = serverSettings.stubPath.getFilePath();
     }
 
     if (serverSettings.logLevel === LogLevel.Log) {
@@ -160,7 +153,7 @@ function getEffectiveCommandLineOptions(
     }
 
     commandLineOptions.autoSearchPaths = serverSettings.autoSearchPaths;
-    commandLineOptions.extraPaths = serverSettings.extraPaths;
+    commandLineOptions.extraPaths = serverSettings.extraPaths?.map((e) => e.getFilePath()) ?? [];
     commandLineOptions.diagnosticSeverityOverrides = serverSettings.diagnosticSeverityOverrides;
 
     commandLineOptions.includeFileSpecs = serverSettings.includeFileSpecs ?? [];
diff --git a/packages/pyright-internal/src/languageService/autoImporter.ts b/packages/pyright-internal/src/languageService/autoImporter.ts
index 0fc2701c7..ac2aad56b 100644
--- a/packages/pyright-internal/src/languageService/autoImporter.ts
+++ b/packages/pyright-internal/src/languageService/autoImporter.ts
@@ -12,15 +12,15 @@ import { DeclarationType } from '../analyzer/declaration';
 import { ImportResolver, ModuleNameAndType } from '../analyzer/importResolver';
 import { ImportType } from '../analyzer/importResult';
 import {
+    ImportGroup,
+    ImportNameInfo,
+    ImportStatements,
+    ModuleNameInfo,
     getImportGroup,
     getImportGroupFromModuleNameAndType,
     getTextEditsForAutoImportInsertion,
     getTextEditsForAutoImportSymbolAddition,
     getTopLevelImports,
-    ImportGroup,
-    ImportNameInfo,
-    ImportStatements,
-    ModuleNameInfo,
 } from '../analyzer/importStatementUtils';
 import { isUserCode } from '../analyzer/sourceFileInfoUtils';
 import { Symbol } from '../analyzer/symbol';
@@ -30,13 +30,14 @@ import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { appendArray } from '../common/collectionUtils';
 import { ExecutionEnvironment } from '../common/configOptions';
 import { TextEditAction } from '../common/editAction';
-import { combinePaths, getDirectoryPath, getFileName, stripFileExtension } from '../common/pathUtils';
+import { SourceFileInfo } from '../common/extensibility';
+import { stripFileExtension } from '../common/pathUtils';
 import * as StringUtils from '../common/stringUtils';
 import { Position } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { ParseNodeType } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
 import { CompletionMap } from './completionProvider';
-import { SourceFileInfo } from '../common/extensibility';
 import { IndexAliasData } from './symbolIndexer';
 
 export interface AutoImportSymbol {
@@ -47,6 +48,7 @@ export interface AutoImportSymbol {
 }
 
 export interface ModuleSymbolTable {
+    uri: Uri;
     forEach(callbackfn: (symbol: AutoImportSymbol, name: string, library: boolean) => void): void;
 }
 
@@ -54,8 +56,8 @@ export type ModuleSymbolMap = Map<string, ModuleSymbolTable>;
 
 export interface AutoImportResult {
     readonly name: string;
-    readonly declPath: string;
-    readonly originalDeclPath: string;
+    readonly declUri: Uri;
+    readonly originalDeclUri: Uri;
     readonly insertionText: string;
     readonly symbol?: Symbol;
     readonly source?: string;
@@ -74,7 +76,7 @@ export interface ImportParts {
     readonly importName: string;
     readonly symbolName?: string;
     readonly importFrom?: string;
-    readonly filePath: string;
+    readonly fileUri: Uri;
     readonly dotCount: number;
     readonly moduleNameAndType: ModuleNameAndType;
 }
@@ -85,7 +87,7 @@ export interface ImportAliasData {
     readonly symbol?: Symbol;
     readonly kind?: SymbolKind;
     readonly itemKind?: CompletionItemKind;
-    readonly filePath: string;
+    readonly fileUri: Uri;
 }
 
 export type AutoImportResultMap = Map<string, AutoImportResult[]>;
@@ -106,13 +108,13 @@ export function addModuleSymbolsMap(files: readonly SourceFileInfo[], moduleSymb
             return;
         }
 
-        const filePath = file.sourceFile.getFilePath();
+        const uri = file.sourceFile.getUri();
         const symbolTable = file.sourceFile.getModuleSymbolTable();
         if (!symbolTable) {
             return;
         }
 
-        const fileName = stripFileExtension(getFileName(filePath));
+        const fileName = stripFileExtension(uri.fileName);
 
         // Don't offer imports from files that are named with private
         // naming semantics like "_ast.py".
@@ -120,7 +122,8 @@ export function addModuleSymbolsMap(files: readonly SourceFileInfo[], moduleSymb
             return;
         }
 
-        moduleSymbolMap.set(filePath, {
+        moduleSymbolMap.set(uri.key, {
+            uri,
             forEach(callbackfn: (value: AutoImportSymbol, key: string, library: boolean) => void): void {
                 symbolTable.forEach((symbol, name) => {
                     if (!isVisibleExternally(symbol)) {
@@ -206,12 +209,12 @@ export class AutoImporter {
         results: AutoImportResultMap,
         token: CancellationToken
     ) {
-        this.moduleSymbolMap.forEach((topLevelSymbols, filePath) => {
+        this.moduleSymbolMap.forEach((topLevelSymbols, key) => {
             // See if this file should be offered as an implicit import.
-            const isStubFileOrHasInit = this.isStubFileOrHasInit(this.moduleSymbolMap!, filePath);
+            const isStubFileOrHasInit = this.isStubFileOrHasInit(this.moduleSymbolMap!, topLevelSymbols.uri);
             this.processModuleSymbolTable(
                 topLevelSymbols,
-                filePath,
+                topLevelSymbols.uri,
                 word,
                 similarityLimit,
                 isStubFileOrHasInit,
@@ -244,7 +247,7 @@ export class AutoImporter {
 
                     // If import statement for the module already exist, then bail out.
                     // ex) import module[.submodule] or from module[.submodule] import symbol
-                    if (this._importStatements.mapByFilePath.has(importAliasData.importParts.filePath)) {
+                    if (this._importStatements.mapByFilePath.has(importAliasData.importParts.fileUri.key)) {
                         return;
                     }
 
@@ -281,7 +284,7 @@ export class AutoImporter {
                     },
                     importAliasData.importParts.importName,
                     importAliasData.importGroup,
-                    importAliasData.importParts.filePath
+                    importAliasData.importParts.fileUri
                 );
 
                 this._addResult(results, {
@@ -292,8 +295,8 @@ export class AutoImporter {
                     source: importAliasData.importParts.importFrom,
                     insertionText: autoImportTextEdits.insertionText,
                     edits: autoImportTextEdits.edits,
-                    declPath: importAliasData.importParts.filePath,
-                    originalDeclPath: importAliasData.filePath,
+                    declUri: importAliasData.importParts.fileUri,
+                    originalDeclUri: importAliasData.fileUri,
                 });
             });
         });
@@ -301,7 +304,7 @@ export class AutoImporter {
 
     protected processModuleSymbolTable(
         topLevelSymbols: ModuleSymbolTable,
-        moduleFilePath: string,
+        moduleUri: Uri,
         word: string,
         similarityLimit: number,
         isStubOrHasInit: { isStub: boolean; hasInit: boolean },
@@ -312,7 +315,7 @@ export class AutoImporter {
     ) {
         throwIfCancellationRequested(token);
 
-        const [importSource, importGroup, moduleNameAndType] = this._getImportPartsForSymbols(moduleFilePath);
+        const [importSource, importGroup, moduleNameAndType] = this._getImportPartsForSymbols(moduleUri);
         if (!importSource) {
             return;
         }
@@ -345,7 +348,7 @@ export class AutoImporter {
                             symbolName: name,
                             importName: name,
                             importFrom: importSource,
-                            filePath: moduleFilePath,
+                            fileUri: moduleUri,
                             dotCount,
                             moduleNameAndType,
                         },
@@ -353,20 +356,20 @@ export class AutoImporter {
                         symbol: autoImportSymbol.symbol,
                         kind: autoImportSymbol.importAlias.kind,
                         itemKind: autoImportSymbol.importAlias.itemKind,
-                        filePath: autoImportSymbol.importAlias.modulePath,
+                        fileUri: autoImportSymbol.importAlias.moduleUri,
                     },
                     importAliasMap
                 );
                 return;
             }
 
-            const nameForImportFrom = this.getNameForImportFrom(library, moduleFilePath);
+            const nameForImportFrom = this.getNameForImportFrom(library, moduleUri);
             const autoImportTextEdits = this._getTextEditsForAutoImportByFilePath(
                 { name, alias: abbrFromUsers },
                 { name: importSource, nameForImportFrom },
                 name,
                 importGroup,
-                moduleFilePath
+                moduleUri
             );
 
             this._addResult(results, {
@@ -377,8 +380,8 @@ export class AutoImporter {
                 kind: autoImportSymbol.itemKind ?? convertSymbolKindToCompletionItemKind(autoImportSymbol.kind),
                 insertionText: autoImportTextEdits.insertionText,
                 edits: autoImportTextEdits.edits,
-                declPath: moduleFilePath,
-                originalDeclPath: moduleFilePath,
+                declUri: moduleUri,
+                originalDeclUri: moduleUri,
             });
         });
 
@@ -389,7 +392,7 @@ export class AutoImporter {
             return;
         }
 
-        const importParts = this._getImportParts(moduleFilePath);
+        const importParts = this._getImportParts(moduleUri);
         if (!importParts) {
             return;
         }
@@ -406,7 +409,7 @@ export class AutoImporter {
 
         this._addToImportAliasMap(
             {
-                modulePath: moduleFilePath,
+                moduleUri,
                 originalName: importParts.importName,
                 kind: SymbolKind.Module,
                 itemKind: CompletionItemKind.Module,
@@ -416,22 +419,22 @@ export class AutoImporter {
                 importGroup,
                 kind: SymbolKind.Module,
                 itemKind: CompletionItemKind.Module,
-                filePath: moduleFilePath,
+                fileUri: moduleUri,
             },
             importAliasMap
         );
     }
 
-    protected getNameForImportFrom(library: boolean, moduleFilePath: string): string | undefined {
+    protected getNameForImportFrom(library: boolean, moduleUri: Uri): string | undefined {
         return undefined;
     }
 
-    protected isStubFileOrHasInit<T>(map: Map<string, T>, filePath: string) {
-        const fileDir = getDirectoryPath(filePath);
-        const initPathPy = combinePaths(fileDir, '__init__.py');
-        const initPathPyi = initPathPy + 'i';
-        const isStub = filePath.endsWith('.pyi');
-        const hasInit = map.has(initPathPy) || map.has(initPathPyi);
+    protected isStubFileOrHasInit<T>(map: Map<string, T>, uri: Uri) {
+        const fileDir = uri.getDirectory();
+        const initPathPy = fileDir.combinePaths('__init__.py');
+        const initPathPyi = initPathPy.addPath('i');
+        const isStub = uri.pathEndsWith('.pyi');
+        const hasInit = map.has(initPathPy.key) || map.has(initPathPyi.key);
         return { isStub, hasInit };
     }
 
@@ -462,14 +465,14 @@ export class AutoImporter {
         // Since we don't resolve alias declaration using type evaluator, there is still a chance
         // where we show multiple aliases for same symbols. but this should still reduce number of
         // such cases.
-        if (!importAliasMap.has(alias.modulePath)) {
+        if (!importAliasMap.has(alias.moduleUri.key)) {
             const map = new Map<string, ImportAliasData>();
             map.set(alias.originalName, data);
-            importAliasMap.set(alias.modulePath, map);
+            importAliasMap.set(alias.moduleUri.key, map);
             return;
         }
 
-        const map = importAliasMap.get(alias.modulePath)!;
+        const map = importAliasMap.get(alias.moduleUri.key)!;
         if (!map.has(alias.originalName)) {
             map.set(alias.originalName, data);
             return;
@@ -508,8 +511,8 @@ export class AutoImporter {
         return StringUtils.getStringComparer()(left.importParts.importName, right.importParts.importName);
     }
 
-    private _getImportPartsForSymbols(filePath: string): [string | undefined, ImportGroup, ModuleNameAndType] {
-        const localImport = this._importStatements.mapByFilePath.get(filePath);
+    private _getImportPartsForSymbols(uri: Uri): [string | undefined, ImportGroup, ModuleNameAndType] {
+        const localImport = this._importStatements.mapByFilePath.get(uri.key);
         if (localImport) {
             return [
                 localImport.moduleName,
@@ -521,7 +524,7 @@ export class AutoImporter {
                 },
             ];
         } else {
-            const moduleNameAndType = this._getModuleNameAndTypeFromFilePath(filePath);
+            const moduleNameAndType = this._getModuleNameAndTypeFromFilePath(uri);
             return [
                 moduleNameAndType.moduleName,
                 getImportGroupFromModuleNameAndType(moduleNameAndType),
@@ -530,15 +533,15 @@ export class AutoImporter {
         }
     }
 
-    private _getImportParts(filePath: string) {
-        const name = stripFileExtension(getFileName(filePath));
+    private _getImportParts(uri: Uri) {
+        const name = stripFileExtension(uri.fileName);
 
         // See if we can import module as "import xxx"
         if (name === '__init__') {
-            return createImportParts(this._getModuleNameAndTypeFromFilePath(getDirectoryPath(filePath)));
+            return createImportParts(this._getModuleNameAndTypeFromFilePath(uri.getDirectory()));
         }
 
-        return createImportParts(this._getModuleNameAndTypeFromFilePath(filePath));
+        return createImportParts(this._getModuleNameAndTypeFromFilePath(uri));
 
         function createImportParts(module: ModuleNameAndType): ImportParts | undefined {
             const moduleName = module.moduleName;
@@ -553,7 +556,7 @@ export class AutoImporter {
                 symbolName: importNamePart,
                 importName: importNamePart ?? moduleName,
                 importFrom,
-                filePath,
+                fileUri: uri,
                 dotCount: StringUtils.getCharacterCount(moduleName, '.'),
                 moduleNameAndType: module,
             };
@@ -601,8 +604,8 @@ export class AutoImporter {
     // Given the file path of a module that we want to import,
     // convert to a module name that can be used in an
     // 'import from' statement.
-    private _getModuleNameAndTypeFromFilePath(filePath: string): ModuleNameAndType {
-        return this.importResolver.getModuleNameForImport(filePath, this.execEnvironment);
+    private _getModuleNameAndTypeFromFilePath(uri: Uri): ModuleNameAndType {
+        return this.importResolver.getModuleNameForImport(uri, this.execEnvironment);
     }
 
     private _getTextEditsForAutoImportByFilePath(
@@ -610,10 +613,10 @@ export class AutoImporter {
         moduleNameInfo: ModuleNameInfo,
         insertionText: string,
         importGroup: ImportGroup,
-        filePath: string
+        fileUri: Uri
     ): { insertionText: string; edits?: TextEditAction[] | undefined } {
         // If there is no symbolName, there can't be existing import statement.
-        const importStatement = this._importStatements.mapByFilePath.get(filePath);
+        const importStatement = this._importStatements.mapByFilePath.get(fileUri.key);
         if (importStatement) {
             // Found import for given module. See whether we can use the module as it is.
             if (importStatement.node.nodeType === ParseNodeType.Import) {
@@ -699,7 +702,7 @@ export class AutoImporter {
             }
 
             // Check whether it is one of implicit imports
-            const importFrom = this._importStatements.implicitImports?.get(filePath);
+            const importFrom = this._importStatements.implicitImports?.get(fileUri.key);
             if (importFrom) {
                 // For now, we don't check whether alias or moduleName got overwritten at
                 // given position
diff --git a/packages/pyright-internal/src/languageService/callHierarchyProvider.ts b/packages/pyright-internal/src/languageService/callHierarchyProvider.ts
index 13298cb79..c21a117cc 100644
--- a/packages/pyright-internal/src/languageService/callHierarchyProvider.ts
+++ b/packages/pyright-internal/src/languageService/callHierarchyProvider.ts
@@ -29,10 +29,10 @@ import { appendArray } from '../common/collectionUtils';
 import { isDefined } from '../common/core';
 import { ProgramView, ReferenceUseCase, SymbolUsageProvider } from '../common/extensibility';
 import { getSymbolKind } from '../common/lspUtils';
-import { convertPathToUri, getFileName } from '../common/pathUtils';
 import { convertOffsetsToRange } from '../common/positionUtils';
 import { ServiceKeys } from '../common/serviceProviderExtensions';
 import { Position, rangesAreEqual } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { ReferencesProvider, ReferencesResult } from '../languageService/referencesProvider';
 import { CallNode, MemberAccessNode, NameNode, ParseNode, ParseNodeType } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
@@ -44,11 +44,11 @@ export class CallHierarchyProvider {
 
     constructor(
         private _program: ProgramView,
-        private _filePath: string,
+        private _fileUri: Uri,
         private _position: Position,
         private _token: CancellationToken
     ) {
-        this._parseResults = this._program.getParseResults(this._filePath);
+        this._parseResults = this._program.getParseResults(this._fileUri);
     }
 
     onPrepare(): CallHierarchyItem[] | null {
@@ -86,18 +86,15 @@ export class CallHierarchyProvider {
         const callItem: CallHierarchyItem = {
             name: symbolName,
             kind: getSymbolKind(targetDecl, this._evaluator, symbolName) ?? SymbolKind.Module,
-            uri: callItemUri,
+            uri: callItemUri.toString(),
             range: targetDecl.range,
             selectionRange: targetDecl.range,
         };
 
-        if (!canNavigateToFile(this._program.fileSystem, callItem.uri)) {
+        if (!canNavigateToFile(this._program.fileSystem, Uri.parse(callItem.uri, this._fileUri.isCaseSensitive))) {
             return null;
         }
 
-        // Convert the file path in the item to proper URI.
-        callItem.uri = convertPathToUri(this._program.fileSystem, callItem.uri);
-
         return [callItem];
     }
 
@@ -117,11 +114,11 @@ export class CallHierarchyProvider {
         const items: CallHierarchyIncomingCall[] = [];
         const sourceFiles =
             targetDecl.type === DeclarationType.Alias
-                ? [this._program.getSourceFileInfo(this._filePath)!]
+                ? [this._program.getSourceFileInfo(this._fileUri)!]
                 : this._program.getSourceFileInfoList();
         for (const curSourceFileInfo of sourceFiles) {
             if (isUserCode(curSourceFileInfo) || curSourceFileInfo.isOpenByClient) {
-                const filePath = curSourceFileInfo.sourceFile.getFilePath();
+                const filePath = curSourceFileInfo.sourceFile.getUri();
                 const itemsToAdd = this._getIncomingCallsForDeclaration(filePath, symbolName, targetDecl);
 
                 if (itemsToAdd) {
@@ -138,14 +135,9 @@ export class CallHierarchyProvider {
             return null;
         }
 
-        const callItems = items.filter((item) => canNavigateToFile(this._program.fileSystem, item.from.uri));
-
-        // Convert the file paths in the items to proper URIs.
-        callItems.forEach((item) => {
-            item.from.uri = convertPathToUri(this._program.fileSystem, item.from.uri);
-        });
-
-        return callItems;
+        return items.filter((item) =>
+            canNavigateToFile(this._program.fileSystem, Uri.parse(item.from.uri, this._fileUri.isCaseSensitive))
+        );
     }
 
     getOutgoingCalls(): CallHierarchyOutgoingCall[] | null {
@@ -209,14 +201,9 @@ export class CallHierarchyProvider {
             return null;
         }
 
-        const callItems = outgoingCalls.filter((item) => canNavigateToFile(this._program.fileSystem, item.to.uri));
-
-        // Convert the file paths in the items to proper URIs.
-        callItems.forEach((item) => {
-            item.to.uri = convertPathToUri(this._program.fileSystem, item.to.uri);
-        });
-
-        return callItems;
+        return outgoingCalls.filter((item) =>
+            canNavigateToFile(this._program.fileSystem, Uri.parse(item.to.uri, this._fileUri.isCaseSensitive))
+        );
     }
 
     private get _evaluator(): TypeEvaluator {
@@ -225,7 +212,7 @@ export class CallHierarchyProvider {
 
     private _getTargetDeclaration(referencesResult: ReferencesResult): {
         targetDecl: Declaration;
-        callItemUri: string;
+        callItemUri: Uri;
         symbolName: string;
     } {
         // If there's more than one declaration, pick the target one.
@@ -253,32 +240,26 @@ export class CallHierarchyProvider {
         // Although the LSP specification requires a URI, we are using a file path
         // here because it is converted to the proper URI by the caller.
         // This simplifies our code and ensures compatibility with the LSP specification.
-        let callItemUri;
+        let callItemUri: Uri;
         if (targetDecl.type === DeclarationType.Alias) {
             symbolName = (referencesResult.nodeAtOffset as NameNode).value;
-            callItemUri = this._filePath;
+            callItemUri = this._fileUri;
         } else {
             symbolName = DeclarationUtils.getNameFromDeclaration(targetDecl) || referencesResult.symbolNames[0];
-            callItemUri = targetDecl.path;
+            callItemUri = targetDecl.uri;
         }
 
         return { targetDecl, callItemUri, symbolName };
     }
 
     private _getIncomingCallsForDeclaration(
-        filePath: string,
+        fileUri: Uri,
         symbolName: string,
         declaration: Declaration
     ): CallHierarchyIncomingCall[] | undefined {
         throwIfCancellationRequested(this._token);
 
-        const callFinder = new FindIncomingCallTreeWalker(
-            this._program,
-            filePath,
-            symbolName,
-            declaration,
-            this._token
-        );
+        const callFinder = new FindIncomingCallTreeWalker(this._program, fileUri, symbolName, declaration, this._token);
 
         const incomingCalls = callFinder.findCalls();
         return incomingCalls.length > 0 ? incomingCalls : undefined;
@@ -287,7 +268,7 @@ export class CallHierarchyProvider {
     private _getDeclaration(): ReferencesResult | undefined {
         return ReferencesProvider.getDeclarationForPosition(
             this._program,
-            this._filePath,
+            this._fileUri,
             this._position,
             /* reporter */ undefined,
             ReferenceUseCase.References,
@@ -394,7 +375,7 @@ class FindOutgoingCallTreeWalker extends ParseTreeWalker {
         const callDest: CallHierarchyItem = {
             name: nameNode.value,
             kind: getSymbolKind(resolvedDecl, this._evaluator, nameNode.value) ?? SymbolKind.Module,
-            uri: resolvedDecl.path,
+            uri: resolvedDecl.uri.toString(),
             range: resolvedDecl.range,
             selectionRange: resolvedDecl.range,
         };
@@ -437,14 +418,14 @@ class FindIncomingCallTreeWalker extends ParseTreeWalker {
 
     constructor(
         private readonly _program: ProgramView,
-        private readonly _filePath: string,
+        private readonly _fileUri: Uri,
         private readonly _symbolName: string,
         private readonly _targetDeclaration: Declaration,
         private readonly _cancellationToken: CancellationToken
     ) {
         super();
 
-        this._parseResults = this._program.getParseResults(this._filePath)!;
+        this._parseResults = this._program.getParseResults(this._fileUri)!;
         this._usageProviders = (this._program.serviceProvider.tryGet(ServiceKeys.symbolUsageProviderFactory) ?? [])
             .map((f) =>
                 f.tryCreateProvider(ReferenceUseCase.References, [this._targetDeclaration], this._cancellationToken)
@@ -570,12 +551,12 @@ class FindIncomingCallTreeWalker extends ParseTreeWalker {
         let callSource: CallHierarchyItem;
         if (executionNode.nodeType === ParseNodeType.Module) {
             const moduleRange = convertOffsetsToRange(0, 0, this._parseResults.tokenizerOutput.lines);
-            const fileName = getFileName(this._filePath);
+            const fileName = this._fileUri.fileName;
 
             callSource = {
                 name: `(module) ${fileName}`,
                 kind: SymbolKind.Module,
-                uri: this._filePath,
+                uri: this._fileUri.toString(),
                 range: moduleRange,
                 selectionRange: moduleRange,
             };
@@ -589,7 +570,7 @@ class FindIncomingCallTreeWalker extends ParseTreeWalker {
             callSource = {
                 name: '(lambda)',
                 kind: SymbolKind.Function,
-                uri: this._filePath,
+                uri: this._fileUri.toString(),
                 range: lambdaRange,
                 selectionRange: lambdaRange,
             };
@@ -603,7 +584,7 @@ class FindIncomingCallTreeWalker extends ParseTreeWalker {
             callSource = {
                 name: executionNode.name.value,
                 kind: SymbolKind.Function,
-                uri: this._filePath,
+                uri: this._fileUri.toString(),
                 range: functionRange,
                 selectionRange: functionRange,
             };
diff --git a/packages/pyright-internal/src/languageService/codeActionProvider.ts b/packages/pyright-internal/src/languageService/codeActionProvider.ts
index 1f73f82a1..14843877f 100644
--- a/packages/pyright-internal/src/languageService/codeActionProvider.ts
+++ b/packages/pyright-internal/src/languageService/codeActionProvider.ts
@@ -12,8 +12,8 @@ import { Commands } from '../commands/commands';
 import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { ActionKind, CreateTypeStubFileAction, RenameShadowedFileAction } from '../common/diagnostic';
 import { FileEditActions } from '../common/editAction';
-import { getShortenedFileName } from '../common/pathUtils';
 import { Range } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { convertToWorkspaceEdit } from '../common/workspaceEditUtils';
 import { Localizer } from '../localization/localize';
 import { Workspace } from '../workspaceFactory';
@@ -29,7 +29,7 @@ export class CodeActionProvider {
     }
     static async getCodeActionsForPosition(
         workspace: Workspace,
-        filePath: string,
+        fileUri: Uri,
         range: Range,
         kinds: CodeActionKind[] | undefined,
         token: CancellationToken
@@ -44,7 +44,7 @@ export class CodeActionProvider {
         }
 
         if (!workspace.disableLanguageServices) {
-            const diags = await workspace.service.getDiagnosticsForRange(filePath, range, token);
+            const diags = await workspace.service.getDiagnosticsForRange(fileUri, range, token);
             const typeStubDiag = diags.find((d) => {
                 const actions = d.getActions();
                 return actions && actions.find((a) => a.action === Commands.createTypeStub);
@@ -60,9 +60,9 @@ export class CodeActionProvider {
                         Command.create(
                             Localizer.CodeAction.createTypeStub(),
                             Commands.createTypeStub,
-                            workspace.rootPath,
+                            workspace.rootUri.toString(),
                             action.moduleName,
-                            filePath
+                            fileUri.toString()
                         ),
                         CodeActionKind.QuickFix
                     );
@@ -80,21 +80,20 @@ export class CodeActionProvider {
                     .find((a) => a.action === ActionKind.RenameShadowedFileAction) as RenameShadowedFileAction;
                 if (action) {
                     const title = Localizer.CodeAction.renameShadowedFile().format({
-                        oldFile: getShortenedFileName(action.oldFile),
-                        newFile: getShortenedFileName(action.newFile),
+                        oldFile: action.oldUri.getShortenedFileName(),
+                        newFile: action.newUri.getShortenedFileName(),
                     });
-                    const fs = workspace.service.getImportResolver().fileSystem;
                     const editActions: FileEditActions = {
                         edits: [],
                         fileOperations: [
                             {
                                 kind: 'rename',
-                                oldFilePath: action.oldFile,
-                                newFilePath: action.newFile,
+                                oldFileUri: action.oldUri,
+                                newFileUri: action.newUri,
                             },
                         ],
                     };
-                    const workspaceEdit = convertToWorkspaceEdit(fs, editActions);
+                    const workspaceEdit = convertToWorkspaceEdit(editActions);
                     const renameAction = CodeAction.create(title, workspaceEdit, CodeActionKind.QuickFix);
                     codeActions.push(renameAction);
                 }
diff --git a/packages/pyright-internal/src/languageService/completionProvider.ts b/packages/pyright-internal/src/languageService/completionProvider.ts
index 650dd030a..e901d35b1 100644
--- a/packages/pyright-internal/src/languageService/completionProvider.ts
+++ b/packages/pyright-internal/src/languageService/completionProvider.ts
@@ -41,7 +41,7 @@ import { Symbol, SymbolTable } from '../analyzer/symbol';
 import * as SymbolNameUtils from '../analyzer/symbolNameUtils';
 import { getLastTypedDeclaredForSymbol, isVisibleExternally } from '../analyzer/symbolUtils';
 import { getTypedDictMembersForClass } from '../analyzer/typedDicts';
-import { getModuleDocStringFromPaths } from '../analyzer/typeDocStringUtils';
+import { getModuleDocStringFromUris } from '../analyzer/typeDocStringUtils';
 import { CallSignatureInfo, TypeEvaluator } from '../analyzer/typeEvaluatorTypes';
 import { printLiteralValue } from '../analyzer/typePrinter';
 import {
@@ -83,6 +83,7 @@ import { PythonVersion } from '../common/pythonVersion';
 import * as StringUtils from '../common/stringUtils';
 import { comparePositions, Position, TextRange } from '../common/textRange';
 import { TextRangeCollection } from '../common/textRangeCollection';
+import { Uri } from '../common/uri/uri';
 import { convertToTextEdits } from '../common/workspaceEditUtils';
 import { Localizer } from '../localization/localize';
 import {
@@ -231,13 +232,13 @@ enum SortCategory {
 // This data allows the resolve handling to disambiguate
 // which item was selected.
 export interface CompletionItemData {
-    filePath: string;
-    workspacePath: string;
+    uri: string; // Have to be strings because this data is passed across the LSP boundary.
+    workspaceUri: string;
     position: Position;
     autoImportText?: string;
     symbolLabel?: string;
     funcParensDisabled?: boolean;
-    modulePath?: string;
+    moduleUri?: string;
 }
 
 export interface CompletionOptions {
@@ -287,20 +288,20 @@ export class CompletionProvider {
 
     constructor(
         protected readonly program: ProgramView,
-        private readonly _workspacePath: string,
-        protected readonly filePath: string,
+        private readonly _workspaceRootUri: Uri,
+        protected readonly fileUri: Uri,
         protected readonly position: Position,
         protected readonly options: CompletionOptions,
         protected readonly cancellationToken: CancellationToken
     ) {
-        this.execEnv = this.configOptions.findExecEnvironment(this.filePath);
+        this.execEnv = this.configOptions.findExecEnvironment(this.fileUri);
 
-        this.parseResults = this.program.getParseResults(this.filePath)!;
-        this.sourceMapper = this.program.getSourceMapper(this.filePath, this.cancellationToken, /* mapCompiled */ true);
+        this.parseResults = this.program.getParseResults(this.fileUri)!;
+        this.sourceMapper = this.program.getSourceMapper(this.fileUri, this.cancellationToken, /* mapCompiled */ true);
     }
 
     getCompletions(): CompletionList | null {
-        if (!this.program.getSourceFileInfo(this.filePath)) {
+        if (!this.program.getSourceFileInfo(this.fileUri)) {
             return null;
         }
 
@@ -347,10 +348,15 @@ export class CompletionProvider {
         }
 
         if (
-            completionItemData.modulePath &&
-            ImportResolver.isSupportedImportSourceFile(completionItemData.modulePath)
+            completionItemData.moduleUri &&
+            ImportResolver.isSupportedImportSourceFile(
+                Uri.parse(completionItemData.moduleUri, this.importResolver.fileSystem.isCaseSensitive)
+            )
         ) {
-            const documentation = getModuleDocStringFromPaths([completionItemData.modulePath], this.sourceMapper);
+            const documentation = getModuleDocStringFromUris(
+                [Uri.parse(completionItemData.moduleUri, this.importResolver.fileSystem.isCaseSensitive)],
+                this.sourceMapper
+            );
             if (!documentation) {
                 return;
             }
@@ -499,7 +505,7 @@ export class CompletionProvider {
                     const methodSignature = this._printMethodSignature(classResults.classType, decl);
 
                     let text: string;
-                    if (isStubFile(this.filePath)) {
+                    if (isStubFile(this.fileUri)) {
                         text = `${methodSignature}: ...`;
                     } else {
                         const methodBody = this.printOverriddenMethodBody(
@@ -826,7 +832,7 @@ export class CompletionProvider {
             return;
         }
 
-        const currentFile = this.program.getSourceFileInfo(this.filePath);
+        const currentFile = this.program.getSourceFileInfo(this.fileUri);
         const moduleSymbolMap = buildModuleSymbolsMap(
             this.program.getSourceFileInfoList().filter((s) => s !== currentFile)
         );
@@ -923,8 +929,8 @@ export class CompletionProvider {
         }
 
         const completionItemData: CompletionItemData = {
-            workspacePath: this._workspacePath,
-            filePath: this.filePath,
+            workspaceUri: this._workspaceRootUri.toString(),
+            uri: this.fileUri.toString(),
             position: this.position,
         };
 
@@ -932,8 +938,8 @@ export class CompletionProvider {
             completionItemData.funcParensDisabled = true;
         }
 
-        if (detail?.modulePath) {
-            completionItemData.modulePath = detail.modulePath;
+        if (detail?.moduleUri) {
+            completionItemData.moduleUri = detail.moduleUri.toString();
         }
 
         completionItem.data = toLSPAny(completionItemData);
@@ -1689,7 +1695,7 @@ export class CompletionProvider {
             return;
         }
 
-        const printFlags = isStubFile(this.filePath)
+        const printFlags = isStubFile(this.fileUri)
             ? ParseTreeUtils.PrintExpressionFlags.ForwardDeclarations |
               ParseTreeUtils.PrintExpressionFlags.DoNotLimitStringLength
             : ParseTreeUtils.PrintExpressionFlags.DoNotLimitStringLength;
@@ -1822,7 +1828,7 @@ export class CompletionProvider {
         const node = decl.node;
 
         let ellipsisForDefault: boolean | undefined;
-        if (isStubFile(this.filePath)) {
+        if (isStubFile(this.fileUri)) {
             // In stubs, always use "...".
             ellipsisForDefault = true;
         } else if (classType.details.moduleName === decl.moduleName) {
@@ -1830,7 +1836,7 @@ export class CompletionProvider {
             ellipsisForDefault = false;
         }
 
-        const printFlags = isStubFile(this.filePath)
+        const printFlags = isStubFile(this.fileUri)
             ? ParseTreeUtils.PrintExpressionFlags.ForwardDeclarations |
               ParseTreeUtils.PrintExpressionFlags.DoNotLimitStringLength
             : ParseTreeUtils.PrintExpressionFlags.DoNotLimitStringLength;
@@ -2190,7 +2196,7 @@ export class CompletionProvider {
             return [];
         }
 
-        if (declaration.path !== this.filePath) {
+        if (!declaration.uri.equals(this.fileUri)) {
             return [];
         }
 
@@ -2200,8 +2206,8 @@ export class CompletionProvider {
 
             // Find the lowest tree to search the symbol.
             if (
-                ParseTreeUtils.getFileInfoFromNode(startingNode)?.filePath ===
-                ParseTreeUtils.getFileInfoFromNode(scopeRoot)?.filePath
+                ParseTreeUtils.getFileInfoFromNode(startingNode)?.fileUri ===
+                ParseTreeUtils.getFileInfoFromNode(scopeRoot)?.fileUri
             ) {
                 startingNode = scopeRoot;
             }
@@ -2731,7 +2737,9 @@ export class CompletionProvider {
 
         const completionMap = new CompletionMap();
         const resolvedPath =
-            importInfo.resolvedPaths.length > 0 ? importInfo.resolvedPaths[importInfo.resolvedPaths.length - 1] : '';
+            importInfo.resolvedUris.length > 0
+                ? importInfo.resolvedUris[importInfo.resolvedUris.length - 1]
+                : Uri.empty();
 
         const parseResults = this.program.getParseResults(resolvedPath);
         if (!parseResults) {
@@ -2775,7 +2783,7 @@ export class CompletionProvider {
         importInfo.implicitImports.forEach((implImport) => {
             if (!importFromNode.imports.find((imp) => imp.name.value === implImport.name)) {
                 this.addNameToCompletions(implImport.name, CompletionItemKind.Module, priorWord, completionMap, {
-                    modulePath: implImport.path,
+                    moduleUri: implImport.uri,
                 });
             }
         });
@@ -2817,8 +2825,8 @@ export class CompletionProvider {
                 completionItem.kind = CompletionItemKind.Variable;
 
                 const completionItemData: CompletionItemData = {
-                    workspacePath: this._workspacePath,
-                    filePath: this.filePath,
+                    workspaceUri: this._workspaceRootUri.toString(),
+                    uri: this.fileUri.toString(),
                     position: this.position,
                 };
                 completionItem.data = toLSPAny(completionItemData);
@@ -2914,8 +2922,7 @@ export class CompletionProvider {
             // exported from this scope, don't include it in the
             // suggestion list unless we are in the same file.
             const hidden =
-                !isVisibleExternally(symbol) &&
-                !symbol.getDeclarations().some((d) => isDefinedInFile(d, this.filePath));
+                !isVisibleExternally(symbol) && !symbol.getDeclarations().some((d) => isDefinedInFile(d, this.fileUri));
             if (!hidden && includeSymbolCallback(symbol, name)) {
                 // Don't add a symbol more than once. It may have already been
                 // added from an inner scope's symbol table.
@@ -3098,7 +3105,7 @@ export class CompletionProvider {
             importedSymbols: new Set<string>(),
         };
 
-        const completions = this.importResolver.getCompletionSuggestions(this.filePath, this.execEnv, moduleDescriptor);
+        const completions = this.importResolver.getCompletionSuggestions(this.fileUri, this.execEnv, moduleDescriptor);
 
         const completionMap = new CompletionMap();
 
@@ -3120,7 +3127,7 @@ export class CompletionProvider {
         completions.forEach((modulePath, completionName) => {
             this.addNameToCompletions(completionName, CompletionItemKind.Module, '', completionMap, {
                 sortText: this._makeSortText(SortCategory.ImportModuleName, completionName),
-                modulePath,
+                moduleUri: modulePath,
             });
         });
 
diff --git a/packages/pyright-internal/src/languageService/completionProviderUtils.ts b/packages/pyright-internal/src/languageService/completionProviderUtils.ts
index 7727e9a22..9e26317c5 100644
--- a/packages/pyright-internal/src/languageService/completionProviderUtils.ts
+++ b/packages/pyright-internal/src/languageService/completionProviderUtils.ts
@@ -11,21 +11,22 @@ import { InsertTextFormat, MarkupContent, MarkupKind, TextEdit } from 'vscode-la
 import { Declaration, DeclarationType } from '../analyzer/declaration';
 import { convertDocStringToMarkdown, convertDocStringToPlainText } from '../analyzer/docStringConversion';
 import { TypeEvaluator } from '../analyzer/typeEvaluatorTypes';
+import { isProperty } from '../analyzer/typeUtils';
 import {
     ClassType,
+    Type,
+    TypeBase,
+    TypeCategory,
+    UnknownType,
     getTypeAliasInfo,
     isClassInstance,
     isFunction,
     isModule,
     isOverloadedFunction,
-    Type,
-    TypeBase,
-    TypeCategory,
-    UnknownType,
 } from '../analyzer/types';
-import { isProperty } from '../analyzer/typeUtils';
 import { SignatureDisplayType } from '../common/configOptions';
 import { TextEditAction } from '../common/editAction';
+import { Uri } from '../common/uri/uri';
 import { getToolTipForType } from './tooltipUtils';
 
 export interface Edits {
@@ -55,7 +56,7 @@ export interface CompletionDetail extends CommonDetail {
     };
     sortText?: string;
     itemDetail?: string;
-    modulePath?: string;
+    moduleUri?: Uri;
 }
 
 export function getTypeDetail(
diff --git a/packages/pyright-internal/src/languageService/definitionProvider.ts b/packages/pyright-internal/src/languageService/definitionProvider.ts
index 32ae95762..a63a212ad 100644
--- a/packages/pyright-internal/src/languageService/definitionProvider.ts
+++ b/packages/pyright-internal/src/languageService/definitionProvider.ts
@@ -24,10 +24,11 @@ import { appendArray } from '../common/collectionUtils';
 import { isDefined } from '../common/core';
 import { ProgramView, ServiceProvider } from '../common/extensibility';
 import { convertPositionToOffset } from '../common/positionUtils';
+import { ServiceKeys } from '../common/serviceProviderExtensions';
 import { DocumentRange, Position, rangesAreEqual } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { ParseNode, ParseNodeType } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
-import { ServiceKeys } from '../common/serviceProviderExtensions';
 
 export enum DefinitionFilter {
     All = 'all',
@@ -50,7 +51,7 @@ export function addDeclarationsToDefinitions(
             allowExternallyHiddenAccess: true,
         });
 
-        if (!resolvedDecl || !resolvedDecl.path) {
+        if (!resolvedDecl || resolvedDecl.uri.isEmpty()) {
             return;
         }
 
@@ -66,13 +67,13 @@ export function addDeclarationsToDefinitions(
             resolvedDecl.type === DeclarationType.Alias &&
             resolvedDecl.symbolName &&
             resolvedDecl.submoduleFallback &&
-            resolvedDecl.submoduleFallback.path
+            !resolvedDecl.submoduleFallback.uri.isEmpty()
         ) {
             resolvedDecl = resolvedDecl.submoduleFallback;
         }
 
         _addIfUnique(definitions, {
-            path: resolvedDecl.path,
+            uri: resolvedDecl.uri,
             range: resolvedDecl.range,
         });
 
@@ -82,22 +83,22 @@ export function addDeclarationsToDefinitions(
             if (functionType && isOverloadedFunction(functionType)) {
                 for (const overloadDecl of functionType.overloads.map((o) => o.details.declaration).filter(isDefined)) {
                     _addIfUnique(definitions, {
-                        path: overloadDecl.path,
+                        uri: overloadDecl.uri,
                         range: overloadDecl.range,
                     });
                 }
             }
         }
 
-        if (!isStubFile(resolvedDecl.path)) {
+        if (!isStubFile(resolvedDecl.uri)) {
             return;
         }
 
         if (resolvedDecl.type === DeclarationType.Alias) {
             // Add matching source module
             sourceMapper
-                .findModules(resolvedDecl.path)
-                .map((m) => getFileInfo(m)?.filePath)
+                .findModules(resolvedDecl.uri)
+                .map((m) => getFileInfo(m)?.fileUri)
                 .filter(isDefined)
                 .forEach((f) => _addIfUnique(definitions, _createModuleEntry(f)));
             return;
@@ -105,9 +106,9 @@ export function addDeclarationsToDefinitions(
 
         const implDecls = sourceMapper.findDeclarations(resolvedDecl);
         for (const implDecl of implDecls) {
-            if (implDecl && implDecl.path) {
+            if (implDecl && !implDecl.uri.isEmpty()) {
                 _addIfUnique(definitions, {
-                    path: implDecl.path,
+                    uri: implDecl.uri,
                     range: implDecl.range,
                 });
             }
@@ -123,7 +124,7 @@ export function filterDefinitions(filter: DefinitionFilter, definitions: Documen
     // If go-to-declaration is supported, attempt to only show only pyi files in go-to-declaration
     // and none in go-to-definition, unless filtering would produce an empty list.
     const preferStubs = filter === DefinitionFilter.PreferStubs;
-    const wantedFile = (v: DocumentRange) => preferStubs === isStubFile(v.path);
+    const wantedFile = (v: DocumentRange) => preferStubs === isStubFile(v.uri);
     if (definitions.find(wantedFile)) {
         return definitions.filter(wantedFile);
     }
@@ -181,13 +182,13 @@ class DefinitionProviderBase {
 export class DefinitionProvider extends DefinitionProviderBase {
     constructor(
         program: ProgramView,
-        filePath: string,
+        fileUri: Uri,
         position: Position,
         filter: DefinitionFilter,
         token: CancellationToken
     ) {
-        const sourceMapper = program.getSourceMapper(filePath, token);
-        const parseResults = program.getParseResults(filePath);
+        const sourceMapper = program.getSourceMapper(fileUri, token);
+        const parseResults = program.getParseResults(fileUri);
         const { node, offset } = _tryGetNode(parseResults, position);
 
         super(sourceMapper, program.evaluator!, program.serviceProvider, node, offset, filter, token);
@@ -222,15 +223,15 @@ export class DefinitionProvider extends DefinitionProviderBase {
 }
 
 export class TypeDefinitionProvider extends DefinitionProviderBase {
-    private readonly _filePath: string;
+    private readonly _fileUri: Uri;
 
-    constructor(program: ProgramView, filePath: string, position: Position, token: CancellationToken) {
-        const sourceMapper = program.getSourceMapper(filePath, token, /*mapCompiled*/ false, /*preferStubs*/ true);
-        const parseResults = program.getParseResults(filePath);
+    constructor(program: ProgramView, fileUri: Uri, position: Position, token: CancellationToken) {
+        const sourceMapper = program.getSourceMapper(fileUri, token, /*mapCompiled*/ false, /*preferStubs*/ true);
+        const parseResults = program.getParseResults(fileUri);
         const { node, offset } = _tryGetNode(parseResults, position);
 
         super(sourceMapper, program.evaluator!, program.serviceProvider, node, offset, DefinitionFilter.All, token);
-        this._filePath = filePath;
+        this._fileUri = fileUri;
     }
 
     getDefinitions(): DocumentRange[] | undefined {
@@ -251,7 +252,7 @@ export class TypeDefinitionProvider extends DefinitionProviderBase {
                     if (subtype?.category === TypeCategory.Class) {
                         appendArray(
                             declarations,
-                            this.sourceMapper.findClassDeclarationsByType(this._filePath, subtype)
+                            this.sourceMapper.findClassDeclarationsByType(this._fileUri, subtype)
                         );
                     }
                 });
@@ -290,9 +291,9 @@ function _tryGetNode(parseResults: ParseResults | undefined, position: Position)
     return { node: ParseTreeUtils.findNodeByOffset(parseResults.parseTree, offset), offset };
 }
 
-function _createModuleEntry(filePath: string): DocumentRange {
+function _createModuleEntry(uri: Uri): DocumentRange {
     return {
-        path: filePath,
+        uri,
         range: {
             start: { line: 0, character: 0 },
             end: { line: 0, character: 0 },
@@ -302,7 +303,7 @@ function _createModuleEntry(filePath: string): DocumentRange {
 
 function _addIfUnique(definitions: DocumentRange[], itemToAdd: DocumentRange) {
     for (const def of definitions) {
-        if (def.path === itemToAdd.path && rangesAreEqual(def.range, itemToAdd.range)) {
+        if (def.uri.equals(itemToAdd.uri) && rangesAreEqual(def.range, itemToAdd.range)) {
             return;
         }
     }
diff --git a/packages/pyright-internal/src/languageService/documentHighlightProvider.ts b/packages/pyright-internal/src/languageService/documentHighlightProvider.ts
index 77c187ef0..6d45a74d2 100644
--- a/packages/pyright-internal/src/languageService/documentHighlightProvider.ts
+++ b/packages/pyright-internal/src/languageService/documentHighlightProvider.ts
@@ -15,6 +15,7 @@ import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { ProgramView, ReferenceUseCase } from '../common/extensibility';
 import { convertOffsetsToRange, convertPositionToOffset } from '../common/positionUtils';
 import { Position, TextRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { ParseNodeType } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
 import { DocumentSymbolCollector } from './documentSymbolCollector';
@@ -24,11 +25,11 @@ export class DocumentHighlightProvider {
 
     constructor(
         private _program: ProgramView,
-        private _filePath: string,
+        private _fileUri: Uri,
         private _position: Position,
         private _token: CancellationToken
     ) {
-        this._parseResults = this._program.getParseResults(this._filePath);
+        this._parseResults = this._program.getParseResults(this._fileUri);
     }
 
     getDocumentHighlight(): DocumentHighlight[] | undefined {
diff --git a/packages/pyright-internal/src/languageService/documentSymbolCollector.ts b/packages/pyright-internal/src/languageService/documentSymbolCollector.ts
index dd3543415..ee9979c55 100644
--- a/packages/pyright-internal/src/languageService/documentSymbolCollector.ts
+++ b/packages/pyright-internal/src/languageService/documentSymbolCollector.ts
@@ -29,12 +29,12 @@ import { TypeEvaluator } from '../analyzer/typeEvaluatorTypes';
 import { TypeCategory } from '../analyzer/types';
 import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { appendArray } from '../common/collectionUtils';
+import { isDefined } from '../common/core';
 import { assert } from '../common/debug';
 import { ProgramView, ReferenceUseCase, SymbolUsageProvider } from '../common/extensibility';
+import { ServiceKeys } from '../common/serviceProviderExtensions';
 import { TextRange } from '../common/textRange';
 import { ImportAsNode, NameNode, ParseNode, ParseNodeType, StringListNode, StringNode } from '../parser/parseNodes';
-import { ServiceKeys } from '../common/serviceProviderExtensions';
-import { isDefined } from '../common/core';
 
 export type CollectionResult = {
     node: NameNode | StringNode;
@@ -184,17 +184,18 @@ export class DocumentSymbolCollector extends ParseTreeWalker {
 
         const declarations = getDeclarationsForNameNode(evaluator, node, /* skipUnreachableCode */ false);
         const fileInfo = AnalyzerNodeInfo.getFileInfo(node);
+        const fileUri = fileInfo.fileUri;
 
         const resolvedDeclarations: Declaration[] = [];
-        const sourceMapper = program.getSourceMapper(fileInfo.filePath, token);
+        const sourceMapper = program.getSourceMapper(fileUri, token);
         declarations.forEach((decl) => {
             const resolvedDecl = evaluator.resolveAliasDeclaration(decl, resolveLocalName);
             if (resolvedDecl) {
                 addDeclarationIfUnique(resolvedDeclarations, resolvedDecl);
-                if (sourceMapper && isStubFile(resolvedDecl.path)) {
+                if (sourceMapper && isStubFile(resolvedDecl.uri)) {
                     const implDecls = sourceMapper.findDeclarations(resolvedDecl);
                     for (const implDecl of implDecls) {
-                        if (implDecl && implDecl.path) {
+                        if (implDecl && !implDecl.uri.isEmpty()) {
                             addDeclarationIfUnique(resolvedDeclarations, implDecl);
                         }
                     }
@@ -202,7 +203,7 @@ export class DocumentSymbolCollector extends ParseTreeWalker {
             }
         });
 
-        const sourceFileInfo = program.getSourceFileInfo(fileInfo.filePath);
+        const sourceFileInfo = program.getSourceFileInfo(fileUri);
         if (sourceFileInfo && sourceFileInfo.sourceFile.getIPythonMode() === IPythonMode.CellDocs) {
             // Add declarations from chained source files
             let builtinsScope = fileInfo.builtinsScope;
@@ -215,7 +216,7 @@ export class DocumentSymbolCollector extends ParseTreeWalker {
             // Add declarations from files that implicitly import the target file.
             const implicitlyImportedBy = collectImportedByCells(program, sourceFileInfo);
             implicitlyImportedBy.forEach((implicitImport) => {
-                const parseTree = program.getParseResults(implicitImport.sourceFile.getFilePath())?.parseTree;
+                const parseTree = program.getParseResults(implicitImport.sourceFile.getUri())?.parseTree;
                 if (parseTree) {
                     const scope = AnalyzerNodeInfo.getScope(parseTree);
                     const symbol = scope?.lookUpSymbol(node.value);
@@ -449,7 +450,7 @@ function _getDeclarationsForNonModuleNameNode(
         const type = evaluator.getType(node);
         if (type?.category === TypeCategory.Module) {
             // Synthesize decl for the module.
-            return [createSynthesizedAliasDeclaration(type.filePath)];
+            return [createSynthesizedAliasDeclaration(type.fileUri)];
         }
     }
 
diff --git a/packages/pyright-internal/src/languageService/documentSymbolProvider.ts b/packages/pyright-internal/src/languageService/documentSymbolProvider.ts
index e72fb6e50..e081aca1f 100644
--- a/packages/pyright-internal/src/languageService/documentSymbolProvider.ts
+++ b/packages/pyright-internal/src/languageService/documentSymbolProvider.ts
@@ -10,23 +10,22 @@
 
 import { CancellationToken, DocumentSymbol, Location, SymbolInformation } from 'vscode-languageserver';
 
+import { getFileInfo } from '../analyzer/analyzerNodeInfo';
 import { throwIfCancellationRequested } from '../common/cancellationUtils';
+import { ProgramView } from '../common/extensibility';
+import { Uri } from '../common/uri/uri';
 import { ParseResults } from '../parser/parser';
 import { IndexSymbolData, SymbolIndexer } from './symbolIndexer';
-import { ProgramView } from '../common/extensibility';
-import { getFileInfo } from '../analyzer/analyzerNodeInfo';
-import { convertPathToUri } from '../common/pathUtils';
 
 export function convertToFlatSymbols(
     program: ProgramView,
-    filePath: string,
+    uri: Uri,
     symbolList: DocumentSymbol[]
 ): SymbolInformation[] {
     const flatSymbols: SymbolInformation[] = [];
-    const documentUri = convertPathToUri(program.fileSystem, filePath);
 
     for (const symbol of symbolList) {
-        _appendToFlatSymbolsRecursive(flatSymbols, documentUri, symbol);
+        _appendToFlatSymbolsRecursive(flatSymbols, uri, symbol);
     }
 
     return flatSymbols;
@@ -37,11 +36,11 @@ export class DocumentSymbolProvider {
 
     constructor(
         protected readonly program: ProgramView,
-        protected readonly filePath: string,
+        protected readonly uri: Uri,
         private readonly _supportHierarchicalDocumentSymbol: boolean,
         private readonly _token: CancellationToken
     ) {
-        this._parseResults = this.program.getParseResults(this.filePath);
+        this._parseResults = this.program.getParseResults(this.uri);
     }
 
     getSymbols(): DocumentSymbol[] | SymbolInformation[] {
@@ -54,12 +53,12 @@ export class DocumentSymbolProvider {
             return symbolList;
         }
 
-        return convertToFlatSymbols(this.program, this.filePath, symbolList);
+        return convertToFlatSymbols(this.program, this.uri, symbolList);
     }
 
     protected getHierarchicalSymbols() {
         const symbolList: DocumentSymbol[] = [];
-        const parseResults = this.program.getParseResults(this.filePath);
+        const parseResults = this.program.getParseResults(this.uri);
         if (!parseResults) {
             return symbolList;
         }
@@ -115,14 +114,14 @@ export class DocumentSymbolProvider {
 
 function _appendToFlatSymbolsRecursive(
     flatSymbols: SymbolInformation[],
-    documentUri: string,
+    documentUri: Uri,
     symbol: DocumentSymbol,
     parent?: DocumentSymbol
 ) {
     const flatSymbol: SymbolInformation = {
         name: symbol.name,
         kind: symbol.kind,
-        location: Location.create(documentUri, symbol.range),
+        location: Location.create(documentUri.toString(), symbol.range),
     };
 
     if (symbol.tags) {
diff --git a/packages/pyright-internal/src/languageService/hoverProvider.ts b/packages/pyright-internal/src/languageService/hoverProvider.ts
index e116bd740..cb7b1d28b 100644
--- a/packages/pyright-internal/src/languageService/hoverProvider.ts
+++ b/packages/pyright-internal/src/languageService/hoverProvider.ts
@@ -30,10 +30,12 @@ import {
     isTypeVar,
 } from '../analyzer/types';
 import { throwIfCancellationRequested } from '../common/cancellationUtils';
+import { SignatureDisplayType } from '../common/configOptions';
 import { assertNever, fail } from '../common/debug';
 import { ProgramView } from '../common/extensibility';
 import { convertOffsetToPosition, convertPositionToOffset } from '../common/positionUtils';
 import { Position, Range, TextRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { ExpressionNode, NameNode, ParseNode, ParseNodeType, StringNode } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
 import {
@@ -43,7 +45,6 @@ import {
     getToolTipForType,
     getTypeForToolTip,
 } from './tooltipUtils';
-import { SignatureDisplayType } from '../common/configOptions';
 
 export interface HoverTextPart {
     python?: boolean;
@@ -151,13 +152,13 @@ export class HoverProvider {
 
     constructor(
         private readonly _program: ProgramView,
-        private readonly _filePath: string,
+        private readonly _fileUri: Uri,
         private readonly _position: Position,
         private readonly _format: MarkupKind,
         private readonly _token: CancellationToken
     ) {
-        this._parseResults = this._program.getParseResults(this._filePath);
-        this._sourceMapper = this._program.getSourceMapper(this._filePath, this._token, /* mapCompiled */ true);
+        this._parseResults = this._program.getParseResults(this._fileUri);
+        this._sourceMapper = this._program.getSourceMapper(this._fileUri, this._token, /* mapCompiled */ true);
     }
 
     getHover(): Hover | null {
diff --git a/packages/pyright-internal/src/languageService/navigationUtils.ts b/packages/pyright-internal/src/languageService/navigationUtils.ts
index a7a266fb8..a5a486548 100644
--- a/packages/pyright-internal/src/languageService/navigationUtils.ts
+++ b/packages/pyright-internal/src/languageService/navigationUtils.ts
@@ -7,10 +7,10 @@
  */
 import { Location } from 'vscode-languageserver-types';
 import { ReadOnlyFileSystem } from '../common/fileSystem';
-import { convertPathToUri } from '../common/pathUtils';
 import { DocumentRange } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 
-export function canNavigateToFile(fs: ReadOnlyFileSystem, path: string): boolean {
+export function canNavigateToFile(fs: ReadOnlyFileSystem, path: Uri): boolean {
     return !fs.isInZip(path);
 }
 
@@ -23,9 +23,9 @@ export function convertDocumentRangesToLocation(
 }
 
 export function convertDocumentRangeToLocation(fs: ReadOnlyFileSystem, range: DocumentRange): Location | undefined {
-    if (!canNavigateToFile(fs, range.path)) {
+    if (!canNavigateToFile(fs, range.uri)) {
         return undefined;
     }
 
-    return Location.create(convertPathToUri(fs, range.path), range.range);
+    return Location.create(range.uri.toString(), range.range);
 }
diff --git a/packages/pyright-internal/src/languageService/quickActions.ts b/packages/pyright-internal/src/languageService/quickActions.ts
index 52a03e10a..d11b731b6 100644
--- a/packages/pyright-internal/src/languageService/quickActions.ts
+++ b/packages/pyright-internal/src/languageService/quickActions.ts
@@ -11,16 +11,17 @@ import { CancellationToken } from 'vscode-languageserver';
 
 import { Commands } from '../commands/commands';
 import { ProgramView } from '../common/extensibility';
+import { Uri } from '../common/uri/uri';
 import { ImportSorter } from './importSorter';
 
 export function performQuickAction(
     programView: ProgramView,
-    filePath: string,
+    uri: Uri,
     command: string,
     args: any[],
     token: CancellationToken
 ) {
-    const sourceFileInfo = programView.getSourceFileInfo(filePath);
+    const sourceFileInfo = programView.getSourceFileInfo(uri);
 
     // This command should be called only for open files, in which
     // case we should have the file contents already loaded.
@@ -29,7 +30,7 @@ export function performQuickAction(
     }
 
     // If we have no completed analysis job, there's nothing to do.
-    const parseResults = programView.getParseResults(filePath);
+    const parseResults = programView.getParseResults(uri);
     if (!parseResults) {
         return [];
     }
diff --git a/packages/pyright-internal/src/languageService/referencesProvider.ts b/packages/pyright-internal/src/languageService/referencesProvider.ts
index c486910f0..daf2d1422 100644
--- a/packages/pyright-internal/src/languageService/referencesProvider.ts
+++ b/packages/pyright-internal/src/languageService/referencesProvider.ts
@@ -19,18 +19,19 @@ import { isVisibleExternally } from '../analyzer/symbolUtils';
 import { TypeEvaluator } from '../analyzer/typeEvaluatorTypes';
 import { maxTypeRecursionCount } from '../analyzer/types';
 import { throwIfCancellationRequested } from '../common/cancellationUtils';
-import { isDefined } from '../common/core';
 import { appendArray } from '../common/collectionUtils';
+import { isDefined } from '../common/core';
 import { assertNever } from '../common/debug';
 import { ProgramView, ReferenceUseCase, SymbolUsageProvider } from '../common/extensibility';
+import { ReadOnlyFileSystem } from '../common/fileSystem';
 import { convertOffsetToPosition, convertPositionToOffset } from '../common/positionUtils';
+import { ServiceKeys } from '../common/serviceProviderExtensions';
 import { DocumentRange, Position, TextRange, doesRangeContain } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { NameNode, ParseNode, ParseNodeType } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
 import { CollectionResult, DocumentSymbolCollector } from './documentSymbolCollector';
-import { ReadOnlyFileSystem } from '../common/fileSystem';
 import { convertDocumentRangesToLocation } from './navigationUtils';
-import { ServiceKeys } from '../common/serviceProviderExtensions';
 
 export type ReferenceCallback = (locations: DocumentRange[]) => void;
 
@@ -103,17 +104,17 @@ export class FindReferencesTreeWalker {
 
     constructor(
         private _program: ProgramView,
-        private _filePath: string,
+        private _fileUri: Uri,
         private _referencesResult: ReferencesResult,
         private _includeDeclaration: boolean,
         private _cancellationToken: CancellationToken,
         private readonly _createDocumentRange: (
-            filePath: string,
+            fileUri: Uri,
             result: CollectionResult,
             parseResults: ParseResults
         ) => DocumentRange = FindReferencesTreeWalker.createDocumentRange
     ) {
-        this._parseResults = this._program.getParseResults(this._filePath);
+        this._parseResults = this._program.getParseResults(this._fileUri);
     }
 
     findReferences(rootNode = this._parseResults?.parseTree) {
@@ -139,16 +140,16 @@ export class FindReferencesTreeWalker {
         for (const result of collector.collect()) {
             // Is it the same symbol?
             if (this._includeDeclaration || result.node !== this._referencesResult.nodeAtOffset) {
-                results.push(this._createDocumentRange(this._filePath, result, this._parseResults));
+                results.push(this._createDocumentRange(this._fileUri, result, this._parseResults));
             }
         }
 
         return results;
     }
 
-    static createDocumentRange(filePath: string, result: CollectionResult, parseResults: ParseResults): DocumentRange {
+    static createDocumentRange(fileUri: Uri, result: CollectionResult, parseResults: ParseResults): DocumentRange {
         return {
-            path: filePath,
+            uri: fileUri,
             range: {
                 start: convertOffsetToPosition(result.range.start, parseResults.tokenizerOutput.lines),
                 end: convertOffsetToPosition(TextRange.getEnd(result.range), parseResults.tokenizerOutput.lines),
@@ -162,7 +163,7 @@ export class ReferencesProvider {
         private _program: ProgramView,
         private _token: CancellationToken,
         private readonly _createDocumentRange?: (
-            filePath: string,
+            fileUri: Uri,
             result: CollectionResult,
             parseResults: ParseResults
         ) => DocumentRange,
@@ -172,17 +173,17 @@ export class ReferencesProvider {
     }
 
     reportReferences(
-        filePath: string,
+        fileUri: Uri,
         position: Position,
         includeDeclaration: boolean,
         resultReporter?: ResultProgressReporter<Location[]>
     ) {
-        const sourceFileInfo = this._program.getSourceFileInfo(filePath);
+        const sourceFileInfo = this._program.getSourceFileInfo(fileUri);
         if (!sourceFileInfo) {
             return;
         }
 
-        const parseResults = this._program.getParseResults(filePath);
+        const parseResults = this._program.getParseResults(fileUri);
         if (!parseResults) {
             return;
         }
@@ -202,7 +203,7 @@ export class ReferencesProvider {
         const invokedFromUserFile = isUserCode(sourceFileInfo);
         const referencesResult = ReferencesProvider.getDeclarationForPosition(
             this._program,
-            filePath,
+            fileUri,
             position,
             reporter,
             ReferenceUseCase.References,
@@ -214,7 +215,7 @@ export class ReferencesProvider {
 
         // Do we need to do a global search as well?
         if (!referencesResult.requiresGlobalSearch) {
-            this.addReferencesToResult(sourceFileInfo.sourceFile.getFilePath(), includeDeclaration, referencesResult);
+            this.addReferencesToResult(sourceFileInfo.sourceFile.getUri(), includeDeclaration, referencesResult);
         }
 
         for (const curSourceFileInfo of this._program.getSourceFileInfoList()) {
@@ -228,7 +229,7 @@ export class ReferencesProvider {
                 const fileContents = curSourceFileInfo.sourceFile.getFileContent();
                 if (!fileContents || referencesResult.symbolNames.some((s) => fileContents.search(s) >= 0)) {
                     this.addReferencesToResult(
-                        curSourceFileInfo.sourceFile.getFilePath(),
+                        curSourceFileInfo.sourceFile.getUri(),
                         includeDeclaration,
                         referencesResult
                     );
@@ -246,12 +247,12 @@ export class ReferencesProvider {
             for (const decl of referencesResult.declarations) {
                 throwIfCancellationRequested(this._token);
 
-                if (referencesResult.locations.some((l) => l.path === decl.path)) {
+                if (referencesResult.locations.some((l) => l.uri.equals(decl.uri))) {
                     // Already included.
                     continue;
                 }
 
-                const declFileInfo = this._program.getSourceFileInfo(decl.path);
+                const declFileInfo = this._program.getSourceFileInfo(decl.uri);
                 if (!declFileInfo) {
                     // The file the declaration belongs to doesn't belong to the program.
                     continue;
@@ -266,10 +267,10 @@ export class ReferencesProvider {
                     referencesResult.providers
                 );
 
-                this.addReferencesToResult(declFileInfo.sourceFile.getFilePath(), includeDeclaration, tempResult);
+                this.addReferencesToResult(declFileInfo.sourceFile.getUri(), includeDeclaration, tempResult);
                 for (const loc of tempResult.locations) {
                     // Include declarations only. And throw away any references
-                    if (loc.path === decl.path && doesRangeContain(decl.range, loc.range)) {
+                    if (loc.uri.equals(decl.uri) && doesRangeContain(decl.range, loc.range)) {
                         referencesResult.addLocations(loc);
                     }
                 }
@@ -279,15 +280,15 @@ export class ReferencesProvider {
         return locations;
     }
 
-    addReferencesToResult(filePath: string, includeDeclaration: boolean, referencesResult: ReferencesResult): void {
-        const parseResults = this._program.getParseResults(filePath);
+    addReferencesToResult(fileUri: Uri, includeDeclaration: boolean, referencesResult: ReferencesResult): void {
+        const parseResults = this._program.getParseResults(fileUri);
         if (!parseResults) {
             return;
         }
 
         const refTreeWalker = new FindReferencesTreeWalker(
             this._program,
-            filePath,
+            fileUri,
             referencesResult,
             includeDeclaration,
             this._token,
@@ -299,7 +300,7 @@ export class ReferencesProvider {
 
     static getDeclarationForNode(
         program: ProgramView,
-        filePath: string,
+        fileUri: Uri,
         node: NameNode,
         reporter: ReferenceCallback | undefined,
         useCase: ReferenceUseCase,
@@ -318,7 +319,7 @@ export class ReferencesProvider {
             return undefined;
         }
 
-        const requiresGlobalSearch = isVisibleOutside(program.evaluator!, filePath, node, declarations);
+        const requiresGlobalSearch = isVisibleOutside(program.evaluator!, fileUri, node, declarations);
         const symbolNames = new Set<string>(declarations.map((d) => getNameFromDeclaration(d)!).filter((n) => !!n));
         symbolNames.add(node.value);
 
@@ -345,14 +346,14 @@ export class ReferencesProvider {
 
     static getDeclarationForPosition(
         program: ProgramView,
-        filePath: string,
+        fileUri: Uri,
         position: Position,
         reporter: ReferenceCallback | undefined,
         useCase: ReferenceUseCase,
         token: CancellationToken
     ): ReferencesResult | undefined {
         throwIfCancellationRequested(token);
-        const parseResults = program.getParseResults(filePath);
+        const parseResults = program.getParseResults(fileUri);
         if (!parseResults) {
             return undefined;
         }
@@ -372,16 +373,11 @@ export class ReferencesProvider {
             return undefined;
         }
 
-        return this.getDeclarationForNode(program, filePath, node, reporter, useCase, token);
+        return this.getDeclarationForNode(program, fileUri, node, reporter, useCase, token);
     }
 }
 
-function isVisibleOutside(
-    evaluator: TypeEvaluator,
-    currentFilePath: string,
-    node: NameNode,
-    declarations: Declaration[]
-) {
+function isVisibleOutside(evaluator: TypeEvaluator, currentUri: Uri, node: NameNode, declarations: Declaration[]) {
     const result = evaluator.lookUpSymbolRecursive(node, node.value, /* honorCodeFlow */ false);
     if (result && !isExternallyVisible(result.symbol)) {
         return false;
@@ -394,7 +390,7 @@ function isVisibleOutside(
     // that is within the current file and cannot be imported directly from other modules.
     return declarations.some((decl) => {
         // If the declaration is outside of this file, a global search is needed.
-        if (decl.path !== currentFilePath) {
+        if (!decl.uri.equals(currentUri)) {
             return true;
         }
 
diff --git a/packages/pyright-internal/src/languageService/renameProvider.ts b/packages/pyright-internal/src/languageService/renameProvider.ts
index 74a222059..14c4a1407 100644
--- a/packages/pyright-internal/src/languageService/renameProvider.ts
+++ b/packages/pyright-internal/src/languageService/renameProvider.ts
@@ -9,27 +9,28 @@
 
 import { CancellationToken, WorkspaceEdit } from 'vscode-languageserver';
 
+import { isUserCode } from '../analyzer/sourceFileInfoUtils';
+import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { assertNever } from '../common/debug';
 import { FileEditAction } from '../common/editAction';
 import { ProgramView, ReferenceUseCase } from '../common/extensibility';
 import { convertTextRangeToRange } from '../common/positionUtils';
 import { Position, Range } from '../common/textRange';
-import { ReferencesProvider, ReferencesResult } from '../languageService/referencesProvider';
-import { isUserCode } from '../analyzer/sourceFileInfoUtils';
-import { throwIfCancellationRequested } from '../common/cancellationUtils';
-import { ParseResults } from '../parser/parser';
+import { Uri } from '../common/uri/uri';
 import { convertToWorkspaceEdit } from '../common/workspaceEditUtils';
+import { ReferencesProvider, ReferencesResult } from '../languageService/referencesProvider';
+import { ParseResults } from '../parser/parser';
 
 export class RenameProvider {
     private readonly _parseResults: ParseResults | undefined;
 
     constructor(
         private _program: ProgramView,
-        private _filePath: string,
+        private _fileUri: Uri,
         private _position: Position,
         private _token: CancellationToken
     ) {
-        this._parseResults = this._program.getParseResults(this._filePath);
+        this._parseResults = this._program.getParseResults(this._fileUri);
     }
 
     canRenameSymbol(isDefaultWorkspace: boolean, isUntitled: boolean): Range | null {
@@ -45,7 +46,7 @@ export class RenameProvider {
 
         const renameMode = RenameProvider.getRenameSymbolMode(
             this._program,
-            this._filePath,
+            this._fileUri,
             referencesResult,
             isDefaultWorkspace,
             isUntitled
@@ -72,7 +73,7 @@ export class RenameProvider {
         const referenceProvider = new ReferencesProvider(this._program, this._token);
         const renameMode = RenameProvider.getRenameSymbolMode(
             this._program,
-            this._filePath,
+            this._fileUri,
             referencesResult,
             isDefaultWorkspace,
             isUntitled
@@ -80,11 +81,7 @@ export class RenameProvider {
 
         switch (renameMode) {
             case 'singleFileMode':
-                referenceProvider.addReferencesToResult(
-                    this._filePath,
-                    /* includeDeclaration */ true,
-                    referencesResult
-                );
+                referenceProvider.addReferencesToResult(this._fileUri, /* includeDeclaration */ true, referencesResult);
                 break;
 
             case 'multiFileMode': {
@@ -99,7 +96,7 @@ export class RenameProvider {
                         }
 
                         referenceProvider.addReferencesToResult(
-                            curSourceFileInfo.sourceFile.getFilePath(),
+                            curSourceFileInfo.sourceFile.getUri(),
                             /* includeDeclaration */ true,
                             referencesResult
                         );
@@ -124,23 +121,23 @@ export class RenameProvider {
         const edits: FileEditAction[] = [];
         referencesResult.locations.forEach((loc) => {
             edits.push({
-                filePath: loc.path,
+                fileUri: loc.uri,
                 range: loc.range,
                 replacementText: newName,
             });
         });
 
-        return convertToWorkspaceEdit(this._program.fileSystem, { edits, fileOperations: [] });
+        return convertToWorkspaceEdit({ edits, fileOperations: [] });
     }
 
     static getRenameSymbolMode(
         program: ProgramView,
-        filePath: string,
+        fileUri: Uri,
         referencesResult: ReferencesResult,
         isDefaultWorkspace: boolean,
         isUntitled: boolean
     ) {
-        const sourceFileInfo = program.getSourceFileInfo(filePath)!;
+        const sourceFileInfo = program.getSourceFileInfo(fileUri)!;
 
         // We have 2 different cases
         // Single file mode.
@@ -156,12 +153,12 @@ export class RenameProvider {
             (userFile && !referencesResult.requiresGlobalSearch) ||
             (!userFile &&
                 sourceFileInfo.isOpenByClient &&
-                referencesResult.declarations.every((d) => program.getSourceFileInfo(d.path) === sourceFileInfo))
+                referencesResult.declarations.every((d) => program.getSourceFileInfo(d.uri) === sourceFileInfo))
         ) {
             return 'singleFileMode';
         }
 
-        if (!isUntitled && referencesResult.declarations.every((d) => isUserCode(program.getSourceFileInfo(d.path)))) {
+        if (!isUntitled && referencesResult.declarations.every((d) => isUserCode(program.getSourceFileInfo(d.uri)))) {
             return 'multiFileMode';
         }
 
@@ -173,7 +170,7 @@ export class RenameProvider {
     private _getReferenceResult() {
         const referencesResult = ReferencesProvider.getDeclarationForPosition(
             this._program,
-            this._filePath,
+            this._fileUri,
             this._position,
             /* reporter */ undefined,
             ReferenceUseCase.Rename,
diff --git a/packages/pyright-internal/src/languageService/signatureHelpProvider.ts b/packages/pyright-internal/src/languageService/signatureHelpProvider.ts
index 79ed9800b..d580c060f 100644
--- a/packages/pyright-internal/src/languageService/signatureHelpProvider.ts
+++ b/packages/pyright-internal/src/languageService/signatureHelpProvider.ts
@@ -31,6 +31,7 @@ import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { ProgramView } from '../common/extensibility';
 import { convertPositionToOffset } from '../common/positionUtils';
 import { Position } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { CallNode, NameNode, ParseNodeType } from '../parser/parseNodes';
 import { ParseResults } from '../parser/parser';
 import { getDocumentationPartsForTypeAndDecl, getFunctionDocStringFromType } from './tooltipUtils';
@@ -41,7 +42,7 @@ export class SignatureHelpProvider {
 
     constructor(
         private _program: ProgramView,
-        private _filePath: string,
+        private _fileUri: Uri,
         private _position: Position,
         private _format: MarkupKind,
         private _hasSignatureLabelOffsetCapability: boolean,
@@ -49,8 +50,8 @@ export class SignatureHelpProvider {
         private _context: SignatureHelpContext | undefined,
         private _token: CancellationToken
     ) {
-        this._parseResults = this._program.getParseResults(this._filePath);
-        this._sourceMapper = this._program.getSourceMapper(this._filePath, this._token, /* mapCompiled */ true);
+        this._parseResults = this._program.getParseResults(this._fileUri);
+        this._sourceMapper = this._program.getSourceMapper(this._fileUri, this._token, /* mapCompiled */ true);
     }
 
     getSignatureHelp(): SignatureHelp | undefined {
diff --git a/packages/pyright-internal/src/languageService/symbolIndexer.ts b/packages/pyright-internal/src/languageService/symbolIndexer.ts
index b66027a68..24e15d361 100644
--- a/packages/pyright-internal/src/languageService/symbolIndexer.ts
+++ b/packages/pyright-internal/src/languageService/symbolIndexer.ts
@@ -13,15 +13,16 @@ import * as AnalyzerNodeInfo from '../analyzer/analyzerNodeInfo';
 import { Declaration, DeclarationType } from '../analyzer/declaration';
 import { getLastTypedDeclaredForSymbol, isVisibleExternally } from '../analyzer/symbolUtils';
 import { throwIfCancellationRequested } from '../common/cancellationUtils';
+import { getSymbolKind } from '../common/lspUtils';
 import { convertOffsetsToRange } from '../common/positionUtils';
 import { Range } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { ParseResults } from '../parser/parser';
 import { convertSymbolKindToCompletionItemKind } from './autoImporter';
-import { getSymbolKind } from '../common/lspUtils';
 
 export interface IndexAliasData {
     readonly originalName: string;
-    readonly modulePath: string;
+    readonly moduleUri: Uri;
     readonly kind: SymbolKind;
     readonly itemKind?: CompletionItemKind | undefined;
 }
diff --git a/packages/pyright-internal/src/languageService/tooltipUtils.ts b/packages/pyright-internal/src/languageService/tooltipUtils.ts
index 031f2fc9b..133edda36 100644
--- a/packages/pyright-internal/src/languageService/tooltipUtils.ts
+++ b/packages/pyright-internal/src/languageService/tooltipUtils.ts
@@ -16,7 +16,7 @@ import {
     getClassDocString,
     getFunctionDocStringInherited,
     getModuleDocString,
-    getModuleDocStringFromPaths,
+    getModuleDocStringFromUris,
     getOverloadedFunctionDocStringsInherited,
     getPropertyDocStringInherited,
     getVariableDocString,
@@ -323,7 +323,7 @@ export function getDocumentationPartsForTypeAndDecl(
             }
         }
 
-        typeDoc = getModuleDocStringFromPaths([resolvedDecl.path], sourceMapper);
+        typeDoc = getModuleDocStringFromUris([resolvedDecl.uri], sourceMapper);
     }
 
     typeDoc =
diff --git a/packages/pyright-internal/src/languageService/workspaceSymbolProvider.ts b/packages/pyright-internal/src/languageService/workspaceSymbolProvider.ts
index 7aff4cf10..982568f40 100644
--- a/packages/pyright-internal/src/languageService/workspaceSymbolProvider.ts
+++ b/packages/pyright-internal/src/languageService/workspaceSymbolProvider.ts
@@ -7,15 +7,15 @@
  */
 
 import { CancellationToken, Location, ResultProgressReporter, SymbolInformation } from 'vscode-languageserver';
-import { throwIfCancellationRequested } from '../common/cancellationUtils';
-import * as StringUtils from '../common/stringUtils';
-import { IndexSymbolData, SymbolIndexer } from './symbolIndexer';
-import { ProgramView } from '../common/extensibility';
-import { isUserCode } from '../analyzer/sourceFileInfoUtils';
 import { getFileInfo } from '../analyzer/analyzerNodeInfo';
-import { convertPathToUri } from '../common/pathUtils';
-import { Workspace } from '../workspaceFactory';
+import { isUserCode } from '../analyzer/sourceFileInfoUtils';
+import { throwIfCancellationRequested } from '../common/cancellationUtils';
 import { appendArray } from '../common/collectionUtils';
+import { ProgramView } from '../common/extensibility';
+import * as StringUtils from '../common/stringUtils';
+import { Uri } from '../common/uri/uri';
+import { Workspace } from '../workspaceFactory';
+import { IndexSymbolData, SymbolIndexer } from './symbolIndexer';
 
 type WorkspaceSymbolCallback = (symbols: SymbolInformation[]) => void;
 
@@ -55,10 +55,10 @@ export class WorkspaceSymbolProvider {
         return this._allSymbols;
     }
 
-    protected getSymbolsForDocument(program: ProgramView, filePath: string): SymbolInformation[] {
+    protected getSymbolsForDocument(program: ProgramView, fileUri: Uri): SymbolInformation[] {
         const symbolList: SymbolInformation[] = [];
 
-        const parseResults = program.getParseResults(filePath);
+        const parseResults = program.getParseResults(fileUri);
         if (!parseResults) {
             return symbolList;
         }
@@ -69,7 +69,7 @@ export class WorkspaceSymbolProvider {
         }
 
         const indexSymbolData = SymbolIndexer.indexSymbols(fileInfo, parseResults, this._token);
-        this.appendWorkspaceSymbolsRecursive(indexSymbolData, program, filePath, '', symbolList);
+        this.appendWorkspaceSymbolsRecursive(indexSymbolData, program, fileUri, '', symbolList);
 
         return symbolList;
     }
@@ -77,7 +77,7 @@ export class WorkspaceSymbolProvider {
     protected appendWorkspaceSymbolsRecursive(
         indexSymbolData: IndexSymbolData[] | undefined,
         program: ProgramView,
-        filePath: string,
+        fileUri: Uri,
         container: string,
         symbolList: SymbolInformation[]
     ) {
@@ -94,7 +94,7 @@ export class WorkspaceSymbolProvider {
 
             if (StringUtils.isPatternInSymbol(this._query, symbolData.name)) {
                 const location: Location = {
-                    uri: convertPathToUri(program.fileSystem, filePath),
+                    uri: fileUri.toString(),
                     range: symbolData.selectionRange!,
                 };
 
@@ -114,7 +114,7 @@ export class WorkspaceSymbolProvider {
             this.appendWorkspaceSymbolsRecursive(
                 symbolData.children,
                 program,
-                filePath,
+                fileUri,
                 this._getContainerName(container, symbolData.name),
                 symbolList
             );
@@ -134,7 +134,7 @@ export class WorkspaceSymbolProvider {
                 continue;
             }
 
-            const symbolList = this.getSymbolsForDocument(program, sourceFileInfo.sourceFile.getFilePath());
+            const symbolList = this.getSymbolsForDocument(program, sourceFileInfo.sourceFile.getUri());
             if (symbolList.length > 0) {
                 this._reporter(symbolList);
             }
diff --git a/packages/pyright-internal/src/pyright.ts b/packages/pyright-internal/src/pyright.ts
index b1b3fe9cc..21fc410c4 100644
--- a/packages/pyright-internal/src/pyright.ts
+++ b/packages/pyright-internal/src/pyright.ts
@@ -28,12 +28,14 @@ import { createDeferred } from './common/deferred';
 import { Diagnostic, DiagnosticCategory } from './common/diagnostic';
 import { FileDiagnostics } from './common/diagnosticSink';
 import { FullAccessHost } from './common/fullAccessHost';
-import { combinePaths, getFileSpec, normalizePath, tryStat } from './common/pathUtils';
+import { combinePaths, normalizePath } from './common/pathUtils';
 import { versionFromString } from './common/pythonVersion';
 import { RealTempFile, createFromRealFileSystem } from './common/realFileSystem';
 import { ServiceProvider } from './common/serviceProvider';
 import { createServiceProvider } from './common/serviceProviderExtensions';
 import { Range, isEmptyRange } from './common/textRange';
+import { Uri } from './common/uri/uri';
+import { getFileSpec, tryStat } from './common/uri/uriUtils';
 import { PyrightFileSystem } from './pyrightFileSystem';
 
 const toolName = 'pyright';
@@ -64,11 +66,11 @@ interface PyrightSymbolCount {
 
 interface PyrightTypeCompletenessReport {
     packageName: string;
-    packageRootDirectory?: string | undefined;
+    packageRootDirectory?: Uri | undefined;
     moduleName: string;
-    moduleRootDirectory?: string | undefined;
+    moduleRootDirectory?: Uri | undefined;
     ignoreUnknownTypesFromImports: boolean;
-    pyTypedPath?: string | undefined;
+    pyTypedPath?: Uri | undefined;
     exportedSymbolCounts: PyrightSymbolCount;
     otherSymbolCounts: PyrightSymbolCount;
     missingFunctionDocStringCount: number;
@@ -95,7 +97,7 @@ interface PyrightPublicSymbolReport {
 }
 
 interface PyrightJsonDiagnostic {
-    file: string;
+    uri: Uri;
     severity: SeverityLevel;
     message: string;
     range?: Range | undefined;
@@ -244,10 +246,9 @@ async function processArgs(): Promise<ExitStatus> {
 
         // Verify the specified file specs to make sure their wildcard roots exist.
         const tempFileSystem = new PyrightFileSystem(createFromRealFileSystem());
-        const tempServiceProvider = createServiceProvider(tempFileSystem, console);
 
         for (const fileDesc of options.includeFileSpecsOverride) {
-            const includeSpec = getFileSpec(tempServiceProvider, '', fileDesc);
+            const includeSpec = getFileSpec(Uri.file(process.cwd(), tempFileSystem.isCaseSensitive), fileDesc);
             try {
                 const stat = tryStat(tempFileSystem, includeSpec.wildcardRoot);
                 if (!stat) {
@@ -361,7 +362,7 @@ async function processArgs(): Promise<ExitStatus> {
     // up the JSON output, which goes to stdout.
     const output = args.outputjson ? new StderrConsole(logLevel) : new StandardConsole(logLevel);
     const fileSystem = new PyrightFileSystem(createFromRealFileSystem(output, new ChokidarFileWatcherProvider(output)));
-    const tempFile = new RealTempFile();
+    const tempFile = new RealTempFile(fileSystem.isCaseSensitive);
     const serviceProvider = createServiceProvider(fileSystem, output, tempFile);
 
     // The package type verification uses a different path.
@@ -386,7 +387,7 @@ async function processArgs(): Promise<ExitStatus> {
     // Refresh service after 2 seconds after the last library file change is detected.
     const service = new AnalyzerService('<default>', serviceProvider, {
         console: output,
-        hostFactory: () => new FullAccessHost(fileSystem),
+        hostFactory: () => new FullAccessHost(serviceProvider),
         libraryReanalysisTimeProvider: () => 2 * 1000,
     });
     const exitStatus = createDeferred<ExitStatus>();
@@ -540,7 +541,7 @@ function buildTypeCompletenessReport(
 
     // Add the general diagnostics.
     completenessReport.generalDiagnostics.forEach((diag) => {
-        const jsonDiag = convertDiagnosticToJson('', diag);
+        const jsonDiag = convertDiagnosticToJson(Uri.empty(), diag);
         if (isDiagnosticIncluded(jsonDiag.severity, minSeverityLevel)) {
             report.generalDiagnostics.push(jsonDiag);
         }
@@ -549,11 +550,11 @@ function buildTypeCompletenessReport(
 
     report.typeCompleteness = {
         packageName,
-        packageRootDirectory: completenessReport.packageRootDirectory,
+        packageRootDirectory: completenessReport.packageRootDirectoryUri,
         moduleName: completenessReport.moduleName,
-        moduleRootDirectory: completenessReport.moduleRootDirectory,
+        moduleRootDirectory: completenessReport.moduleRootDirectoryUri,
         ignoreUnknownTypesFromImports: completenessReport.ignoreExternal,
-        pyTypedPath: completenessReport.pyTypedPath,
+        pyTypedPath: completenessReport.pyTypedPathUri,
         exportedSymbolCounts: {
             withKnownType: 0,
             withAmbiguousType: 0,
@@ -587,7 +588,7 @@ function buildTypeCompletenessReport(
 
         // Convert and filter the diagnostics.
         symbol.diagnostics.forEach((diag) => {
-            const jsonDiag = convertDiagnosticToJson(diag.filePath, diag.diagnostic);
+            const jsonDiag = convertDiagnosticToJson(diag.uri, diag.diagnostic);
             if (isDiagnosticIncluded(jsonDiag.severity, minSeverityLevel)) {
                 diagnostics.push(jsonDiag);
             }
@@ -811,7 +812,7 @@ function reportDiagnosticsAsJson(
                 diag.category === DiagnosticCategory.Warning ||
                 diag.category === DiagnosticCategory.Information
             ) {
-                const jsonDiag = convertDiagnosticToJson(fileDiag.filePath, diag);
+                const jsonDiag = convertDiagnosticToJson(fileDiag.fileUri, diag);
                 if (isDiagnosticIncluded(jsonDiag.severity, minSeverityLevel)) {
                     report.generalDiagnostics.push(jsonDiag);
                 }
@@ -862,9 +863,9 @@ function convertDiagnosticCategoryToSeverity(category: DiagnosticCategory): Seve
     }
 }
 
-function convertDiagnosticToJson(filePath: string, diag: Diagnostic): PyrightJsonDiagnostic {
+function convertDiagnosticToJson(uri: Uri, diag: Diagnostic): PyrightJsonDiagnostic {
     return {
-        file: filePath,
+        uri,
         severity: convertDiagnosticCategoryToSeverity(diag.category),
         message: diag.message,
         range: isEmptyRange(diag.range) ? undefined : diag.range,
@@ -891,9 +892,9 @@ function reportDiagnosticsAsText(
         );
 
         if (fileErrorsAndWarnings.length > 0) {
-            console.info(`${fileDiagnostics.filePath}`);
+            console.info(`${fileDiagnostics.fileUri.toUserVisibleString()}`);
             fileErrorsAndWarnings.forEach((diag) => {
-                const jsonDiag = convertDiagnosticToJson(fileDiagnostics.filePath, diag);
+                const jsonDiag = convertDiagnosticToJson(fileDiagnostics.fileUri, diag);
                 logDiagnosticToConsole(jsonDiag);
 
                 if (diag.category === DiagnosticCategory.Error) {
@@ -923,8 +924,8 @@ function reportDiagnosticsAsText(
 
 function logDiagnosticToConsole(diag: PyrightJsonDiagnostic, prefix = '  ') {
     let message = prefix;
-    if (diag.file) {
-        message += `${diag.file}:`;
+    if (!diag.uri.isEmpty()) {
+        message += `${diag.uri.toUserVisibleString()}:`;
     }
     if (diag.range && !isEmptyRange(diag.range)) {
         message +=
diff --git a/packages/pyright-internal/src/pyrightFileSystem.ts b/packages/pyright-internal/src/pyrightFileSystem.ts
index 78436e1f3..51a62b2b4 100644
--- a/packages/pyright-internal/src/pyrightFileSystem.ts
+++ b/packages/pyright-internal/src/pyrightFileSystem.ts
@@ -15,13 +15,14 @@ import { getPyTypedInfo } from './analyzer/pyTypedUtils';
 import { ExecutionEnvironment } from './common/configOptions';
 import { FileSystem, MkDirOptions } from './common/fileSystem';
 import { stubsSuffix } from './common/pathConsts';
-import { combinePaths, ensureTrailingDirectorySeparator, isDirectory, tryStat } from './common/pathUtils';
+import { Uri } from './common/uri/uri';
+import { isDirectory, tryStat } from './common/uri/uriUtils';
 import { ReadOnlyAugmentedFileSystem } from './readonlyAugmentedFileSystem';
 
 export interface SupportPartialStubs {
     isPartialStubPackagesScanned(execEnv: ExecutionEnvironment): boolean;
-    isPathScanned(path: string): boolean;
-    processPartialStubPackages(paths: string[], roots: string[], bundledStubPath?: string): void;
+    isPathScanned(path: Uri): boolean;
+    processPartialStubPackages(paths: Uri[], roots: Uri[], bundledStubPath?: Uri): void;
     clearPartialStubs(): void;
 }
 
@@ -49,49 +50,45 @@ export class PyrightFileSystem extends ReadOnlyAugmentedFileSystem implements IP
         super(realFS);
     }
 
-    override mkdirSync(path: string, options?: MkDirOptions): void {
-        this.realFS.mkdirSync(path, options);
+    override mkdirSync(uri: Uri, options?: MkDirOptions): void {
+        this.realFS.mkdirSync(uri, options);
     }
 
-    override chdir(path: string): void {
-        this.realFS.chdir(path);
+    override chdir(uri: Uri): void {
+        this.realFS.chdir(uri);
     }
 
-    override writeFileSync(path: string, data: string | Buffer, encoding: BufferEncoding | null): void {
-        this.realFS.writeFileSync(this.getOriginalPath(path), data, encoding);
+    override writeFileSync(uri: Uri, data: string | Buffer, encoding: BufferEncoding | null): void {
+        this.realFS.writeFileSync(this.getOriginalPath(uri), data, encoding);
     }
 
-    override rmdirSync(path: string): void {
-        this.realFS.rmdirSync(this.getOriginalPath(path));
+    override rmdirSync(uri: Uri): void {
+        this.realFS.rmdirSync(this.getOriginalPath(uri));
     }
 
-    override unlinkSync(path: string): void {
-        this.realFS.unlinkSync(this.getOriginalPath(path));
+    override unlinkSync(uri: Uri): void {
+        this.realFS.unlinkSync(this.getOriginalPath(uri));
     }
 
-    override createWriteStream(path: string): fs.WriteStream {
-        return this.realFS.createWriteStream(this.getOriginalPath(path));
+    override createWriteStream(uri: Uri): fs.WriteStream {
+        return this.realFS.createWriteStream(this.getOriginalPath(uri));
     }
 
-    override copyFileSync(src: string, dst: string): void {
+    override copyFileSync(src: Uri, dst: Uri): void {
         this.realFS.copyFileSync(this.getOriginalPath(src), this.getOriginalPath(dst));
     }
 
-    override getUri(originalPath: string): string {
-        return this.realFS.getUri(originalPath);
-    }
-
     isPartialStubPackagesScanned(execEnv: ExecutionEnvironment): boolean {
-        return this.isPathScanned(execEnv.root ?? '');
+        return execEnv.root ? this.isPathScanned(execEnv.root) : false;
     }
 
-    isPathScanned(path: string): boolean {
-        return this._rootSearched.has(path);
+    isPathScanned(uri: Uri): boolean {
+        return this._rootSearched.has(uri.key);
     }
 
-    processPartialStubPackages(paths: string[], roots: string[], bundledStubPath?: string) {
+    processPartialStubPackages(paths: Uri[], roots: Uri[], bundledStubPath?: Uri) {
         for (const path of paths) {
-            this._rootSearched.add(path);
+            this._rootSearched.add(path.key);
 
             if (!this.realFS.existsSync(path) || !isDirectory(this.realFS, path)) {
                 continue;
@@ -105,9 +102,9 @@ export class PyrightFileSystem extends ReadOnlyAugmentedFileSystem implements IP
                 // Leave empty set of dir entries to process.
             }
 
-            const isBundledStub = path === bundledStubPath;
+            const isBundledStub = path.equals(bundledStubPath);
             for (const entry of dirEntries) {
-                const partialStubPackagePath = combinePaths(path, entry.name);
+                const partialStubPackagePath = path.combinePaths(entry.name);
                 const isDirectory = !entry.isSymbolicLink()
                     ? entry.isDirectory()
                     : !!tryStat(this.realFS, partialStubPackagePath)?.isDirectory();
@@ -123,13 +120,13 @@ export class PyrightFileSystem extends ReadOnlyAugmentedFileSystem implements IP
                 }
 
                 // We found partially typed stub-packages.
-                this._partialStubPackagePaths.add(partialStubPackagePath);
+                this._partialStubPackagePaths.add(partialStubPackagePath.key);
 
                 // Search the root to see whether we have matching package installed.
                 let partialStubs: string[] | undefined;
                 const packageName = entry.name.substr(0, entry.name.length - stubsSuffix.length);
                 for (const root of roots) {
-                    const packagePath = combinePaths(root, packageName);
+                    const packagePath = root.combinePaths(packageName);
                     try {
                         const stat = tryStat(this.realFS, packagePath);
                         if (!stat?.isDirectory()) {
@@ -149,8 +146,8 @@ export class PyrightFileSystem extends ReadOnlyAugmentedFileSystem implements IP
                         // Merge partial stub packages to the library.
                         partialStubs = partialStubs ?? this._getRelativePathPartialStubs(partialStubPackagePath);
                         for (const partialStub of partialStubs) {
-                            const originalPyiFile = combinePaths(partialStubPackagePath, partialStub);
-                            const mappedPyiFile = combinePaths(packagePath, partialStub);
+                            const originalPyiFile = partialStubPackagePath.combinePaths(partialStub);
+                            const mappedPyiFile = packagePath.combinePaths(partialStub);
                             this.recordMovedEntry(mappedPyiFile, originalPyiFile, packagePath);
                         }
                     } catch {
@@ -168,17 +165,15 @@ export class PyrightFileSystem extends ReadOnlyAugmentedFileSystem implements IP
         this._partialStubPackagePaths.clear();
     }
 
-    protected override isMovedEntry(path: string) {
-        return this._partialStubPackagePaths.has(path) || super.isMovedEntry(path);
+    protected override isMovedEntry(uri: Uri) {
+        return this._partialStubPackagePaths.has(uri.key) || super.isMovedEntry(uri);
     }
 
-    private _getRelativePathPartialStubs(path: string) {
-        const paths: string[] = [];
-
-        const partialStubPathLength = ensureTrailingDirectorySeparator(path).length;
-        const searchAllStubs = (path: string) => {
-            for (const entry of this.realFS.readdirEntriesSync(path)) {
-                const filePath = combinePaths(path, entry.name);
+    private _getRelativePathPartialStubs(partialStubPath: Uri) {
+        const relativePaths: string[] = [];
+        const searchAllStubs = (uri: Uri) => {
+            for (const entry of this.realFS.readdirEntriesSync(uri)) {
+                const filePath = uri.combinePaths(entry.name);
 
                 let isDirectory = entry.isDirectory();
                 let isFile = entry.isFile();
@@ -195,15 +190,15 @@ export class PyrightFileSystem extends ReadOnlyAugmentedFileSystem implements IP
                 }
 
                 if (isFile && entry.name.endsWith('.pyi')) {
-                    const relative = filePath.substring(partialStubPathLength);
+                    const relative = partialStubPath.getRelativePathComponents(filePath).join('/');
                     if (relative) {
-                        paths.push(relative);
+                        relativePaths.push(relative);
                     }
                 }
             }
         };
 
-        searchAllStubs(path);
-        return paths;
+        searchAllStubs(partialStubPath);
+        return relativePaths;
     }
 }
diff --git a/packages/pyright-internal/src/readonlyAugmentedFileSystem.ts b/packages/pyright-internal/src/readonlyAugmentedFileSystem.ts
index 170ea4936..5a6855014 100644
--- a/packages/pyright-internal/src/readonlyAugmentedFileSystem.ts
+++ b/packages/pyright-internal/src/readonlyAugmentedFileSystem.ts
@@ -12,57 +12,53 @@ import type * as fs from 'fs';
 import { appendArray, getOrAdd } from './common/collectionUtils';
 import { FileSystem, MkDirOptions, Stats, VirtualDirent } from './common/fileSystem';
 import { FileWatcher, FileWatcherEventHandler } from './common/fileWatcher';
-import {
-    combinePaths,
-    ensureTrailingDirectorySeparator,
-    getDirectoryPath,
-    getFileName,
-    getRelativePathComponentsFromDirectory,
-} from './common/pathUtils';
+import { Uri } from './common/uri/uri';
 
 export class ReadOnlyAugmentedFileSystem implements FileSystem {
     // Mapped file to original file map
-    private readonly _entryMap = new Map<string, string>();
+    private readonly _entryMap = new Map<string, Uri>();
 
     // Original file to mapped file map
-    private readonly _reverseEntryMap = new Map<string, string>();
+    private readonly _reverseEntryMap = new Map<string, Uri>();
 
     // Mapped files per a containing folder map
     private readonly _folderMap = new Map<string, { name: string; isFile: boolean }[]>();
 
     constructor(protected realFS: FileSystem) {}
 
-    existsSync(path: string): boolean {
-        if (this.isMovedEntry(path)) {
+    get isCaseSensitive(): boolean {
+        return this.realFS.isCaseSensitive;
+    }
+
+    existsSync(uri: Uri): boolean {
+        if (this.isMovedEntry(uri)) {
             // Pretend partial stub folder and its files not exist
             return false;
         }
 
-        return this.realFS.existsSync(this.getOriginalPath(path));
+        return this.realFS.existsSync(this.getOriginalPath(uri));
     }
 
-    mkdirSync(path: string, options?: MkDirOptions): void {
+    mkdirSync(uri: Uri, options?: MkDirOptions): void {
         throw new Error('Operation is not allowed.');
     }
 
-    chdir(path: string): void {
+    chdir(uri: Uri): void {
         throw new Error('Operation is not allowed.');
     }
 
-    readdirEntriesSync(path: string): fs.Dirent[] {
-        const maybeDirectory = ensureTrailingDirectorySeparator(path);
-
+    readdirEntriesSync(uri: Uri): fs.Dirent[] {
         const entries: fs.Dirent[] = [];
-        const movedEntries = this._folderMap.get(maybeDirectory);
-        if (!movedEntries || this.realFS.existsSync(path)) {
+        const movedEntries = this._folderMap.get(uri.key);
+        if (!movedEntries || this.realFS.existsSync(uri)) {
             appendArray(
                 entries,
-                this.realFS.readdirEntriesSync(path).filter((item) => {
+                this.realFS.readdirEntriesSync(uri).filter((item) => {
                     // Filter out the stub package directory and any
                     // entries that will be overwritten by stub package
                     // virtual items.
                     return (
-                        !this.isMovedEntry(combinePaths(path, item.name)) &&
+                        !this.isMovedEntry(uri.combinePaths(item.name)) &&
                         !movedEntries?.some((movedEntry) => movedEntry.name === item.name)
                     );
                 })
@@ -76,129 +72,124 @@ export class ReadOnlyAugmentedFileSystem implements FileSystem {
         return entries.concat(movedEntries.map((e) => new VirtualDirent(e.name, e.isFile)));
     }
 
-    readdirSync(path: string): string[] {
-        return this.readdirEntriesSync(path).map((p) => p.name);
+    readdirSync(uri: Uri): string[] {
+        return this.readdirEntriesSync(uri).map((p) => p.name);
     }
 
-    readFileSync(path: string, encoding?: null): Buffer;
-    readFileSync(path: string, encoding: BufferEncoding): string;
-    readFileSync(path: string, encoding?: BufferEncoding | null): string | Buffer {
-        return this.realFS.readFileSync(this.getOriginalPath(path), encoding);
+    readFileSync(uri: Uri, encoding?: null): Buffer;
+    readFileSync(uri: Uri, encoding: BufferEncoding): string;
+    readFileSync(uri: Uri, encoding?: BufferEncoding | null): string | Buffer {
+        return this.realFS.readFileSync(this.getOriginalPath(uri), encoding);
     }
 
-    writeFileSync(path: string, data: string | Buffer, encoding: BufferEncoding | null): void {
+    writeFileSync(uri: Uri, data: string | Buffer, encoding: BufferEncoding | null): void {
         throw new Error('Operation is not allowed.');
     }
 
-    statSync(path: string): Stats {
-        return this.realFS.statSync(this.getOriginalPath(path));
+    statSync(uri: Uri): Stats {
+        return this.realFS.statSync(this.getOriginalPath(uri));
     }
 
-    rmdirSync(path: string): void {
+    rmdirSync(uri: Uri): void {
         throw new Error('Operation is not allowed.');
     }
 
-    unlinkSync(path: string): void {
+    unlinkSync(uri: Uri): void {
         throw new Error('Operation is not allowed.');
     }
 
-    realpathSync(path: string): string {
-        if (this._entryMap.has(path)) {
-            return path;
+    realpathSync(uri: Uri): Uri {
+        if (this._entryMap.has(uri.key)) {
+            return uri;
         }
 
-        return this.realFS.realpathSync(path);
+        return this.realFS.realpathSync(uri);
     }
 
-    getModulePath(): string {
+    getModulePath(): Uri {
         return this.realFS.getModulePath();
     }
 
-    createFileSystemWatcher(paths: string[], listener: FileWatcherEventHandler): FileWatcher {
+    createFileSystemWatcher(paths: Uri[], listener: FileWatcherEventHandler): FileWatcher {
         return this.realFS.createFileSystemWatcher(paths, listener);
     }
 
-    createReadStream(path: string): fs.ReadStream {
-        return this.realFS.createReadStream(this.getOriginalPath(path));
+    createReadStream(uri: Uri): fs.ReadStream {
+        return this.realFS.createReadStream(this.getOriginalPath(uri));
     }
 
-    createWriteStream(path: string): fs.WriteStream {
+    createWriteStream(uri: Uri): fs.WriteStream {
         throw new Error('Operation is not allowed.');
     }
 
-    copyFileSync(src: string, dst: string): void {
+    copyFileSync(src: Uri, dst: Uri): void {
         throw new Error('Operation is not allowed.');
     }
 
     // Async I/O
-    readFile(path: string): Promise<Buffer> {
-        return this.realFS.readFile(this.getOriginalPath(path));
+    readFile(uri: Uri): Promise<Buffer> {
+        return this.realFS.readFile(this.getOriginalPath(uri));
     }
 
-    readFileText(path: string, encoding?: BufferEncoding): Promise<string> {
-        return this.realFS.readFileText(this.getOriginalPath(path), encoding);
+    readFileText(uri: Uri, encoding?: BufferEncoding): Promise<string> {
+        return this.realFS.readFileText(this.getOriginalPath(uri), encoding);
     }
 
-    realCasePath(path: string): string {
-        return this.realFS.realCasePath(path);
-    }
-
-    getUri(originalPath: string): string {
-        return this.realFS.getUri(originalPath);
+    realCasePath(uri: Uri): Uri {
+        return this.realFS.realCasePath(uri);
     }
 
     // See whether the file is mapped to another location.
-    isMappedFilePath(filepath: string): boolean {
-        return this._entryMap.has(filepath) || this.realFS.isMappedFilePath(filepath);
+    isMappedUri(fileUri: Uri): boolean {
+        return this._entryMap.has(fileUri.key) || this.realFS.isMappedUri(fileUri);
     }
 
     // Get original filepath if the given filepath is mapped.
-    getOriginalFilePath(mappedFilePath: string) {
-        return this.realFS.getOriginalFilePath(this.getOriginalPath(mappedFilePath));
+    getOriginalUri(mappedFileUri: Uri) {
+        return this.realFS.getOriginalUri(this.getOriginalPath(mappedFileUri));
     }
 
     // Get mapped filepath if the given filepath is mapped.
-    getMappedFilePath(originalFilepath: string) {
-        const mappedFilePath = this.realFS.getMappedFilePath(originalFilepath);
-        return this._reverseEntryMap.get(mappedFilePath) ?? mappedFilePath;
+    getMappedUri(originalFileUri: Uri) {
+        const mappedFileUri = this.realFS.getMappedUri(originalFileUri);
+        return this._reverseEntryMap.get(mappedFileUri.key) ?? mappedFileUri;
     }
 
-    isInZip(path: string): boolean {
-        return this.realFS.isInZip(path);
+    isInZip(uri: Uri): boolean {
+        return this.realFS.isInZip(uri);
     }
 
-    protected recordMovedEntry(mappedPath: string, originalPath: string, rootPath: string) {
-        this._entryMap.set(mappedPath, originalPath);
-        this._reverseEntryMap.set(originalPath, mappedPath);
+    protected recordMovedEntry(mappedUri: Uri, originalUri: Uri, rootPath: Uri) {
+        this._entryMap.set(mappedUri.key, originalUri);
+        this._reverseEntryMap.set(originalUri.key, mappedUri);
 
-        const directory = ensureTrailingDirectorySeparator(getDirectoryPath(mappedPath));
-        const folderInfo = getOrAdd(this._folderMap, directory, () => []);
+        const directory = mappedUri.getDirectory();
+        const folderInfo = getOrAdd(this._folderMap, directory.key, () => []);
 
-        const name = getFileName(mappedPath);
+        const name = mappedUri.fileName;
         if (!folderInfo.some((entry) => entry.name === name)) {
             folderInfo.push({ name, isFile: true });
         }
 
-        // Add the directory entries for the sub paths as well. We should ignoreCase here because
-        // the paths are just combining of already known paths.
-        const subPathEntries = getRelativePathComponentsFromDirectory(rootPath, directory, /* ignoreCase */ false);
-        for (let i = 1; i < subPathEntries.length; i++) {
-            const subdir = combinePaths(rootPath, ...subPathEntries.slice(1, i + 1));
-            const parent = ensureTrailingDirectorySeparator(getDirectoryPath(subdir));
+        // Add the directory entries for the sub paths as well.
+        const subPathEntries = rootPath.getRelativePathComponents(directory);
+        for (let i = 0; i < subPathEntries.length; i++) {
+            const subdir = rootPath.combinePaths(...subPathEntries.slice(0, i + 1));
+            const parent = subdir.getDirectory().key;
             const dirInfo = getOrAdd(this._folderMap, parent, () => []);
-            const dirName = getFileName(subdir);
+            const dirName = subdir.fileName;
             if (!dirInfo.some((entry) => entry.name === dirName)) {
                 dirInfo.push({ name: dirName, isFile: false });
             }
         }
     }
 
-    protected getOriginalPath(mappedFilePath: string) {
-        return this._entryMap.get(mappedFilePath) ?? mappedFilePath;
+    protected getOriginalPath(mappedFileUri: Uri) {
+        return this._entryMap.get(mappedFileUri.key) ?? mappedFileUri;
     }
 
-    protected isMovedEntry(path: string) {
-        return this._reverseEntryMap.has(path);
+    protected isMovedEntry(uri: Uri) {
+        return this._reverseEntryMap.has(uri.key);
     }
 
     protected clear() {
diff --git a/packages/pyright-internal/src/server.ts b/packages/pyright-internal/src/server.ts
index 9b34e0b9a..61f16397e 100644
--- a/packages/pyright-internal/src/server.ts
+++ b/packages/pyright-internal/src/server.ts
@@ -30,11 +30,12 @@ import { expandPathVariables } from './common/envVarUtils';
 import { FileBasedCancellationProvider } from './common/fileBasedCancellationUtils';
 import { FullAccessHost } from './common/fullAccessHost';
 import { Host } from './common/host';
-import { realCasePath, resolvePaths } from './common/pathUtils';
 import { ProgressReporter } from './common/progressReporter';
 import { RealTempFile, WorkspaceFileWatcherProvider, createFromRealFileSystem } from './common/realFileSystem';
 import { ServiceProvider } from './common/serviceProvider';
 import { createServiceProvider } from './common/serviceProviderExtensions';
+import { Uri } from './common/uri/uri';
+import { getRootUri } from './common/uri/uriUtils';
 import { LanguageServerBase, ServerSettings } from './languageServerBase';
 import { CodeActionProvider } from './languageService/codeActionProvider';
 import { PyrightFileSystem } from './pyrightFileSystem';
@@ -49,20 +50,21 @@ export class PyrightServer extends LanguageServerBase {
         // eslint-disable-next-line @typescript-eslint/no-var-requires
         const version = require('../package.json').version || '';
 
-        // When executed from CLI command (pyright-langserver), __rootDirectory is
-        // already defined. When executed from VSCode extension, rootDirectory should
-        // be __dirname.
-        const rootDirectory = (global as any).__rootDirectory || __dirname;
-
         const console = new ConsoleWithLogLevel(connection.console);
         const fileWatcherProvider = new WorkspaceFileWatcherProvider();
         const fileSystem = createFromRealFileSystem(console, fileWatcherProvider);
         const pyrightFs = new PyrightFileSystem(fileSystem);
-        const tempFile = new RealTempFile();
+        const tempFile = new RealTempFile(pyrightFs.isCaseSensitive);
         const cacheManager = new CacheManager();
 
         const serviceProvider = createServiceProvider(pyrightFs, tempFile, console, cacheManager);
-        const realPathRoot = realCasePath(rootDirectory, pyrightFs);
+
+        // When executed from CLI command (pyright-langserver), __rootDirectory is
+        // already defined. When executed from VSCode extension, rootDirectory should
+        // be __dirname.
+        const rootDirectory: Uri =
+            getRootUri(pyrightFs.isCaseSensitive) || Uri.file(__dirname, pyrightFs.isCaseSensitive);
+        const realPathRoot = pyrightFs.realCasePath(rootDirectory);
 
         super(
             {
@@ -98,44 +100,40 @@ export class PyrightServer extends LanguageServerBase {
         };
 
         try {
-            const pythonSection = await this.getConfiguration(workspace.uri, 'python');
+            const pythonSection = await this.getConfiguration(workspace.rootUri, 'python');
             if (pythonSection) {
                 const pythonPath = pythonSection.pythonPath;
                 if (pythonPath && isString(pythonPath) && !isPythonBinary(pythonPath)) {
-                    serverSettings.pythonPath = resolvePaths(
-                        workspace.rootPath,
-                        expandPathVariables(workspace.rootPath, pythonPath)
+                    serverSettings.pythonPath = workspace.rootUri.combinePaths(
+                        expandPathVariables(workspace.rootUri, pythonPath)
                     );
                 }
 
                 const venvPath = pythonSection.venvPath;
 
                 if (venvPath && isString(venvPath)) {
-                    serverSettings.venvPath = resolvePaths(
-                        workspace.rootPath,
-                        expandPathVariables(workspace.rootPath, venvPath)
+                    serverSettings.venvPath = workspace.rootUri.combinePaths(
+                        expandPathVariables(workspace.rootUri, venvPath)
                     );
                 }
             }
 
-            const pythonAnalysisSection = await this.getConfiguration(workspace.uri, 'python.analysis');
+            const pythonAnalysisSection = await this.getConfiguration(workspace.rootUri, 'python.analysis');
             if (pythonAnalysisSection) {
                 const typeshedPaths = pythonAnalysisSection.typeshedPaths;
                 if (typeshedPaths && Array.isArray(typeshedPaths) && typeshedPaths.length > 0) {
                     const typeshedPath = typeshedPaths[0];
                     if (typeshedPath && isString(typeshedPath)) {
-                        serverSettings.typeshedPath = resolvePaths(
-                            workspace.rootPath,
-                            expandPathVariables(workspace.rootPath, typeshedPath)
+                        serverSettings.typeshedPath = workspace.rootUri.combinePaths(
+                            expandPathVariables(workspace.rootUri, typeshedPath)
                         );
                     }
                 }
 
                 const stubPath = pythonAnalysisSection.stubPath;
                 if (stubPath && isString(stubPath)) {
-                    serverSettings.stubPath = resolvePaths(
-                        workspace.rootPath,
-                        expandPathVariables(workspace.rootPath, stubPath)
+                    serverSettings.stubPath = workspace.rootUri.combinePaths(
+                        expandPathVariables(workspace.rootUri, stubPath)
                     );
                 }
 
@@ -167,7 +165,7 @@ export class PyrightServer extends LanguageServerBase {
                 if (extraPaths && Array.isArray(extraPaths) && extraPaths.length > 0) {
                     serverSettings.extraPaths = extraPaths
                         .filter((p) => p && isString(p))
-                        .map((p) => resolvePaths(workspace.rootPath, expandPathVariables(workspace.rootPath, p)));
+                        .map((p) => workspace.rootUri.combinePaths(expandPathVariables(workspace.rootUri, p)));
                 }
 
                 serverSettings.includeFileSpecs = this._getStringValues(pythonAnalysisSection.include);
@@ -196,7 +194,7 @@ export class PyrightServer extends LanguageServerBase {
                 serverSettings.autoSearchPaths = true;
             }
 
-            const pyrightSection = await this.getConfiguration(workspace.uri, 'pyright');
+            const pyrightSection = await this.getConfiguration(workspace.rootUri, 'pyright');
             if (pyrightSection) {
                 if (pyrightSection.openFilesOnly !== undefined) {
                     serverSettings.openFilesOnly = !!pyrightSection.openFilesOnly;
@@ -227,11 +225,11 @@ export class PyrightServer extends LanguageServerBase {
             return undefined;
         }
 
-        return new BackgroundAnalysis(this.console);
+        return new BackgroundAnalysis(this.serverOptions.serviceProvider);
     }
 
     protected override createHost() {
-        return new FullAccessHost(this.fs);
+        return new FullAccessHost(this.serverOptions.serviceProvider);
     }
 
     protected override createImportResolver(
@@ -262,15 +260,9 @@ export class PyrightServer extends LanguageServerBase {
     ): Promise<(Command | CodeAction)[] | undefined | null> {
         this.recordUserInteractionTime();
 
-        const filePath = this.uriParser.decodeTextDocumentUri(params.textDocument.uri);
-        const workspace = await this.getWorkspaceForFile(filePath);
-        return CodeActionProvider.getCodeActionsForPosition(
-            workspace,
-            filePath,
-            params.range,
-            params.context.only,
-            token
-        );
+        const uri = Uri.parse(params.textDocument.uri, this.serverOptions.serviceProvider.fs().isCaseSensitive);
+        const workspace = await this.getWorkspaceForFile(uri);
+        return CodeActionProvider.getCodeActionsForPosition(workspace, uri, params.range, params.context.only, token);
     }
 
     protected createProgressReporter(): ProgressReporter {
diff --git a/packages/pyright-internal/src/tests/chainedSourceFiles.test.ts b/packages/pyright-internal/src/tests/chainedSourceFiles.test.ts
index 878fff26a..bd5cc1859 100644
--- a/packages/pyright-internal/src/tests/chainedSourceFiles.test.ts
+++ b/packages/pyright-internal/src/tests/chainedSourceFiles.test.ts
@@ -17,13 +17,14 @@ import { ConfigOptions } from '../common/configOptions';
 import { NullConsole } from '../common/console';
 import { normalizeSlashes } from '../common/pathUtils';
 import { convertOffsetsToRange, convertOffsetToPosition } from '../common/positionUtils';
+import { ServiceProvider } from '../common/serviceProvider';
+import { Uri } from '../common/uri/uri';
+import { CompletionProvider } from '../languageService/completionProvider';
 import { parseTestData } from './harness/fourslash/fourSlashParser';
 import { TestAccessHost } from './harness/testAccessHost';
 import * as host from './harness/testHost';
 import { createFromFileSystem, distlibFolder, libFolder } from './harness/vfs/factory';
 import * as vfs from './harness/vfs/filesystem';
-import { CompletionProvider } from '../languageService/completionProvider';
-import { ServiceProvider } from '../common/serviceProvider';
 
 test('check chained files', () => {
     const code = `
@@ -40,16 +41,17 @@ test('check chained files', () => {
 //// [|foo/*marker*/|]
     `;
 
-    const basePath = normalizeSlashes('/');
+    const basePath = Uri.file(normalizeSlashes('/'));
     const { data, service } = createServiceWithChainedSourceFiles(basePath, code);
 
     const marker = data.markerPositions.get('marker')!;
+    const markerUri = Uri.file(marker.fileName);
 
-    const parseResult = service.getParseResult(marker.fileName)!;
+    const parseResult = service.getParseResult(markerUri)!;
     const result = new CompletionProvider(
         service.test_program,
         basePath,
-        marker.fileName,
+        markerUri,
         convertOffsetToPosition(marker.position, parseResult.tokenizerOutput.lines),
         {
             format: MarkupKind.Markdown,
@@ -80,15 +82,16 @@ test('modify chained files', () => {
 //// [|foo/*marker*/|]
     `;
 
-    const basePath = normalizeSlashes('/');
+    const basePath = Uri.file(normalizeSlashes('/'));
     const { data, service } = createServiceWithChainedSourceFiles(basePath, code);
 
     // Make sure files are all realized.
     const marker = data.markerPositions.get('marker')!;
-    const parseResult = service.getParseResult(marker.fileName)!;
+    const markerUri = Uri.file(marker.fileName);
+    const parseResult = service.getParseResult(markerUri)!;
 
     // Close file in the middle of the chain
-    service.setFileClosed(data.markerPositions.get('delete')!.fileName);
+    service.setFileClosed(Uri.file(data.markerPositions.get('delete')!.fileName));
 
     // Make sure we don't get suggestion from auto import but from chained files.
     service.test_program.configOptions.autoImportCompletions = false;
@@ -96,7 +99,7 @@ test('modify chained files', () => {
     const result = new CompletionProvider(
         service.test_program,
         basePath,
-        marker.fileName,
+        markerUri,
         convertOffsetToPosition(marker.position, parseResult.tokenizerOutput.lines),
         {
             format: MarkupKind.Markdown,
@@ -129,18 +132,19 @@ test('modify chained files', async () => {
 //// [|/*marker*/foo1()|]
     `;
 
-    const basePath = normalizeSlashes('/');
+    const basePath = Uri.file(normalizeSlashes('/'));
     const { data, service } = createServiceWithChainedSourceFiles(basePath, code);
 
     const marker = data.markerPositions.get('marker')!;
+    const markerUri = Uri.file(marker.fileName);
     const range = data.ranges.find((r) => r.marker === marker)!;
 
-    const parseResults = service.getParseResult(marker.fileName)!;
+    const parseResults = service.getParseResult(markerUri)!;
     analyze(service.test_program);
 
     // Initially, there should be no error.
     const initialDiags = await service.getDiagnosticsForRange(
-        marker.fileName,
+        markerUri,
         convertOffsetsToRange(range.pos, range.end, parseResults.tokenizerOutput.lines),
         CancellationToken.None
     );
@@ -148,11 +152,11 @@ test('modify chained files', async () => {
     assert.strictEqual(initialDiags.length, 0);
 
     // Change test1 content
-    service.updateOpenFileContents(data.markerPositions.get('changed')!.fileName, 2, 'def foo5(): pass');
+    service.updateOpenFileContents(Uri.file(data.markerPositions.get('changed')!.fileName), 2, 'def foo5(): pass');
     analyze(service.test_program);
 
     const finalDiags = await service.getDiagnosticsForRange(
-        marker.fileName,
+        markerUri,
         convertOffsetsToRange(range.pos, range.end, parseResults.tokenizerOutput.lines),
         CancellationToken.None
     );
@@ -178,17 +182,18 @@ test('chained files with 1000s of files', async () => {
 //// [|/*marker*/foo1()|]
     `;
     const code = generateChainedFiles(1000, lastFile);
-    const basePath = normalizeSlashes('/');
+    const basePath = Uri.file(normalizeSlashes('/'));
     const { data, service } = createServiceWithChainedSourceFiles(basePath, code);
     const marker = data.markerPositions.get('marker')!;
+    const markerUri = Uri.file(marker.fileName);
     const range = data.ranges.find((r) => r.marker === marker)!;
 
-    const parseResults = service.getParseResult(marker.fileName)!;
+    const parseResults = service.getParseResult(markerUri)!;
     analyze(service.test_program);
 
     // There should be no error as it should find the foo1 in the first chained file.
     const initialDiags = await service.getDiagnosticsForRange(
-        marker.fileName,
+        markerUri,
         convertOffsetsToRange(range.pos, range.end, parseResults.tokenizerOutput.lines),
         CancellationToken.None
     );
@@ -205,16 +210,17 @@ test('imported by files', async () => {
 //// os.path.join()
     `;
 
-    const basePath = normalizeSlashes('/');
+    const basePath = Uri.file(normalizeSlashes('/'));
     const { data, service } = createServiceWithChainedSourceFiles(basePath, code);
     analyze(service.test_program);
 
     const marker = data.markerPositions.get('marker')!;
+    const markerUri = Uri.file(marker.fileName);
     const range = data.ranges.find((r) => r.marker === marker)!;
 
-    const parseResults = service.getParseResult(marker.fileName)!;
+    const parseResults = service.getParseResult(markerUri)!;
     const diagnostics = await service.getDiagnosticsForRange(
-        marker.fileName,
+        markerUri,
         convertOffsetsToRange(range.pos, range.end, parseResults.tokenizerOutput.lines),
         CancellationToken.None
     );
@@ -231,22 +237,24 @@ test('re ordering cells', async () => {
 //// /*bottom*/os.path.join()
     `;
 
-    const basePath = normalizeSlashes('/');
+    const basePath = Uri.file(normalizeSlashes('/'));
     const { data, service } = createServiceWithChainedSourceFiles(basePath, code);
     analyze(service.test_program);
 
     const marker = data.markerPositions.get('marker')!;
+    const markerUri = Uri.file(marker.fileName);
     const range = data.ranges.find((r) => r.marker === marker)!;
 
     const bottom = data.markerPositions.get('bottom')!;
+    const bottomUri = Uri.file(bottom.fileName);
 
-    service.updateChainedFilePath(bottom.fileName, undefined);
-    service.updateChainedFilePath(marker.fileName, bottom.fileName);
+    service.updateChainedUri(bottomUri, undefined);
+    service.updateChainedUri(markerUri, bottomUri);
     analyze(service.test_program);
 
-    const parseResults = service.getParseResult(marker.fileName)!;
+    const parseResults = service.getParseResult(markerUri)!;
     const diagnostics = await service.getDiagnosticsForRange(
-        marker.fileName,
+        markerUri,
         convertOffsetsToRange(range.pos, range.end, parseResults.tokenizerOutput.lines),
         CancellationToken.None
     );
@@ -254,22 +262,23 @@ test('re ordering cells', async () => {
     assert.strictEqual(diagnostics.length, 1);
 });
 
-function createServiceWithChainedSourceFiles(basePath: string, code: string) {
-    const fs = createFromFileSystem(host.HOST, /*ignoreCase*/ false, { cwd: basePath });
+function createServiceWithChainedSourceFiles(basePath: Uri, code: string) {
+    const fs = createFromFileSystem(host.HOST, /*ignoreCase*/ false, { cwd: basePath.getFilePath() });
     const service = new AnalyzerService('test service', new ServiceProvider(), {
         console: new NullConsole(),
-        hostFactory: () => new TestAccessHost(vfs.MODULE_PATH, [libFolder, distlibFolder]),
+        hostFactory: () => new TestAccessHost(Uri.file(vfs.MODULE_PATH), [libFolder, distlibFolder]),
         importResolverFactory: AnalyzerService.createImportResolver,
         configOptions: new ConfigOptions(basePath),
         fileSystem: fs,
     });
 
-    const data = parseTestData(basePath, code, '');
+    const data = parseTestData(basePath.getFilePath(), code, '');
 
-    let chainedFilePath: string | undefined;
+    let chainedFilePath: Uri | undefined;
     for (const file of data.files) {
-        service.setFileOpened(file.fileName, 1, file.content, IPythonMode.CellDocs, chainedFilePath);
-        chainedFilePath = file.fileName;
+        const uri = Uri.file(file.fileName);
+        service.setFileOpened(uri, 1, file.content, IPythonMode.CellDocs, chainedFilePath);
+        chainedFilePath = uri;
     }
     return { data, service };
 }
diff --git a/packages/pyright-internal/src/tests/checker.test.ts b/packages/pyright-internal/src/tests/checker.test.ts
index 9da325f29..4ad58f1a9 100644
--- a/packages/pyright-internal/src/tests/checker.test.ts
+++ b/packages/pyright-internal/src/tests/checker.test.ts
@@ -11,6 +11,7 @@
 
 import { ConfigOptions } from '../common/configOptions';
 import { PythonVersion } from '../common/pythonVersion';
+import { Uri } from '../common/uri/uri';
 import * as TestUtils from './testUtils';
 
 test('BadToken1', () => {
@@ -34,7 +35,7 @@ test('CircularBaseClass', () => {
 });
 
 test('Private1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, optional diagnostics are ignored.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['private1.py'], configOptions);
@@ -47,7 +48,7 @@ test('Private1', () => {
 });
 
 test('Constant1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, optional diagnostics are ignored.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['constant1.py'], configOptions);
@@ -168,7 +169,7 @@ test('With3', () => {
 });
 
 test('With4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['with4.py'], configOptions);
@@ -216,7 +217,7 @@ test('Mro4', () => {
 });
 
 test('DefaultInitializer1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, the reportCallInDefaultInitializer is disabled.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['defaultInitializer1.py'], configOptions);
@@ -229,7 +230,7 @@ test('DefaultInitializer1', () => {
 });
 
 test('UnnecessaryIsInstance1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['unnecessaryIsInstance1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 1);
@@ -241,7 +242,7 @@ test('UnnecessaryIsInstance1', () => {
 });
 
 test('UnnecessaryIsSubclass1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['unnecessaryIsSubclass1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -253,7 +254,7 @@ test('UnnecessaryIsSubclass1', () => {
 });
 
 test('UnnecessaryCast1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['unnecessaryCast1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -265,7 +266,7 @@ test('UnnecessaryCast1', () => {
 });
 
 test('UnnecessaryContains1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['unnecessaryContains1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -277,7 +278,7 @@ test('UnnecessaryContains1', () => {
 });
 
 test('TypeIgnore1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeIgnore1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -289,7 +290,7 @@ test('TypeIgnore1', () => {
 });
 
 test('TypeIgnore2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeIgnore2.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -301,7 +302,7 @@ test('TypeIgnore2', () => {
 });
 
 test('TypeIgnore3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeIgnore3.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -313,7 +314,7 @@ test('TypeIgnore3', () => {
 });
 
 test('TypeIgnore4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeIgnore4.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -324,7 +325,7 @@ test('TypeIgnore4', () => {
 });
 
 test('TypeIgnore5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeIgnore5.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0);
@@ -335,14 +336,14 @@ test('TypeIgnore5', () => {
 });
 
 test('PyrightIgnore1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['pyrightIgnore1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 1);
 });
 
 test('PyrightIgnore2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['pyrightIgnore2.py'], configOptions);
     TestUtils.validateResults(analysisResults, 2);
@@ -353,14 +354,14 @@ test('PyrightIgnore2', () => {
 });
 
 test('PyrightComment1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['pyrightComment1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 9);
 });
 
 test('DuplicateImports1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, optional diagnostics are ignored.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['duplicateImports1.py'], configOptions);
@@ -373,7 +374,7 @@ test('DuplicateImports1', () => {
 });
 
 test('ParamNames1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['paramNames1.py'], configOptions);
     TestUtils.validateResults(analysisResults, 0, 7);
@@ -423,7 +424,7 @@ test('DuplicateDeclaration2', () => {
 });
 
 test('Strings1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['strings1.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
 
@@ -433,7 +434,7 @@ test('Strings1', () => {
 });
 
 test('UnusedExpression1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, this is a warning.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['unusedExpression1.py'], configOptions);
@@ -451,7 +452,7 @@ test('UnusedExpression1', () => {
 });
 
 test('UnusedImport1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Enabled it
     configOptions.diagnosticRuleSet.reportUnusedImport = 'warning';
@@ -470,7 +471,7 @@ test('UnusedImport1', () => {
 });
 
 test('UninitializedVariable1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, this is off.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['uninitializedVariable1.py'], configOptions);
@@ -483,7 +484,7 @@ test('UninitializedVariable1', () => {
 });
 
 test('UninitializedVariable2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, this is off.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['uninitializedVariable2.py'], configOptions);
@@ -502,7 +503,7 @@ test('RegionComments1', () => {
 });
 
 test('Deprecated1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['deprecated1.py'], configOptions);
@@ -548,7 +549,7 @@ test('Deprecated1', () => {
 });
 
 test('Deprecated2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['deprecated2.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0, 0, 0, undefined, undefined, 12);
@@ -559,7 +560,7 @@ test('Deprecated2', () => {
 });
 
 test('Deprecated3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['deprecated3.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0, 0, 0, undefined, undefined, 5);
@@ -570,7 +571,7 @@ test('Deprecated3', () => {
 });
 
 test('Deprecated4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['deprecated4.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0, 0, 0, undefined, undefined, 6);
@@ -581,7 +582,7 @@ test('Deprecated4', () => {
 });
 
 test('Deprecated5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['deprecated5.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0, 0, 0, undefined, undefined, 2);
diff --git a/packages/pyright-internal/src/tests/completions.test.ts b/packages/pyright-internal/src/tests/completions.test.ts
index 47cb19700..0f1d8b140 100644
--- a/packages/pyright-internal/src/tests/completions.test.ts
+++ b/packages/pyright-internal/src/tests/completions.test.ts
@@ -8,6 +8,7 @@ import assert from 'assert';
 import { CancellationToken } from 'vscode-languageserver';
 import { CompletionItemKind, MarkupKind } from 'vscode-languageserver-types';
 
+import { Uri } from '../common/uri/uri';
 import { CompletionOptions, CompletionProvider } from '../languageService/completionProvider';
 import { parseAndGetTestState } from './harness/fourslash/testState';
 
@@ -798,6 +799,7 @@ test('completion quote trigger', async () => {
     const state = parseAndGetTestState(code).state;
     const marker = state.getMarkerByName('marker');
     const filePath = marker.fileName;
+    const uri = Uri.file(filePath);
     const position = state.convertOffsetToPosition(filePath, marker.position);
 
     const options: CompletionOptions = {
@@ -809,8 +811,8 @@ test('completion quote trigger', async () => {
 
     const result = new CompletionProvider(
         state.program,
-        state.workspace.rootPath,
-        filePath,
+        state.workspace.rootUri,
+        uri,
         position,
         options,
         CancellationToken.None
@@ -836,6 +838,7 @@ test('completion quote trigger - middle', async () => {
     const state = parseAndGetTestState(code).state;
     const marker = state.getMarkerByName('marker');
     const filePath = marker.fileName;
+    const uri = Uri.file(filePath);
     const position = state.convertOffsetToPosition(filePath, marker.position);
 
     const options: CompletionOptions = {
@@ -847,8 +850,8 @@ test('completion quote trigger - middle', async () => {
 
     const result = new CompletionProvider(
         state.program,
-        state.workspace.rootPath,
-        filePath,
+        state.workspace.rootUri,
+        uri,
         position,
         options,
         CancellationToken.None
@@ -882,6 +885,7 @@ test('auto import sort text', async () => {
     while (state.workspace.service.test_program.analyze());
 
     const filePath = marker.fileName;
+    const uri = Uri.file(filePath);
     const position = state.convertOffsetToPosition(filePath, marker.position);
 
     const options: CompletionOptions = {
@@ -892,8 +896,8 @@ test('auto import sort text', async () => {
 
     const result = new CompletionProvider(
         state.program,
-        state.workspace.rootPath,
-        filePath,
+        state.workspace.rootUri,
+        uri,
         position,
         options,
         CancellationToken.None
diff --git a/packages/pyright-internal/src/tests/config.test.ts b/packages/pyright-internal/src/tests/config.test.ts
index 87bff940f..2fcd4a6ab 100644
--- a/packages/pyright-internal/src/tests/config.test.ts
+++ b/packages/pyright-internal/src/tests/config.test.ts
@@ -15,10 +15,11 @@ import { CommandLineOptions } from '../common/commandLineOptions';
 import { ConfigOptions, ExecutionEnvironment } from '../common/configOptions';
 import { ConsoleInterface, NullConsole } from '../common/console';
 import { NoAccessHost } from '../common/host';
-import { combinePaths, getBaseFileName, normalizePath, normalizeSlashes, realCasePath } from '../common/pathUtils';
+import { combinePaths, normalizePath, normalizeSlashes } from '../common/pathUtils';
 import { PythonVersion } from '../common/pythonVersion';
 import { createFromRealFileSystem } from '../common/realFileSystem';
 import { createServiceProvider } from '../common/serviceProviderExtensions';
+import { Uri } from '../common/uri/uri';
 import { TestAccessHost } from './harness/testAccessHost';
 import { TestFileSystem } from './harness/vfs/filesystem';
 
@@ -41,8 +42,8 @@ test('FindFilesWithConfigFile', () => {
     // The config file specifies a single file spec (a directory).
     assert.strictEqual(configOptions.include.length, 1, `failed creating options from ${cwd}`);
     assert.strictEqual(
-        normalizeSlashes(configOptions.projectRoot),
-        realCasePath(combinePaths(cwd, commandLineOptions.configFilePath), service.fs)
+        configOptions.projectRoot.key,
+        service.fs.realCasePath(Uri.file(combinePaths(cwd, commandLineOptions.configFilePath))).key
     );
 
     const fileList = service.test_getFileNamesFromFileSpecs();
@@ -67,7 +68,7 @@ test('FindFilesVirtualEnvAutoDetectExclude', () => {
 
     // There are 3 python files in the workspace, outside of myvenv
     // There is 1 python file in myvenv, which should be excluded
-    const fileNames = fileList.map((p) => getBaseFileName(p)).sort();
+    const fileNames = fileList.map((p) => p.fileName).sort();
     assert.deepStrictEqual(fileNames, ['sample1.py', 'sample2.py', 'sample3.py']);
 });
 
@@ -85,7 +86,7 @@ test('FindFilesVirtualEnvAutoDetectInclude', () => {
     // There are 3 python files in the workspace, outside of myvenv
     // There is 1 more python file in excluded folder
     // There is 1 python file in myvenv, which should be included
-    const fileNames = fileList.map((p) => getBaseFileName(p)).sort();
+    const fileNames = fileList.map((p) => p.fileName).sort();
     assert.deepStrictEqual(fileNames, ['library1.py', 'sample1.py', 'sample2.py', 'sample3.py']);
 });
 
@@ -132,8 +133,8 @@ test('SomeFileSpecsAreInvalid', () => {
     assert.strictEqual(configOptions.include.length, 4, `failed creating options from ${cwd}`);
     assert.strictEqual(configOptions.exclude.length, 1);
     assert.strictEqual(
-        normalizeSlashes(configOptions.projectRoot),
-        realCasePath(combinePaths(cwd, commandLineOptions.configFilePath), service.fs)
+        configOptions.projectRoot.getFilePath(),
+        service.fs.realCasePath(Uri.file(combinePaths(cwd, commandLineOptions.configFilePath))).getFilePath()
     );
 
     const fileList = service.test_getFileNamesFromFileSpecs();
@@ -157,13 +158,13 @@ test('ConfigBadJson', () => {
 });
 
 test('FindExecEnv1', () => {
-    const cwd = normalizePath(process.cwd());
+    const cwd = Uri.file(normalizePath(process.cwd()));
     const configOptions = new ConfigOptions(cwd);
 
     // Build a config option with three execution environments.
     const execEnv1 = new ExecutionEnvironment(
         'python',
-        'src/foo',
+        cwd.combinePaths('src/foo'),
         /* defaultPythonVersion */ undefined,
         /* defaultPythonPlatform */ undefined,
         /* defaultExtraPaths */ undefined
@@ -171,28 +172,29 @@ test('FindExecEnv1', () => {
     configOptions.executionEnvironments.push(execEnv1);
     const execEnv2 = new ExecutionEnvironment(
         'python',
-        'src',
+        cwd.combinePaths('src'),
         /* defaultPythonVersion */ undefined,
         /* defaultPythonPlatform */ undefined,
         /* defaultExtraPaths */ undefined
     );
     configOptions.executionEnvironments.push(execEnv2);
 
-    const file1 = normalizeSlashes(combinePaths(cwd, 'src/foo/bar.py'));
+    const file1 = cwd.combinePaths('src/foo/bar.py');
     assert.strictEqual(configOptions.findExecEnvironment(file1), execEnv1);
-    const file2 = normalizeSlashes(combinePaths(cwd, 'src/foo2/bar.py'));
+    const file2 = cwd.combinePaths('src/foo2/bar.py');
     assert.strictEqual(configOptions.findExecEnvironment(file2), execEnv2);
 
     // If none of the execution environments matched, we should get
     // a default environment with the root equal to that of the config.
-    const file4 = '/nothing/bar.py';
+    const file4 = Uri.file('/nothing/bar.py');
     const defaultExecEnv = configOptions.findExecEnvironment(file4);
     assert(defaultExecEnv.root);
-    assert.strictEqual(normalizeSlashes(defaultExecEnv.root), normalizeSlashes(configOptions.projectRoot));
+    const rootFilePath = Uri.isUri(defaultExecEnv.root) ? defaultExecEnv.root.getFilePath() : defaultExecEnv.root;
+    assert.strictEqual(normalizeSlashes(rootFilePath), normalizeSlashes(configOptions.projectRoot.getFilePath()));
 });
 
 test('PythonPlatform', () => {
-    const cwd = normalizePath(process.cwd());
+    const cwd = Uri.file(normalizePath(process.cwd()));
 
     const configOptions = new ConfigOptions(cwd);
 
@@ -216,16 +218,16 @@ test('PythonPlatform', () => {
 });
 
 test('AutoSearchPathsOn', () => {
-    const cwd = normalizePath(combinePaths(process.cwd(), 'src/tests/samples/project_src'));
+    const cwd = Uri.file(normalizePath(combinePaths(process.cwd(), 'src/tests/samples/project_src')));
     const nullConsole = new NullConsole();
     const service = createAnalyzer(nullConsole);
-    const commandLineOptions = new CommandLineOptions(cwd, /* fromVsCodeExtension */ false);
+    const commandLineOptions = new CommandLineOptions(cwd.getFilePath(), /* fromVsCodeExtension */ false);
     commandLineOptions.autoSearchPaths = true;
     service.setOptions(commandLineOptions);
 
     const configOptions = service.test_getConfigOptions(commandLineOptions);
 
-    const expectedExtraPaths = [realCasePath(combinePaths(cwd, 'src'), service.fs)];
+    const expectedExtraPaths = [service.fs.realCasePath(cwd.combinePaths('src'))];
     assert.deepStrictEqual(configOptions.defaultExtraPaths, expectedExtraPaths);
 });
 
@@ -274,19 +276,22 @@ test('AutoSearchPathsOnWithConfigExecEnv', () => {
 });
 
 test('AutoSearchPathsOnAndExtraPaths', () => {
-    const cwd = normalizePath(combinePaths(process.cwd(), 'src/tests/samples/project_src_with_config_no_extra_paths'));
     const nullConsole = new NullConsole();
     const service = createAnalyzer(nullConsole);
-    const commandLineOptions = new CommandLineOptions(cwd, /* fromVsCodeExtension */ false);
+    const cwd = Uri.file(
+        normalizePath(combinePaths(process.cwd(), 'src/tests/samples/project_src_with_config_no_extra_paths')),
+        service.fs.isCaseSensitive
+    );
+    const commandLineOptions = new CommandLineOptions(cwd.getFilePath(), /* fromVsCodeExtension */ false);
     commandLineOptions.autoSearchPaths = true;
     commandLineOptions.extraPaths = ['src/_vendored'];
     service.setOptions(commandLineOptions);
 
     const configOptions = service.test_getConfigOptions(commandLineOptions);
 
-    const expectedExtraPaths: string[] = [
-        realCasePath(combinePaths(cwd, 'src'), service.fs),
-        realCasePath(combinePaths(cwd, 'src', '_vendored'), service.fs),
+    const expectedExtraPaths: Uri[] = [
+        service.fs.realCasePath(cwd.combinePaths('src')),
+        service.fs.realCasePath(cwd.combinePaths('src', '_vendored')),
     ];
 
     assert.deepStrictEqual(configOptions.defaultExtraPaths, expectedExtraPaths);
@@ -314,11 +319,11 @@ test('FindFilesInMemoryOnly', () => {
     service.setOptions(commandLineOptions);
 
     // Open a file that is not backed by the file system.
-    const untitled = 'untitled:Untitled-1.py';
+    const untitled = Uri.parse('untitled:Untitled-1.py', true);
     service.setFileOpened(untitled, 1, '# empty');
 
     const fileList = service.test_getFileNamesFromFileSpecs();
-    assert(fileList.filter((f) => f === untitled));
+    assert(fileList.filter((f) => f.equals(untitled)));
 });
 
 test('verify config fileSpecs after cloning', () => {
@@ -327,7 +332,7 @@ test('verify config fileSpecs after cloning', () => {
         ignore: ['**/node_modules/**'],
     };
 
-    const config = new ConfigOptions(process.cwd());
+    const config = new ConfigOptions(Uri.file(process.cwd()));
     const sp = createServiceProvider(fs, new NullConsole());
     config.initializeFromJson(configFile, undefined, sp, new TestAccessHost());
     const cloned = createConfigOptionsFrom(config);
diff --git a/packages/pyright-internal/src/tests/documentSymbolCollector.test.ts b/packages/pyright-internal/src/tests/documentSymbolCollector.test.ts
index 4bf83a5ad..beafc270a 100644
--- a/packages/pyright-internal/src/tests/documentSymbolCollector.test.ts
+++ b/packages/pyright-internal/src/tests/documentSymbolCollector.test.ts
@@ -6,6 +6,7 @@
  * Tests documentSymbolCollector
  */
 
+import { Uri } from '../common/uri/uri';
 import { parseAndGetTestState } from './harness/fourslash/testState';
 import { verifyReferencesAtPosition } from './testStateUtils';
 
@@ -225,7 +226,7 @@ test('use localName import alias', () => {
     const references = state
         .getRangesByText()
         .get('tools')!
-        .map((r) => ({ path: r.fileName, range: state.convertPositionRange(r) }));
+        .map((r) => ({ uri: Uri.file(r.fileName), range: state.convertPositionRange(r) }));
 
     state.verifyFindAllReferences({
         marker1: { references },
@@ -288,7 +289,7 @@ test('use localName import module', () => {
     const references = state
         .getRangesByText()
         .get('tools')!
-        .map((r) => ({ path: r.fileName, range: state.convertPositionRange(r) }));
+        .map((r) => ({ uri: Uri.file(r.fileName), range: state.convertPositionRange(r) }));
 
     state.verifyFindAllReferences({
         marker1: { references },
diff --git a/packages/pyright-internal/src/tests/filesystem.test.ts b/packages/pyright-internal/src/tests/filesystem.test.ts
index 8961631cc..d08470c66 100644
--- a/packages/pyright-internal/src/tests/filesystem.test.ts
+++ b/packages/pyright-internal/src/tests/filesystem.test.ts
@@ -9,6 +9,7 @@
 import assert from 'assert';
 
 import { combinePaths, normalizeSlashes } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
 import * as host from './harness/testHost';
 import * as factory from './harness/vfs/factory';
 import * as vfs from './harness/vfs/filesystem';
@@ -20,54 +21,55 @@ test('CreateVFS', () => {
 });
 
 test('Folders', () => {
-    const cwd = normalizeSlashes('/');
-    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd });
+    const cwd = Uri.file(normalizeSlashes('/'));
+    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd: cwd.getFilePath() });
 
     // no such dir exist
     assert.throws(() => {
-        fs.chdir('a');
+        fs.chdir(cwd.combinePaths('a'));
     });
 
-    fs.mkdirSync('a');
-    fs.chdir('a');
+    fs.mkdirSync(cwd.combinePaths('a'));
+    fs.chdir(cwd.combinePaths('a'));
     assert.equal(fs.cwd(), normalizeSlashes('/a'));
 
-    fs.chdir('..');
-    fs.rmdirSync('a');
+    fs.chdir(cwd.combinePaths('..'));
+    fs.rmdirSync(cwd.combinePaths('a'));
 
     // no such dir exist
     assert.throws(() => {
-        fs.chdir('a');
+        fs.chdir(cwd.combinePaths('a'));
     });
 });
 
 test('Folders Recursive', () => {
-    const cwd = normalizeSlashes('/');
-    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd });
+    const cwd = Uri.file(normalizeSlashes('/'));
+    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd: cwd.getFilePath() });
 
     // no such dir exist
     assert.throws(() => {
-        fs.chdir('a');
+        fs.chdir(cwd.combinePaths('a'));
     });
 
-    const path = combinePaths('/', 'a', 'b', 'c');
+    const path = cwd.combinePaths('a', 'b', 'c');
     fs.mkdirSync(path, { recursive: true });
 
     assert(fs.existsSync(path));
 });
 
 test('Files', () => {
-    const cwd = normalizeSlashes('/');
-    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd });
+    const cwd = Uri.file(normalizeSlashes('/'));
+    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd: cwd.getFilePath() });
 
-    fs.writeFileSync('1.txt', 'hello', 'utf8');
-    const buffer1 = fs.readFileSync('1.txt');
+    const uri = cwd.combinePaths('1.txt');
+    fs.writeFileSync(uri, 'hello', 'utf8');
+    const buffer1 = fs.readFileSync(uri);
     assert.equal(buffer1.toString(), 'hello');
 
-    const p = normalizeSlashes('a/b/c');
-    fs.mkdirpSync(p);
+    const p = cwd.combinePaths('a/b/c');
+    fs.mkdirpSync(p.getFilePath());
 
-    const f = combinePaths(p, '2.txt');
+    const f = p.combinePaths('2.txt');
     fs.writeFileSync(f, 'hi');
 
     const str = fs.readFileSync(f, 'utf8');
@@ -90,11 +92,11 @@ test('CreateRich', () => {
     // files + directory + root
     assert.equal(entries.length, 10);
 
-    assert.equal(fs.readFileSync(normalizeSlashes('/a/b/c/1.txt'), 'ascii'), 'hello1');
-    assert.equal(fs.readFileSync(normalizeSlashes('/a/b/2.txt'), 'utf8'), 'hello2');
-    assert.equal(fs.readFileSync(normalizeSlashes('/a/3.txt'), 'utf-8'), 'hello3');
-    assert.equal(fs.readFileSync(normalizeSlashes('/4.txt'), 'utf16le'), 'hello4');
-    assert.equal(fs.readFileSync(normalizeSlashes('/a/c/5.txt'), 'ucs2'), 'hello5');
+    assert.equal(fs.readFileSync(Uri.file(normalizeSlashes('/a/b/c/1.txt')), 'ascii'), 'hello1');
+    assert.equal(fs.readFileSync(Uri.file(normalizeSlashes('/a/b/2.txt')), 'utf8'), 'hello2');
+    assert.equal(fs.readFileSync(Uri.file(normalizeSlashes('/a/3.txt')), 'utf-8'), 'hello3');
+    assert.equal(fs.readFileSync(Uri.file(normalizeSlashes('/4.txt')), 'utf16le'), 'hello4');
+    assert.equal(fs.readFileSync(Uri.file(normalizeSlashes('/a/c/5.txt')), 'ucs2'), 'hello5');
 });
 
 test('Shadow', () => {
@@ -124,19 +126,19 @@ test('Shadow', () => {
 });
 
 test('Diffing', () => {
-    const cwd = normalizeSlashes('/');
-    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd });
+    const cwd = Uri.file(normalizeSlashes('/'));
+    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd: cwd.getFilePath() });
 
     // first snapshot
     fs.snapshot();
-    fs.writeFileSync('test1.txt', 'hello1');
+    fs.writeFileSync(cwd.combinePaths('test1.txt'), 'hello1');
 
     // compared with original
     assert.equal(countFile(fs.diff()!), 1);
 
     // second snapshot
     fs.snapshot();
-    fs.writeFileSync('test2.txt', 'hello2');
+    fs.writeFileSync(cwd.combinePaths('test2.txt'), 'hello2');
 
     // compared with first snapshot
     assert.equal(countFile(fs.diff()!), 1);
@@ -148,11 +150,11 @@ test('Diffing', () => {
     const s = fs.shadowRoot!.shadow();
 
     // "test2.txt" only exist in first snapshot
-    assert(!s.existsSync('test2.txt'));
+    assert(!s.existsSync(cwd.combinePaths('test2.txt')));
 
     // create parallel universe where it has another version of test2.txt with different content
     // compared to second snapshot which forked from same first snapshot
-    s.writeFileSync('test2.txt', 'hello3');
+    s.writeFileSync(cwd.combinePaths('test2.txt'), 'hello3');
 
     // diff between non direct snapshots
     // diff gives test2.txt even though it exist in both snapshot
@@ -170,16 +172,16 @@ test('createFromFileSystem1', () => {
     });
 
     // check existing typeshed folder on virtual path inherited from base snapshot from physical file system
-    const entries = fs.readdirSync(factory.typeshedFolder);
+    const entries = fs.readdirSync(Uri.file(factory.typeshedFolder));
     assert(entries.length > 0);
 
     // confirm file
-    assert.equal(fs.readFileSync(filepath, 'utf8'), content);
+    assert.equal(fs.readFileSync(Uri.file(filepath), 'utf8'), content);
 });
 
 test('createFromFileSystem2', () => {
     const fs = factory.createFromFileSystem(host.HOST, /* ignoreCase */ true, { cwd: factory.srcFolder });
-    const entries = fs.readdirSync(factory.typeshedFolder.toUpperCase());
+    const entries = fs.readdirSync(Uri.file(factory.typeshedFolder.toUpperCase()));
     assert(entries.length > 0);
 });
 
@@ -190,7 +192,7 @@ test('createFromFileSystemWithCustomTypeshedPath', () => {
         meta: { [factory.typeshedFolder]: invalidpath },
     });
 
-    const entries = fs.readdirSync(factory.typeshedFolder);
+    const entries = fs.readdirSync(Uri.file(factory.typeshedFolder));
     assert(entries.filter((e) => e.endsWith('.md')).length > 0);
 });
 
@@ -200,7 +202,7 @@ test('createFromFileSystemWithMetadata', () => {
         meta: { unused: 'unused' },
     });
 
-    assert(fs.existsSync(factory.srcFolder));
+    assert(fs.existsSync(Uri.file(factory.srcFolder)));
 });
 
 function countFile(files: vfs.FileSet): number {
diff --git a/packages/pyright-internal/src/tests/fourSlashParser.test.ts b/packages/pyright-internal/src/tests/fourSlashParser.test.ts
index de53f3112..77dbc7919 100644
--- a/packages/pyright-internal/src/tests/fourSlashParser.test.ts
+++ b/packages/pyright-internal/src/tests/fourSlashParser.test.ts
@@ -9,8 +9,9 @@
 
 import assert from 'assert';
 
-import { combinePaths, getBaseFileName, normalizeSlashes } from '../common/pathUtils';
+import { getBaseFileName, normalizeSlashes } from '../common/pathUtils';
 import { compareStringsCaseSensitive } from '../common/stringUtils';
+import { Uri } from '../common/uri/uri';
 import { parseTestData } from './harness/fourslash/fourSlashParser';
 import { CompilerSettings } from './harness/fourslash/fourSlashTypes';
 import * as host from './harness/testHost';
@@ -89,7 +90,7 @@ test('Library options', () => {
 
     const data = parseTestData('.', code, 'test.py');
 
-    assert.equal(data.files[0].fileName, normalizeSlashes(combinePaths(factory.libFolder, 'file1.py')));
+    assert.equal(data.files[0].fileName, factory.libFolder.combinePaths('file1.py').getFilePath());
 });
 
 test('Range', () => {
@@ -222,8 +223,7 @@ test('Multiple Files', () => {
 
     assert.equal(data.files.filter((f) => f.fileName === normalizeSlashes('./src/A.py'))[0].content, getContent('A'));
     assert.equal(
-        data.files.filter((f) => f.fileName === normalizeSlashes(combinePaths(factory.libFolder, 'src/B.py')))[0]
-            .content,
+        data.files.filter((f) => f.fileName === factory.libFolder.combinePaths('src/B.py').getFilePath())[0].content,
         getContent('B')
     );
     assert.equal(data.files.filter((f) => f.fileName === normalizeSlashes('./src/C.py'))[0].content, getContent('C'));
@@ -312,7 +312,10 @@ test('fourSlashWithFileSystem', () => {
     });
 
     for (const file of data.files) {
-        assert.equal(fs.readFileSync(file.fileName, 'utf8'), getContent(getBaseFileName(file.fileName, '.py', false)));
+        assert.equal(
+            fs.readFileSync(Uri.file(file.fileName), 'utf8'),
+            getContent(getBaseFileName(file.fileName, '.py', false))
+        );
     }
 });
 
diff --git a/packages/pyright-internal/src/tests/harness/fourslash/fourSlashParser.ts b/packages/pyright-internal/src/tests/harness/fourslash/fourSlashParser.ts
index 62badb436..59f7185b8 100644
--- a/packages/pyright-internal/src/tests/harness/fourslash/fourSlashParser.ts
+++ b/packages/pyright-internal/src/tests/harness/fourslash/fourSlashParser.ts
@@ -17,13 +17,13 @@ import {
 } from '../../../common/pathUtils';
 import { distlibFolder, libFolder } from '../vfs/factory';
 import {
-    fileMetadataNames,
     FourSlashData,
     FourSlashFile,
     GlobalMetadataOptionNames,
     Marker,
     MetadataOptionNames,
     Range,
+    fileMetadataNames,
 } from './fourSlashTypes';
 
 /**
@@ -70,13 +70,13 @@ export function parseTestData(basePath: string, contents: string, fileName: stri
 
         if (toBoolean(currentFileOptions[MetadataOptionNames.library])) {
             currentFileName = normalizePath(
-                combinePaths(libFolder, getRelativePath(currentFileName, normalizedBasePath))
+                combinePaths(libFolder.getFilePath(), getRelativePath(currentFileName, normalizedBasePath))
             );
         }
 
         if (toBoolean(currentFileOptions[MetadataOptionNames.distLibrary])) {
             currentFileName = normalizePath(
-                combinePaths(distlibFolder, getRelativePath(currentFileName, normalizedBasePath))
+                combinePaths(distlibFolder.getFilePath(), getRelativePath(currentFileName, normalizedBasePath))
             );
         }
 
diff --git a/packages/pyright-internal/src/tests/harness/fourslash/testLanguageService.ts b/packages/pyright-internal/src/tests/harness/fourslash/testLanguageService.ts
index 26d4598ee..73cc2b578 100644
--- a/packages/pyright-internal/src/tests/harness/fourslash/testLanguageService.ts
+++ b/packages/pyright-internal/src/tests/harness/fourslash/testLanguageService.ts
@@ -6,7 +6,6 @@
  * Test mock that implements LanguageServiceInterface
  */
 
-import * as path from 'path';
 import { CancellationToken, CodeAction, ExecuteCommandParams } from 'vscode-languageserver';
 
 import {
@@ -22,8 +21,9 @@ import { ConfigOptions } from '../../../common/configOptions';
 import { ConsoleInterface } from '../../../common/console';
 import * as debug from '../../../common/debug';
 import { FileSystem } from '../../../common/fileSystem';
+import { ServiceProvider } from '../../../common/serviceProvider';
 import { Range } from '../../../common/textRange';
-import { UriParser } from '../../../common/uriParser';
+import { Uri } from '../../../common/uri/uri';
 import { LanguageServerInterface, MessageAction, ServerSettings, WindowInterface } from '../../../languageServerBase';
 import { CodeActionProvider } from '../../../languageService/codeActionProvider';
 import {
@@ -34,7 +34,6 @@ import {
 } from '../../../workspaceFactory';
 import { TestAccessHost } from '../testAccessHost';
 import { HostSpecificFeatures } from './testState';
-import { ServiceProvider } from '../../../common/serviceProvider';
 
 export class TestFeatures implements HostSpecificFeatures {
     importResolverFactory: ImportResolverFactory = AnalyzerService.createImportResolver;
@@ -62,11 +61,11 @@ export class TestFeatures implements HostSpecificFeatures {
 
     getCodeActionsForPosition(
         workspace: Workspace,
-        filePath: string,
+        fileUri: Uri,
         range: Range,
         token: CancellationToken
     ): Promise<CodeAction[]> {
-        return CodeActionProvider.getCodeActionsForPosition(workspace, filePath, range, undefined, token);
+        return CodeActionProvider.getCodeActionsForPosition(workspace, fileUri, range, undefined, token);
     }
     execute(ls: LanguageServerInterface, params: ExecuteCommandParams, token: CancellationToken): Promise<any> {
         const controller = new CommandController(ls);
@@ -75,21 +74,18 @@ export class TestFeatures implements HostSpecificFeatures {
 }
 
 export class TestLanguageService implements LanguageServerInterface {
-    readonly rootPath = path.sep;
+    readonly rootUri = Uri.file('/');
     readonly window = new TestWindow();
     readonly supportAdvancedEdits = true;
 
     private readonly _workspace: Workspace;
     private readonly _defaultWorkspace: Workspace;
-    private readonly _uriParser: UriParser;
 
     constructor(workspace: Workspace, readonly console: ConsoleInterface, readonly fs: FileSystem) {
         this._workspace = workspace;
-        this._uriParser = new UriParser(this.fs);
         this._defaultWorkspace = {
             workspaceName: '',
-            rootPath: '',
-            uri: '',
+            rootUri: Uri.empty(),
             pythonPath: undefined,
             pythonPathKind: WorkspacePythonPathKind.Mutable,
             kinds: [WellKnownWorkspaceKinds.Test],
@@ -97,7 +93,7 @@ export class TestLanguageService implements LanguageServerInterface {
                 console: this.console,
                 hostFactory: () => new TestAccessHost(),
                 importResolverFactory: AnalyzerService.createImportResolver,
-                configOptions: new ConfigOptions('.'),
+                configOptions: new ConfigOptions(Uri.empty()),
                 fileSystem: this.fs,
             }),
             disableLanguageServices: false,
@@ -109,16 +105,12 @@ export class TestLanguageService implements LanguageServerInterface {
         };
     }
 
-    decodeTextDocumentUri(uriString: string): string {
-        return this._uriParser.decodeTextDocumentUri(uriString);
-    }
-
     getWorkspaces(): Promise<Workspace[]> {
         return Promise.resolve([this._workspace, this._defaultWorkspace]);
     }
 
-    getWorkspaceForFile(filePath: string): Promise<Workspace> {
-        if (filePath.startsWith(this._workspace.rootPath)) {
+    getWorkspaceForFile(uri: Uri): Promise<Workspace> {
+        if (uri.startsWith(this._workspace.rootUri)) {
             return Promise.resolve(this._workspace);
         }
 
diff --git a/packages/pyright-internal/src/tests/harness/fourslash/testState.ts b/packages/pyright-internal/src/tests/harness/fourslash/testState.ts
index 06ba5d2a1..4798c5beb 100644
--- a/packages/pyright-internal/src/tests/harness/fourslash/testState.ts
+++ b/packages/pyright-internal/src/tests/harness/fourslash/testState.ts
@@ -39,22 +39,15 @@ import * as debug from '../../../common/debug';
 import { DiagnosticCategory } from '../../../common/diagnostic';
 import { FileEditAction } from '../../../common/editAction';
 import { ReadOnlyFileSystem } from '../../../common/fileSystem';
-import {
-    combinePaths,
-    convertPathToUri,
-    getDirectoryPath,
-    getFileExtension,
-    getFileSpec,
-    normalizePath,
-    normalizeSlashes,
-    setTestingMode,
-} from '../../../common/pathUtils';
+import { getFileExtension, normalizePath, normalizeSlashes } from '../../../common/pathUtils';
 import { convertOffsetToPosition, convertPositionToOffset } from '../../../common/positionUtils';
 import { ServiceProvider } from '../../../common/serviceProvider';
 import { createServiceProvider } from '../../../common/serviceProviderExtensions';
 import { compareStringsCaseInsensitive, compareStringsCaseSensitive } from '../../../common/stringUtils';
 import { DocumentRange, Position, Range as PositionRange, TextRange, rangesAreEqual } from '../../../common/textRange';
 import { TextRangeCollection } from '../../../common/textRangeCollection';
+import { Uri } from '../../../common/uri/uri';
+import { getFileSpec, setTestingMode } from '../../../common/uri/uriUtils';
 import { convertToWorkspaceEdit } from '../../../common/workspaceEditUtils';
 import { LanguageServerInterface } from '../../../languageServerBase';
 import { CallHierarchyProvider } from '../../../languageService/callHierarchyProvider';
@@ -113,7 +106,7 @@ export interface HostSpecificFeatures {
     runIndexer(workspace: Workspace, noStdLib: boolean, options?: string): void;
     getCodeActionsForPosition(
         workspace: Workspace,
-        filePath: string,
+        fileUri: Uri,
         range: PositionRange,
         token: CancellationToken
     ): Promise<CodeAction[]>;
@@ -121,7 +114,7 @@ export interface HostSpecificFeatures {
     execute(ls: LanguageServerInterface, params: ExecuteCommandParams, token: CancellationToken): Promise<any>;
 }
 
-const testAccessHost = new TestAccessHost(vfs.MODULE_PATH, [libFolder, distlibFolder]);
+const testAccessHost = new TestAccessHost(Uri.file(vfs.MODULE_PATH), [libFolder, distlibFolder]);
 
 export class TestState {
     private readonly _cancellationToken: TestCancellationToken;
@@ -195,10 +188,9 @@ export class TestState {
 
         this.workspace = {
             workspaceName: 'test workspace',
-            rootPath: vfsInfo.projectRoot,
+            rootUri: Uri.file(vfsInfo.projectRoot),
             pythonPath: undefined,
             pythonPathKind: WorkspacePythonPathKind.Mutable,
-            uri: convertPathToUri(this.fs, vfsInfo.projectRoot),
             kinds: [WellKnownWorkspaceKinds.Test],
             service: service,
             disableLanguageServices: false,
@@ -255,7 +247,7 @@ export class TestState {
         for (const filePath of this.files) {
             const file = this._vfsFiles[filePath] as vfs.File;
             if (file.meta?.[MetadataOptionNames.ipythonMode]) {
-                this.program.getSourceFile(filePath)?.test_enableIPythonMode(true);
+                this.program.getSourceFile(Uri.file(filePath))?.test_enableIPythonMode(true);
             }
         }
     }
@@ -294,8 +286,9 @@ export class TestState {
     }
 
     getMappedFilePath(path: string): string {
-        this.importResolver.ensurePartialStubPackages(this.configOptions.findExecEnvironment(path));
-        return this.fs.getMappedFilePath(path);
+        const uri = Uri.file(path);
+        this.importResolver.ensurePartialStubPackages(this.configOptions.findExecEnvironment(uri));
+        return this.fs.getMappedUri(uri).getFilePath();
     }
 
     getMarkerName(m: Marker): string {
@@ -346,14 +339,6 @@ export class TestState {
         return this.convertOffsetsToRange(range.fileName, range.pos, range.end);
     }
 
-    convertPathToUri(path: string) {
-        return convertPathToUri(this.fs, path);
-    }
-
-    getDirectoryPath(path: string) {
-        return getDirectoryPath(path);
-    }
-
     getPathSep() {
         return path.sep;
     }
@@ -461,7 +446,7 @@ export class TestState {
         fileToOpen.fileName = normalizeSlashes(fileToOpen.fileName);
         this.activeFile = fileToOpen;
 
-        this.program.setFileOpened(this.activeFile.fileName, 1, fileToOpen.content);
+        this.program.setFileOpened(Uri.file(this.activeFile.fileName), 1, fileToOpen.content);
 
         return fileToOpen;
     }
@@ -671,7 +656,7 @@ export class TestState {
             resultPerFile: Map<
                 string,
                 {
-                    filePath: string;
+                    fileUri: Uri;
                     parseResults: ParseResults | undefined;
                     errors: Diagnostic[];
                     warnings: Diagnostic[];
@@ -757,6 +742,11 @@ export class TestState {
         function convertToString(args: any[] | undefined): string[] | undefined {
             return args?.map((a) => {
                 if (isString(a)) {
+                    // Might be a URI. For comparison purposes in a test, convert it into a
+                    // file path.
+                    if (a.startsWith('file://')) {
+                        return normalizeSlashes(Uri.parse(a, true).getFilePath());
+                    }
                     return normalizeSlashes(a);
                 }
 
@@ -768,6 +758,15 @@ export class TestState {
     async verifyCommand(command: Command, files: { [filePath: string]: string }): Promise<any> {
         this.analyze();
 
+        // Convert command arguments to file Uri strings. That's the expected input for command arguments.
+        const convertedArgs = command.arguments?.map((arg) => {
+            if (typeof arg === 'string' && (arg.endsWith('.py') || arg.endsWith('.pyi'))) {
+                return Uri.file(arg).toString();
+            }
+            return arg;
+        });
+        command.arguments = convertedArgs;
+
         const commandResult = await this._hostSpecificFeatures.execute(
             new TestLanguageService(this.workspace, this.console, this.fs),
             { command: command.command, arguments: command.arguments || [] },
@@ -874,7 +873,7 @@ export class TestState {
             const rangePos = this.convertOffsetsToRange(range.fileName, range.pos, range.end);
             const provider = new HoverProvider(
                 this.program,
-                range.fileName,
+                Uri.file(range.fileName),
                 rangePos.start,
                 kind,
                 CancellationToken.None
@@ -1091,7 +1090,7 @@ export class TestState {
 
             const actual = new SignatureHelpProvider(
                 this.program,
-                fileName,
+                Uri.file(fileName),
                 position,
                 docFormat,
                 /* hasSignatureLabelOffsetCapability */ true,
@@ -1154,7 +1153,7 @@ export class TestState {
                 references: DocumentRange[];
             };
         },
-        createDocumentRange?: (filePath: string, result: CollectionResult, parseResults: ParseResults) => DocumentRange,
+        createDocumentRange?: (fileUri: Uri, result: CollectionResult, parseResults: ParseResults) => DocumentRange,
         convertToLocation?: (fs: ReadOnlyFileSystem, ranges: DocumentRange) => Location | undefined
     ) {
         this.analyze();
@@ -1167,7 +1166,13 @@ export class TestState {
                 continue;
             }
 
-            const expected = map[name].references;
+            let expected = map[name].references;
+            expected = expected.map((c) => {
+                return {
+                    ...c,
+                    uri: c.uri ?? Uri.file((c as any).path),
+                };
+            });
 
             const position = this.convertOffsetToPosition(fileName, marker.position);
 
@@ -1176,7 +1181,7 @@ export class TestState {
                 CancellationToken.None,
                 createDocumentRange,
                 convertToLocation
-            ).reportReferences(fileName, position, /* includeDeclaration */ true);
+            ).reportReferences(Uri.file(fileName), position, /* includeDeclaration */ true);
             assert.strictEqual(actual?.length ?? 0, expected.length, `${name} has failed`);
 
             for (const r of convertDocumentRangesToLocation(this.program.fileSystem, expected, convertToLocation)) {
@@ -1207,7 +1212,7 @@ export class TestState {
             const position = this.convertOffsetToPosition(fileName, marker.position);
             const actual = new CallHierarchyProvider(
                 this.program,
-                fileName,
+                Uri.file(fileName),
                 position,
                 CancellationToken.None
             ).getIncomingCalls();
@@ -1221,9 +1226,7 @@ export class TestState {
                     assert.strictEqual(expectedRange?.filter((e) => this._deepEqual(a.from.range, e)).length, 1);
                     assert.strictEqual(expectedName?.filter((e) => this._deepEqual(a.from.name, e)).length, 1);
                     assert.ok(
-                        expectedFilePath?.filter((e) =>
-                            this._deepEqual(a.from.uri, convertPathToUri(this.program.fileSystem, e))
-                        ).length >= 1
+                        expectedFilePath?.filter((e) => this._deepEqual(a.from.uri, Uri.file(e).toString())).length >= 1
                     );
                 }
             }
@@ -1252,7 +1255,7 @@ export class TestState {
             const position = this.convertOffsetToPosition(fileName, marker.position);
             const actual = new CallHierarchyProvider(
                 this.program,
-                fileName,
+                Uri.file(fileName),
                 position,
                 CancellationToken.None
             ).getOutgoingCalls();
@@ -1265,9 +1268,7 @@ export class TestState {
                     assert.strictEqual(expectedRange?.filter((e) => this._deepEqual(a.to.range, e)).length, 1);
                     assert.strictEqual(expectedName?.filter((e) => this._deepEqual(a.to.name, e)).length, 1);
                     assert.ok(
-                        expectedFilePath?.filter((e) =>
-                            this._deepEqual(a.to.uri, convertPathToUri(this.program.fileSystem, e))
-                        ).length >= 1
+                        expectedFilePath?.filter((e) => this._deepEqual(a.to.uri, Uri.file(e).toString())).length >= 1
                     );
                 }
             }
@@ -1304,7 +1305,7 @@ export class TestState {
             const position = this.convertOffsetToPosition(fileName, marker.position);
             const actual = new DocumentHighlightProvider(
                 this.program,
-                fileName,
+                Uri.file(fileName),
                 position,
                 CancellationToken.None
             ).getDocumentHighlight();
@@ -1322,6 +1323,16 @@ export class TestState {
         }
     }
 
+    fixupDefinitionsToMatchExpected(actual: DocumentRange[] | undefined): any {
+        return actual?.map((a) => {
+            const { uri, ...restOfActual } = a;
+            return {
+                ...restOfActual,
+                path: uri.getFilePath(),
+            };
+        });
+    }
+
     verifyFindDefinitions(
         map: {
             [marker: string]: {
@@ -1341,25 +1352,26 @@ export class TestState {
             }
 
             const expected = map[name].definitions;
-
+            const uri = Uri.file(fileName);
             // If we're going to def from a file, act like it's open.
-            if (!this.program.getSourceFileInfo(fileName)) {
+            if (!this.program.getSourceFileInfo(uri)) {
                 const file = this.testData.files.find((v) => v.fileName === fileName);
                 if (file) {
-                    this.program.setFileOpened(fileName, file.version, file.content);
+                    this.program.setFileOpened(uri, file.version, file.content);
                 }
             }
 
             const position = this.convertOffsetToPosition(fileName, marker.position);
-            const actual = new DefinitionProvider(
+            let actual = new DefinitionProvider(
                 this.program,
-                fileName,
+                uri,
                 position,
                 filter,
                 CancellationToken.None
             ).getDefinitions();
 
             assert.equal(actual?.length ?? 0, expected.length, `No definitions found for marker "${name}"`);
+            actual = this.fixupDefinitionsToMatchExpected(actual!);
 
             for (const r of expected) {
                 assert.equal(
@@ -1389,12 +1401,13 @@ export class TestState {
             const expected = map[name].definitions;
 
             const position = this.convertOffsetToPosition(fileName, marker.position);
-            const actual = new TypeDefinitionProvider(
+            let actual = new TypeDefinitionProvider(
                 this.program,
-                fileName,
+                Uri.file(fileName),
                 position,
                 CancellationToken.None
             ).getDefinitions();
+            actual = this.fixupDefinitionsToMatchExpected(actual!);
 
             assert.strictEqual(actual?.length ?? 0, expected.length, name);
 
@@ -1424,16 +1437,23 @@ export class TestState {
             }
 
             const expected = map[name];
+            expected.changes = expected.changes.map((c) => {
+                return {
+                    ...c,
+                    fileUri: c.fileUri ?? Uri.file((c as any).filePath),
+                };
+            });
 
             const position = this.convertOffsetToPosition(fileName, marker.position);
-            const actual = new RenameProvider(this.program, fileName, position, CancellationToken.None).renameSymbol(
-                expected.newName,
-                /* isDefaultWorkspace */ false,
-                isUntitled
-            );
+            const actual = new RenameProvider(
+                this.program,
+                Uri.file(fileName),
+                position,
+                CancellationToken.None
+            ).renameSymbol(expected.newName, /* isDefaultWorkspace */ false, isUntitled);
 
             verifyWorkspaceEdit(
-                convertToWorkspaceEdit(this.program.fileSystem, { edits: expected.changes, fileOperations: [] }),
+                convertToWorkspaceEdit({ edits: expected.changes, fileOperations: [] }),
                 actual ?? { documentChanges: [] }
             );
         }
@@ -1510,8 +1530,8 @@ export class TestState {
 
         const provider = new CompletionProvider(
             this.program,
-            this.workspace.rootPath,
-            filePath,
+            this.workspace.rootUri,
+            Uri.file(filePath),
             completionPosition,
             options,
             CancellationToken.None
@@ -1606,7 +1626,7 @@ export class TestState {
     }
 
     private _convertGlobalOptionsToConfigOptions(projectRoot: string, mountPaths?: Map<string, string>): ConfigOptions {
-        const configOptions = new ConfigOptions(projectRoot);
+        const configOptions = new ConfigOptions(Uri.file(projectRoot));
 
         // add more global options as we need them
         const newConfigOptions = this._applyTestConfigOptions(configOptions, mountPaths);
@@ -1626,17 +1646,17 @@ export class TestState {
 
         // make sure we set typing path
         if (configOptions.stubPath === undefined) {
-            configOptions.stubPath = normalizePath(combinePaths(vfs.MODULE_PATH, 'typings'));
+            configOptions.stubPath = Uri.file(vfs.MODULE_PATH).combinePaths('typings');
         }
 
-        configOptions.include.push(getFileSpec(this.serviceProvider, configOptions.projectRoot, '.'));
-        configOptions.exclude.push(getFileSpec(this.serviceProvider, configOptions.projectRoot, typeshedFolder));
-        configOptions.exclude.push(getFileSpec(this.serviceProvider, configOptions.projectRoot, distlibFolder));
-        configOptions.exclude.push(getFileSpec(this.serviceProvider, configOptions.projectRoot, libFolder));
+        configOptions.include.push(getFileSpec(configOptions.projectRoot, '.'));
+        configOptions.exclude.push(getFileSpec(configOptions.projectRoot, typeshedFolder));
+        configOptions.exclude.push(getFileSpec(configOptions.projectRoot, distlibFolder.getFilePath()));
+        configOptions.exclude.push(getFileSpec(configOptions.projectRoot, libFolder.getFilePath()));
 
         if (mountPaths) {
             for (const mountPath of mountPaths.keys()) {
-                configOptions.exclude.push(getFileSpec(this.serviceProvider, configOptions.projectRoot, mountPath));
+                configOptions.exclude.push(getFileSpec(configOptions.projectRoot, mountPath));
             }
         }
 
@@ -1648,7 +1668,7 @@ export class TestState {
     }
 
     private _getParseResult(fileName: string) {
-        const file = this.program.getBoundSourceFile(fileName)!;
+        const file = this.program.getBoundSourceFile(Uri.file(fileName))!;
         return file?.getParseResults();
     }
 
@@ -1661,7 +1681,7 @@ export class TestState {
         }
 
         // slow path
-        const fileContents = this.fs.readFileSync(fileName, 'utf8');
+        const fileContents = this.fs.readFileSync(Uri.file(fileName), 'utf8');
         const tokenizer = new Tokenizer();
         return tokenizer.tokenize(fileContents).lines;
     }
@@ -1680,10 +1700,11 @@ export class TestState {
     private _editScriptAndUpdateMarkers(fileName: string, editStart: number, editEnd: number, newText: string) {
         let fileContent = this.getFileContent(fileName);
         fileContent = fileContent.slice(0, editStart) + newText + fileContent.slice(editEnd);
+        const uri = Uri.file(fileName);
 
-        this.testFS.writeFileSync(fileName, fileContent, 'utf8');
-        const newVersion = (this.program.getSourceFile(fileName)?.getClientVersion() ?? -1) + 1;
-        this.program.setFileOpened(fileName, newVersion, fileContent);
+        this.testFS.writeFileSync(uri, fileContent, 'utf8');
+        const newVersion = (this.program.getSourceFile(uri)?.getClientVersion() ?? -1) + 1;
+        this.program.setFileOpened(uri, newVersion, fileContent);
 
         for (const marker of this.testData.markers) {
             if (marker.fileName === fileName) {
@@ -1834,20 +1855,23 @@ export class TestState {
     }
 
     private _getDiagnosticsPerFile() {
-        const sourceFiles = this.files.map((f) => this.program.getSourceFile(f));
+        const sourceFiles = this.files.map((f) => this.program.getSourceFile(Uri.file(f)));
         const results = sourceFiles.map((sourceFile, index) => {
             if (sourceFile) {
                 const diagnostics = sourceFile.getDiagnostics(this.configOptions) || [];
-                const filePath = sourceFile.getFilePath();
+                const fileUri = sourceFile.getUri();
                 const value = {
-                    filePath,
+                    fileUri,
                     parseResults: sourceFile.getParseResults(),
                     errors: diagnostics.filter((diag) => diag.category === DiagnosticCategory.Error),
                     warnings: diagnostics.filter((diag) => diag.category === DiagnosticCategory.Warning),
                     information: diagnostics.filter((diag) => diag.category === DiagnosticCategory.Information),
                     unused: diagnostics.filter((diag) => diag.category === DiagnosticCategory.UnusedCode),
                 };
-                return [filePath, value] as [string, typeof value];
+
+                // Don't use the uri key, but rather the file name, because other spots
+                // in the test data assume file paths.
+                return [this.files[index], value] as [string, typeof value];
             } else {
                 this.raiseError(`Source file not found for ${this.files[index]}`);
             }
@@ -1880,6 +1904,7 @@ export class TestState {
                     const fileExtension = getFileExtension(path).toLowerCase();
                     return fileExtension === '.py' || fileExtension === '.pyi';
                 })
+                .map((path) => Uri.file(path))
                 .filter((path) => service.isTracked(path))
         );
 
@@ -1898,7 +1923,8 @@ export class TestState {
     }
 
     private async _waitForFile(filePath: string) {
-        while (!this.fs.existsSync(filePath)) {
+        const uri = Uri.file(filePath);
+        while (!this.fs.existsSync(uri)) {
             await new Promise<void>((res) =>
                 setTimeout(() => {
                     res();
@@ -1916,7 +1942,7 @@ export class TestState {
 
         return this._hostSpecificFeatures.getCodeActionsForPosition(
             this.workspace,
-            file,
+            Uri.file(file),
             textRange,
             CancellationToken.None
         );
@@ -1930,7 +1956,7 @@ export class TestState {
             // wait until the file exists
             await this._waitForFile(normalizedFilePath);
 
-            const actual = this.fs.readFileSync(normalizedFilePath, 'utf8');
+            const actual = this.fs.readFileSync(Uri.file(normalizedFilePath), 'utf8');
             if (actual !== expected) {
                 this.raiseError(
                     `doesn't contain expected result: ${stringify(expected)}, actual: ${stringify(actual)}`
@@ -2020,7 +2046,7 @@ export function getNodeAtMarker(codeOrState: string | TestState, markerName = 'm
     const state = isString(codeOrState) ? parseAndGetTestState(codeOrState).state : codeOrState;
     const marker = state.getMarkerByName(markerName);
 
-    const sourceFile = state.program.getBoundSourceFile(marker.fileName);
+    const sourceFile = state.program.getBoundSourceFile(Uri.file(marker.fileName));
     assert(sourceFile);
 
     const parserResults = sourceFile.getParseResults();
diff --git a/packages/pyright-internal/src/tests/harness/testAccessHost.ts b/packages/pyright-internal/src/tests/harness/testAccessHost.ts
index 2e845ad49..c93aa2c42 100644
--- a/packages/pyright-internal/src/tests/harness/testAccessHost.ts
+++ b/packages/pyright-internal/src/tests/harness/testAccessHost.ts
@@ -8,13 +8,14 @@
 
 import { PythonPathResult } from '../../analyzer/pythonPathUtils';
 import { NoAccessHost } from '../../common/host';
+import { Uri } from '../../common/uri/uri';
 
 export class TestAccessHost extends NoAccessHost {
-    constructor(private _modulePath = '', private _searchPaths: string[] = []) {
+    constructor(private _modulePath = Uri.empty(), private _searchPaths: Uri[] = []) {
         super();
     }
 
-    override getPythonSearchPaths(pythonPath?: string, logInfo?: string[]): PythonPathResult {
+    override getPythonSearchPaths(pythonPath?: Uri, logInfo?: string[]): PythonPathResult {
         return {
             paths: this._searchPaths,
             prefix: this._modulePath,
diff --git a/packages/pyright-internal/src/tests/harness/testHost.ts b/packages/pyright-internal/src/tests/harness/testHost.ts
index c6802e06d..52454f040 100644
--- a/packages/pyright-internal/src/tests/harness/testHost.ts
+++ b/packages/pyright-internal/src/tests/harness/testHost.ts
@@ -8,16 +8,11 @@ import * as os from 'os';
 import * as pathModule from 'path';
 
 import { NullConsole } from '../../common/console';
-import {
-    combinePaths,
-    directoryExists,
-    fileExists,
-    FileSystemEntries,
-    getFileSize,
-    resolvePaths,
-} from '../../common/pathUtils';
+import { combinePaths, FileSystemEntries, resolvePaths } from '../../common/pathUtils';
 import { createFromRealFileSystem } from '../../common/realFileSystem';
 import { compareStringsCaseInsensitive, compareStringsCaseSensitive } from '../../common/stringUtils';
+import { Uri } from '../../common/uri/uri';
+import { directoryExists, fileExists, getFileSize } from '../../common/uri/uriUtils';
 
 export const HOST: TestHost = createHost();
 
@@ -57,7 +52,7 @@ function createHost(): TestHost {
             return false;
         }
         // If this file exists under a different case, we must be case-insensitve.
-        return !vfs.existsSync(swapCase(__filename));
+        return !vfs.existsSync(Uri.file(swapCase(__filename)));
 
         /** Convert all lowercase chars to uppercase, and vice-versa */
         function swapCase(s: string): string {
@@ -72,9 +67,9 @@ function createHost(): TestHost {
         function filesInFolder(folder: string): string[] {
             let paths: string[] = [];
 
-            for (const file of vfs.readdirSync(folder)) {
+            for (const file of vfs.readdirSync(Uri.file(folder))) {
                 const pathToFile = pathModule.join(folder, file);
-                const stat = vfs.statSync(pathToFile);
+                const stat = vfs.statSync(Uri.file(pathToFile));
                 if (options.recursive && stat.isDirectory()) {
                     paths = paths.concat(filesInFolder(pathToFile));
                 } else if (stat.isFile() && (!spec || file.match(spec))) {
@@ -91,7 +86,7 @@ function createHost(): TestHost {
     function getAccessibleFileSystemEntries(dirname: string): FileSystemEntries {
         try {
             const entries: string[] = vfs
-                .readdirSync(dirname || '.')
+                .readdirSync(Uri.file(dirname || '.'))
                 .sort(useCaseSensitiveFileNames ? compareStringsCaseSensitive : compareStringsCaseInsensitive);
             const files: string[] = [];
             const directories: string[] = [];
@@ -101,7 +96,7 @@ function createHost(): TestHost {
                 }
                 const name = combinePaths(dirname, entry);
                 try {
-                    const stat = vfs.statSync(name);
+                    const stat = vfs.statSync(Uri.file(name));
                     if (!stat) {
                         continue;
                     }
@@ -121,10 +116,10 @@ function createHost(): TestHost {
     }
 
     function readFile(fileName: string, _encoding?: string): string | undefined {
-        if (!fileExists(vfs, fileName)) {
+        if (!fileExists(vfs, Uri.file(fileName))) {
             return undefined;
         }
-        const buffer = vfs.readFileSync(fileName);
+        const buffer = vfs.readFileSync(Uri.file(fileName));
         let len = buffer.length;
         if (len >= 2 && buffer[0] === 0xfe && buffer[1] === 0xff) {
             // Big endian UTF-16 byte order mark detected. Since big endian is not supported by node.js,
@@ -155,18 +150,18 @@ function createHost(): TestHost {
             data = byteOrderMarkIndicator + data;
         }
 
-        vfs.writeFileSync(fileName, data, 'utf8');
+        vfs.writeFileSync(Uri.file(fileName), data, 'utf8');
     }
 
     return {
         useCaseSensitiveFileNames: () => useCaseSensitiveFileNames,
-        getFileSize: (path: string) => getFileSize(vfs, path),
+        getFileSize: (path: string) => getFileSize(vfs, Uri.file(path)),
         readFile: (path) => readFile(path),
         writeFile: (path, content) => {
             writeFile(path, content);
         },
-        fileExists: (path) => fileExists(vfs, path),
-        directoryExists: (path) => directoryExists(vfs, path),
+        fileExists: (path) => fileExists(vfs, Uri.file(path)),
+        directoryExists: (path) => directoryExists(vfs, Uri.file(path)),
         listFiles,
         log: (s) => {
             console.log(s);
diff --git a/packages/pyright-internal/src/tests/harness/vfs/factory.ts b/packages/pyright-internal/src/tests/harness/vfs/factory.ts
index da65e7763..8d89ffb61 100644
--- a/packages/pyright-internal/src/tests/harness/vfs/factory.ts
+++ b/packages/pyright-internal/src/tests/harness/vfs/factory.ts
@@ -8,6 +8,7 @@
 
 import * as pathConsts from '../../../common/pathConsts';
 import { combinePaths, getDirectoryPath, normalizeSlashes, resolvePaths } from '../../../common/pathUtils';
+import { Uri } from '../../../common/uri/uri';
 import { GlobalMetadataOptionNames } from '../fourslash/fourSlashTypes';
 import { TestHost } from '../testHost';
 import { bufferFrom } from '../utils';
@@ -39,13 +40,11 @@ export interface FileSystemCreateOptions extends FileSystemOptions {
     documents?: readonly TextDocument[];
 }
 
-export const libFolder = combinePaths(
-    MODULE_PATH,
-    normalizeSlashes(combinePaths(pathConsts.lib, pathConsts.sitePackages))
+export const libFolder = Uri.file(
+    combinePaths(MODULE_PATH, normalizeSlashes(combinePaths(pathConsts.lib, pathConsts.sitePackages)))
 );
-export const distlibFolder = combinePaths(
-    MODULE_PATH,
-    normalizeSlashes(combinePaths(pathConsts.lib, pathConsts.distPackages))
+export const distlibFolder = Uri.file(
+    combinePaths(MODULE_PATH, normalizeSlashes(combinePaths(pathConsts.lib, pathConsts.distPackages)))
 );
 export const typeshedFolder = combinePaths(MODULE_PATH, normalizeSlashes(pathConsts.typeshedFallback));
 export const srcFolder = normalizeSlashes('/.src');
@@ -88,12 +87,12 @@ export function createFromFileSystem(
     }
     if (cwd) {
         fs.mkdirpSync(cwd);
-        fs.chdir(cwd);
+        fs.chdir(Uri.file(cwd));
     }
     if (documents) {
         for (const document of documents) {
             fs.mkdirpSync(getDirectoryPath(document.file));
-            fs.writeFileSync(document.file, document.text, 'utf8');
+            fs.writeFileSync(Uri.file(document.file), document.text, 'utf8');
             fs.filemeta(document.file).set('document', document);
             // Add symlinks
             const symlink = document.meta.get('symlink');
diff --git a/packages/pyright-internal/src/tests/harness/vfs/filesystem.ts b/packages/pyright-internal/src/tests/harness/vfs/filesystem.ts
index 471dd5891..92f689c3b 100644
--- a/packages/pyright-internal/src/tests/harness/vfs/filesystem.ts
+++ b/packages/pyright-internal/src/tests/harness/vfs/filesystem.ts
@@ -8,15 +8,15 @@
 
 /* eslint-disable no-dupe-class-members */
 import { Dirent, ReadStream, WriteStream } from 'fs';
-import { URI } from 'vscode-uri';
 
 import { FileSystem, MkDirOptions, TempFile, TmpfileOptions } from '../../../common/fileSystem';
 import { FileWatcher, FileWatcherEventHandler, FileWatcherEventType } from '../../../common/fileWatcher';
 import * as pathUtil from '../../../common/pathUtils';
+import { compareStringsCaseInsensitive, compareStringsCaseSensitive } from '../../../common/stringUtils';
+import { Uri } from '../../../common/uri/uri';
 import { bufferFrom, createIOError } from '../utils';
 import { Metadata, SortedMap, closeIterator, getIterator, nextResult } from './../utils';
 import { ValidationFlags, validate } from './pathValidation';
-import { compareStringsCaseInsensitive, compareStringsCaseSensitive } from '../../../common/stringUtils';
 
 export const MODULE_PATH = pathUtil.normalizeSlashes('/');
 
@@ -28,18 +28,14 @@ export interface DiffOptions {
 }
 
 export class TestFileSystemWatcher implements FileWatcher {
-    private _paths: string[] = [];
-    constructor(paths: string[], private _listener: FileWatcherEventHandler) {
-        this._paths = paths.map((p) => pathUtil.normalizePath(p));
-    }
+    constructor(private _paths: Uri[], private _listener: FileWatcherEventHandler) {}
     close() {
         // Do nothing.
     }
 
-    fireFileChange(path: string, eventType: FileWatcherEventType): boolean {
-        const normalized = pathUtil.normalizePath(path);
-        if (this._paths.some((p) => normalized.startsWith(p))) {
-            this._listener(eventType, normalized);
+    fireFileChange(path: Uri, eventType: FileWatcherEventType): boolean {
+        if (this._paths.some((p) => path.startsWith(p))) {
+            this._listener(eventType, path);
             return true;
         }
         return false;
@@ -90,7 +86,7 @@ export class TestFileSystem implements FileSystem, TempFile {
         }
 
         let cwd = options.cwd;
-        if ((!cwd || (!pathUtil.isDiskPathRoot(cwd) && !pathUtil.isUri(cwd))) && this._lazy.links) {
+        if ((!cwd || !pathUtil.isDiskPathRoot(cwd)) && this._lazy.links) {
             const iterator = getIterator(this._lazy.links.keys());
             try {
                 for (let i = nextResult(iterator); i; i = nextResult(iterator)) {
@@ -111,6 +107,10 @@ export class TestFileSystem implements FileSystem, TempFile {
         this._cwd = cwd || '';
     }
 
+    get isCaseSensitive() {
+        return !this.ignoreCase;
+    }
+
     /**
      * Gets metadata for this `FileSystem`.
      */
@@ -242,7 +242,8 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * @link http://pubs.opengroup.org/onlinepubs/9699919799/functions/chdir.html
      */
-    chdir(path: string) {
+    chdir(uri: Uri) {
+        let path = uri.getFilePath();
         if (this.isReadonly) {
             throw createIOError('EPERM');
         }
@@ -274,7 +275,7 @@ export class TestFileSystem implements FileSystem, TempFile {
             this._dirStack.push(this._cwd);
         }
         if (path && path !== this._cwd) {
-            this.chdir(path);
+            this.chdir(Uri.file(path));
         }
     }
 
@@ -287,7 +288,7 @@ export class TestFileSystem implements FileSystem, TempFile {
         }
         const path = this._dirStack && this._dirStack.pop();
         if (path) {
-            this.chdir(path);
+            this.chdir(Uri.file(path));
         }
     }
 
@@ -331,7 +332,7 @@ export class TestFileSystem implements FileSystem, TempFile {
         return results;
     }
 
-    createFileSystemWatcher(paths: string[], listener: FileWatcherEventHandler): FileWatcher {
+    createFileSystemWatcher(paths: Uri[], listener: FileWatcherEventHandler): FileWatcher {
         const watcher = new TestFileSystemWatcher(paths, listener);
         this._watchers.push(watcher);
         return watcher;
@@ -339,58 +340,49 @@ export class TestFileSystem implements FileSystem, TempFile {
 
     fireFileWatcherEvent(path: string, event: FileWatcherEventType) {
         for (const watcher of this._watchers) {
-            if (watcher.fireFileChange(path, event)) {
+            if (watcher.fireFileChange(Uri.file(path), event)) {
                 break;
             }
         }
     }
 
-    getModulePath(): string {
-        return MODULE_PATH;
+    getModulePath(): Uri {
+        return Uri.file(MODULE_PATH);
     }
 
-    tmpdir(): string {
+    tmpdir(): Uri {
         this.mkdirpSync('/tmp');
-        return pathUtil.normalizeSlashes('/tmp');
+        return Uri.parse('file:///tmp', true);
     }
 
-    tmpfile(options?: TmpfileOptions): string {
+    tmpfile(options?: TmpfileOptions): Uri {
         // Use an algorithm similar to tmp's.
         const prefix = options?.prefix || 'tmp';
         const postfix = options?.prefix ? '-' + options.prefix : '';
         const name = `${prefix}-${this._tmpfileCounter++}${postfix}`;
-        const path = pathUtil.combinePaths(this.tmpdir(), name);
+        const path = this.tmpdir().combinePaths(name);
         this.writeFileSync(path, '');
         return path;
     }
 
-    realCasePath(path: string): string {
+    realCasePath(path: Uri): Uri {
         return path;
     }
 
-    isMappedFilePath(filepath: string): boolean {
+    isMappedUri(filepath: Uri): boolean {
         return false;
     }
 
     // Get original filepath if the given filepath is mapped.
-    getOriginalFilePath(mappedFilePath: string) {
+    getOriginalUri(mappedFilePath: Uri) {
         return mappedFilePath;
     }
 
     // Get mapped filepath if the given filepath is mapped.
-    getMappedFilePath(originalFilepath: string) {
+    getMappedUri(originalFilepath: Uri) {
         return originalFilepath;
     }
 
-    getUri(path: string): string {
-        // If this is not a file path, just return the original path.
-        if (pathUtil.isUri(path)) {
-            return path;
-        }
-
-        return URI.file(path).toString();
-    }
-
     /**
      * Mounts a physical or virtual file system at a location in this virtual file system.
      *
@@ -424,12 +416,12 @@ export class TestFileSystem implements FileSystem, TempFile {
         try {
             const stats = this.lstatSync(path);
             if (stats.isFile() || stats.isSymbolicLink()) {
-                this.unlinkSync(path);
+                this.unlinkSync(Uri.file(path));
             } else if (stats.isDirectory()) {
-                for (const file of this.readdirSync(path)) {
+                for (const file of this.readdirSync(Uri.file(path))) {
                     this.rimrafSync(pathUtil.combinePaths(path, file));
                 }
-                this.rmdirSync(path);
+                this.rmdirSync(Uri.file(path));
             }
         } catch (e: any) {
             if (e.code === 'ENOENT') {
@@ -506,8 +498,11 @@ export class TestFileSystem implements FileSystem, TempFile {
     /**
      * Determines whether a path exists.
      */
-    existsSync(path: string) {
-        const result = this._walk(this._resolve(path), /* noFollow */ true, () => 'stop');
+    existsSync(path: Uri) {
+        if (path.isEmpty()) {
+            return false;
+        }
+        const result = this._walk(this._resolve(path.getFilePath()), /* noFollow */ true, () => 'stop');
         return result !== undefined && result.node !== undefined;
     }
 
@@ -518,8 +513,8 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    statSync(path: string) {
-        return this._stat(this._walk(this._resolve(path)));
+    statSync(path: Uri) {
+        return this._stat(this._walk(this._resolve(path.getFilePath())));
     }
 
     /**
@@ -562,8 +557,8 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    readdirSync(path: string) {
-        const { node } = this._walk(this._resolve(path));
+    readdirSync(path: Uri) {
+        const { node } = this._walk(this._resolve(path.getFilePath()));
         if (!node) {
             throw createIOError('ENOENT');
         }
@@ -580,8 +575,8 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    readdirEntriesSync(path: string): Dirent[] {
-        const { node } = this._walk(this._resolve(path));
+    readdirEntriesSync(path: Uri): Dirent[] {
+        const { node } = this._walk(this._resolve(path.getFilePath()));
         if (!node) {
             throw createIOError('ENOENT');
         }
@@ -599,17 +594,17 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    mkdirSync(path: string, options?: MkDirOptions) {
+    mkdirSync(path: Uri, options?: MkDirOptions) {
         if (this.isReadonly) {
             throw createIOError('EROFS');
         }
 
         if (options?.recursive) {
-            this.mkdirpSync(path);
+            this.mkdirpSync(path.getFilePath());
             return;
         }
 
-        this._mkdir(this._walk(this._resolve(path), /* noFollow */ true));
+        this._mkdir(this._walk(this._resolve(path.getFilePath()), /* noFollow */ true));
     }
 
     /**
@@ -619,11 +614,11 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    rmdirSync(path: string) {
+    rmdirSync(uri: Uri) {
         if (this.isReadonly) {
             throw createIOError('EROFS');
         }
-        path = this._resolve(path);
+        const path = this._resolve(uri.getFilePath());
 
         const { parent, links, node, basename } = this._walk(path, /* noFollow */ true);
         if (!parent) {
@@ -677,12 +672,12 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    unlinkSync(path: string) {
+    unlinkSync(path: Uri) {
         if (this.isReadonly) {
             throw createIOError('EROFS');
         }
 
-        const { parent, links, node, basename } = this._walk(this._resolve(path), /* noFollow */ true);
+        const { parent, links, node, basename } = this._walk(this._resolve(path.getFilePath()), /* noFollow */ true);
         if (!parent) {
             throw createIOError('EPERM');
         }
@@ -791,10 +786,10 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    realpathSync(path: string) {
+    realpathSync(path: Uri) {
         try {
-            const { realpath } = this._walk(this._resolve(path));
-            return realpath;
+            const { realpath } = this._walk(this._resolve(path.getFilePath()));
+            return Uri.file(realpath);
         } catch (e: any) {
             return path;
         }
@@ -805,21 +800,21 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    readFileSync(path: string, encoding?: null): Buffer;
+    readFileSync(path: Uri, encoding?: null): Buffer;
     /**
      * Read from a file.
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    readFileSync(path: string, encoding: BufferEncoding): string;
+    readFileSync(path: Uri, encoding: BufferEncoding): string;
     /**
      * Read from a file.
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    readFileSync(path: string, encoding?: BufferEncoding | null): string | Buffer;
-    readFileSync(path: string, encoding: BufferEncoding | null = null) {
-        const { node } = this._walk(this._resolve(path));
+    readFileSync(path: Uri, encoding?: BufferEncoding | null): string | Buffer;
+    readFileSync(path: Uri, encoding: BufferEncoding | null = null) {
+        const { node } = this._walk(this._resolve(path.getFilePath()));
         if (!node) {
             throw createIOError('ENOENT');
         }
@@ -839,12 +834,17 @@ export class TestFileSystem implements FileSystem, TempFile {
      *
      * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
      */
-    writeFileSync(path: string, data: string | Buffer, encoding: BufferEncoding | null = null) {
+    writeFileSync(uri: Uri, data: string | Buffer, encoding: BufferEncoding | null = null) {
         if (this.isReadonly) {
             throw createIOError('EROFS');
         }
 
-        const { parent, links, node: existingNode, basename } = this._walk(this._resolve(path), /* noFollow */ false);
+        const {
+            parent,
+            links,
+            node: existingNode,
+            basename,
+        } = this._walk(this._resolve(uri.getFilePath()), /* noFollow */ false);
         if (!parent) {
             throw createIOError('EPERM');
         }
@@ -870,21 +870,21 @@ export class TestFileSystem implements FileSystem, TempFile {
         node.ctimeMs = time;
     }
 
-    readFile(filePath: string): Promise<Buffer> {
-        return Promise.resolve(this.readFileSync(filePath));
+    readFile(fileUri: Uri): Promise<Buffer> {
+        return Promise.resolve(this.readFileSync(fileUri));
     }
-    readFileText(filePath: string, encoding?: BufferEncoding): Promise<string> {
-        return Promise.resolve(this.readFileSync(filePath, encoding || 'utf8'));
+    readFileText(fileUri: Uri, encoding?: BufferEncoding): Promise<string> {
+        return Promise.resolve(this.readFileSync(fileUri, encoding || 'utf8'));
     }
 
-    createReadStream(path: string): ReadStream {
+    createReadStream(path: Uri): ReadStream {
         throw new Error('Not implemented in test file system.');
     }
-    createWriteStream(path: string): WriteStream {
+    createWriteStream(path: Uri): WriteStream {
         throw new Error('Not implemented in test file system.');
     }
 
-    copyFileSync(src: string, dst: string): void {
+    copyFileSync(src: Uri, dst: Uri): void {
         throw new Error('Not implemented in test file system.');
     }
 
@@ -908,7 +908,7 @@ export class TestFileSystem implements FileSystem, TempFile {
         return TestFileSystem._rootDiff(differences, changed, base, options) ? differences : undefined;
     }
 
-    isInZip(path: string): boolean {
+    isInZip(path: Uri): boolean {
         return false;
     }
 
@@ -954,7 +954,7 @@ export class TestFileSystem implements FileSystem, TempFile {
         }
         if (axis === 'descendants-or-self' || axis === 'descendants') {
             if (stats.isDirectory() && (!traversal.traverse || traversal.traverse(path, stats))) {
-                for (const file of this.readdirSync(path)) {
+                for (const file of this.readdirSync(Uri.file(path))) {
                     try {
                         const childpath = pathUtil.combinePaths(path, file);
                         const stats = this._stat(this._walk(childpath, noFollow));
@@ -1588,7 +1588,7 @@ export class TestFileSystem implements FileSystem, TempFile {
                     throw new TypeError('Roots cannot be files.');
                 }
                 this.mkdirpSync(pathUtil.getDirectoryPath(path));
-                this.writeFileSync(path, value.data, value.encoding);
+                this.writeFileSync(Uri.file(path), value.data, value.encoding);
                 this._applyFileExtendedOptions(path, value);
             } else if (value instanceof Directory) {
                 this.mkdirpSync(path);
diff --git a/packages/pyright-internal/src/tests/harness/vfs/pathValidation.ts b/packages/pyright-internal/src/tests/harness/vfs/pathValidation.ts
index 1af7b87f7..f32bfdbc8 100644
--- a/packages/pyright-internal/src/tests/harness/vfs/pathValidation.ts
+++ b/packages/pyright-internal/src/tests/harness/vfs/pathValidation.ts
@@ -8,7 +8,6 @@ import { sep } from 'path';
 
 import * as pu from '../../../common/pathUtils';
 import { createIOError } from '../utils';
-import { URI } from 'vscode-uri';
 
 const invalidRootComponentRegExp = getInvalidRootComponentRegExp();
 const invalidNavigableComponentRegExp = /[:*?"<>|]/;
@@ -124,13 +123,7 @@ function validateComponents(components: string[], flags: ValidationFlags, hasTra
     }
 
     // Validate component strings
-    if (pu.isUri(components[0])) {
-        try {
-            URI.parse(components[0]);
-        } catch {
-            return false;
-        }
-    } else if (invalidRootComponentRegExp.test(components[0])) {
+    if (invalidRootComponentRegExp.test(components[0])) {
         return false;
     }
     for (let i = 1; i < components.length; i++) {
diff --git a/packages/pyright-internal/src/tests/importResolver.test.ts b/packages/pyright-internal/src/tests/importResolver.test.ts
index 5c310f794..5dacaf2d6 100644
--- a/packages/pyright-internal/src/tests/importResolver.test.ts
+++ b/packages/pyright-internal/src/tests/importResolver.test.ts
@@ -17,7 +17,8 @@ import { lib, sitePackages, typeshedFallback } from '../common/pathConsts';
 import { combinePaths, getDirectoryPath, normalizeSlashes } from '../common/pathUtils';
 import { createFromRealFileSystem } from '../common/realFileSystem';
 import { ServiceProvider } from '../common/serviceProvider';
-import { createServiceProvider } from '../common/serviceProviderExtensions';
+import { ServiceKeys, createServiceProvider } from '../common/serviceProviderExtensions';
+import { Uri } from '../common/uri/uri';
 import { PyrightFileSystem } from '../pyrightFileSystem';
 import { TestAccessHost } from './harness/testAccessHost';
 import { TestFileSystem } from './harness/vfs/filesystem';
@@ -51,8 +52,9 @@ if (!usingTrueVenv()) {
             assert(importResult.isStubFile);
             assert.strictEqual(
                 1,
-                importResult.resolvedPaths.filter((f) => f === combinePaths(libraryRoot, 'myLib', 'partialStub.pyi'))
-                    .length
+                importResult.resolvedUris.filter(
+                    (f) => !f.isEmpty() && f.getFilePath() === combinePaths(libraryRoot, 'myLib', 'partialStub.pyi')
+                ).length
             );
         });
 
@@ -77,8 +79,9 @@ if (!usingTrueVenv()) {
             assert(importResult.isStubFile);
             assert.strictEqual(
                 1,
-                importResult.resolvedPaths.filter((f) => f === combinePaths(libraryRoot, 'myLib', '__init__.pyi'))
-                    .length
+                importResult.resolvedUris.filter(
+                    (f) => f.getFilePath() === combinePaths(libraryRoot, 'myLib', '__init__.pyi')
+                ).length
             );
         });
 
@@ -120,13 +123,14 @@ if (!usingTrueVenv()) {
                 },
             ];
 
-            const importResult = getImportResult(files, ['myLib'], (c) => (c.stubPath = typingFolder));
+            const importResult = getImportResult(files, ['myLib'], (c) => (c.stubPath = Uri.file(typingFolder)));
             assert(importResult.isImportFound);
             assert(importResult.isStubFile);
             assert.strictEqual(
                 1,
-                importResult.resolvedPaths.filter((f) => f === combinePaths(libraryRoot, 'myLib', '__init__.pyi'))
-                    .length
+                importResult.resolvedUris.filter(
+                    (f) => f.getFilePath() === combinePaths(libraryRoot, 'myLib', '__init__.pyi')
+                ).length
             );
         });
 
@@ -152,13 +156,14 @@ if (!usingTrueVenv()) {
             ];
 
             // Stub packages win over typeshed.
-            const importResult = getImportResult(files, ['myLib'], (c) => (c.typeshedPath = typeshedFolder));
+            const importResult = getImportResult(files, ['myLib'], (c) => (c.typeshedPath = Uri.file(typeshedFolder)));
             assert(importResult.isImportFound);
             assert(importResult.isStubFile);
             assert.strictEqual(
                 1,
-                importResult.resolvedPaths.filter((f) => f === combinePaths(libraryRoot, 'myLib', '__init__.pyi'))
-                    .length
+                importResult.resolvedUris.filter(
+                    (f) => f.getFilePath() === combinePaths(libraryRoot, 'myLib', '__init__.pyi')
+                ).length
             );
         });
 
@@ -188,8 +193,9 @@ if (!usingTrueVenv()) {
             assert(importResult.isStubFile);
             assert.strictEqual(
                 1,
-                importResult.resolvedPaths.filter((f) => f === combinePaths(libraryRoot, 'myLib', '__init__.pyi'))
-                    .length
+                importResult.resolvedUris.filter(
+                    (f) => f.getFilePath() === combinePaths(libraryRoot, 'myLib', '__init__.pyi')
+                ).length
             );
         });
 
@@ -237,7 +243,10 @@ if (!usingTrueVenv()) {
 
             const importResult = getImportResult(files, ['os']);
             assert(importResult.isImportFound);
-            assert.strictEqual(files[0].path, importResult.resolvedPaths[importResult.resolvedPaths.length - 1]);
+            assert.strictEqual(
+                files[0].path,
+                importResult.resolvedUris[importResult.resolvedUris.length - 1].getFilePath()
+            );
         });
 
         test('import side by side file sub under lib folder', () => {
@@ -292,15 +301,16 @@ describe('Import tests that can run with or without a true venv', () => {
         ];
 
         const sp = createServiceProviderFromFiles(files);
-        const configOptions = new ConfigOptions(normalizeSlashes('/'));
+        const configOptions = new ConfigOptions(Uri.file('/'));
         const importResolver = new ImportResolver(
             sp,
             configOptions,
-            new TestAccessHost(sp.fs().getModulePath(), [libraryRoot])
+            new TestAccessHost(sp.fs().getModulePath(), [Uri.file(libraryRoot)])
         );
 
         // Stub package wins over original package (per PEP 561 rules).
-        const sideBySideResult = importResolver.resolveImport(myFile, configOptions.findExecEnvironment(myFile), {
+        const myUri = Uri.file(myFile);
+        const sideBySideResult = importResolver.resolveImport(myUri, configOptions.findExecEnvironment(myUri), {
             leadingDots: 0,
             nameParts: ['myLib', 'partialStub'],
             importedSymbols: new Set<string>(),
@@ -309,12 +319,12 @@ describe('Import tests that can run with or without a true venv', () => {
         assert(sideBySideResult.isImportFound);
         assert(sideBySideResult.isStubFile);
 
-        const sideBySideStubFile = combinePaths(libraryRoot, 'myLib', 'partialStub.pyi');
-        assert.strictEqual(1, sideBySideResult.resolvedPaths.filter((f) => f === sideBySideStubFile).length);
+        const sideBySideStubFile = Uri.file(combinePaths(libraryRoot, 'myLib', 'partialStub.pyi'));
+        assert.strictEqual(1, sideBySideResult.resolvedUris.filter((f) => f.key === sideBySideStubFile.key).length);
         assert.strictEqual('def test(): ...', sp.fs().readFileSync(sideBySideStubFile, 'utf8'));
 
         // Side by side stub doesn't completely disable partial stub.
-        const partialStubResult = importResolver.resolveImport(myFile, configOptions.findExecEnvironment(myFile), {
+        const partialStubResult = importResolver.resolveImport(myUri, configOptions.findExecEnvironment(myUri), {
             leadingDots: 0,
             nameParts: ['myLib', 'partialStub2'],
             importedSymbols: new Set<string>(),
@@ -323,8 +333,8 @@ describe('Import tests that can run with or without a true venv', () => {
         assert(partialStubResult.isImportFound);
         assert(partialStubResult.isStubFile);
 
-        const partialStubFile = combinePaths(libraryRoot, 'myLib', 'partialStub2.pyi');
-        assert.strictEqual(1, partialStubResult.resolvedPaths.filter((f) => f === partialStubFile).length);
+        const partialStubFile = Uri.file(combinePaths(libraryRoot, 'myLib', 'partialStub2.pyi'));
+        assert.strictEqual(1, partialStubResult.resolvedUris.filter((f) => f.key === partialStubFile.key).length);
     });
 
     test('stub namespace package', () => {
@@ -345,7 +355,9 @@ describe('Import tests that can run with or without a true venv', () => {
         assert(!importResult.isStubFile);
         assert.strictEqual(
             1,
-            importResult.resolvedPaths.filter((f) => f === combinePaths(libraryRoot, 'myLib', 'partialStub.py')).length
+            importResult.resolvedUris.filter(
+                (f) => !f.isEmpty() && f.getFilePath() === combinePaths(libraryRoot, 'myLib', 'partialStub.py')
+            ).length
         );
     });
 
@@ -371,12 +383,14 @@ describe('Import tests that can run with or without a true venv', () => {
         ];
 
         // If the package exists in typing folder, that gets picked up first.
-        const importResult = getImportResult(files, ['myLib'], (c) => (c.stubPath = typingFolder));
+        const importResult = getImportResult(files, ['myLib'], (c) => (c.stubPath = Uri.file(typingFolder)));
         assert(importResult.isImportFound);
         assert(importResult.isStubFile);
         assert.strictEqual(
             0,
-            importResult.resolvedPaths.filter((f) => f === combinePaths(libraryRoot, 'myLib', '__init__.pyi')).length
+            importResult.resolvedUris.filter(
+                (f) => f.getFilePath() === combinePaths(libraryRoot, 'myLib', '__init__.pyi')
+            ).length
         );
     });
 
@@ -394,16 +408,19 @@ describe('Import tests that can run with or without a true venv', () => {
 
         const importResult = getImportResult(files, ['os']);
         assert(importResult.isImportFound);
-        assert.strictEqual(files[1].path, importResult.resolvedPaths[importResult.resolvedPaths.length - 1]);
+        assert.strictEqual(
+            files[1].path,
+            importResult.resolvedUris[importResult.resolvedUris.length - 1].getFilePath()
+        );
     });
 
     test('no empty import roots', () => {
         const sp = createServiceProviderFromFiles([]);
-        const configOptions = new ConfigOptions(''); // Empty, like open-file mode.
+        const configOptions = new ConfigOptions(Uri.empty()); // Empty, like open-file mode.
         const importResolver = new ImportResolver(
             sp,
             configOptions,
-            new TestAccessHost(sp.fs().getModulePath(), [libraryRoot])
+            new TestAccessHost(sp.fs().getModulePath(), [Uri.file(libraryRoot)])
         );
         importResolver.getImportRoots(configOptions.getDefaultExecEnvironment()).forEach((path) => assert(path));
     });
@@ -421,21 +438,25 @@ describe('Import tests that can run with or without a true venv', () => {
         ];
 
         const sp = createServiceProviderFromFiles(files);
-        const configOptions = new ConfigOptions(''); // Empty, like open-file mode.
+        const configOptions = new ConfigOptions(Uri.empty()); // Empty, like open-file mode.
         const importResolver = new ImportResolver(
             sp,
             configOptions,
-            new TestAccessHost(sp.fs().getModulePath(), [libraryRoot])
+            new TestAccessHost(sp.fs().getModulePath(), [Uri.file(libraryRoot)])
         );
         const importRoots = importResolver.getImportRoots(configOptions.getDefaultExecEnvironment());
 
         assert.strictEqual(
             1,
-            importRoots.filter((f) => f === combinePaths('/', typeshedFallback, 'stubs', 'aLib')).length
+            importRoots.filter(
+                (f) => !f.isEmpty() && f.getFilePath() === combinePaths('/', typeshedFallback, 'stubs', 'aLib')
+            ).length
         );
         assert.strictEqual(
             1,
-            importRoots.filter((f) => f === combinePaths('/', typeshedFallback, 'stubs', 'bLib')).length
+            importRoots.filter(
+                (f) => !f.isEmpty() && f.getFilePath() === combinePaths('/', typeshedFallback, 'stubs', 'bLib')
+            ).length
         );
     });
 
@@ -453,7 +474,10 @@ describe('Import tests that can run with or without a true venv', () => {
 
         const importResult = getImportResult(files, ['file1']);
         assert(importResult.isImportFound);
-        assert.strictEqual(1, importResult.resolvedPaths.filter((f) => f === combinePaths('/', 'file1.py')).length);
+        assert.strictEqual(
+            1,
+            importResult.resolvedUris.filter((f) => f.getFilePath() === combinePaths('/', 'file1.py')).length
+        );
     });
 
     test('import side by side file sub folder', () => {
@@ -470,7 +494,10 @@ describe('Import tests that can run with or without a true venv', () => {
 
         const importResult = getImportResult(files, ['file1']);
         assert(importResult.isImportFound);
-        assert.strictEqual(1, importResult.resolvedPaths.filter((f) => f === combinePaths('/test', 'file1.py')).length);
+        assert.strictEqual(
+            1,
+            importResult.resolvedUris.filter((f) => f.getFilePath() === combinePaths('/test', 'file1.py')).length
+        );
     });
 
     test('import side by side file sub under src folder', () => {
@@ -489,7 +516,7 @@ describe('Import tests that can run with or without a true venv', () => {
         assert(importResult.isImportFound);
         assert.strictEqual(
             1,
-            importResult.resolvedPaths.filter((f) => f === combinePaths('/src/nested', 'file1.py')).length
+            importResult.resolvedUris.filter((f) => f.getFilePath() === combinePaths('/src/nested', 'file1.py')).length
         );
     });
 
@@ -509,7 +536,7 @@ describe('Import tests that can run with or without a true venv', () => {
         assert(importResult.isImportFound);
         assert.strictEqual(
             1,
-            importResult.resolvedPaths.filter((f) => f === combinePaths('/src/nested', 'file1.py')).length
+            importResult.resolvedUris.filter((f) => f.getFilePath() === combinePaths('/src/nested', 'file1.py')).length
         );
     });
 
@@ -521,7 +548,7 @@ describe('Import tests that can run with or without a true venv', () => {
             },
         ];
 
-        const importResult = getImportResult(files, ['notExist'], (c) => (c.projectRoot = ''));
+        const importResult = getImportResult(files, ['notExist'], (c) => (c.projectRoot = Uri.empty()));
         assert(!importResult.isImportFound);
     });
 
@@ -542,7 +569,10 @@ describe('Import tests that can run with or without a true venv', () => {
         ];
 
         const importResult = getImportResult(files, ['a', 'b', 'c', 'd'], (config) => {
-            config.defaultExtraPaths = [combinePaths('/', 'packages1'), combinePaths('/', 'packages2')];
+            config.defaultExtraPaths = [
+                Uri.file(combinePaths('/', 'packages1')),
+                Uri.file(combinePaths('/', 'packages2')),
+            ];
         });
         assert(importResult.isImportFound);
     });
@@ -564,7 +594,10 @@ describe('Import tests that can run with or without a true venv', () => {
         ];
 
         const importResult = getImportResult(files, ['a', 'b', 'c', 'd'], (config) => {
-            config.defaultExtraPaths = [combinePaths('/', 'packages1'), combinePaths('/', 'packages2')];
+            config.defaultExtraPaths = [
+                Uri.file(combinePaths('/', 'packages1')),
+                Uri.file(combinePaths('/', 'packages2')),
+            ];
         });
         assert(importResult.isImportFound);
     });
@@ -582,7 +615,10 @@ describe('Import tests that can run with or without a true venv', () => {
         ];
 
         const importResult = getImportResult(files, ['a', 'b', 'c', 'd'], (config) => {
-            config.defaultExtraPaths = [combinePaths('/', 'packages1'), combinePaths('/', 'packages2')];
+            config.defaultExtraPaths = [
+                Uri.file(combinePaths('/', 'packages1')),
+                Uri.file(combinePaths('/', 'packages2')),
+            ];
         });
         assert(!importResult.isImportFound);
     });
@@ -608,7 +644,10 @@ describe('Import tests that can run with or without a true venv', () => {
         ];
 
         const importResult = getImportResult(files, ['a', 'b', 'c'], (config) => {
-            config.defaultExtraPaths = [combinePaths('/', 'packages1'), combinePaths('/', 'packages2')];
+            config.defaultExtraPaths = [
+                Uri.file(combinePaths('/', 'packages1')),
+                Uri.file(combinePaths('/', 'packages2')),
+            ];
         });
         assert(!importResult.isImportFound);
     });
@@ -635,7 +674,8 @@ function getImportResult(
     nameParts: string[],
     setup?: (c: ConfigOptions) => void
 ) {
-    const defaultHostFactory = (sp: ServiceProvider) => new TestAccessHost(sp.fs().getModulePath(), [libraryRoot]);
+    const defaultHostFactory = (sp: ServiceProvider) =>
+        new TestAccessHost(sp.fs().getModulePath(), [Uri.file(libraryRoot)]);
     const defaultSetup =
         setup ??
         ((c) => {
@@ -652,16 +692,24 @@ function getImportResult(
     if (process.env.CI_IMPORT_TEST_VENVPATH) {
         configModifier = (c: ConfigOptions) => {
             defaultSetup(c);
-            c.venvPath = process.env.CI_IMPORT_TEST_VENVPATH;
+            c.venvPath = Uri.file(
+                process.env.CI_IMPORT_TEST_VENVPATH!,
+                /* isCaseSensitive */ true,
+                /* checkRelative */ true
+            );
             c.venv = process.env.CI_IMPORT_TEST_VENV;
         };
         spFactory = (files: { path: string; content: string }[]) => createServiceProviderWithCombinedFs(files);
     } else if (process.env.CI_IMPORT_TEST_PYTHONPATH) {
         configModifier = (c: ConfigOptions) => {
             defaultSetup(c);
-            c.pythonPath = process.env.CI_IMPORT_TEST_PYTHONPATH;
+            c.pythonPath = Uri.file(
+                process.env.CI_IMPORT_TEST_PYTHONPATH!,
+                /* isCaseSensitive */ true,
+                /* checkRelative */ true
+            );
         };
-        hostFactory = (sp: ServiceProvider) => new TruePythonTestAccessHost();
+        hostFactory = (sp: ServiceProvider) => new TruePythonTestAccessHost(sp);
         spFactory = (files: { path: string; content: string }[]) => createServiceProviderWithCombinedFs(files);
     }
 
@@ -676,7 +724,7 @@ function getImportResultImpl(
     hostFactory: (sp: ServiceProvider) => Host
 ) {
     const sp = spFactory(files);
-    const configOptions = new ConfigOptions(normalizeSlashes('/'));
+    const configOptions = new ConfigOptions(Uri.file('/'));
     configModifier(configOptions);
 
     const file = files.length > 0 ? files[files.length - 1].path : combinePaths('src', 'file.py');
@@ -687,13 +735,20 @@ function getImportResultImpl(
         });
     }
 
+    const uri = Uri.file(file);
     const importResolver = new ImportResolver(sp, configOptions, hostFactory(sp));
-    const importResult = importResolver.resolveImport(file, configOptions.findExecEnvironment(file), {
+    const importResult = importResolver.resolveImport(uri, configOptions.findExecEnvironment(uri), {
         leadingDots: 0,
         nameParts: nameParts,
         importedSymbols: new Set<string>(),
     });
 
+    // Add the config venvpath to the import result so we can output it on failure.
+    if (!importResult.isImportFound) {
+        importResult.importFailureInfo = importResult.importFailureInfo ?? [];
+        importResult.importFailureInfo.push(`venvPath: ${configOptions.venvPath}`);
+    }
+
     return importResult;
 }
 function createTestFileSystem(files: { path: string; content: string }[]): TestFileSystem {
@@ -704,7 +759,7 @@ function createTestFileSystem(files: { path: string; content: string }[]): TestF
         const dir = getDirectoryPath(path);
         fs.mkdirpSync(dir);
 
-        fs.writeFileSync(path, file.content);
+        fs.writeFileSync(Uri.file(path), file.content);
     }
 
     return fs;
@@ -720,8 +775,11 @@ function createServiceProviderWithCombinedFs(files: { path: string; content: str
 }
 
 class TruePythonTestAccessHost extends FullAccessHost {
-    constructor() {
-        super(createFromRealFileSystem());
+    constructor(sp: ServiceProvider) {
+        // Make sure the service provide in use is using a real file system
+        const clone = sp.clone();
+        clone.add(ServiceKeys.fs, createFromRealFileSystem());
+        super(clone);
     }
 }
 
@@ -730,123 +788,123 @@ class CombinedFileSystem implements FileSystem {
 
     constructor(private _testFS: FileSystem) {}
 
-    mkdirSync(path: string, options?: MkDirOptions | undefined): void {
+    get isCaseSensitive(): boolean {
+        return this._testFS.isCaseSensitive;
+    }
+
+    mkdirSync(path: Uri, options?: MkDirOptions | undefined): void {
         this._testFS.mkdirSync(path, options);
     }
 
-    writeFileSync(path: string, data: string | Buffer, encoding: BufferEncoding | null): void {
+    writeFileSync(path: Uri, data: string | Buffer, encoding: BufferEncoding | null): void {
         this._testFS.writeFileSync(path, data, encoding);
     }
 
-    unlinkSync(path: string): void {
+    unlinkSync(path: Uri): void {
         this._testFS.unlinkSync(path);
     }
 
-    rmdirSync(path: string): void {
+    rmdirSync(path: Uri): void {
         this._testFS.rmdirSync(path);
     }
 
-    createFileSystemWatcher(paths: string[], listener: FileWatcherEventHandler): FileWatcher {
+    createFileSystemWatcher(paths: Uri[], listener: FileWatcherEventHandler): FileWatcher {
         return this._testFS.createFileSystemWatcher(paths, listener);
     }
 
-    createReadStream(path: string): ReadStream {
+    createReadStream(path: Uri): ReadStream {
         return this._testFS.createReadStream(path);
     }
 
-    createWriteStream(path: string): WriteStream {
+    createWriteStream(path: Uri): WriteStream {
         return this._testFS.createWriteStream(path);
     }
 
-    copyFileSync(src: string, dst: string): void {
+    copyFileSync(src: Uri, dst: Uri): void {
         this._testFS.copyFileSync(src, dst);
     }
 
-    existsSync(path: string): boolean {
+    existsSync(path: Uri): boolean {
         return this._testFS.existsSync(path) || this._realFS.existsSync(path);
     }
 
-    chdir(path: string): void {
+    chdir(path: Uri): void {
         this._testFS.chdir(path);
     }
 
-    readdirEntriesSync(path: string): Dirent[] {
+    readdirEntriesSync(path: Uri): Dirent[] {
         if (this._testFS.existsSync(path)) {
             return this._testFS.readdirEntriesSync(path);
         }
         return this._realFS.readdirEntriesSync(path);
     }
 
-    readdirSync(path: string): string[] {
+    readdirSync(path: Uri): string[] {
         if (this._testFS.existsSync(path)) {
             return this._testFS.readdirSync(path);
         }
         return this._realFS.readdirSync(path);
     }
 
-    readFileSync(path: string, encoding?: null): Buffer;
-    readFileSync(path: string, encoding: BufferEncoding): string;
-    readFileSync(path: string, encoding?: BufferEncoding | null): string | Buffer;
-    readFileSync(path: string, encoding: BufferEncoding | null = null) {
+    readFileSync(path: Uri, encoding?: null): Buffer;
+    readFileSync(path: Uri, encoding: BufferEncoding): string;
+    readFileSync(path: Uri, encoding?: BufferEncoding | null): string | Buffer;
+    readFileSync(path: Uri, encoding: BufferEncoding | null = null) {
         if (this._testFS.existsSync(path)) {
             return this._testFS.readFileSync(path, encoding);
         }
         return this._realFS.readFileSync(path, encoding);
     }
 
-    statSync(path: string): Stats {
+    statSync(path: Uri): Stats {
         if (this._testFS.existsSync(path)) {
             return this._testFS.statSync(path);
         }
         return this._realFS.statSync(path);
     }
 
-    realpathSync(path: string): string {
+    realpathSync(path: Uri): Uri {
         if (this._testFS.existsSync(path)) {
             return this._testFS.realpathSync(path);
         }
         return this._realFS.realpathSync(path);
     }
 
-    getModulePath(): string {
+    getModulePath(): Uri {
         return this._testFS.getModulePath();
     }
 
-    readFile(path: string): Promise<Buffer> {
+    readFile(path: Uri): Promise<Buffer> {
         if (this._testFS.existsSync(path)) {
             return this._testFS.readFile(path);
         }
         return this._realFS.readFile(path);
     }
 
-    readFileText(path: string, encoding?: BufferEncoding | undefined): Promise<string> {
+    readFileText(path: Uri, encoding?: BufferEncoding | undefined): Promise<string> {
         if (this._testFS.existsSync(path)) {
             return this._testFS.readFileText(path, encoding);
         }
         return this._realFS.readFileText(path, encoding);
     }
 
-    realCasePath(path: string): string {
+    realCasePath(path: Uri): Uri {
         return this._testFS.realCasePath(path);
     }
 
-    isMappedFilePath(filepath: string): boolean {
-        return this._testFS.isMappedFilePath(filepath);
+    isMappedUri(filepath: Uri): boolean {
+        return this._testFS.isMappedUri(filepath);
     }
 
-    getOriginalFilePath(mappedFilePath: string): string {
-        return this._testFS.getOriginalFilePath(mappedFilePath);
+    getOriginalUri(mappedFilePath: Uri): Uri {
+        return this._testFS.getOriginalUri(mappedFilePath);
     }
 
-    getMappedFilePath(originalFilepath: string): string {
-        return this._testFS.getMappedFilePath(originalFilepath);
+    getMappedUri(originalFilePath: Uri): Uri {
+        return this._testFS.getMappedUri(originalFilePath);
     }
 
-    getUri(path: string): string {
-        return this._testFS.getUri(path);
-    }
-
-    isInZip(path: string): boolean {
+    isInZip(path: Uri): boolean {
         return this._testFS.isInZip(path);
     }
 }
diff --git a/packages/pyright-internal/src/tests/importStatementUtils.test.ts b/packages/pyright-internal/src/tests/importStatementUtils.test.ts
index 5e2369724..3141a4a02 100644
--- a/packages/pyright-internal/src/tests/importStatementUtils.test.ts
+++ b/packages/pyright-internal/src/tests/importStatementUtils.test.ts
@@ -21,9 +21,9 @@ import {
 import { findNodeByOffset } from '../analyzer/parseTreeUtils';
 import { isArray } from '../common/core';
 import { TextEditAction } from '../common/editAction';
-import { combinePaths, getDirectoryPath } from '../common/pathUtils';
 import { convertOffsetToPosition } from '../common/positionUtils';
 import { rangesAreEqual } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { NameNode } from '../parser/parseNodes';
 import { Range } from './harness/fourslash/fourSlashTypes';
 import { parseAndGetTestState, TestState } from './harness/fourslash/testState';
@@ -417,12 +417,12 @@ test('getRelativeModuleName over fake file', () => {
     `;
 
     const state = parseAndGetTestState(code).state;
-    const dest = state.getMarkerByName('dest')!.fileName;
+    const dest = Uri.file(state.getMarkerByName('dest')!.fileName);
 
     assert.strictEqual(
         getRelativeModuleName(
             state.fs,
-            combinePaths(getDirectoryPath(dest), 'source.py'),
+            dest.getDirectory().combinePaths('source.py'),
             dest,
             /*ignoreFolderStructure*/ false,
             /*sourceIsFile*/ true
@@ -453,12 +453,13 @@ test('resolve alias of not needed file', () => {
     const evaluator = state.workspace.service.getEvaluator()!;
     state.openFile(marker.fileName);
 
-    const parseResults = state.workspace.service.getParseResult(marker.fileName)!;
+    const markerUri = Uri.file(marker.fileName);
+    const parseResults = state.workspace.service.getParseResult(markerUri)!;
     const nameNode = findNodeByOffset(parseResults.parseTree, marker.position) as NameNode;
     const aliasDecls = evaluator.getDeclarationsForNameNode(nameNode)!;
 
     // Unroot the file. we can't explicitly close the file since it will unload the file from test program.
-    state.workspace.service.test_program.getSourceFileInfo(marker.fileName)!.isOpenByClient = false;
+    state.workspace.service.test_program.getSourceFileInfo(markerUri)!.isOpenByClient = false;
 
     const unresolved = evaluator.resolveAliasDeclaration(aliasDecls[0], /*resolveLocalNames*/ false);
     assert(!unresolved);
@@ -473,8 +474,8 @@ test('resolve alias of not needed file', () => {
 
 function testRelativeModuleName(code: string, expected: string, ignoreFolderStructure = false) {
     const state = parseAndGetTestState(code).state;
-    const src = state.getMarkerByName('src')!.fileName;
-    const dest = state.getMarkerByName('dest')!.fileName;
+    const src = Uri.file(state.getMarkerByName('src')!.fileName);
+    const dest = Uri.file(state.getMarkerByName('dest')!.fileName);
 
     assert.strictEqual(getRelativeModuleName(state.fs, src, dest, ignoreFolderStructure), expected);
 }
@@ -487,7 +488,7 @@ function testAddition(
 ) {
     const state = parseAndGetTestState(code).state;
     const marker = state.getMarkerByName(markerName)!;
-    const parseResults = state.program.getBoundSourceFile(marker!.fileName)!.getParseResults()!;
+    const parseResults = state.program.getBoundSourceFile(Uri.file(marker!.fileName))!.getParseResults()!;
 
     const importStatement = getTopLevelImports(parseResults.parseTree).orderedImports.find(
         (i) => i.moduleName === moduleName
@@ -507,7 +508,7 @@ function testInsertions(
 ) {
     const state = parseAndGetTestState(code).state;
     const marker = state.getMarkerByName(markerName)!;
-    const parseResults = state.program.getBoundSourceFile(marker!.fileName)!.getParseResults()!;
+    const parseResults = state.program.getBoundSourceFile(Uri.file(marker!.fileName))!.getParseResults()!;
 
     const importStatements = getTopLevelImports(parseResults.parseTree);
     const edits = getTextEditsForAutoImportInsertions(
diff --git a/packages/pyright-internal/src/tests/ipythonMode.test.ts b/packages/pyright-internal/src/tests/ipythonMode.test.ts
index adf8d3eaf..d93ca989e 100644
--- a/packages/pyright-internal/src/tests/ipythonMode.test.ts
+++ b/packages/pyright-internal/src/tests/ipythonMode.test.ts
@@ -12,6 +12,7 @@ import { CompletionItemKind, MarkupKind } from 'vscode-languageserver-types';
 import { DiagnosticRule } from '../common/diagnosticRules';
 import { TextRange } from '../common/textRange';
 import { TextRangeCollection } from '../common/textRangeCollection';
+import { Uri } from '../common/uri/uri';
 import { Localizer } from '../localization/localize';
 import { Comment, CommentType, Token } from '../parser/tokenizerTypes';
 import { parseAndGetTestState } from './harness/fourslash/testState';
@@ -263,7 +264,7 @@ test('top level await raises errors in regular mode', () => {
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(diagnostics?.some((d) => d.message === Localizer.Diagnostic.awaitNotInAsync()));
@@ -281,7 +282,7 @@ test('top level await raises no errors in ipython mode', () => {
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(!diagnostics?.some((d) => d.message === Localizer.Diagnostic.awaitNotInAsync()));
@@ -300,7 +301,7 @@ test('await still raises errors when used in wrong context in ipython mode', ()
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(diagnostics?.some((d) => d.message === Localizer.Diagnostic.awaitNotInAsync()));
@@ -319,7 +320,7 @@ test('top level async for raises errors in regular mode', () => {
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(diagnostics?.some((d) => d.message === Localizer.Diagnostic.asyncNotInAsyncFunction()));
@@ -339,7 +340,7 @@ test('top level async for raises no errors in ipython mode', () => {
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(!diagnostics?.some((d) => d.message === Localizer.Diagnostic.asyncNotInAsyncFunction()));
@@ -357,7 +358,7 @@ test('top level async for in list comprehension raises errors in regular mode',
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(diagnostics?.some((d) => d.message === Localizer.Diagnostic.asyncNotInAsyncFunction()));
@@ -376,7 +377,7 @@ test('top level async for in list comprehension raises no errors in ipython mode
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(!diagnostics?.some((d) => d.message === Localizer.Diagnostic.asyncNotInAsyncFunction()));
@@ -395,7 +396,7 @@ test('top level async with raises errors in regular mode', () => {
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(diagnostics?.some((d) => d.message === Localizer.Diagnostic.asyncNotInAsyncFunction()));
@@ -415,7 +416,7 @@ test('top level async with raises no errors in ipython mode', () => {
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert(!diagnostics?.some((d) => d.message === Localizer.Diagnostic.asyncNotInAsyncFunction()));
@@ -474,7 +475,7 @@ function testIPython(code: string, expectMagic = true) {
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
 
-    const results = state.program.getBoundSourceFile(range.fileName)!.getParseResults()!;
+    const results = state.program.getBoundSourceFile(Uri.file(range.fileName))!.getParseResults()!;
 
     const text = results.text.substring(range.pos, range.end);
     const type = getCommentType(text);
@@ -567,7 +568,7 @@ function verifyAnalysisDiagnosticCount(code: string, expectedCount: number, expe
     state.analyze();
 
     const range = state.getRangeByMarkerName('marker')!;
-    const source = state.program.getBoundSourceFile(range.fileName)!;
+    const source = state.program.getBoundSourceFile(Uri.file(range.fileName))!;
     const diagnostics = source.getDiagnostics(state.configOptions);
 
     assert.strictEqual(diagnostics?.length, expectedCount);
diff --git a/packages/pyright-internal/src/tests/logger.test.ts b/packages/pyright-internal/src/tests/logger.test.ts
index 82835280e..ed6573a3a 100644
--- a/packages/pyright-internal/src/tests/logger.test.ts
+++ b/packages/pyright-internal/src/tests/logger.test.ts
@@ -12,6 +12,7 @@ import { ConfigOptions } from '../common/configOptions';
 import { ConsoleInterface, ConsoleWithLogLevel, LogLevel } from '../common/console';
 import { test_setDebugMode } from '../common/core';
 import { timingStats } from '../common/timing';
+import { Uri } from '../common/uri/uri';
 import * as TestUtils from './testUtils';
 
 class TestConsole implements ConsoleInterface {
@@ -44,7 +45,7 @@ class TestConsole implements ConsoleInterface {
 describe('TypeEvaluatorWithTracker tests', () => {
     const consoleInterface = new TestConsole();
     const console = new ConsoleWithLogLevel(consoleInterface);
-    const config = new ConfigOptions('.');
+    const config = new ConfigOptions(Uri.empty());
 
     beforeEach(() => {
         consoleInterface.clear();
diff --git a/packages/pyright-internal/src/tests/parseTreeUtils.test.ts b/packages/pyright-internal/src/tests/parseTreeUtils.test.ts
index 8c93db78a..32d758b5b 100644
--- a/packages/pyright-internal/src/tests/parseTreeUtils.test.ts
+++ b/packages/pyright-internal/src/tests/parseTreeUtils.test.ts
@@ -25,6 +25,7 @@ import {
     printExpression,
 } from '../analyzer/parseTreeUtils';
 import { TextRange, rangesAreEqual } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
 import { MemberAccessNode, NameNode, ParseNodeType, StringNode, isExpressionNode } from '../parser/parseNodes';
 import { TestState, getNodeAtMarker, getNodeForRange, parseAndGetTestState } from './harness/fourslash/testState';
 
@@ -320,7 +321,7 @@ test('printExpression', () => {
 
 function testNodeRange(state: TestState, markerName: string, type: ParseNodeType, includeTrailingBlankLines = false) {
     const range = state.getRangeByMarkerName(markerName)!;
-    const sourceFile = state.program.getBoundSourceFile(range.marker!.fileName)!;
+    const sourceFile = state.program.getBoundSourceFile(Uri.file(range.marker!.fileName))!;
 
     const statementNode = getFirstAncestorOrSelfOfKind(getNodeAtMarker(state, markerName), type)!;
     const statementRange = getFullStatementRange(statementNode, sourceFile.getParseResults()!, {
diff --git a/packages/pyright-internal/src/tests/pathUtils.test.ts b/packages/pyright-internal/src/tests/pathUtils.test.ts
index 871f2064e..fefaeda7b 100644
--- a/packages/pyright-internal/src/tests/pathUtils.test.ts
+++ b/packages/pyright-internal/src/tests/pathUtils.test.ts
@@ -8,44 +8,31 @@
  */
 
 import assert from 'assert';
-import * as nodefs from 'fs-extra';
-import * as os from 'os';
 import * as path from 'path';
 
-import { expandPathVariables } from '../common/envVarUtils';
 import {
-    changeAnyExtension,
     combinePathComponents,
     combinePaths,
     containsPath,
-    convertUriToPath,
-    deduplicateFolders,
     ensureTrailingDirectorySeparator,
     getAnyExtensionFromPath,
     getBaseFileName,
-    getDirectoryPath,
     getFileExtension,
     getFileName,
     getPathComponents,
     getRelativePath,
-    getRelativePathFromDirectory,
     getRootLength,
     getWildcardRegexPattern,
     getWildcardRoot,
     hasTrailingDirectorySeparator,
     isDirectoryWildcardPatternPresent,
-    isFileSystemCaseSensitiveInternal,
     isRootedDiskPath,
-    isUri,
     normalizeSlashes,
-    realCasePath,
     reducePathComponents,
     resolvePaths,
     stripFileExtension,
     stripTrailingDirectorySeparator,
 } from '../common/pathUtils';
-import { createFromRealFileSystem } from '../common/realFileSystem';
-import * as vfs from './harness/vfs/filesystem';
 
 test('getPathComponents1', () => {
     const components = getPathComponents('');
@@ -94,8 +81,8 @@ test('getPathComponents6', () => {
 test('getPathComponents7', () => {
     const components = getPathComponents('ab:cdef/test');
     assert.equal(components.length, 3);
-    assert.equal(components[0], 'ab:');
-    assert.equal(components[1], 'cdef');
+    assert.equal(components[0], '');
+    assert.equal(components[1], 'ab:cdef');
     assert.equal(components[2], 'test');
 });
 
@@ -111,7 +98,7 @@ test('combinePaths2', () => {
 
 test('combinePaths3', () => {
     const p = combinePaths('untitled:foo', 'ab:c');
-    assert.equal(p, normalizeSlashes('untitled:foo/ab%3Ac'));
+    assert.equal(p, normalizeSlashes('untitled:foo/ab:c'));
 });
 
 test('ensureTrailingDirectorySeparator1', () => {
@@ -267,32 +254,6 @@ test('resolvePath2', () => {
     assert.equal(resolvePaths('/path', 'to', '..', 'from', 'file.ext/'), normalizeSlashes('/path/from/file.ext/'));
 });
 
-test('resolvePath3 ~ escape', () => {
-    const homedir = os.homedir();
-    assert.equal(
-        resolvePaths(expandPathVariables('', '~/path'), 'to', '..', 'from', 'file.ext/'),
-        normalizeSlashes(`${homedir}/path/from/file.ext/`)
-    );
-});
-
-test('resolvePath4 ~ escape in middle', () => {
-    const homedir = os.homedir();
-    assert.equal(
-        resolvePaths('/path', expandPathVariables('', '~/file.ext/')),
-        normalizeSlashes(`${homedir}/file.ext/`)
-    );
-});
-
-test('invalid ~ without root', () => {
-    const path = combinePaths('Library', 'Mobile Documents', 'com~apple~CloudDocs', 'Development', 'mysuperproject');
-    assert.equal(resolvePaths(expandPathVariables('/src', path)), path);
-});
-
-test('invalid ~ with root', () => {
-    const path = combinePaths('/', 'Library', 'com~apple~CloudDocs', 'Development', 'mysuperproject');
-    assert.equal(resolvePaths(expandPathVariables('/src', path)), path);
-});
-
 test('containsPath1', () => {
     assert.equal(containsPath('/a/b/c/', '/a/d/../b/c/./d'), true);
 });
@@ -305,22 +266,6 @@ test('containsPath3', () => {
     assert.equal(containsPath('/a', '/A/B', true), true);
 });
 
-test('changeAnyExtension1', () => {
-    assert.equal(changeAnyExtension('/path/to/file.ext', '.js', ['.ext', '.ts'], true), '/path/to/file.js');
-});
-
-test('changeAnyExtension2', () => {
-    assert.equal(changeAnyExtension('/path/to/file.ext', '.js'), '/path/to/file.js');
-});
-
-test('changeAnyExtension3', () => {
-    assert.equal(changeAnyExtension('/path/to/file.ext', '.js', '.ts', false), '/path/to/file.ext');
-});
-
-test('changeAnyExtension1', () => {
-    assert.equal(getAnyExtensionFromPath('/path/to/file.ext'), '.ext');
-});
-
 test('changeAnyExtension2', () => {
     assert.equal(getAnyExtensionFromPath('/path/to/file.ext', '.ts', true), '');
 });
@@ -345,14 +290,6 @@ test('getBaseFileName4', () => {
     assert.equal(getBaseFileName('/path/to/file.ext', ['.ext'], true), 'file');
 });
 
-test('getRelativePathFromDirectory1', () => {
-    assert.equal(getRelativePathFromDirectory('/a', '/a/b/c/d', true), normalizeSlashes('b/c/d'));
-});
-
-test('getRelativePathFromDirectory2', () => {
-    assert.equal(getRelativePathFromDirectory('/a', '/b/c/d', true), normalizeSlashes('../b/c/d'));
-});
-
 test('getRootLength1', () => {
     assert.equal(getRootLength('a'), 0);
 });
@@ -381,14 +318,6 @@ test('getRootLength7', () => {
     assert.equal(getRootLength(fixSeparators('//server/share')), 9);
 });
 
-test('getRootLength8', () => {
-    assert.equal(getRootLength('scheme:/no/authority'), 7);
-});
-
-test('getRootLength9', () => {
-    assert.equal(getRootLength('scheme://with/authority'), 9);
-});
-
 test('isRootedDiskPath1', () => {
     assert(isRootedDiskPath(normalizeSlashes('C:/a/b')));
 });
@@ -423,121 +352,3 @@ test('getRelativePath', () => {
         normalizeSlashes('./d/e/f')
     );
 });
-
-test('getDirectoryPath', () => {
-    assert.equal(getDirectoryPath(normalizeSlashes('/a/b/c/d/e/f')), normalizeSlashes('/a/b/c/d/e'));
-    assert.equal(
-        getDirectoryPath(normalizeSlashes('untitled:/a/b/c/d/e/f?query#frag')),
-        normalizeSlashes('untitled:/a/b/c/d/e')
-    );
-});
-
-test('isUri', () => {
-    assert.ok(isUri('untitled:/a/b/c/d/e/f?query#frag'));
-    assert.ok(isUri('untitled:/a/b/c/d/e/f'));
-    assert.ok(isUri('untitled:a/b/c/d/e/f'));
-    assert.ok(isUri('untitled:/a/b/c/d/e/f?query'));
-    assert.ok(isUri('untitled:/a/b/c/d/e/f#frag'));
-    assert.ok(!isUri('c:/foo/bar'));
-    assert.ok(!isUri('c:/foo#/bar'));
-    assert.ok(!isUri('222/dd:/foo/bar'));
-});
-test('CaseSensitivity', () => {
-    const cwd = normalizeSlashes('/');
-
-    const fsCaseInsensitive = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd });
-    assert.equal(isFileSystemCaseSensitiveInternal(fsCaseInsensitive, fsCaseInsensitive), false);
-
-    const fsCaseSensitive = new vfs.TestFileSystem(/*ignoreCase*/ false, { cwd });
-    assert.equal(isFileSystemCaseSensitiveInternal(fsCaseSensitive, fsCaseSensitive), true);
-});
-
-test('deduplicateFolders', () => {
-    const listOfFolders = [
-        ['/user', '/user/temp', '/xuser/app', '/lib/python', '/home/p/.venv/lib/site-packages'],
-        ['/user', '/user/temp', '/xuser/app', '/lib/python/Python310.zip', '/home/z/.venv/lib/site-packages'],
-        ['/main/python/lib/site-packages', '/home/p'],
-    ];
-
-    const folders = deduplicateFolders(listOfFolders);
-
-    const expected = [
-        '/user',
-        '/xuser/app',
-        '/lib/python',
-        '/home/z/.venv/lib/site-packages',
-        '/main/python/lib/site-packages',
-        '/home/p',
-    ];
-
-    assert.deepStrictEqual(folders.sort(), expected.sort());
-});
-
-test('convert UNC path', () => {
-    const cwd = normalizeSlashes('/');
-    const fs = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd });
-
-    const path = convertUriToPath(fs, 'file://server/c$/folder/file.py');
-
-    // When converting UNC path, server part shouldn't be removed.
-    assert(path.indexOf('server') > 0);
-});
-
-test('Realcase', () => {
-    const fs = createFromRealFileSystem();
-    const cwd = process.cwd();
-    const dir = path.join(cwd, 'src', 'tests', '..', 'tests');
-    const entries = nodefs.readdirSync(dir).map((entry) => path.basename(nodefs.realpathSync(path.join(dir, entry))));
-    const fsentries = fs.readdirSync(dir);
-    assert.deepStrictEqual(entries, fsentries);
-
-    const paths = entries.map((entry) => nodefs.realpathSync(path.join(dir, entry)));
-    const fspaths = fsentries.map((entry) => fs.realCasePath(path.join(dir, entry)));
-    assert.deepStrictEqual(paths, fspaths);
-
-    // Check that the '..' has been removed.
-    assert.ok(!fspaths.some((p) => p.indexOf('..') >= 0));
-
-    // If windows, check that the case is correct.
-    if (process.platform === 'win32') {
-        for (const p of fspaths) {
-            const upper = p.toUpperCase();
-            const real = fs.realCasePath(upper);
-            assert.strictEqual(p, real);
-        }
-    }
-});
-
-test('Realcase use cwd implicitly', () => {
-    const fs = createFromRealFileSystem();
-    const empty = realCasePath('', fs);
-    assert.deepStrictEqual(empty, '');
-    const cwd = process.cwd();
-    const dir = path.join(cwd, 'src', 'tests');
-
-    const entries = nodefs.readdirSync(dir).map((entry) => path.basename(nodefs.realpathSync(path.join(dir, entry))));
-    const fsentries = fs.readdirSync(path.join('src', 'tests'));
-    const paths = entries.map((entry) => nodefs.realpathSync(path.join(dir, entry)));
-    const fspaths = fsentries.map((entry) => fs.realCasePath(path.join(dir, entry)));
-    assert.deepStrictEqual(paths, fspaths);
-});
-
-test('Realcase drive letter', () => {
-    const fs = createFromRealFileSystem();
-
-    const cwd = process.cwd();
-
-    assert.strictEqual(
-        getDriveLetter(fs.realCasePath(cwd)),
-        getDriveLetter(fs.realCasePath(combinePaths(cwd.toLowerCase(), 'notExist.txt')))
-    );
-
-    function getDriveLetter(path: string) {
-        const driveLetter = getRootLength(path);
-        if (driveLetter === 0) {
-            return '';
-        }
-
-        return path.substring(0, driveLetter);
-    }
-});
diff --git a/packages/pyright-internal/src/tests/pyrightFileSystem.test.ts b/packages/pyright-internal/src/tests/pyrightFileSystem.test.ts
index 05710d4f2..c1d807982 100644
--- a/packages/pyright-internal/src/tests/pyrightFileSystem.test.ts
+++ b/packages/pyright-internal/src/tests/pyrightFileSystem.test.ts
@@ -8,10 +8,12 @@ import assert from 'assert';
 
 import { lib, sitePackages } from '../common/pathConsts';
 import { combinePaths, getDirectoryPath, normalizeSlashes } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
 import { PyrightFileSystem } from '../pyrightFileSystem';
 import { TestFileSystem } from './harness/vfs/filesystem';
 
 const libraryRoot = combinePaths(normalizeSlashes('/'), lib, sitePackages);
+const libraryRootUri = Uri.file(libraryRoot);
 
 test('virtual file exists', () => {
     const files = [
@@ -34,24 +36,24 @@ test('virtual file exists', () => {
     ];
 
     const fs = createFileSystem(files);
-    fs.processPartialStubPackages([libraryRoot], [libraryRoot]);
+    fs.processPartialStubPackages([libraryRootUri], [libraryRootUri]);
 
-    const stubFile = combinePaths(libraryRoot, 'myLib', 'partialStub.pyi');
+    const stubFile = libraryRootUri.combinePaths('myLib', 'partialStub.pyi');
     assert(fs.existsSync(stubFile));
-    assert(fs.isMappedFilePath(stubFile));
+    assert(fs.isMappedUri(stubFile));
 
-    const myLib = combinePaths(libraryRoot, 'myLib');
+    const myLib = libraryRootUri.combinePaths('myLib');
     const entries = fs.readdirEntriesSync(myLib);
     assert.strictEqual(3, entries.length);
 
-    const subDirFile = combinePaths(libraryRoot, 'myLib', 'subdir', '__init__.pyi');
+    const subDirFile = libraryRootUri.combinePaths('myLib', 'subdir', '__init__.pyi');
     assert(fs.existsSync(subDirFile));
-    assert(fs.isMappedFilePath(subDirFile));
+    assert(fs.isMappedUri(subDirFile));
 
     const fakeFile = entries.filter((e) => e.name.endsWith('.pyi'))[0];
     assert(fakeFile.isFile());
 
-    assert(!fs.existsSync(combinePaths(libraryRoot, 'myLib-stubs')));
+    assert(!fs.existsSync(libraryRootUri.combinePaths('myLib-stubs')));
 });
 
 test('virtual file coexists with real', () => {
@@ -79,26 +81,27 @@ test('virtual file coexists with real', () => {
     ];
 
     const fs = createFileSystem(files);
-    fs.processPartialStubPackages([libraryRoot], [libraryRoot]);
+    fs.processPartialStubPackages([libraryRootUri], [libraryRootUri]);
 
-    const stubFile = combinePaths(libraryRoot, 'myLib', 'partialStub.pyi');
+    const stubFile = libraryRootUri.combinePaths('myLib', 'partialStub.pyi');
     assert(fs.existsSync(stubFile));
-    assert(fs.isMappedFilePath(stubFile));
+    assert(fs.isMappedUri(stubFile));
 
-    const myLib = combinePaths(libraryRoot, 'myLib');
+    const myLib = libraryRootUri.combinePaths('myLib');
     const entries = fs.readdirEntriesSync(myLib);
     assert.strictEqual(3, entries.length);
 
-    const subDirFile = combinePaths(libraryRoot, 'myLib', 'subdir', '__init__.py');
+    const subDirFile = libraryRootUri.combinePaths('myLib', 'subdir', '__init__.pyi');
     assert(fs.existsSync(subDirFile));
-    assert(!fs.isMappedFilePath(subDirFile));
-    const subDirPyiFile = combinePaths(libraryRoot, 'myLib', 'subdir', '__init__.pyi');
+    assert(fs.isMappedUri(subDirFile));
+
+    const subDirPyiFile = libraryRootUri.combinePaths('myLib', 'subdir', '__init__.pyi');
     assert(fs.existsSync(subDirPyiFile));
 
     const fakeFile = entries.filter((e) => e.name.endsWith('.pyi'))[0];
     assert(fakeFile.isFile());
 
-    assert(!fs.existsSync(combinePaths(libraryRoot, 'myLib-stubs')));
+    assert(!fs.existsSync(libraryRootUri.combinePaths('myLib-stubs')));
 });
 
 test('virtual file not exist', () => {
@@ -114,17 +117,17 @@ test('virtual file not exist', () => {
     ];
 
     const fs = createFileSystem(files);
-    fs.processPartialStubPackages([libraryRoot], [libraryRoot]);
+    fs.processPartialStubPackages([libraryRootUri], [libraryRootUri]);
 
-    assert(!fs.existsSync(combinePaths(libraryRoot, 'myLib', 'partialStub.pyi')));
+    assert(!fs.existsSync(libraryRootUri.combinePaths('myLib', 'partialStub.pyi')));
 
-    const myLib = combinePaths(libraryRoot, 'myLib');
+    const myLib = libraryRootUri.combinePaths('myLib');
     const entries = fs.readdirEntriesSync(myLib);
     assert.strictEqual(1, entries.length);
 
     assert.strictEqual(0, entries.filter((e) => e.name.endsWith('.pyi')).length);
 
-    assert(fs.existsSync(combinePaths(libraryRoot, 'myLib-stubs')));
+    assert(fs.existsSync(libraryRootUri.combinePaths('myLib-stubs')));
 });
 
 test('existing stub file', () => {
@@ -148,22 +151,23 @@ test('existing stub file', () => {
     ];
 
     const fs = createFileSystem(files);
-    fs.processPartialStubPackages([libraryRoot], [libraryRoot]);
+    fs.processPartialStubPackages([libraryRootUri], [libraryRootUri]);
 
-    const stubFile = combinePaths(libraryRoot, 'myLib', 'partialStub.pyi');
+    const stubFile = libraryRootUri.combinePaths('myLib', 'partialStub.pyi');
     assert(fs.existsSync(stubFile));
 
-    const myLib = combinePaths(libraryRoot, 'myLib');
+    const myLib = libraryRootUri.combinePaths('myLib');
     const entries = fs.readdirEntriesSync(myLib);
     assert.strictEqual(2, entries.length);
 
     assert.strictEqual('def test(): ...', fs.readFileSync(stubFile, 'utf8'));
 
-    assert(!fs.existsSync(combinePaths(libraryRoot, 'myLib-stubs')));
+    assert(!fs.existsSync(libraryRootUri.combinePaths('myLib-stubs')));
 });
 
 test('multiple package installed', () => {
     const extraRoot = combinePaths(normalizeSlashes('/'), lib, 'extra');
+    const extraRootUri = Uri.file(extraRoot);
     const files = [
         {
             path: combinePaths(libraryRoot, 'myLib-stubs', 'partialStub.pyi'),
@@ -184,20 +188,21 @@ test('multiple package installed', () => {
     ];
 
     const fs = createFileSystem(files);
-    fs.processPartialStubPackages([libraryRoot, extraRoot], [libraryRoot, extraRoot]);
+    fs.processPartialStubPackages([libraryRootUri, extraRootUri], [libraryRootUri, extraRootUri]);
 
-    assert(fs.isPathScanned(libraryRoot));
-    assert(fs.isPathScanned(extraRoot));
+    assert(fs.isPathScanned(libraryRootUri));
+    assert(fs.isPathScanned(extraRootUri));
 
-    assert(fs.existsSync(combinePaths(libraryRoot, 'myLib', 'partialStub.pyi')));
-    assert(fs.existsSync(combinePaths(extraRoot, 'myLib', 'partialStub.pyi')));
+    assert(fs.existsSync(libraryRootUri.combinePaths('myLib', 'partialStub.pyi')));
+    assert(fs.existsSync(extraRootUri.combinePaths('myLib', 'partialStub.pyi')));
 
-    assert.strictEqual(2, fs.readdirEntriesSync(combinePaths(libraryRoot, 'myLib')).length);
-    assert.strictEqual(2, fs.readdirEntriesSync(combinePaths(extraRoot, 'myLib')).length);
+    assert.strictEqual(2, fs.readdirEntriesSync(libraryRootUri.combinePaths('myLib')).length);
+    assert.strictEqual(2, fs.readdirEntriesSync(extraRootUri.combinePaths('myLib')).length);
 });
 
 test('bundled partial stubs', () => {
     const bundledPath = combinePaths(normalizeSlashes('/'), 'bundled');
+    const bundledPathUri = Uri.file(bundledPath);
 
     const files = [
         {
@@ -219,12 +224,12 @@ test('bundled partial stubs', () => {
     ];
 
     const fs = createFileSystem(files);
-    fs.processPartialStubPackages([bundledPath], [libraryRoot], bundledPath);
+    fs.processPartialStubPackages([bundledPathUri], [libraryRootUri], bundledPathUri);
 
-    const stubFile = combinePaths(libraryRoot, 'myLib', 'partialStub.pyi');
+    const stubFile = libraryRootUri.combinePaths('myLib', 'partialStub.pyi');
     assert(!fs.existsSync(stubFile));
 
-    const myLib = combinePaths(libraryRoot, 'myLib');
+    const myLib = libraryRootUri.combinePaths('myLib');
     const entries = fs.readdirEntriesSync(myLib);
     assert.strictEqual(2, entries.length);
 });
@@ -237,7 +242,7 @@ function createFileSystem(files: { path: string; content: string }[]): PyrightFi
         const dir = getDirectoryPath(path);
         fs.mkdirpSync(dir);
 
-        fs.writeFileSync(path, file.content);
+        fs.writeFileSync(Uri.file(path), file.content);
     }
 
     return new PyrightFileSystem(fs);
diff --git a/packages/pyright-internal/src/tests/service.test.ts b/packages/pyright-internal/src/tests/service.test.ts
index f6870f80a..cf12685f3 100644
--- a/packages/pyright-internal/src/tests/service.test.ts
+++ b/packages/pyright-internal/src/tests/service.test.ts
@@ -6,16 +6,19 @@
 
 import assert from 'assert';
 
-import { combinePaths, getDirectoryPath } from '../common/pathUtils';
-import { parseAndGetTestState } from './harness/fourslash/testState';
 import { CancellationToken } from 'vscode-jsonrpc';
 import { IPythonMode } from '../analyzer/sourceFile';
+import { combinePaths, getDirectoryPath } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
+import { parseAndGetTestState } from './harness/fourslash/testState';
 
 test('random library file changed', () => {
     const state = parseAndGetTestState('', '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/site-packages/test.py', ['/site-packages']),
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(Uri.file('/site-packages/test.py'), [
+            Uri.file('/site-packages'),
+        ]),
         true
     );
 });
@@ -24,7 +27,9 @@ test('random library file starting with . changed', () => {
     const state = parseAndGetTestState('', '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/site-packages/.test.py', ['/site-packages']),
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(Uri.file('/site-packages/.test.py'), [
+            Uri.file('/site-packages'),
+        ]),
         false
     );
 });
@@ -33,10 +38,10 @@ test('random library file changed, nested search paths', () => {
     const state = parseAndGetTestState('', '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/lib/.venv/site-packages/myFile.py', [
-            '/lib',
-            '/lib/.venv/site-packages',
-        ]),
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(
+            Uri.file('/lib/.venv/site-packages/myFile.py'),
+            [Uri.file('/lib'), Uri.file('/lib/.venv/site-packages')]
+        ),
         true
     );
 });
@@ -49,10 +54,10 @@ test('random library file changed, nested search paths, fs is not case sensitive
     const state = parseAndGetTestState(code, '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/lib/.venv/site-packages/myFile.py', [
-            '/lib',
-            '/LIB/.venv/site-packages',
-        ]),
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(
+            Uri.file('/lib/.venv/site-packages/myFile.py', false),
+            [Uri.file('/lib', false), Uri.file('/LIB/.venv/site-packages', false)]
+        ),
         true
     );
 });
@@ -65,10 +70,10 @@ test('random library file changed, nested search paths, fs is case sensitive', (
     const state = parseAndGetTestState(code, '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/lib/.venv/site-packages/myFile.py', [
-            '/lib',
-            '/LIB/.venv/site-packages',
-        ]),
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(
+            Uri.file('/lib/.venv/site-packages/myFile.py'),
+            [Uri.file('/lib'), Uri.file('/LIB/.venv/site-packages')]
+        ),
         false
     );
 });
@@ -81,9 +86,9 @@ test('random library file starting with . changed, fs is not case sensitive', ()
     const state = parseAndGetTestState(code, '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/lib/.test.py', [
-            '/LIB',
-            '/lib/site-packages',
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(Uri.file('/lib/.test.py', false), [
+            Uri.file('/LIB', false),
+            Uri.file('/lib/site-packages', false),
         ]),
         false
     );
@@ -97,9 +102,9 @@ test('random library file starting with . changed, fs is case sensitive', () =>
     const state = parseAndGetTestState(code, '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/lib/.test.py', [
-            '/LIB',
-            '/lib/site-packages',
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(Uri.file('/lib/.test.py'), [
+            Uri.file('/LIB'),
+            Uri.file('/lib/site-packages'),
         ]),
         true
     );
@@ -109,9 +114,10 @@ test('random library file under a folder starting with . changed', () => {
     const state = parseAndGetTestState('', '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleLibraryFileWatchChanges('/site-packages/.testFolder/test.py', [
-            '/site-packages',
-        ]),
+        state.workspace.service.test_shouldHandleLibraryFileWatchChanges(
+            Uri.file('/site-packages/.testFolder/test.py'),
+            [Uri.file('/site-packages')]
+        ),
         false
     );
 });
@@ -180,7 +186,7 @@ test('excluded but still part of program', () => {
     while (state.workspace.service.test_program.analyze());
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleSourceFileWatchChanges(marker.fileName, /* isFile */ true),
+        state.workspace.service.test_shouldHandleSourceFileWatchChanges(Uri.file(marker.fileName), /* isFile */ true),
         true
     );
 });
@@ -194,7 +200,7 @@ test('random folder changed', () => {
     const state = parseAndGetTestState(code, '/projectRoot').state;
 
     assert.strictEqual(
-        state.workspace.service.test_shouldHandleSourceFileWatchChanges('/randomFolder', /* isFile */ false),
+        state.workspace.service.test_shouldHandleSourceFileWatchChanges(Uri.file('/randomFolder'), /* isFile */ false),
         false
     );
 });
@@ -296,7 +302,7 @@ test('program containsSourceFileIn', () => {
     `;
 
     const state = parseAndGetTestState(code, '/projectRoot').state;
-    assert(state.workspace.service.test_program.containsSourceFileIn(state.activeFile.fileName));
+    assert(state.workspace.service.test_program.containsSourceFileIn(Uri.file(state.activeFile.fileName)));
 });
 
 test('service runEditMode', () => {
@@ -311,15 +317,16 @@ test('service runEditMode', () => {
     const state = parseAndGetTestState(code, '/projectRoot').state;
     const open = state.getMarkerByName('open');
     const closed = state.getMarkerByName('closed');
+    const openUri = Uri.file(open.fileName);
+    const closedUri = Uri.file(closed.fileName);
 
-    const newFilePath = combinePaths(getDirectoryPath(open.fileName), 'interimFile.py');
-    state.testFS.writeFileSync(newFilePath, '# empty', 'utf8');
+    const newFileUri = Uri.file(combinePaths(getDirectoryPath(open.fileName), 'interimFile.py'));
+    state.testFS.writeFileSync(newFileUri, '# empty', 'utf8');
 
     const options = {
         isTracked: true,
         ipythonMode: IPythonMode.None,
-        chainedFilePath: newFilePath,
-        realFilePath: closed.fileName,
+        chainedFileUri: newFileUri,
     };
 
     // try run edit mode
@@ -330,34 +337,34 @@ test('service runEditMode', () => {
 
     function verifyRunEditMode(value: string) {
         state.workspace.service.runEditMode((p) => {
-            p.addInterimFile(newFilePath);
-            p.setFileOpened(open.fileName, 0, value, options);
-            p.setFileOpened(closed.fileName, 0, value, options);
+            p.addInterimFile(newFileUri);
+            p.setFileOpened(openUri, 0, value, options);
+            p.setFileOpened(closedUri, 0, value, options);
 
-            const interim = p.getSourceFileInfo(newFilePath);
+            const interim = p.getSourceFileInfo(newFileUri);
             assert(interim);
 
-            const openFile = p.getSourceFileInfo(open.fileName);
+            const openFile = p.getSourceFileInfo(openUri);
             assert(openFile);
             assert(openFile.isOpenByClient);
             assert.strictEqual(value, openFile.sourceFile.getFileContent());
 
-            const closedFile = p.getSourceFileInfo(closed.fileName);
+            const closedFile = p.getSourceFileInfo(closedUri);
             assert(closedFile);
             assert(closedFile.isOpenByClient);
             assert.strictEqual(value, closedFile.sourceFile.getFileContent());
         }, CancellationToken.None);
 
-        const interim = state.workspace.service.test_program.getSourceFileInfo(newFilePath);
+        const interim = state.workspace.service.test_program.getSourceFileInfo(newFileUri);
         assert(!interim);
 
-        const openFile = state.workspace.service.test_program.getSourceFileInfo(open.fileName);
+        const openFile = state.workspace.service.test_program.getSourceFileInfo(openUri);
         assert(openFile);
         assert(openFile.isOpenByClient);
 
         assert.strictEqual('', openFile.sourceFile.getFileContent()?.trim());
 
-        const closedFile = state.workspace.service.test_program.getSourceFileInfo(closed.fileName);
+        const closedFile = state.workspace.service.test_program.getSourceFileInfo(closedUri);
         assert(closedFile);
         assert(!closedFile.isOpenByClient);
 
@@ -371,5 +378,8 @@ function testSourceFileWatchChange(code: string, expected = true, isFile = true)
     const marker = state.getMarkerByName('marker');
     const path = isFile ? marker.fileName : getDirectoryPath(marker.fileName);
 
-    assert.strictEqual(state.workspace.service.test_shouldHandleSourceFileWatchChanges(path, isFile), expected);
+    assert.strictEqual(
+        state.workspace.service.test_shouldHandleSourceFileWatchChanges(Uri.file(path), isFile),
+        expected
+    );
 }
diff --git a/packages/pyright-internal/src/tests/signatureHelp.test.ts b/packages/pyright-internal/src/tests/signatureHelp.test.ts
index 1c7319fd2..8bea82530 100644
--- a/packages/pyright-internal/src/tests/signatureHelp.test.ts
+++ b/packages/pyright-internal/src/tests/signatureHelp.test.ts
@@ -10,6 +10,7 @@ import assert from 'assert';
 import { CancellationToken, MarkupKind } from 'vscode-languageserver';
 
 import { convertOffsetToPosition } from '../common/positionUtils';
+import { Uri } from '../common/uri/uri';
 import { SignatureHelpProvider } from '../languageService/signatureHelpProvider';
 import { parseAndGetTestState } from './harness/fourslash/testState';
 
@@ -77,12 +78,12 @@ function checkSignatureHelp(code: string, expects: boolean) {
     const state = parseAndGetTestState(code).state;
     const marker = state.getMarkerByName('marker');
 
-    const parseResults = state.workspace.service.getParseResult(marker.fileName)!;
+    const parseResults = state.workspace.service.getParseResult(Uri.file(marker.fileName))!;
     const position = convertOffsetToPosition(marker.position, parseResults.tokenizerOutput.lines);
 
     const actual = new SignatureHelpProvider(
         state.workspace.service.test_program,
-        marker.fileName,
+        Uri.file(marker.fileName),
         position,
         MarkupKind.Markdown,
         /*hasSignatureLabelOffsetCapability*/ true,
diff --git a/packages/pyright-internal/src/tests/sourceFile.test.ts b/packages/pyright-internal/src/tests/sourceFile.test.ts
index b709cf744..03d425f58 100644
--- a/packages/pyright-internal/src/tests/sourceFile.test.ts
+++ b/packages/pyright-internal/src/tests/sourceFile.test.ts
@@ -14,17 +14,18 @@ import { ConfigOptions } from '../common/configOptions';
 import { FullAccessHost } from '../common/fullAccessHost';
 import { combinePaths } from '../common/pathUtils';
 import { createFromRealFileSystem } from '../common/realFileSystem';
-import { parseAndGetTestState } from './harness/fourslash/testState';
 import { createServiceProvider } from '../common/serviceProviderExtensions';
+import { Uri } from '../common/uri/uri';
+import { parseAndGetTestState } from './harness/fourslash/testState';
 
 test('Empty', () => {
     const filePath = combinePaths(process.cwd(), 'tests/samples/test_file1.py');
     const fs = createFromRealFileSystem();
     const serviceProvider = createServiceProvider(fs);
-    const sourceFile = new SourceFile(serviceProvider, filePath, '', false, false, { isEditMode: false });
-    const configOptions = new ConfigOptions(process.cwd());
+    const sourceFile = new SourceFile(serviceProvider, Uri.file(filePath), '', false, false, { isEditMode: false });
+    const configOptions = new ConfigOptions(Uri.file(process.cwd()));
     const sp = createServiceProvider(fs);
-    const importResolver = new ImportResolver(sp, configOptions, new FullAccessHost(fs));
+    const importResolver = new ImportResolver(sp, configOptions, new FullAccessHost(sp));
 
     sourceFile.parse(configOptions, importResolver);
 });
@@ -39,10 +40,13 @@ test('Empty Open file', () => {
     const marker = state.getMarkerByName('marker');
 
     assert.strictEqual(
-        state.workspace.service.test_program.getSourceFile(marker.fileName)?.getFileContent(),
+        state.workspace.service.test_program.getSourceFile(Uri.file(marker.fileName))?.getFileContent(),
         '# Content'
     );
 
-    state.workspace.service.updateOpenFileContents(marker.fileName, 1, '');
-    assert.strictEqual(state.workspace.service.test_program.getSourceFile(marker.fileName)?.getFileContent(), '');
+    state.workspace.service.updateOpenFileContents(Uri.file(marker.fileName), 1, '');
+    assert.strictEqual(
+        state.workspace.service.test_program.getSourceFile(Uri.file(marker.fileName))?.getFileContent(),
+        ''
+    );
 });
diff --git a/packages/pyright-internal/src/tests/sourceMapperUtils.test.ts b/packages/pyright-internal/src/tests/sourceMapperUtils.test.ts
index 3c85c0be9..6588368aa 100644
--- a/packages/pyright-internal/src/tests/sourceMapperUtils.test.ts
+++ b/packages/pyright-internal/src/tests/sourceMapperUtils.test.ts
@@ -6,9 +6,27 @@
  * Unit tests for pyright sourceMapperUtils module.
  */
 import * as assert from 'assert';
-import { CancellationTokenSource } from 'vscode-jsonrpc';
+import { CancellationToken, CancellationTokenSource } from 'vscode-jsonrpc';
 
-import { buildImportTree } from '../analyzer/sourceMapperUtils';
+import { buildImportTree as buildImportTreeImpl } from '../analyzer/sourceMapperUtils';
+import { Uri } from '../common/uri/uri';
+
+function buildImportTree(
+    sourceFile: string,
+    targetFile: string,
+    importResolver: (f: string) => string[],
+    token: CancellationToken
+): string[] {
+    return buildImportTreeImpl(
+        Uri.file(sourceFile),
+        Uri.file(targetFile),
+        (from) => {
+            const resolved = importResolver(from.getFilePath().slice(1));
+            return resolved.map((f) => Uri.file(f));
+        },
+        token
+    ).map((u) => u.getFilePath().slice(1));
+}
 
 describe('BuildImportTree', () => {
     const tokenSource = new CancellationTokenSource();
diff --git a/packages/pyright-internal/src/tests/testState.test.ts b/packages/pyright-internal/src/tests/testState.test.ts
index 2836ea2e8..546414c2e 100644
--- a/packages/pyright-internal/src/tests/testState.test.ts
+++ b/packages/pyright-internal/src/tests/testState.test.ts
@@ -10,6 +10,7 @@ import assert from 'assert';
 
 import { combinePaths, getFileName, normalizeSlashes } from '../common/pathUtils';
 import { compareStringsCaseSensitive } from '../common/stringUtils';
+import { Uri } from '../common/uri/uri';
 import { Range } from './harness/fourslash/fourSlashTypes';
 import { runFourSlashTestContent } from './harness/fourslash/runner';
 import { parseAndGetTestState } from './harness/fourslash/testState';
@@ -44,7 +45,7 @@ test('Multiple files', () => {
     const state = parseAndGetTestState(code, factory.srcFolder).state;
 
     assert.equal(state.cwd(), normalizeSlashes('/'));
-    assert(state.fs.existsSync(normalizeSlashes(combinePaths(factory.srcFolder, 'file1.py'))));
+    assert(state.fs.existsSync(Uri.file(normalizeSlashes(combinePaths(factory.srcFolder, 'file1.py')))));
 });
 
 test('Configuration', () => {
@@ -114,11 +115,11 @@ test('Configuration', () => {
     const state = parseAndGetTestState(code, factory.srcFolder).state;
 
     assert.equal(state.cwd(), normalizeSlashes('/'));
-    assert(state.fs.existsSync(normalizeSlashes(combinePaths(factory.srcFolder, 'file1.py'))));
+    assert(state.fs.existsSync(Uri.file(normalizeSlashes(combinePaths(factory.srcFolder, 'file1.py')))));
 
     assert.equal(state.configOptions.diagnosticRuleSet.reportMissingImports, 'error');
     assert.equal(state.configOptions.diagnosticRuleSet.reportMissingModuleSource, 'warning');
-    assert.equal(state.configOptions.stubPath, normalizeSlashes('/src/typestubs'));
+    assert.equal(state.configOptions.stubPath?.getFilePath(), normalizeSlashes('/src/typestubs'));
 });
 
 test('stubPath configuration', () => {
@@ -130,7 +131,7 @@ test('stubPath configuration', () => {
     `;
 
     const state = parseAndGetTestState(code).state;
-    assert.equal(state.configOptions.stubPath, normalizeSlashes('/src/typestubs'));
+    assert.equal(state.configOptions.stubPath?.getFilePath(), normalizeSlashes('/src/typestubs'));
 });
 
 test('Duplicated stubPath configuration', () => {
@@ -143,7 +144,7 @@ test('Duplicated stubPath configuration', () => {
     `;
 
     const state = parseAndGetTestState(code).state;
-    assert.equal(state.configOptions.stubPath, normalizeSlashes('/src/typestubs2'));
+    assert.equal(state.configOptions.stubPath?.getFilePath(), normalizeSlashes('/src/typestubs2'));
 });
 
 test('ProjectRoot', () => {
@@ -159,9 +160,9 @@ test('ProjectRoot', () => {
     const state = parseAndGetTestState(code).state;
 
     assert.equal(state.cwd(), normalizeSlashes('/root'));
-    assert(state.fs.existsSync(normalizeSlashes('/root/file1.py')));
+    assert(state.fs.existsSync(Uri.file(normalizeSlashes('/root/file1.py'))));
 
-    assert.equal(state.configOptions.projectRoot, normalizeSlashes('/root'));
+    assert.equal(state.configOptions.projectRoot.getFilePath(), normalizeSlashes('/root'));
 });
 
 test('CustomTypeshedFolder', () => {
@@ -177,7 +178,7 @@ test('CustomTypeshedFolder', () => {
     // mount the folder this file is in as typeshed folder and check whether
     // in typeshed folder in virtual file system, this file exists.
     const state = parseAndGetTestState(code).state;
-    assert(state.fs.existsSync(combinePaths(factory.typeshedFolder, getFileName(__filename))));
+    assert(state.fs.existsSync(Uri.file(combinePaths(factory.typeshedFolder, getFileName(__filename)))));
 });
 
 test('IgnoreCase', () => {
@@ -192,7 +193,7 @@ test('IgnoreCase', () => {
 
     const state = parseAndGetTestState(code, factory.srcFolder).state;
 
-    assert(state.fs.existsSync(normalizeSlashes(combinePaths(factory.srcFolder, 'FILE1.py'))));
+    assert(state.fs.existsSync(Uri.file(normalizeSlashes(combinePaths(factory.srcFolder, 'FILE1.py')))));
 });
 
 test('GoToMarker', () => {
diff --git a/packages/pyright-internal/src/tests/testStateUtils.ts b/packages/pyright-internal/src/tests/testStateUtils.ts
index fdd1dd85f..ff5e87bf6 100644
--- a/packages/pyright-internal/src/tests/testStateUtils.ts
+++ b/packages/pyright-internal/src/tests/testStateUtils.ts
@@ -7,27 +7,26 @@
  */
 
 import assert from 'assert';
-import { WorkspaceEdit } from 'vscode-languageserver-protocol';
 
-import { createMapFromItems } from '../common/collectionUtils';
-import { assertNever } from '../common/debug';
-import { FileEditAction, FileEditActions, FileOperations } from '../common/editAction';
-import { FileSystem } from '../common/fileSystem';
-import { convertUriToPath, getDirectoryPath, isFile } from '../common/pathUtils';
-import { TextRange, rangesAreEqual } from '../common/textRange';
-import { applyTextEditsToString } from '../common/workspaceEditUtils';
-import { Range } from './harness/fourslash/fourSlashTypes';
-import { TestState } from './harness/fourslash/testState';
-import { CancellationToken, CreateFile, DeleteFile, RenameFile, TextDocumentEdit } from 'vscode-languageserver';
-import { Program } from '../analyzer/program';
-import { ConfigOptions } from '../common/configOptions';
+import { CancellationToken } from 'vscode-languageserver';
 import { findNodeByOffset } from '../analyzer/parseTreeUtils';
+import { Program } from '../analyzer/program';
+import { createMapFromItems } from '../common/collectionUtils';
+import { ConfigOptions } from '../common/configOptions';
+import { isArray } from '../common/core';
+import { assertNever } from '../common/debug';
+import { FileEditAction, FileEditActions } from '../common/editAction';
+import { TextRange, rangesAreEqual } from '../common/textRange';
+import { Uri } from '../common/uri/uri';
+import { isFile } from '../common/uri/uriUtils';
+import { applyTextEditsToString } from '../common/workspaceEditUtils';
 import { DocumentSymbolCollector } from '../languageService/documentSymbolCollector';
 import { NameNode } from '../parser/parseNodes';
-import { isArray } from '../common/core';
+import { Range } from './harness/fourslash/fourSlashTypes';
+import { TestState } from './harness/fourslash/testState';
 
 export function convertFileEditActionToString(edit: FileEditAction): string {
-    return `'${edit.replacementText.replace(/\n/g, '!n!')}'@'${edit.filePath}:(${edit.range.start.line},${
+    return `'${edit.replacementText.replace(/\n/g, '!n!')}'@'${edit.fileUri}:(${edit.range.start.line},${
         edit.range.start.character
     })-(${edit.range.end.line},${edit.range.end.character})'`;
 }
@@ -35,7 +34,7 @@ export function convertFileEditActionToString(edit: FileEditAction): string {
 export function convertRangeToFileEditAction(state: TestState, range: Range, replacementText?: string): FileEditAction {
     const data = range.marker?.data as { r: string } | undefined;
     return {
-        filePath: range.fileName,
+        fileUri: Uri.file(range.fileName),
         replacementText: (replacementText ?? data?.r ?? 'N/A').replace(/!n!/g, '\n'),
         range: state.convertPositionRange(range),
     };
@@ -52,7 +51,7 @@ export function verifyEdits(
         assert(
             expected.some((a) => {
                 return (
-                    a.filePath === edit.filePath &&
+                    a.fileUri === edit.fileUri &&
                     rangesAreEqual(a.range, edit.range) &&
                     a.replacementText === edit.replacementText
                 );
@@ -67,24 +66,24 @@ export function verifyEdits(
 export function applyFileEditActions(state: TestState, fileEditActions: FileEditActions) {
     // Apply changes
     // First, apply text changes
-    const editsPerFileMap = createMapFromItems(fileEditActions.edits, (e) => e.filePath);
+    const editsPerFileMap = createMapFromItems(fileEditActions.edits, (e) => e.fileUri.key);
 
     for (const [editFileName, editsPerFile] of editsPerFileMap) {
         const result = _applyEdits(state, editFileName, editsPerFile);
-        state.testFS.writeFileSync(editFileName, result.text, 'utf8');
+        state.testFS.writeFileSync(Uri.file(editFileName), result.text, 'utf8');
 
         // Update open file content if the file is in opened state.
         if (result.version) {
             let openedFilePath = editFileName;
             const renamed = fileEditActions.fileOperations.find(
-                (o) => o.kind === 'rename' && o.oldFilePath === editFileName
+                (o) => o.kind === 'rename' && o.oldFileUri.getFilePath() === editFileName
             );
             if (renamed?.kind === 'rename') {
-                openedFilePath = renamed.newFilePath;
-                state.program.setFileClosed(renamed.oldFilePath);
+                openedFilePath = renamed.newFileUri.getFilePath();
+                state.program.setFileClosed(renamed.oldFileUri);
             }
 
-            state.program.setFileOpened(openedFilePath, result.version + 1, result.text);
+            state.program.setFileOpened(Uri.file(openedFilePath), result.version + 1, result.text);
         }
     }
 
@@ -92,24 +91,30 @@ export function applyFileEditActions(state: TestState, fileEditActions: FileEdit
     for (const fileOperation of fileEditActions.fileOperations) {
         switch (fileOperation.kind) {
             case 'create': {
-                state.testFS.mkdirpSync(getDirectoryPath(fileOperation.filePath));
-                state.testFS.writeFileSync(fileOperation.filePath, '');
+                state.testFS.mkdirpSync(fileOperation.fileUri.getDirectory().getFilePath());
+                state.testFS.writeFileSync(fileOperation.fileUri, '');
                 break;
             }
             case 'rename': {
-                if (isFile(state.testFS, fileOperation.oldFilePath)) {
-                    state.testFS.mkdirpSync(getDirectoryPath(fileOperation.newFilePath));
-                    state.testFS.renameSync(fileOperation.oldFilePath, fileOperation.newFilePath);
+                if (isFile(state.testFS, fileOperation.oldFileUri)) {
+                    state.testFS.mkdirpSync(fileOperation.newFileUri.getDirectory().getFilePath());
+                    state.testFS.renameSync(
+                        fileOperation.oldFileUri.getFilePath(),
+                        fileOperation.newFileUri.getFilePath()
+                    );
 
                     // Add new file as tracked file
-                    state.program.addTrackedFile(fileOperation.newFilePath);
+                    state.program.addTrackedFile(fileOperation.newFileUri);
                 } else {
-                    state.testFS.renameSync(fileOperation.oldFilePath, fileOperation.newFilePath);
+                    state.testFS.renameSync(
+                        fileOperation.oldFileUri.getFilePath(),
+                        fileOperation.newFileUri.getFilePath()
+                    );
                 }
                 break;
             }
             case 'delete': {
-                state.testFS.rimrafSync(fileOperation.filePath);
+                state.testFS.rimrafSync(fileOperation.fileUri.getFilePath());
                 break;
             }
             default:
@@ -123,11 +128,11 @@ export function applyFileEditActions(state: TestState, fileEditActions: FileEdit
 }
 
 function _applyEdits(state: TestState, filePath: string, edits: FileEditAction[]) {
-    const sourceFile = state.program.getBoundSourceFile(filePath)!;
+    const sourceFile = state.program.getBoundSourceFile(Uri.file(filePath))!;
     const parseResults = sourceFile.getParseResults()!;
 
     const current = applyTextEditsToString(
-        edits.filter((e) => e.filePath === filePath),
+        edits.filter((e) => e.fileUri.getFilePath() === filePath),
         parseResults.tokenizerOutput.lines,
         parseResults.text
     );
@@ -135,43 +140,6 @@ function _applyEdits(state: TestState, filePath: string, edits: FileEditAction[]
     return { version: sourceFile.getClientVersion(), text: current };
 }
 
-export function convertWorkspaceEditToFileEditActions(fs: FileSystem, edit: WorkspaceEdit): FileEditActions {
-    const edits: FileEditAction[] = [];
-    const fileOperations: FileOperations[] = [];
-
-    if (edit.changes) {
-        for (const kv of Object.entries(edit.changes)) {
-            const filePath = convertUriToPath(fs, kv[0]);
-            kv[1].forEach((e) => edits.push({ filePath, range: e.range, replacementText: e.newText }));
-        }
-    }
-
-    if (edit.documentChanges) {
-        for (const change of edit.documentChanges) {
-            if (TextDocumentEdit.is(change)) {
-                for (const e of change.edits) {
-                    edits.push({
-                        filePath: convertUriToPath(fs, change.textDocument.uri),
-                        range: e.range,
-                        replacementText: e.newText,
-                    });
-                }
-            } else if (CreateFile.is(change)) {
-                fileOperations.push({ kind: 'create', filePath: convertUriToPath(fs, change.uri) });
-            } else if (RenameFile.is(change)) {
-                fileOperations.push({
-                    kind: 'rename',
-                    oldFilePath: convertUriToPath(fs, change.oldUri),
-                    newFilePath: convertUriToPath(fs, change.newUri),
-                });
-            } else if (DeleteFile.is(change)) {
-                fileOperations.push({ kind: 'delete', filePath: convertUriToPath(fs, change.uri) });
-            }
-        }
-    }
-    return { edits, fileOperations: fileOperations };
-}
-
 export function verifyReferencesAtPosition(
     program: Program,
     configOption: ConfigOptions,
@@ -180,7 +148,7 @@ export function verifyReferencesAtPosition(
     position: number,
     ranges: Range[]
 ) {
-    const sourceFile = program.getBoundSourceFile(fileName);
+    const sourceFile = program.getBoundSourceFile(Uri.file(fileName));
     assert(sourceFile);
 
     const node = findNodeByOffset(sourceFile.getParseResults()!.parseTree, position);
@@ -197,7 +165,7 @@ export function verifyReferencesAtPosition(
             program,
             isArray(symbolNames) ? symbolNames : [symbolNames],
             decls,
-            program.getBoundSourceFile(rangeFileName)!.getParseResults()!.parseTree,
+            program.getBoundSourceFile(Uri.file(rangeFileName))!.getParseResults()!.parseTree,
             CancellationToken.None,
             {
                 treatModuleInImportAndFromImportSame: true,
diff --git a/packages/pyright-internal/src/tests/testUtils.ts b/packages/pyright-internal/src/tests/testUtils.ts
index 46ec0c540..8872b965b 100644
--- a/packages/pyright-internal/src/tests/testUtils.ts
+++ b/packages/pyright-internal/src/tests/testUtils.ts
@@ -11,22 +11,20 @@ import * as assert from 'assert';
 import * as fs from 'fs';
 import * as path from 'path';
 
-import { AnalyzerFileInfo } from '../analyzer/analyzerFileInfo';
-import { Binder } from '../analyzer/binder';
 import { ImportResolver } from '../analyzer/importResolver';
 import { Program } from '../analyzer/program';
-import { IPythonMode } from '../analyzer/sourceFile';
 import { NameTypeWalker } from '../analyzer/testWalker';
 import { TypeEvaluator } from '../analyzer/typeEvaluatorTypes';
-import { cloneDiagnosticRuleSet, ConfigOptions, ExecutionEnvironment } from '../common/configOptions';
+import { ConfigOptions, ExecutionEnvironment } from '../common/configOptions';
 import { ConsoleWithLogLevel, NullConsole } from '../common/console';
 import { fail } from '../common/debug';
 import { Diagnostic, DiagnosticCategory } from '../common/diagnostic';
-import { DiagnosticSink, TextRangeDiagnosticSink } from '../common/diagnosticSink';
+import { DiagnosticSink } from '../common/diagnosticSink';
 import { FullAccessHost } from '../common/fullAccessHost';
 import { createFromRealFileSystem } from '../common/realFileSystem';
 import { createServiceProvider } from '../common/serviceProviderExtensions';
-import { ParseOptions, Parser, ParseResults } from '../parser/parser';
+import { Uri } from '../common/uri/uri';
+import { ParseOptions, ParseResults, Parser } from '../parser/parser';
 
 // This is a bit gross, but it's necessary to allow the fallback typeshed
 // directory to be located when running within the jest environment. This
@@ -35,7 +33,7 @@ import { ParseOptions, Parser, ParseResults } from '../parser/parser';
 (global as any).__rootDirectory = path.resolve();
 
 export interface FileAnalysisResult {
-    filePath: string;
+    fileUri: Uri;
     parseResults?: ParseResults | undefined;
     errors: Diagnostic[];
     warnings: Diagnostic[];
@@ -79,7 +77,7 @@ export function parseSampleFile(
     diagSink: DiagnosticSink,
     execEnvironment = new ExecutionEnvironment(
         'python',
-        '.',
+        Uri.file('.'),
         /* defaultPythonVersion */ undefined,
         /* defaultPythonPlatform */ undefined,
         /* defaultExtraPaths */ undefined
@@ -98,65 +96,9 @@ export function parseSampleFile(
     };
 }
 
-export function buildAnalyzerFileInfo(
-    filePath: string,
-    fileContents: string,
-    parseResults: ParseResults,
-    configOptions: ConfigOptions
-): AnalyzerFileInfo {
-    const analysisDiagnostics = new TextRangeDiagnosticSink(parseResults.tokenizerOutput.lines);
-
-    const fileInfo: AnalyzerFileInfo = {
-        importLookup: (_) => undefined,
-        futureImports: new Set<string>(),
-        builtinsScope: undefined,
-        diagnosticSink: analysisDiagnostics,
-        executionEnvironment: configOptions.findExecEnvironment(filePath),
-        diagnosticRuleSet: cloneDiagnosticRuleSet(configOptions.diagnosticRuleSet),
-        definedConstants: configOptions.defineConstant,
-        fileContents,
-        lines: parseResults.tokenizerOutput.lines,
-        filePath,
-        moduleName: '',
-        isStubFile: filePath.endsWith('.pyi'),
-        isTypingStubFile: false,
-        isInPyTypedPackage: false,
-        isTypingExtensionsStubFile: false,
-        isTypeshedStubFile: false,
-        isBuiltInStubFile: false,
-        ipythonMode: IPythonMode.None,
-        accessedSymbolSet: new Set<number>(),
-        typingSymbolAliases: new Map<string, string>(),
-    };
-
-    return fileInfo;
-}
-
-export function bindSampleFile(fileName: string, configOptions = new ConfigOptions('.')): FileAnalysisResult {
-    const diagSink = new DiagnosticSink();
-    const filePath = resolveSampleFilePath(fileName);
-    const execEnvironment = configOptions.findExecEnvironment(filePath);
-    const parseInfo = parseSampleFile(fileName, diagSink, execEnvironment);
-
-    const fileInfo = buildAnalyzerFileInfo(filePath, parseInfo.fileContents, parseInfo.parseResults, configOptions);
-    const binder = new Binder(fileInfo);
-    binder.bindModule(parseInfo.parseResults.parseTree);
-
-    return {
-        filePath,
-        parseResults: parseInfo.parseResults,
-        errors: fileInfo.diagnosticSink.getErrors(),
-        warnings: fileInfo.diagnosticSink.getWarnings(),
-        infos: fileInfo.diagnosticSink.getInformation(),
-        unusedCodes: fileInfo.diagnosticSink.getUnusedCode(),
-        unreachableCodes: fileInfo.diagnosticSink.getUnreachableCode(),
-        deprecateds: fileInfo.diagnosticSink.getDeprecated(),
-    };
-}
-
 export function typeAnalyzeSampleFiles(
     fileNames: string[],
-    configOptions = new ConfigOptions('.'),
+    configOptions = new ConfigOptions(Uri.empty()),
     console?: ConsoleWithLogLevel
 ): FileAnalysisResult[] {
     // Always enable "test mode".
@@ -164,11 +106,11 @@ export function typeAnalyzeSampleFiles(
 
     const fs = createFromRealFileSystem();
     const serviceProvider = createServiceProvider(fs, console || new NullConsole());
-    const importResolver = new ImportResolver(serviceProvider, configOptions, new FullAccessHost(fs));
+    const importResolver = new ImportResolver(serviceProvider, configOptions, new FullAccessHost(serviceProvider));
 
     const program = new Program(importResolver, configOptions, serviceProvider);
-    const filePaths = fileNames.map((name) => resolveSampleFilePath(name));
-    program.setTrackedFiles(filePaths);
+    const fileUris = fileNames.map((name) => Uri.file(resolveSampleFilePath(name)));
+    program.setTrackedFiles(fileUris);
 
     // Set a "pre-check callback" so we can evaluate the types of each NameNode
     // prior to checking the full document. This will exercise the contextual
@@ -178,7 +120,7 @@ export function typeAnalyzeSampleFiles(
         nameTypeWalker.walk(parseResults.parseTree);
     });
 
-    const results = getAnalysisResults(program, filePaths, configOptions);
+    const results = getAnalysisResults(program, fileUris, configOptions);
 
     program.dispose();
     return results;
@@ -186,8 +128,8 @@ export function typeAnalyzeSampleFiles(
 
 export function getAnalysisResults(
     program: Program,
-    filePaths: string[],
-    configOptions = new ConfigOptions('.')
+    fileUris: Uri[],
+    configOptions = new ConfigOptions(Uri.empty())
 ): FileAnalysisResult[] {
     // Always enable "test mode".
     configOptions.internalTestMode = true;
@@ -197,12 +139,12 @@ export function getAnalysisResults(
         // specifying a timeout, it should complete the first time.
     }
 
-    const sourceFiles = filePaths.map((filePath) => program.getSourceFile(filePath));
+    const sourceFiles = fileUris.map((filePath) => program.getSourceFile(filePath));
     return sourceFiles.map((sourceFile, index) => {
         if (sourceFile) {
             const diagnostics = sourceFile.getDiagnostics(configOptions) || [];
             const analysisResult: FileAnalysisResult = {
-                filePath: sourceFile.getFilePath(),
+                fileUri: sourceFile.getUri(),
                 parseResults: sourceFile.getParseResults(),
                 errors: diagnostics.filter((diag) => diag.category === DiagnosticCategory.Error),
                 warnings: diagnostics.filter((diag) => diag.category === DiagnosticCategory.Warning),
@@ -213,10 +155,10 @@ export function getAnalysisResults(
             };
             return analysisResult;
         } else {
-            fail(`Source file not found for ${filePaths[index]}`);
+            fail(`Source file not found for ${fileUris[index]}`);
 
             const analysisResult: FileAnalysisResult = {
-                filePath: '',
+                fileUri: Uri.empty(),
                 parseResults: undefined,
                 errors: [],
                 warnings: [],
@@ -232,14 +174,14 @@ export function getAnalysisResults(
 
 export function printDiagnostics(fileResults: FileAnalysisResult) {
     if (fileResults.errors.length > 0) {
-        console.error(`Errors in ${fileResults.filePath}:`);
+        console.error(`Errors in ${fileResults.fileUri}:`);
         for (const diag of fileResults.errors) {
             console.error(`  ${diag.message}`);
         }
     }
 
     if (fileResults.warnings.length > 0) {
-        console.error(`Warnings in ${fileResults.filePath}:`);
+        console.error(`Warnings in ${fileResults.fileUri}:`);
         for (const diag of fileResults.warnings) {
             console.error(`  ${diag.message}`);
         }
diff --git a/packages/pyright-internal/src/tests/textEditUtil.test.ts b/packages/pyright-internal/src/tests/textEditUtil.test.ts
index a6416e7e7..38eb0cc97 100644
--- a/packages/pyright-internal/src/tests/textEditUtil.test.ts
+++ b/packages/pyright-internal/src/tests/textEditUtil.test.ts
@@ -7,12 +7,13 @@
 import assert from 'assert';
 import { CancellationToken } from 'vscode-jsonrpc';
 
+import { findNodeByOffset } from '../analyzer/parseTreeUtils';
 import { FileEditAction } from '../common/editAction';
 import { TextEditTracker } from '../common/textEditTracker';
+import { Uri } from '../common/uri/uri';
 import { Range } from './harness/fourslash/fourSlashTypes';
 import { parseAndGetTestState, TestState } from './harness/fourslash/testState';
 import { convertRangeToFileEditAction } from './testStateUtils';
-import { findNodeByOffset } from '../analyzer/parseTreeUtils';
 
 test('simple add', () => {
     const code = `
@@ -114,7 +115,7 @@ function verifyRemoveNodes(code: string) {
     const ranges = state.getRanges();
     const changeRanges = _getChangeRanges(ranges);
     for (const range of changeRanges) {
-        const parseResults = state.program.getParseResults(range.fileName)!;
+        const parseResults = state.program.getParseResults(Uri.file(range.fileName))!;
         const node = findNodeByOffset(parseResults.parseTree, range.pos)!;
         tracker.removeNodes({ node, parseResults });
     }
@@ -139,7 +140,7 @@ function verifyEdits(code: string, mergeOnlyDuplications = true) {
     const changeRanges = _getChangeRanges(ranges);
     for (const range of changeRanges) {
         const edit = convertRangeToFileEditAction(state, range);
-        tracker.addEdit(edit.filePath, edit.range, edit.replacementText);
+        tracker.addEdit(edit.fileUri, edit.range, edit.replacementText);
     }
 
     const edits = tracker.getEdits(CancellationToken.None);
diff --git a/packages/pyright-internal/src/tests/typeEvaluator1.test.ts b/packages/pyright-internal/src/tests/typeEvaluator1.test.ts
index 64c07be3b..260df47b3 100644
--- a/packages/pyright-internal/src/tests/typeEvaluator1.test.ts
+++ b/packages/pyright-internal/src/tests/typeEvaluator1.test.ts
@@ -14,6 +14,7 @@ import * as AnalyzerNodeInfo from '../analyzer/analyzerNodeInfo';
 import { ScopeType } from '../analyzer/scope';
 import { ConfigOptions } from '../common/configOptions';
 import { PythonVersion } from '../common/pythonVersion';
+import { Uri } from '../common/uri/uri';
 import * as TestUtils from './testUtils';
 
 test('Unreachable1', () => {
@@ -628,7 +629,7 @@ test('Unpack2', () => {
 });
 
 test('Unpack3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.7 settings.
     configOptions.defaultPythonVersion = PythonVersion.V3_7;
@@ -642,7 +643,7 @@ test('Unpack3', () => {
 });
 
 test('Unpack4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.8 settings.
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
@@ -656,7 +657,7 @@ test('Unpack4', () => {
 });
 
 test('Unpack4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['unpack5.py'], configOptions);
@@ -760,7 +761,7 @@ test('Call2', () => {
 });
 
 test('Call3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.7 settings. This will generate more errors.
     configOptions.defaultPythonVersion = PythonVersion.V3_7;
@@ -888,7 +889,7 @@ test('KwargsUnpack1', () => {
 });
 
 test('FunctionMember1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportFunctionMemberAccess = 'none';
     const analysisResult1 = TestUtils.typeAnalyzeSampleFiles(['functionMember1.py'], configOptions);
@@ -978,7 +979,7 @@ test('AnnotatedVar6', () => {
 });
 
 test('AnnotatedVar7', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['annotatedVar7.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
@@ -1079,7 +1080,7 @@ test('Property5', () => {
 });
 
 test('Property6', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with reportPropertyTypeMismatch enabled.
     configOptions.diagnosticRuleSet.reportPropertyTypeMismatch = 'error';
@@ -1219,7 +1220,7 @@ test('Operator11', () => {
 });
 
 test('Optional1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Disable diagnostics.
     configOptions.diagnosticRuleSet.reportOptionalSubscript = 'none';
@@ -1253,7 +1254,7 @@ test('Optional1', () => {
 });
 
 test('Optional2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Disable diagnostics.
     configOptions.diagnosticRuleSet.reportOptionalOperand = 'none';
@@ -1441,7 +1442,7 @@ test('Slots3', () => {
 });
 
 test('Parameters1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportMissingParameterType = 'none';
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['parameters1.py'], configOptions);
@@ -1513,7 +1514,7 @@ test('Self10', () => {
 });
 
 test('UnusedVariable1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportUnusedVariable = 'none';
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['unusedVariable1.py'], configOptions);
@@ -1585,7 +1586,7 @@ test('TupleUnpack1', () => {
 });
 
 test('TupleUnpack2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['tupleUnpack2.py'], configOptions);
@@ -1597,7 +1598,7 @@ test('TupleUnpack2', () => {
 });
 
 test('TupleUnpack3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['tupleUnpack3.py'], configOptions);
@@ -1677,7 +1678,7 @@ test('Dictionary4', () => {
 });
 
 test('StaticExpression1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
     configOptions.defaultPythonPlatform = 'windows';
diff --git a/packages/pyright-internal/src/tests/typeEvaluator2.test.ts b/packages/pyright-internal/src/tests/typeEvaluator2.test.ts
index c561fdbb9..717569bd5 100644
--- a/packages/pyright-internal/src/tests/typeEvaluator2.test.ts
+++ b/packages/pyright-internal/src/tests/typeEvaluator2.test.ts
@@ -10,6 +10,7 @@
 
 import { ConfigOptions } from '../common/configOptions';
 import { PythonVersion } from '../common/pythonVersion';
+import { Uri } from '../common/uri/uri';
 import * as TestUtils from './testUtils';
 
 test('CallbackProtocol1', () => {
@@ -133,7 +134,7 @@ test('Assignment11', () => {
 });
 
 test('Assignment12', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['assignment12.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
@@ -228,7 +229,7 @@ test('Super11', () => {
 });
 
 test('MissingSuper1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['missingSuper1.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
@@ -287,7 +288,7 @@ test('isInstance2', () => {
 });
 
 test('isInstance3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_9;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['isinstance3.py'], configOptions);
@@ -335,7 +336,7 @@ test('Unbound5', () => {
 });
 
 test('Assert1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, this is reported as a warning.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['assert1.py'], configOptions);
@@ -479,7 +480,7 @@ test('ConstrainedTypeVar14', () => {
 });
 
 test('ConstrainedTypeVar15', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.disableBytesTypePromotions = true;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['constrainedTypeVar15.py'], configOptions);
@@ -506,7 +507,7 @@ test('ConstrainedTypeVar18', () => {
 });
 
 test('MissingTypeArg1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, reportMissingTypeArgument is disabled.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['missingTypeArg1.py']);
@@ -1185,7 +1186,7 @@ test('Protocol16', () => {
 });
 
 test('Protocol17', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.reportInvalidTypeVarUse = 'error';
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['protocol17.py']);
 
@@ -1217,7 +1218,7 @@ test('Protocol21', () => {
 });
 
 test('Protocol22', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.reportInvalidTypeVarUse = 'error';
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['protocol22.py']);
 
@@ -1519,7 +1520,7 @@ test('TypedDict24', () => {
 });
 
 test('TypedDictInline1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.enableExperimentalFeatures = true;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typedDictInline1.py'], configOptions);
diff --git a/packages/pyright-internal/src/tests/typeEvaluator3.test.ts b/packages/pyright-internal/src/tests/typeEvaluator3.test.ts
index eebd2bbbf..2f4b7c999 100644
--- a/packages/pyright-internal/src/tests/typeEvaluator3.test.ts
+++ b/packages/pyright-internal/src/tests/typeEvaluator3.test.ts
@@ -10,6 +10,7 @@
 
 import { ConfigOptions } from '../common/configOptions';
 import { PythonVersion } from '../common/pythonVersion';
+import { Uri } from '../common/uri/uri';
 import * as TestUtils from './testUtils';
 
 test('Module1', () => {
@@ -139,7 +140,7 @@ test('Await2', () => {
 });
 
 test('Coroutines1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // This functionality is deprecated in Python 3.11, so the type no longer
     // exists in typing.pyi after that point.
@@ -156,7 +157,7 @@ test('Coroutines2', () => {
 });
 
 test('Coroutines3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // This functionality is deprecated in Python 3.11, so the type no longer
     // exists in typing.pyi after that point.
@@ -551,7 +552,7 @@ test('TypeAlias3', () => {
 });
 
 test('TypeAlias4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_9;
     const analysisResults3_9 = TestUtils.typeAnalyzeSampleFiles(['typeAlias4.py'], configOptions);
@@ -635,7 +636,7 @@ test('TypeAlias16', () => {
 });
 
 test('TypeAlias17', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['typeAlias17.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 4);
@@ -682,7 +683,7 @@ test('RecursiveTypeAlias2', () => {
 });
 
 test('RecursiveTypeAlias3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['recursiveTypeAlias3.py'], configOptions);
@@ -775,7 +776,7 @@ test('Classes4', () => {
 });
 
 test('Classes5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportIncompatibleVariableOverride = 'none';
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['classes5.py'], configOptions);
@@ -829,7 +830,7 @@ test('Methods1', () => {
 });
 
 test('MethodOverride1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportIncompatibleMethodOverride = 'none';
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['methodOverride1.py'], configOptions);
@@ -841,7 +842,7 @@ test('MethodOverride1', () => {
 });
 
 test('MethodOverride2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportIncompatibleMethodOverride = 'none';
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['methodOverride2.py'], configOptions);
@@ -853,7 +854,7 @@ test('MethodOverride2', () => {
 });
 
 test('MethodOverride3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportIncompatibleMethodOverride = 'none';
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['methodOverride3.py'], configOptions);
@@ -870,7 +871,7 @@ test('MethodOverride4', () => {
 });
 
 test('MethodOverride5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['methodOverride5.py'], configOptions);
@@ -878,7 +879,7 @@ test('MethodOverride5', () => {
 });
 
 test('MethodOverride6', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportIncompatibleMethodOverride = 'none';
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['methodOverride6.py'], configOptions);
@@ -962,7 +963,7 @@ test('TypeGuard2', () => {
 });
 
 test('TypeGuard3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.enableExperimentalFeatures = true;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeGuard3.py'], configOptions);
@@ -970,7 +971,7 @@ test('TypeGuard3', () => {
 });
 
 test('TypeGuard4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.enableExperimentalFeatures = true;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeGuard4.py'], configOptions);
@@ -1014,7 +1015,7 @@ test('ProtocolModule4', () => {
 });
 
 test('VariadicTypeVar1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar1.py'], configOptions);
@@ -1022,7 +1023,7 @@ test('VariadicTypeVar1', () => {
 });
 
 test('VariadicTypeVar2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar2.py'], configOptions);
@@ -1030,7 +1031,7 @@ test('VariadicTypeVar2', () => {
 });
 
 test('VariadicTypeVar3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar3.py'], configOptions);
@@ -1038,7 +1039,7 @@ test('VariadicTypeVar3', () => {
 });
 
 test('VariadicTypeVar4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar4.py'], configOptions);
@@ -1046,7 +1047,7 @@ test('VariadicTypeVar4', () => {
 });
 
 test('VariadicTypeVar5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar5.py'], configOptions);
@@ -1054,7 +1055,7 @@ test('VariadicTypeVar5', () => {
 });
 
 test('VariadicTypeVar6', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar6.py'], configOptions);
@@ -1062,7 +1063,7 @@ test('VariadicTypeVar6', () => {
 });
 
 test('VariadicTypeVar7', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar7.py'], configOptions);
@@ -1070,7 +1071,7 @@ test('VariadicTypeVar7', () => {
 });
 
 test('VariadicTypeVar8', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar8.py'], configOptions);
@@ -1078,7 +1079,7 @@ test('VariadicTypeVar8', () => {
 });
 
 test('VariadicTypeVar9', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar9.py'], configOptions);
@@ -1086,7 +1087,7 @@ test('VariadicTypeVar9', () => {
 });
 
 test('VariadicTypeVar10', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar10.py'], configOptions);
@@ -1094,7 +1095,7 @@ test('VariadicTypeVar10', () => {
 });
 
 test('VariadicTypeVar11', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar11.py'], configOptions);
@@ -1102,7 +1103,7 @@ test('VariadicTypeVar11', () => {
 });
 
 test('VariadicTypeVar12', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar12.py'], configOptions);
@@ -1110,7 +1111,7 @@ test('VariadicTypeVar12', () => {
 });
 
 test('VariadicTypeVar13', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar13.py'], configOptions);
@@ -1118,7 +1119,7 @@ test('VariadicTypeVar13', () => {
 });
 
 test('VariadicTypeVar14', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar14.py'], configOptions);
@@ -1126,7 +1127,7 @@ test('VariadicTypeVar14', () => {
 });
 
 test('VariadicTypeVar15', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar15.py'], configOptions);
@@ -1134,7 +1135,7 @@ test('VariadicTypeVar15', () => {
 });
 
 test('VariadicTypeVar16', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar16.py'], configOptions);
@@ -1142,7 +1143,7 @@ test('VariadicTypeVar16', () => {
 });
 
 test('VariadicTypeVar17', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar17.py'], configOptions);
@@ -1150,7 +1151,7 @@ test('VariadicTypeVar17', () => {
 });
 
 test('VariadicTypeVar18', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar18.py'], configOptions);
@@ -1158,7 +1159,7 @@ test('VariadicTypeVar18', () => {
 });
 
 test('VariadicTypeVar19', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar19.py'], configOptions);
@@ -1166,7 +1167,7 @@ test('VariadicTypeVar19', () => {
 });
 
 test('VariadicTypeVar20', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar20.py'], configOptions);
@@ -1174,7 +1175,7 @@ test('VariadicTypeVar20', () => {
 });
 
 test('VariadicTypeVar21', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar21.py'], configOptions);
@@ -1182,7 +1183,7 @@ test('VariadicTypeVar21', () => {
 });
 
 test('VariadicTypeVar22', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar22.py'], configOptions);
@@ -1190,7 +1191,7 @@ test('VariadicTypeVar22', () => {
 });
 
 test('VariadicTypeVar23', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar23.py'], configOptions);
@@ -1198,7 +1199,7 @@ test('VariadicTypeVar23', () => {
 });
 
 test('VariadicTypeVar24', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar24.py'], configOptions);
@@ -1206,7 +1207,7 @@ test('VariadicTypeVar24', () => {
 });
 
 test('VariadicTypeVar25', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar25.py'], configOptions);
@@ -1214,7 +1215,7 @@ test('VariadicTypeVar25', () => {
 });
 
 test('VariadicTypeVar26', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['variadicTypeVar26.py'], configOptions);
@@ -1222,7 +1223,7 @@ test('VariadicTypeVar26', () => {
 });
 
 test('Match1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['match1.py'], configOptions);
@@ -1230,7 +1231,7 @@ test('Match1', () => {
 });
 
 test('Match2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['match2.py'], configOptions);
@@ -1238,7 +1239,7 @@ test('Match2', () => {
 });
 
 test('Match3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['match3.py'], configOptions);
@@ -1246,7 +1247,7 @@ test('Match3', () => {
 });
 
 test('MatchSequence1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchSequence1.py'], configOptions);
@@ -1254,7 +1255,7 @@ test('MatchSequence1', () => {
 });
 
 test('MatchClass1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchClass1.py'], configOptions);
@@ -1262,7 +1263,7 @@ test('MatchClass1', () => {
 });
 
 test('MatchClass2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchClass2.py'], configOptions);
@@ -1270,7 +1271,7 @@ test('MatchClass2', () => {
 });
 
 test('MatchClass3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchClass3.py'], configOptions);
@@ -1278,7 +1279,7 @@ test('MatchClass3', () => {
 });
 
 test('MatchClass4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchClass4.py'], configOptions);
@@ -1286,7 +1287,7 @@ test('MatchClass4', () => {
 });
 
 test('MatchClass5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchClass5.py'], configOptions);
@@ -1294,7 +1295,7 @@ test('MatchClass5', () => {
 });
 
 test('MatchClass6', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchClass6.py'], configOptions);
@@ -1302,7 +1303,7 @@ test('MatchClass6', () => {
 });
 
 test('MatchValue1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchValue1.py'], configOptions);
@@ -1310,7 +1311,7 @@ test('MatchValue1', () => {
 });
 
 test('MatchMapping1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchMapping1.py'], configOptions);
@@ -1318,7 +1319,7 @@ test('MatchMapping1', () => {
 });
 
 test('MatchLiteral1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['matchLiteral1.py'], configOptions);
@@ -1326,7 +1327,7 @@ test('MatchLiteral1', () => {
 });
 
 test('MatchExhaustion1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     configOptions.diagnosticRuleSet.reportMatchNotExhaustive = 'none';
@@ -1339,7 +1340,7 @@ test('MatchExhaustion1', () => {
 });
 
 test('MatchUnnecessary1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['matchUnnecessary1.py'], configOptions);
@@ -1366,7 +1367,7 @@ test('List3', () => {
 });
 
 test('Comparison1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['comparison1.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
@@ -1377,7 +1378,7 @@ test('Comparison1', () => {
 });
 
 test('Comparison2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['comparison2.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
@@ -1555,7 +1556,7 @@ test('Constructor23', () => {
 });
 
 test('Constructor24', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.strictParameterNoneValue = false;
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['constructor24.py'], configOptions);
@@ -1597,7 +1598,7 @@ test('Constructor29', () => {
 });
 
 test('InconsistentConstructor1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportInconsistentConstructor = 'none';
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['inconsistentConstructor1.py'], configOptions);
@@ -1616,7 +1617,7 @@ test('ClassGetItem1', () => {
 });
 
 test('UnusedCallResult1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, this is disabled.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['unusedCallResult1.py'], configOptions);
@@ -1652,7 +1653,7 @@ test('FunctionAnnotation3', () => {
 });
 
 test('FunctionAnnotation4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['functionAnnotation4.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
@@ -1663,7 +1664,7 @@ test('FunctionAnnotation4', () => {
 });
 
 test('Subscript1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.8 settings.
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
@@ -1682,7 +1683,7 @@ test('Subscript2', () => {
 });
 
 test('Subscript3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.9 settings.
     configOptions.defaultPythonVersion = PythonVersion.V3_9;
@@ -1714,7 +1715,7 @@ test('Decorator2', () => {
 });
 
 test('Decorator3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.8 settings.
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
diff --git a/packages/pyright-internal/src/tests/typeEvaluator4.test.ts b/packages/pyright-internal/src/tests/typeEvaluator4.test.ts
index 3e63d38df..ad1f12fa8 100644
--- a/packages/pyright-internal/src/tests/typeEvaluator4.test.ts
+++ b/packages/pyright-internal/src/tests/typeEvaluator4.test.ts
@@ -12,11 +12,12 @@ import * as assert from 'assert';
 
 import { ConfigOptions } from '../common/configOptions';
 import { PythonVersion } from '../common/pythonVersion';
+import { Uri } from '../common/uri/uri';
 import * as TestUtils from './testUtils';
 
 test('Required1', () => {
     // Analyze with Python 3.10 settings.
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['required1.py'], configOptions);
 
@@ -25,7 +26,7 @@ test('Required1', () => {
 
 test('Required2', () => {
     // Analyze with Python 3.10 settings.
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['required2.py'], configOptions);
 
@@ -34,7 +35,7 @@ test('Required2', () => {
 
 test('Required3', () => {
     // Analyze with Python 3.10 settings.
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['required3.py'], configOptions);
 
@@ -182,7 +183,7 @@ test('Import11', () => {
 });
 
 test('Import12', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, optional diagnostics are ignored.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['import12.py'], configOptions);
@@ -223,7 +224,7 @@ test('Import18', () => {
 });
 
 test('DunderAll1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, reportUnsupportedDunderAll is a warning.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['dunderAll1.py'], configOptions);
@@ -241,7 +242,7 @@ test('DunderAll1', () => {
 });
 
 test('DunderAll2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // By default, reportUnsupportedDunderAll is a warning.
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['dunderAll2.py'], configOptions);
@@ -259,7 +260,7 @@ test('DunderAll2', () => {
 });
 
 test('DunderAll3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Turn on error.
     configOptions.diagnosticRuleSet.reportUnsupportedDunderAll = 'error';
@@ -288,7 +289,7 @@ test('Overload4', () => {
 });
 
 test('Overload5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.diagnosticRuleSet.reportOverlappingOverload = 'none';
     let analysisResults = TestUtils.typeAnalyzeSampleFiles(['overload5.py'], configOptions);
@@ -400,7 +401,7 @@ test('CallSite2', () => {
 });
 
 test('FString1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['fstring1.py'], configOptions);
@@ -427,7 +428,7 @@ test('FString4', () => {
 });
 
 test('FString5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.7 settings. This will generate errors.
     configOptions.defaultPythonVersion = PythonVersion.V3_7;
@@ -675,7 +676,7 @@ test('DataClassFrozen1', () => {
 });
 
 test('DataClassKwOnly1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['dataclassKwOnly1.py'], configOptions);
 
@@ -683,7 +684,7 @@ test('DataClassKwOnly1', () => {
 });
 
 test('DataClassSlots1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['dataclassSlots1.py'], configOptions);
 
@@ -793,7 +794,7 @@ test('Generic3', () => {
 });
 
 test('Unions1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.disableBytesTypePromotions = true;
 
     // Analyze with Python 3.9 settings. This will generate errors.
@@ -808,7 +809,7 @@ test('Unions1', () => {
 });
 
 test('Unions2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.8 settings.
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
@@ -817,7 +818,7 @@ test('Unions2', () => {
 });
 
 test('Unions3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     // Analyze with Python 3.9 settings. This will generate errors.
     configOptions.defaultPythonVersion = PythonVersion.V3_9;
@@ -854,7 +855,7 @@ test('ParamSpec1', () => {
 });
 
 test('ParamSpec2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_9;
     const analysisResults39 = TestUtils.typeAnalyzeSampleFiles(['paramSpec2.py'], configOptions);
@@ -1197,7 +1198,7 @@ test('TypeVar12', () => {
 });
 
 test('Annotated1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_8;
     const analysisResults38 = TestUtils.typeAnalyzeSampleFiles(['annotated1.py'], configOptions);
@@ -1263,7 +1264,7 @@ test('TryExcept6', () => {
 });
 
 test('TryExcept7', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_10;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['tryExcept7.py'], configOptions);
@@ -1275,7 +1276,7 @@ test('TryExcept7', () => {
 });
 
 test('TryExcept8', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['tryExcept8.py'], configOptions);
diff --git a/packages/pyright-internal/src/tests/typeEvaluator5.test.ts b/packages/pyright-internal/src/tests/typeEvaluator5.test.ts
index ada9f897a..e295d4505 100644
--- a/packages/pyright-internal/src/tests/typeEvaluator5.test.ts
+++ b/packages/pyright-internal/src/tests/typeEvaluator5.test.ts
@@ -10,10 +10,11 @@
 
 import { ConfigOptions } from '../common/configOptions';
 import { PythonVersion } from '../common/pythonVersion';
+import { Uri } from '../common/uri/uri';
 import * as TestUtils from './testUtils';
 
 test('TypeParams1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeParams1.py'], configOptions);
@@ -21,7 +22,7 @@ test('TypeParams1', () => {
 });
 
 test('TypeParams2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['typeParams2.py'], configOptions);
@@ -33,7 +34,7 @@ test('TypeParams2', () => {
 });
 
 test('TypeParams3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeParams3.py'], configOptions);
@@ -41,7 +42,7 @@ test('TypeParams3', () => {
 });
 
 test('TypeParams4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeParams4.py'], configOptions);
@@ -49,7 +50,7 @@ test('TypeParams4', () => {
 });
 
 test('TypeParams5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeParams5.py'], configOptions);
@@ -57,7 +58,7 @@ test('TypeParams5', () => {
 });
 
 test('TypeParams6', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeParams6.py'], configOptions);
@@ -65,7 +66,7 @@ test('TypeParams6', () => {
 });
 
 test('TypeParams7', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeParams7.py'], configOptions);
@@ -73,7 +74,7 @@ test('TypeParams7', () => {
 });
 
 test('AutoVariance1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['autoVariance1.py'], configOptions);
@@ -81,7 +82,7 @@ test('AutoVariance1', () => {
 });
 
 test('AutoVariance2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['autoVariance2.py'], configOptions);
@@ -89,7 +90,7 @@ test('AutoVariance2', () => {
 });
 
 test('AutoVariance3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['autoVariance3.py'], configOptions);
@@ -97,7 +98,7 @@ test('AutoVariance3', () => {
 });
 
 test('AutoVariance4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['autoVariance4.py'], configOptions);
@@ -110,7 +111,7 @@ test('AutoVariance5', () => {
 });
 
 test('TypeAliasStatement1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeAliasStatement1.py'], configOptions);
@@ -118,7 +119,7 @@ test('TypeAliasStatement1', () => {
 });
 
 test('TypeAliasStatement2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     configOptions.defaultPythonVersion = PythonVersion.V3_11;
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['typeAliasStatement2.py'], configOptions);
@@ -130,7 +131,7 @@ test('TypeAliasStatement2', () => {
 });
 
 test('TypeAliasStatement3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeAliasStatement3.py'], configOptions);
@@ -138,7 +139,7 @@ test('TypeAliasStatement3', () => {
 });
 
 test('TypeAliasStatement4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeAliasStatement4.py'], configOptions);
@@ -166,7 +167,7 @@ test('Override1', () => {
 });
 
 test('Override2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
 
     const analysisResults1 = TestUtils.typeAnalyzeSampleFiles(['override2.py'], configOptions);
     TestUtils.validateResults(analysisResults1, 0);
@@ -182,7 +183,7 @@ test('TypeVarDefault1', () => {
 });
 
 test('TypeVarDefault2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefault2.py'], configOptions);
@@ -195,7 +196,7 @@ test('TypeVarDefault3', () => {
 });
 
 test('TypeVarDefault4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefault4.py'], configOptions);
@@ -203,7 +204,7 @@ test('TypeVarDefault4', () => {
 });
 
 test('TypeVarDefault5', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefault5.py'], configOptions);
@@ -216,7 +217,7 @@ test('TypeVarDefaultClass1', () => {
 });
 
 test('TypeVarDefaultClass2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefaultClass2.py'], configOptions);
@@ -224,7 +225,7 @@ test('TypeVarDefaultClass2', () => {
 });
 
 test('TypeVarDefaultClass3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefaultClass3.py'], configOptions);
@@ -232,7 +233,7 @@ test('TypeVarDefaultClass3', () => {
 });
 
 test('TypeVarDefaultClass4', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefaultClass4.py'], configOptions);
@@ -250,7 +251,7 @@ test('TypeVarDefaultTypeAlias2', () => {
 });
 
 test('TypeVarDefaultTypeAlias3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefaultTypeAlias3.py'], configOptions);
@@ -268,7 +269,7 @@ test('TypeVarDefaultFunction2', () => {
 });
 
 test('TypeVarDefaultFunction3', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_13;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVarDefaultFunction3.py'], configOptions);
@@ -306,7 +307,7 @@ test('TypePrinter3', () => {
 });
 
 test('TypeAliasType1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.defaultPythonVersion = PythonVersion.V3_12;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeAliasType1.py'], configOptions);
@@ -319,7 +320,7 @@ test('TypeAliasType2', () => {
 });
 
 test('TypedDictReadOnly1', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.enableExperimentalFeatures = true;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typedDictReadOnly1.py'], configOptions);
@@ -327,7 +328,7 @@ test('TypedDictReadOnly1', () => {
 });
 
 test('TypedDictReadOnly2', () => {
-    const configOptions = new ConfigOptions('.');
+    const configOptions = new ConfigOptions(Uri.empty());
     configOptions.diagnosticRuleSet.enableExperimentalFeatures = true;
 
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typedDictReadOnly2.py'], configOptions);
diff --git a/packages/pyright-internal/src/tests/typePrinter.test.ts b/packages/pyright-internal/src/tests/typePrinter.test.ts
index c7c881aad..c389b2274 100644
--- a/packages/pyright-internal/src/tests/typePrinter.test.ts
+++ b/packages/pyright-internal/src/tests/typePrinter.test.ts
@@ -23,6 +23,7 @@ import {
     UnboundType,
     UnknownType,
 } from '../analyzer/types';
+import { Uri } from '../common/uri/uri';
 import { ParameterCategory } from '../parser/parseNodes';
 
 function returnTypeCallback(type: FunctionType) {
@@ -45,7 +46,7 @@ test('SimpleTypes', () => {
     assert.strictEqual(printType(unboundType, PrintTypeFlags.None, returnTypeCallback), 'Unbound');
     assert.strictEqual(printType(unboundType, PrintTypeFlags.PythonSyntax, returnTypeCallback), 'Any');
 
-    const moduleType = ModuleType.create('Test', '');
+    const moduleType = ModuleType.create('Test', Uri.empty());
     assert.strictEqual(printType(moduleType, PrintTypeFlags.None, returnTypeCallback), 'Module("Test")');
     assert.strictEqual(printType(moduleType, PrintTypeFlags.PythonSyntax, returnTypeCallback), 'Any');
 });
@@ -68,7 +69,7 @@ test('ClassTypes', () => {
         'A',
         '',
         '',
-        '',
+        Uri.empty(),
         ClassTypeFlags.None,
         0,
         /* declaredMetaclass*/ undefined,
@@ -89,7 +90,7 @@ test('ClassTypes', () => {
         'int',
         '',
         '',
-        '',
+        Uri.empty(),
         ClassTypeFlags.None,
         0,
         /* declaredMetaclass*/ undefined,
diff --git a/packages/pyright-internal/src/tests/uri.test.ts b/packages/pyright-internal/src/tests/uri.test.ts
new file mode 100644
index 000000000..342383417
--- /dev/null
+++ b/packages/pyright-internal/src/tests/uri.test.ts
@@ -0,0 +1,789 @@
+/*
+ * pathUtils.test.ts
+ * Copyright (c) Microsoft Corporation.
+ * Licensed under the MIT license.
+ * Author: Eric Traut
+ *
+ * Unit tests for pathUtils module.
+ */
+
+import assert from 'assert';
+import * as nodefs from 'fs-extra';
+import * as os from 'os';
+import * as path from 'path';
+
+import { expandPathVariables } from '../common/envVarUtils';
+import { isRootedDiskPath, normalizeSlashes } from '../common/pathUtils';
+import { createFromRealFileSystem } from '../common/realFileSystem';
+import { Uri } from '../common/uri/uri';
+import {
+    deduplicateFolders,
+    getWildcardRegexPattern,
+    getWildcardRoot,
+    isFileSystemCaseSensitiveInternal,
+} from '../common/uri/uriUtils';
+import * as vfs from './harness/vfs/filesystem';
+
+test('parse', () => {
+    assert.throws(() => Uri.parse('\\c:\\foo : bar', true));
+    assert.throws(() => Uri.parse('foo:////server/b/c', true)); // No authority component
+    assert.ok(Uri.parse('foo:///a/b/c', true));
+    assert.ok(Uri.parse('foo:a/b/c', true));
+    assert.ok(Uri.parse('foo:/a/b/c', true));
+    assert.ok(Uri.parse('foo://server/share/dir/file.py', true));
+    assert.ok(Uri.parse('foo://server/share/dir/file.py?query#fragment', true));
+    assert.ok(Uri.parse('foo:///c:/users/me', true));
+    assert.ok(Uri.parse('foo:///c%3A%52users%52me', true));
+    assert.ok(Uri.parse('', true));
+    assert.ok(Uri.parse(undefined, true));
+});
+
+test('file', () => {
+    const cwd = process.cwd();
+    const uri1 = Uri.file('a/b/c', true, true);
+    assert.ok(uri1.getFilePath().length > 6);
+    assert.ok(
+        uri1.getFilePath().toLowerCase().startsWith(cwd.toLowerCase()),
+        `${uri1.getFilePath()} does not start with ${cwd}`
+    );
+    const uri2 = Uri.file('a/b/c', true, false);
+    assert.equal(uri2.getFilePath().length, 6);
+});
+
+test('key', () => {
+    const key = Uri.parse('foo:///a/b/c', true).key;
+    const key2 = Uri.parse('foo:///a/b/c', true).key;
+    assert.equal(key, key2);
+    const key3 = Uri.parse('foo:///a/b/d', true).key;
+    assert.notEqual(key, key3);
+    const key4 = Uri.file('/a/b/c').key;
+    assert.notEqual(key, key4);
+    const key5 = Uri.parse('file:///a/b/c', true).key;
+    assert.equal(key4, key5);
+    const key6 = Uri.file(normalizeSlashes('c:\\foo\\bar\\d.txt')).key;
+    const key7 = Uri.parse('file:///c%3A/foo/bar/d.txt', true).key;
+    const key8 = Uri.parse('file:///c:/foo/bar/d.txt', true).key;
+    assert.equal(key6, key7);
+    assert.equal(key6, key8);
+    const key9 = Uri.parse('file:///c%3A/foo/bar/D.txt', true).key;
+    const key10 = Uri.parse('file:///c:/foo/bar/d.txt', true).key;
+    assert.notEqual(key9, key10);
+    const key11 = Uri.parse('file:///c%3A/foo/bar/D.txt', false).key;
+    const key12 = Uri.parse('file:///c%3A/foo/bar/d.txt', false).key;
+    assert.equal(key11, key12);
+});
+
+test('filename', () => {
+    const filename = Uri.parse('foo:///a/b/c', true).fileName;
+    assert.equal(filename, 'c');
+    const filename2 = Uri.parse('foo:///a/b/c/', true).fileName;
+    assert.equal(filename2, 'c');
+    const filename3 = Uri.parse('foo:///a/b/c.py', true).fileName;
+    assert.equal(filename3, 'c.py');
+    const filename4 = Uri.parse('foo:///a/b/c.py?query#fragment', true).fileName;
+    assert.equal(filename4, 'c.py');
+    const filename5 = Uri.file('/a/b/c').fileName;
+    assert.equal(filename5, 'c');
+    const filename6 = Uri.parse('file:///a/b/c', true).fileName;
+    assert.equal(filename6, 'c');
+});
+
+test('extname', () => {
+    const extname = Uri.parse('foo:///a/b/c', true).lastExtension;
+    assert.equal(extname, '');
+    const extname2 = Uri.parse('foo:///a/b/c/', true).lastExtension;
+    assert.equal(extname2, '');
+    const extname3 = Uri.parse('foo:///a/b/c.py', true).lastExtension;
+    assert.equal(extname3, '.py');
+    const extname4 = Uri.parse('foo:///a/b/c.py?query#fragment', true).lastExtension;
+    assert.equal(extname4, '.py');
+    const extname5 = Uri.file('/a/b/c.py.foo').lastExtension;
+    assert.equal(extname5, '.foo');
+    const extname6 = Uri.parse('file:///a/b/c.py.foo', true).lastExtension;
+    assert.equal(extname6, '.foo');
+});
+
+test('root', () => {
+    const root1 = Uri.parse('foo://authority/a/b/c', true).root;
+    assert.equal(root1.toString(), 'foo://authority/');
+    const root = Uri.parse('file://server/b/c', true).root;
+    assert.equal(root.toString(), 'file://server/');
+    assert.equal(root.getRootPathLength(), 9);
+    const root2 = Uri.parse('foo:///', true).root;
+    assert.equal(root2.toString(), 'foo:///');
+    const root3 = Uri.parse('foo:///a/b/c/', true).root;
+    assert.equal(root3.toString(), 'foo:///');
+    assert.ok(root3.isRoot());
+    const root4 = Uri.parse('foo:///a/b/c.py', true).root;
+    assert.equal(root4.toString(), 'foo:///');
+    const root5 = Uri.parse('foo:///a/b/c.py?query#fragment', true).root;
+    assert.equal(root5.toString(), 'foo:///');
+    const root6 = Uri.file('/a/b/c.py.foo').root;
+    assert.equal(root6.toString(), 'file:///');
+    const root7 = Uri.parse('file:///a/b/c.py.foo', true).root;
+    assert.equal(root7.toString(), 'file:///');
+    assert.equal(root7.getRootPathLength(), 1);
+    const root8 = Uri.parse('untitled:Untitled-1', true).root;
+    assert.equal(root8.toString(), 'untitled://');
+    assert.equal(root8.getRootPathLength(), 0);
+    assert.equal(root8.isRoot(), false);
+    const root9 = Uri.parse('file://a/b/c/d.py', true).root;
+    assert.equal(root9.toString(), 'file://a/');
+    assert.equal(root9.getRootPathLength(), 4);
+    assert.ok(root9.isRoot());
+    const root10 = Uri.parse('file://c%3A/b/c/d.py', true).root;
+    assert.equal(root10.toString(), 'file://c:/');
+    assert.equal(root10.getRootPathLength(), 5);
+    assert.ok(root10.isRoot());
+});
+
+test('empty', () => {
+    const empty = Uri.parse('', true);
+    assert.equal(empty.isEmpty(), true);
+    const empty2 = Uri.parse('foo:///', true).isEmpty();
+    assert.equal(empty2, false);
+    const empty3 = Uri.empty();
+    assert.equal(empty3.isEmpty(), true);
+    const empty4 = Uri.parse(undefined, true);
+    assert.equal(empty4.isEmpty(), true);
+    assert.ok(empty4.equals(empty3));
+    assert.ok(empty3.equals(empty));
+});
+
+test('file', () => {
+    const file1 = Uri.file(normalizeSlashes('/a/b/c')).getFilePath();
+    assert.equal(file1, normalizeSlashes('/a/b/c'));
+    const file2 = Uri.file('file:///a/b/c').getFilePath();
+    assert.equal(file2, normalizeSlashes('/a/b/c'));
+});
+
+test('isUri', () => {
+    const isUri = Uri.isUri('foo:///a/b/c');
+    assert.equal(isUri, false);
+    const isUri2 = Uri.isUri('/a/b/c');
+    assert.equal(isUri2, false);
+    const isUri3 = Uri.isUri(undefined);
+    assert.equal(isUri3, false);
+    const isUri4 = Uri.isUri(Uri.parse('foo:///a/b/c', true));
+    assert.equal(isUri4, true);
+    const isUri5 = Uri.isUri(Uri.empty());
+    assert.equal(isUri5, true);
+});
+
+test('matchesRegex', () => {
+    const includeFiles = /\.pyi?$/;
+    const uri = Uri.parse('file:///a/b/c.pyi', true);
+    assert.ok(uri.matchesRegex(includeFiles));
+    const uri2 = Uri.parse('file:///a/b/c.px', true);
+    assert.equal(uri2.matchesRegex(includeFiles), false);
+    const uri3 = Uri.parse('vscode-vfs:///a/b/c.pyi', true);
+    assert.ok(uri3.matchesRegex(includeFiles));
+    const fileRegex = /^(c:\/foo\/bar)($|\/)/i;
+    const uri4 = Uri.parse('file:///C%3A/foo/bar', true);
+    assert.ok(uri4.matchesRegex(fileRegex));
+    const uri5 = Uri.parse('file:///c%3A/foo/bar', true);
+    assert.ok(uri5.matchesRegex(fileRegex));
+    const uri6 = Uri.parse('file:///c:/foo/bar', true);
+    assert.ok(uri6.matchesRegex(fileRegex));
+    const uri7 = Uri.parse('file:///c:/foo/bar/', true);
+    assert.ok(uri7.matchesRegex(fileRegex));
+    const uri8 = Uri.parse('file:///c:/foo/baz/', true);
+    assert.equal(uri8.matchesRegex(fileRegex), false);
+});
+
+test('replaceExtension', () => {
+    const uri = Uri.parse('file:///a/b/c.pyi', true);
+    const uri2 = uri.replaceExtension('.py');
+    assert.equal(uri2.toString(), 'file:///a/b/c.py');
+    const uri3 = Uri.parse('file:///a/b/c', true);
+    const uri4 = uri3.replaceExtension('.py');
+    assert.equal(uri4.toString(), 'file:///a/b/c.py');
+    const uri5 = Uri.parse('file:///a/b/c.foo.py', true);
+    const uri6 = uri5.replaceExtension('.pyi');
+    assert.equal(uri6.toString(), 'file:///a/b/c.foo.pyi');
+});
+
+test('addExtension', () => {
+    const uri = Uri.parse('file:///a/b/c.pyi?query#fragment', true);
+    const uri2 = uri.addExtension('.py');
+    assert.equal(uri2.toString(), 'file:///a/b/c.pyi.py');
+    const uri3 = Uri.parse('file:///a/b/c', true);
+    const uri4 = uri3.addExtension('.py');
+    assert.equal(uri4.toString(), 'file:///a/b/c.py');
+});
+
+test('addPath', () => {
+    const uri = Uri.parse('file:///a/b/c.pyi?query#fragment', true);
+    const uri2 = uri.addPath('d');
+    assert.equal(uri2.toString(), 'file:///a/b/c.pyid');
+});
+
+test('directory', () => {
+    const uri = Uri.parse('file:///a/b/c.pyi?query#fragment', true);
+    const uri2 = uri.getDirectory();
+    assert.equal(uri2.toString(), 'file:///a/b');
+    const uri3 = uri2.getDirectory();
+    assert.equal(uri3.toString(), 'file:///a');
+    const uri4 = Uri.parse('file:///a/b/', true);
+    const uri5 = uri4.getDirectory();
+    assert.equal(uri5.toString(), 'file:///a');
+    const uri6 = uri4.getDirectory();
+    assert.ok(uri6.equals(uri5));
+});
+
+test('init and pytyped', () => {
+    const uri = Uri.parse('file:///a/b/c?query#fragment', true);
+    const uri2 = uri.pytypedUri;
+    assert.equal(uri2.toString(), 'file:///a/b/c/py.typed');
+    const uri3 = uri.initPyUri;
+    assert.equal(uri3.toString(), 'file:///a/b/c/__init__.py');
+    const uri4 = uri.initPyiUri;
+    assert.equal(uri4.toString(), 'file:///a/b/c/__init__.pyi');
+    const uri5 = uri.packageUri;
+    assert.equal(uri5.toString(), 'file:///a/b/c.py');
+    const uri6 = uri.packageStubUri;
+    assert.equal(uri6.toString(), 'file:///a/b/c.pyi');
+    const uri7 = Uri.parse('foo://microsoft.com/a/b/c.py', true);
+    const uri8 = uri7.pytypedUri;
+    assert.equal(uri8.toString(), 'foo://microsoft.com/a/b/c.py/py.typed');
+    const uri9 = uri7.initPyUri;
+    assert.equal(uri9.toString(), 'foo://microsoft.com/a/b/c.py/__init__.py');
+    const uri10 = uri7.initPyiUri;
+    assert.equal(uri10.toString(), 'foo://microsoft.com/a/b/c.py/__init__.pyi');
+    const uri11 = uri7.packageUri;
+    assert.equal(uri11.toString(), 'foo://microsoft.com/a/b/c.py.py');
+    const uri12 = uri7.packageStubUri;
+    assert.equal(uri12.toString(), 'foo://microsoft.com/a/b/c.py.pyi');
+});
+
+test('isChild', () => {
+    const parent = Uri.parse('file:///a/b/?query#fragment', true);
+    const child = Uri.parse('file:///a/b/c.pyi?query#fragment', true);
+    assert.ok(child.isChild(parent));
+    const parent2 = Uri.parse('file:///a/b', true);
+    const child2 = Uri.parse('file:///a/b/c.pyi', true);
+    const child2DifferentCase = Uri.parse('file:///a/B/C.pyi', false);
+    assert.ok(child2.isChild(parent2));
+    assert.ok(child2DifferentCase.isChild(parent2));
+    const parent3 = Uri.parse('file:///a/b/', true);
+    const child3 = Uri.parse('file:///a/b/c.pyi', true);
+    assert.ok(child3.isChild(parent3));
+    const parent4 = Uri.parse('file:///a/b/', true);
+    const notChild4 = Uri.parse('file:///a/bb/c.pyi', true);
+    assert.ok(!notChild4.isChild(parent4));
+    assert.ok(!notChild4.isChild(parent2));
+    const notChild5 = Uri.parse('file:///a/b/', true);
+    assert.ok(!notChild5.isChild(parent4));
+});
+
+test('equals', () => {
+    const uri1 = Uri.parse('file:///a/b/c.pyi?query#fragment', true);
+    const uri2 = Uri.file('/a/b/c.pyi');
+    assert.ok(!uri1.equals(uri2));
+    const uri3 = uri1.stripExtension().addExtension('.pyi');
+    assert.ok(uri2.equals(uri3));
+    const uri4 = Uri.parse('foo:///a/b/c', true);
+    const uri5 = Uri.parse('foo:///a/b/c', true);
+    const uri6 = Uri.parse('foo:///a/b/c/', true);
+    assert.ok(uri4.equals(uri5));
+    assert.ok(uri4.equals(uri6));
+    const uri7 = Uri.parse('file://c%3A/b/c/d.py', true).root;
+    const uri8 = Uri.parse('file://c:/', true);
+    assert.ok(uri7.equals(uri8));
+    const uri9 = Uri.parse('foo:///a/b/c?query', true);
+    assert.ok(!uri9.equals(uri4));
+    // Web uris are always case sensitive
+    const uri10 = Uri.parse('foo:///a/b/c', false);
+    const uri11 = Uri.parse('foo:///a/B/c', false);
+    assert.ok(!uri10.equals(uri11));
+    // Filre uris pay attention to the parameter.
+    const uri12 = Uri.parse('file:///a/b/c', false);
+    const uri13 = Uri.parse('file:///a/B/c', false);
+    assert.ok(uri12.equals(uri13));
+    const uri14 = Uri.parse('file:///a/b/c', true);
+    const uri15 = Uri.parse('file:///a/B/c', true);
+    assert.ok(!uri14.equals(uri15));
+});
+
+test('startsWith', () => {
+    const parent = Uri.parse('file:///a/b/?query#fragment', true);
+    const child = Uri.parse('file:///a/b/c.pyi?query#fragment', true);
+    assert.ok(child.startsWith(parent));
+    const parent2 = Uri.parse('file:///a/b', true);
+    const child2 = Uri.parse('file:///a/b/c.pyi', true);
+    assert.ok(child2.startsWith(parent2));
+    const parent3 = Uri.parse('file:///a/b/', true);
+    const child3 = Uri.parse('file:///a/b/c.pyi', true);
+    assert.ok(child3.startsWith(parent3));
+    const parent4 = Uri.parse('file:///a/b/', true);
+    const notChild4 = Uri.parse('file:///a/bb/c.pyi', true);
+    assert.ok(!notChild4.startsWith(parent4));
+    assert.ok(!notChild4.startsWith(parent2));
+});
+
+test('path comparisons', () => {
+    const uri = Uri.parse('foo:///a/b/c.pyi?query#fragment', true);
+    assert.ok(uri.pathEndsWith('c.pyi'));
+    assert.ok(uri.pathEndsWith('b/c.pyi'));
+    assert.ok(uri.pathEndsWith('a/b/c.pyi'));
+    assert.ok(!uri.pathEndsWith('a/b/c.py'));
+    assert.ok(!uri.pathEndsWith('b/c.py'));
+    assert.ok(uri.pathIncludes('c.pyi'));
+    assert.ok(uri.pathIncludes('b/c'));
+    assert.ok(uri.pathIncludes('a/b/c'));
+    const uri2 = Uri.parse('file:///C%3A/a/b/c.pyi?query#fragment', true);
+    assert.ok(uri2.pathEndsWith('c.pyi'));
+    assert.ok(uri2.pathEndsWith('b/c.pyi'));
+    assert.ok(!uri2.pathStartsWith('C:/a'));
+    assert.ok(!uri2.pathStartsWith('C:/a/b'));
+    assert.ok(uri2.pathStartsWith('c:/a'));
+    assert.ok(uri2.pathStartsWith('c:/a/b'));
+});
+
+test('combinePaths', () => {
+    const uri1 = Uri.parse('file:///a/b/c.pyi?query#fragment', true);
+    const uri2 = uri1.combinePaths('d', 'e');
+    assert.equal(uri2.toString(), 'file:///a/b/c.pyi/d/e');
+    const uri3 = uri1.combinePaths('d', 'e/');
+    assert.equal(uri3.toString(), 'file:///a/b/c.pyi/d/e');
+    const uri4 = uri1.combinePaths('d', 'e', 'f/');
+    assert.equal(uri4.toString(), 'file:///a/b/c.pyi/d/e/f');
+    const uri5 = uri1.combinePaths('d', '..', 'e');
+    assert.equal(uri5.toString(), 'file:///a/b/c.pyi/e');
+    const rootedPath = process.platform === 'win32' ? 'D:' : '/D';
+    const rootedResult = process.platform === 'win32' ? 'file:///d%3A/e/f' : 'file:///D/e/f';
+    const uri6 = uri1.combinePaths(rootedPath, 'e', 'f');
+    assert.equal(uri6.toString(), rootedResult);
+    const uri7 = Uri.parse('foo:', true);
+    const uri8 = uri7.combinePaths('d', 'e');
+    assert.equal(uri8.toString(), 'foo://d/e');
+    const uri9 = Uri.parse('foo:/', true);
+    const uri10 = uri9.combinePaths('d', 'e');
+    assert.equal(uri10.toString(), 'foo:///d/e');
+    const uri11 = Uri.empty().combinePaths('d', 'e');
+    assert.equal(uri11.toString(), Uri.empty().toString());
+});
+
+test('combinePaths non file', () => {
+    const uri1 = Uri.parse('baz://authority/a/b/c.pyi?query#fragment', true);
+    const uri2 = uri1.combinePaths('d', 'e');
+    assert.equal(uri2.toString(), 'baz://authority/a/b/c.pyi/d/e');
+    const uri3 = uri1.combinePaths('d', 'e/');
+    assert.equal(uri3.toString(), 'baz://authority/a/b/c.pyi/d/e');
+    const uri4 = uri1.combinePaths('d', 'e', 'f/');
+    assert.equal(uri4.toString(), 'baz://authority/a/b/c.pyi/d/e/f');
+    const uri5 = uri1.combinePaths('d', '..', 'e');
+    assert.equal(uri5.toString(), 'baz://authority/a/b/c.pyi/e');
+});
+
+test('getPathComponents1', () => {
+    const components = Uri.parse('', true).getPathComponents();
+    assert.equal(components.length, 0);
+});
+
+test('getPathComponents2', () => {
+    const components = Uri.parse('/users/', true).getPathComponents();
+    assert.equal(components.length, 2);
+    assert.equal(components[0], '/');
+    assert.equal(components[1], 'users');
+});
+
+test('getPathComponents3', () => {
+    const components = Uri.parse('/users/hello.py', true).getPathComponents();
+    assert.equal(components.length, 3);
+    assert.equal(components[0], '/');
+    assert.equal(components[1], 'users');
+    assert.equal(components[2], 'hello.py');
+});
+
+test('getPathComponents4', () => {
+    const components = Uri.parse('/users/hello/../', true).getPathComponents();
+    assert.equal(components.length, 2);
+    assert.equal(components[0], '/');
+    assert.equal(components[1], 'users');
+});
+
+test('getPathComponents5', () => {
+    const components = Uri.parse('./hello.py', true).getPathComponents();
+    assert.equal(components.length, 2);
+    assert.equal(components[0], '/');
+    assert.equal(components[1], 'hello.py');
+});
+
+test('getPathComponents6', () => {
+    const components = Uri.parse('file://server/share/dir/file.py', true).getPathComponents();
+    assert.equal(components.length, 4);
+    assert.ok(components[0].slice(2).includes('server'));
+    assert.equal(components[1], 'share');
+    assert.equal(components[2], 'dir');
+    assert.equal(components[3], 'file.py');
+});
+
+test('getRelativePathComponents1', () => {
+    const components = Uri.parse('foo:///users/', true).getRelativePathComponents(Uri.parse('foo:///users/', true));
+    assert.equal(components.length, 0);
+});
+
+test('getRelativePathComponents2', () => {
+    const components = Uri.parse('foo:///users/', true).getRelativePathComponents(Uri.parse('foo:///users/bar', true));
+    assert.equal(components.length, 1);
+    assert.equal(components[0], 'bar');
+});
+
+test('getRelativePathComponents3', () => {
+    const components = Uri.parse('bar:///users/', true).getRelativePathComponents(Uri.parse('foo:///users/bar', true));
+    assert.equal(components.length, 1);
+    assert.equal(components[0], 'bar');
+});
+
+test('getRelativePathComponents4', () => {
+    const components = Uri.parse('foo:///users', true).getRelativePathComponents(Uri.parse('foo:///users/', true));
+    assert.equal(components.length, 0);
+});
+
+test('getRelativePathComponents5', () => {
+    const components = Uri.parse('foo:///users/', true).getRelativePathComponents(
+        Uri.parse('foo:///users/bar/baz/../foo', true)
+    );
+    assert.equal(components.length, 2);
+    assert.equal(components[0], 'bar');
+    assert.equal(components[1], 'foo');
+});
+
+test('getRelativePathComponents6', () => {
+    const components = Uri.parse('foo:///users/bar', true).getRelativePathComponents(
+        Uri.parse('foo:///users/foo', true)
+    );
+    assert.equal(components.length, 2);
+    assert.equal(components[0], '..');
+    assert.equal(components[1], 'foo');
+});
+
+test('getFileExtension1', () => {
+    const ext = Uri.parse('foo:///blah.blah/hello.JsOn', true).lastExtension;
+    assert.equal(ext, '.JsOn');
+});
+
+test('getFileName1', () => {
+    const fileName = Uri.parse('foo:///blah.blah/HeLLo.JsOn', true).fileName;
+    assert.equal(fileName, 'HeLLo.JsOn');
+});
+
+test('getFileName2', () => {
+    const fileName1 = Uri.parse('foo:///blah.blah/hello.cpython-32m.so', true).fileName;
+    assert.equal(fileName1, 'hello.cpython-32m.so');
+});
+
+test('stripFileExtension1', () => {
+    const path = Uri.parse('foo:///blah.blah/HeLLo.JsOn', true).stripExtension().getPath();
+    assert.equal(path, '/blah.blah/HeLLo');
+});
+
+test('stripFileExtension2', () => {
+    const path1 = Uri.parse('foo:/blah.blah/hello.cpython-32m.so', true).stripAllExtensions().getPath();
+    assert.equal(path1, '/blah.blah/hello');
+    const path2 = Uri.parse('foo:/blah.blah/hello.cpython-32m.so', true).stripExtension().getPath();
+    assert.equal(path2, '/blah.blah/hello.cpython-32m');
+});
+
+test('getWildcardRegexPattern1', () => {
+    const pattern = getWildcardRegexPattern(Uri.parse('foo:///users/me', true), './blah/');
+    const regex = new RegExp(pattern);
+    assert.ok(regex.test('/users/me/blah/d'));
+    assert.ok(!regex.test('/users/me/blad/d'));
+});
+
+test('getWildcardRegexPattern2', () => {
+    const pattern = getWildcardRegexPattern(Uri.parse('foo:///users/me', true), './**/*.py?');
+    const regex = new RegExp(pattern);
+    assert.ok(regex.test('/users/me/.blah/foo.pyd'));
+    assert.ok(!regex.test('/users/me/.blah/foo.py')); // No char after
+});
+
+test('getWildcardRegexPattern3', () => {
+    const pattern = getWildcardRegexPattern(Uri.parse('foo:///users/me', true), './**/.*.py');
+    const regex = new RegExp(pattern);
+    assert.ok(regex.test('/users/me/.blah/.foo.py'));
+    assert.ok(!regex.test('/users/me/.blah/foo.py'));
+});
+
+test('getWildcardRegexPattern4', () => {
+    const pattern = getWildcardRegexPattern(Uri.parse('//server/share/dir', true), '.');
+    const regex = new RegExp(pattern);
+    assert.ok(regex.test('//server/share/dir/foo.py'));
+    assert.ok(!regex.test('//server/share/dix/foo.py'));
+});
+
+test('getWildcardRoot1', () => {
+    const p = getWildcardRoot(Uri.parse('foo:///users/me', true), './blah/');
+    assert.equal(p.toString(), 'foo:///users/me/blah');
+});
+
+test('getWildcardRoot2', () => {
+    const p = getWildcardRoot(Uri.parse('foo:///users/me', true), './**/*.py?/');
+    assert.equal(p.toString(), 'foo:///users/me');
+});
+
+test('getWildcardRoot with root', () => {
+    const p = getWildcardRoot(Uri.parse('foo:///', true), '.');
+    assert.equal(p.toString(), 'foo:///');
+});
+
+test('getWildcardRoot with drive letter', () => {
+    const p = getWildcardRoot(Uri.parse('file:///c:/', true), '.');
+    assert.equal(p.toString(), 'file:///c%3A');
+});
+
+function resolvePaths(uri: string, ...paths: string[]) {
+    return Uri.file(uri)
+        .combinePaths(...paths)
+        .toString();
+}
+
+test('resolvePath1', () => {
+    assert.equal(resolvePaths('/path', 'to', 'file.ext'), 'file:///path/to/file.ext');
+});
+
+test('resolvePath2', () => {
+    assert.equal(resolvePaths('/path', 'to', '..', 'from', 'file.ext/'), 'file:///path/from/file.ext');
+});
+
+function getHomeDirUri() {
+    return Uri.file(os.homedir());
+}
+
+test('resolvePath3 ~ escape', () => {
+    assert.equal(
+        resolvePaths(expandPathVariables(Uri.empty(), '~/path'), 'to', '..', 'from', 'file.ext/'),
+        `${getHomeDirUri().toString()}/path/from/file.ext`
+    );
+});
+
+test('resolvePath4 ~ escape in middle', () => {
+    assert.equal(
+        resolvePaths('/path', expandPathVariables(Uri.empty(), '~/file.ext/')),
+        `${getHomeDirUri().toString()}/file.ext`
+    );
+});
+
+function combinePaths(uri: string, ...paths: string[]) {
+    return resolvePaths(uri, ...paths);
+}
+
+test('invalid ~ without root', () => {
+    const path = combinePaths('Library', 'Mobile Documents', 'com~apple~CloudDocs', 'Development', 'mysuperproject');
+    assert.equal(resolvePaths(expandPathVariables(Uri.parse('foo:///src', true), path)), path);
+});
+
+test('invalid ~ with root', () => {
+    const path = combinePaths('/', 'Library', 'com~apple~CloudDocs', 'Development', 'mysuperproject');
+    assert.equal(resolvePaths(expandPathVariables(Uri.parse('foo:///src', true), path)), path);
+});
+
+function containsPath(uri: string, child: string) {
+    return Uri.parse(child, true).isChild(Uri.parse(uri, true));
+}
+
+test('containsPath1', () => {
+    assert.equal(containsPath('/a/b/c/', '/a/d/../b/c/./d'), true);
+});
+
+test('containsPath2', () => {
+    assert.equal(containsPath('/', '\\a'), true);
+});
+
+test('containsPath3', () => {
+    assert.equal(containsPath('/a', '/a/B'), true);
+});
+
+function getAnyExtensionFromPath(uri: string): string {
+    return Uri.parse(uri, true).lastExtension;
+}
+test('getAnyExtension1', () => {
+    assert.equal(getAnyExtensionFromPath('/path/to/file.ext'), '.ext');
+});
+
+function getBaseFileName(uri: string): string {
+    return Uri.parse(uri, true).fileName;
+}
+
+test('getBaseFileName1', () => {
+    assert.equal(getBaseFileName('/path/to/file.ext'), 'file.ext');
+});
+
+test('getBaseFileName2', () => {
+    assert.equal(getBaseFileName('/path/to/'), 'to');
+});
+
+test('getBaseFileName3', () => {
+    assert.equal(getBaseFileName('c:/'), '');
+});
+
+function getUriRootLength(uri: string): number {
+    return Uri.file(uri).getRootPathLength();
+}
+
+test('getRootLength1', () => {
+    assert.equal(getUriRootLength('a'), 1);
+});
+
+test('getRootLength2', () => {
+    assert.equal(getUriRootLength('/'), 1);
+});
+
+test('getRootLength3', () => {
+    assert.equal(getUriRootLength('c:'), 2);
+});
+
+test('getRootLength4', () => {
+    assert.equal(getUriRootLength('c:d'), 0);
+});
+
+test('getRootLength5', () => {
+    assert.equal(getUriRootLength('c:/'), 2);
+});
+
+test('getRootLength6', () => {
+    assert.equal(getUriRootLength('//server'), 9);
+});
+
+test('getRootLength7', () => {
+    assert.equal(getUriRootLength('//server/share'), 9);
+});
+
+test('getRootLength8', () => {
+    assert.equal(getUriRootLength('scheme:/no/authority'), 1);
+});
+
+test('getRootLength9', () => {
+    assert.equal(getUriRootLength('scheme://with/authority'), 1);
+});
+
+function isRootedDiskUri(uri: string) {
+    return isRootedDiskPath(Uri.file(uri).getFilePath());
+}
+
+test('isRootedDiskPath1', () => {
+    assert(isRootedDiskUri('C:/a/b'));
+});
+
+test('isRootedDiskPath2', () => {
+    assert(isRootedDiskUri('/'));
+});
+
+test('isRootedDiskPath3', () => {
+    assert(isRootedDiskUri('a/b'));
+});
+
+test('isDiskPathRoot1', () => {
+    assert(isRootedDiskUri('/'));
+});
+
+test('isDiskPathRoot2', () => {
+    assert(isRootedDiskUri('c:/'));
+});
+
+test('isDiskPathRoot3', () => {
+    assert(isRootedDiskUri('c:'));
+});
+
+test('isDiskPathRoot4', () => {
+    assert(!isRootedDiskUri('c:d'));
+});
+
+function getRelativePath(parent: string, child: string) {
+    return Uri.parse(parent, true).getRelativePath(Uri.parse(child, true));
+}
+
+test('getRelativePath', () => {
+    assert.equal(getRelativePath('/a/b/c', '/a/b/c/d/e/f'), './d/e/f');
+    assert.equal(getRelativePath('/a/b/c/d/e/f', '/a/b/c/'), undefined);
+    assert.equal(getRelativePath('/a/b/c', '/d/e/f'), undefined);
+});
+
+test('CaseSensitivity', () => {
+    const cwd = '/';
+
+    const fsCaseInsensitive = new vfs.TestFileSystem(/*ignoreCase*/ true, { cwd });
+    assert.equal(isFileSystemCaseSensitiveInternal(fsCaseInsensitive, fsCaseInsensitive), false);
+
+    const fsCaseSensitive = new vfs.TestFileSystem(/*ignoreCase*/ false, { cwd });
+    assert.equal(isFileSystemCaseSensitiveInternal(fsCaseSensitive, fsCaseSensitive), true);
+});
+
+test('deduplicateFolders', () => {
+    const listOfFolders = [
+        ['/user', '/user/temp', '/xuser/app', '/lib/python', '/home/p/.venv/lib/site-packages'].map((p) => Uri.file(p)),
+        ['/user', '/user/temp', '/xuser/app', '/lib/python/Python310.zip', '/home/z/.venv/lib/site-packages'].map((p) =>
+            Uri.file(p)
+        ),
+        ['/main/python/lib/site-packages', '/home/p'].map((p) => Uri.file(p)),
+    ];
+
+    const folders = deduplicateFolders(listOfFolders).map((f) => f.getPath());
+
+    const expected = [
+        '/user',
+        '/xuser/app',
+        '/lib/python',
+        '/home/z/.venv/lib/site-packages',
+        '/main/python/lib/site-packages',
+        '/home/p',
+    ];
+
+    assert.deepStrictEqual(folders.sort(), expected.sort());
+});
+
+test('convert UNC path', () => {
+    const path = Uri.file('file:///server/c$/folder/file.py');
+
+    // When converting UNC path, server part shouldn't be removed.
+    assert(path.getPath().indexOf('server') > 0);
+});
+
+function lowerCaseDrive(entries: string[]) {
+    return entries.map((p) => (process.platform === 'win32' ? p[0].toLowerCase() + p.slice(1) : p));
+}
+
+test('Realcase', () => {
+    const fs = createFromRealFileSystem();
+    const cwd = process.cwd();
+    const dir = Uri.file(path.join(cwd, 'src', 'tests', '..', 'tests'));
+    const dirFilePath = dir.getFilePath()!;
+    const entries = nodefs
+        .readdirSync(dirFilePath)
+        .map((entry) => path.basename(nodefs.realpathSync(path.join(dirFilePath, entry))));
+    const normalizedEntries = lowerCaseDrive(entries);
+    const fsentries = fs.readdirSync(dir);
+    assert.deepStrictEqual(normalizedEntries, fsentries);
+
+    const paths = entries.map((entry) => nodefs.realpathSync(path.join(dirFilePath, entry)));
+    const fspaths = fsentries.map((entry) => fs.realCasePath(dir.combinePaths(entry)).getFilePath()!);
+    assert.deepStrictEqual(lowerCaseDrive(paths), fspaths);
+
+    // Check that the '..' has been removed.
+    assert.ok(!fspaths.some((p) => p.toString().indexOf('..') >= 0));
+
+    // If windows, check that the case is correct.
+    if (process.platform === 'win32') {
+        for (const p of fspaths) {
+            const upper = Uri.file(p.toString().toUpperCase());
+            const real = fs.realCasePath(upper);
+            assert.strictEqual(p, real.getFilePath());
+        }
+    }
+});
+
+test('Realcase use cwd implicitly', () => {
+    const fs = createFromRealFileSystem();
+    const cwd = process.cwd();
+    const dir = path.join(cwd, 'src', 'tests');
+    const uri = Uri.file(dir);
+
+    const entries = nodefs.readdirSync(dir).map((entry) => path.basename(nodefs.realpathSync(path.join(dir, entry))));
+    const fsentries = fs.readdirSync(uri);
+    const paths = entries.map((entry) => nodefs.realpathSync(path.join(dir, entry)));
+
+    const fspaths = fsentries.map((entry) => fs.realCasePath(uri.combinePaths(entry)).getFilePath());
+    assert.deepStrictEqual(lowerCaseDrive(paths), fspaths);
+});
diff --git a/packages/pyright-internal/src/tests/workspaceEditUtils.test.ts b/packages/pyright-internal/src/tests/workspaceEditUtils.test.ts
index 12b324e02..c5337c870 100644
--- a/packages/pyright-internal/src/tests/workspaceEditUtils.test.ts
+++ b/packages/pyright-internal/src/tests/workspaceEditUtils.test.ts
@@ -10,14 +10,15 @@ import * as assert from 'assert';
 import { TextDocumentEdit, WorkspaceEdit } from 'vscode-languageserver-types';
 
 import { CancellationToken } from 'vscode-languageserver';
+import { AnalyzerService } from '../analyzer/service';
 import { IPythonMode } from '../analyzer/sourceFile';
-import { combinePaths, convertPathToUri, getDirectoryPath } from '../common/pathUtils';
+import { combinePaths, getDirectoryPath } from '../common/pathUtils';
+import { Uri } from '../common/uri/uri';
 import { applyWorkspaceEdit, generateWorkspaceEdit } from '../common/workspaceEditUtils';
 import { AnalyzerServiceExecutor } from '../languageService/analyzerServiceExecutor';
 import { TestLanguageService } from './harness/fourslash/testLanguageService';
 import { TestState, parseAndGetTestState } from './harness/fourslash/testState';
 import { verifyWorkspaceEdit } from './harness/fourslash/workspaceEditTestUtils';
-import { AnalyzerService } from '../analyzer/service';
 
 test('test applyWorkspaceEdits changes', async () => {
     const code = `
@@ -29,12 +30,12 @@ test('test applyWorkspaceEdits changes', async () => {
     const cloned = await getClonedService(state);
     const range = state.getRangeByMarkerName('marker')!;
 
-    const fileChanged = new Set<string>();
+    const fileChanged = new Map<string, Uri>();
     applyWorkspaceEditToService(
         cloned,
         {
             changes: {
-                [convertPathToUri(cloned.fs, range.fileName)]: [
+                [Uri.file(range.fileName).toString()]: [
                     {
                         range: state.convertPositionRange(range),
                         newText: 'Text Changed',
@@ -46,7 +47,7 @@ test('test applyWorkspaceEdits changes', async () => {
     );
 
     assert.strictEqual(fileChanged.size, 1);
-    assert.strictEqual(cloned.test_program.getSourceFile(range.fileName)?.getFileContent(), 'Text Changed');
+    assert.strictEqual(cloned.test_program.getSourceFile(Uri.file(range.fileName))?.getFileContent(), 'Text Changed');
 });
 
 test('test edit mode for workspace', async () => {
@@ -57,16 +58,16 @@ test('test edit mode for workspace', async () => {
 
     const state = parseAndGetTestState(code).state;
     const range = state.getRangeByMarkerName('marker')!;
-    const addedFilePath = combinePaths(getDirectoryPath(range.fileName), 'test2.py');
+    const addedFileUri = Uri.file(combinePaths(getDirectoryPath(range.fileName), 'test2.py'));
     const edits = state.workspace.service.runEditMode((program) => {
-        const fileChanged = new Set<string>();
+        const fileChanged = new Map<string, Uri>();
         applyWorkspaceEdit(
             program,
             {
                 documentChanges: [
                     TextDocumentEdit.create(
                         {
-                            uri: convertPathToUri(program.fileSystem, range.fileName),
+                            uri: Uri.file(range.fileName).toString(),
                             version: null,
                         },
                         [
@@ -82,19 +83,18 @@ test('test edit mode for workspace', async () => {
         );
 
         assert.strictEqual(fileChanged.size, 1);
-        const info = program.getSourceFileInfo(range.fileName)!;
+        const info = program.getSourceFileInfo(Uri.file(range.fileName))!;
         const sourceFile = info.sourceFile;
 
-        program.analyzeFile(sourceFile.getFilePath(), CancellationToken.None);
+        program.analyzeFile(sourceFile.getUri(), CancellationToken.None);
         assert.strictEqual(sourceFile.getFileContent(), 'import sys');
         assert.strictEqual(info.imports.length, 2);
 
         // Add a new file.
-        program.setFileOpened(addedFilePath, 0, '', {
+        program.setFileOpened(addedFileUri, 0, '', {
             isTracked: true,
             ipythonMode: IPythonMode.None,
-            chainedFilePath: undefined,
-            realFilePath: addedFilePath,
+            chainedFileUri: undefined,
         });
 
         applyWorkspaceEdit(
@@ -103,7 +103,7 @@ test('test edit mode for workspace', async () => {
                 documentChanges: [
                     TextDocumentEdit.create(
                         {
-                            uri: convertPathToUri(program.fileSystem, addedFilePath),
+                            uri: addedFileUri.toString(),
                             version: null,
                         },
                         [
@@ -127,7 +127,7 @@ test('test edit mode for workspace', async () => {
                 documentChanges: [
                     TextDocumentEdit.create(
                         {
-                            uri: convertPathToUri(program.fileSystem, addedFilePath),
+                            uri: addedFileUri.toString(),
                             version: null,
                         },
                         [
@@ -145,17 +145,17 @@ test('test edit mode for workspace', async () => {
             fileChanged
         );
 
-        const addedInfo = program.getSourceFileInfo(addedFilePath)!;
+        const addedInfo = program.getSourceFileInfo(addedFileUri)!;
         const addedSourceFile = addedInfo.sourceFile;
-        program.analyzeFile(addedSourceFile.getFilePath(), CancellationToken.None);
+        program.analyzeFile(addedSourceFile.getUri(), CancellationToken.None);
 
         assert.strictEqual(addedSourceFile.getFileContent(), 'import os');
         assert.strictEqual(addedInfo.imports.length, 2);
     }, CancellationToken.None);
 
     // After leaving edit mode, we should be back to where we were.
-    const oldSourceFile = state.workspace.service.test_program.getSourceFile(range.fileName);
-    state.workspace.service.backgroundAnalysisProgram.analyzeFile(oldSourceFile!.getFilePath(), CancellationToken.None);
+    const oldSourceFile = state.workspace.service.test_program.getSourceFile(Uri.file(range.fileName));
+    state.workspace.service.backgroundAnalysisProgram.analyzeFile(oldSourceFile!.getUri(), CancellationToken.None);
 
     assert.strictEqual(oldSourceFile?.getFileContent(), '');
     assert.strictEqual(oldSourceFile.getImports().length, 1);
@@ -164,7 +164,7 @@ test('test edit mode for workspace', async () => {
     assert.deepStrictEqual(edits[0].replacementText, 'import sys');
     assert.deepStrictEqual(edits[1].replacementText, 'import os');
 
-    const addedSourceFile = state.workspace.service.test_program.getSourceFile(addedFilePath);
+    const addedSourceFile = state.workspace.service.test_program.getSourceFile(addedFileUri);
 
     // The added file should not be there.
     assert.ok(!addedSourceFile);
@@ -180,14 +180,14 @@ test('test applyWorkspaceEdits documentChanges', async () => {
     const cloned = await getClonedService(state);
     const range = state.getRangeByMarkerName('marker')!;
 
-    const fileChanged = new Set<string>();
+    const fileChanged = new Map<string, Uri>();
     applyWorkspaceEditToService(
         cloned,
         {
             documentChanges: [
                 TextDocumentEdit.create(
                     {
-                        uri: convertPathToUri(cloned.fs, range.fileName),
+                        uri: Uri.file(range.fileName).toString(),
                         version: null,
                     },
                     [
@@ -203,7 +203,7 @@ test('test applyWorkspaceEdits documentChanges', async () => {
     );
 
     assert.strictEqual(fileChanged.size, 1);
-    assert.strictEqual(cloned.test_program.getSourceFile(range.fileName)?.getFileContent(), 'Text Changed');
+    assert.strictEqual(cloned.test_program.getSourceFile(Uri.file(range.fileName))?.getFileContent(), 'Text Changed');
 });
 
 test('test generateWorkspaceEdits', async () => {
@@ -219,12 +219,12 @@ test('test generateWorkspaceEdits', async () => {
     const cloned = await getClonedService(state);
     const range1 = state.getRangeByMarkerName('marker1')!;
 
-    const fileChanged = new Set<string>();
+    const fileChanged = new Map<string, Uri>();
     applyWorkspaceEditToService(
         cloned,
         {
             changes: {
-                [convertPathToUri(cloned.fs, range1.fileName)]: [
+                [Uri.file(range1.fileName).toString()]: [
                     {
                         range: state.convertPositionRange(range1),
                         newText: 'Test1 Changed',
@@ -241,7 +241,7 @@ test('test generateWorkspaceEdits', async () => {
             documentChanges: [
                 TextDocumentEdit.create(
                     {
-                        uri: convertPathToUri(cloned.fs, range1.fileName),
+                        uri: Uri.file(range1.fileName).toString(),
                         version: null,
                     },
                     [
@@ -263,7 +263,7 @@ test('test generateWorkspaceEdits', async () => {
             documentChanges: [
                 TextDocumentEdit.create(
                     {
-                        uri: convertPathToUri(cloned.fs, range2.fileName),
+                        uri: Uri.file(range2.fileName).toString(),
                         version: null,
                     },
                     [
@@ -282,7 +282,7 @@ test('test generateWorkspaceEdits', async () => {
         cloned,
         {
             changes: {
-                [convertPathToUri(cloned.fs, range2.fileName)]: [
+                [Uri.file(range2.fileName).toString()]: [
                     {
                         range: { start: { line: 0, character: 0 }, end: { line: 0, character: 5 } },
                         newText: 'NewTest2',
@@ -299,13 +299,13 @@ test('test generateWorkspaceEdits', async () => {
     verifyWorkspaceEdit(
         {
             changes: {
-                [convertPathToUri(cloned.fs, range1.fileName)]: [
+                [Uri.file(range1.fileName).toString()]: [
                     {
                         range: state.convertPositionRange(range1),
                         newText: 'NewTest1 Changed',
                     },
                 ],
-                [convertPathToUri(cloned.fs, range2.fileName)]: [
+                [Uri.file(range2.fileName).toString()]: [
                     {
                         range: state.convertPositionRange(range1),
                         newText: 'NewTest2 Changed',
@@ -317,7 +317,7 @@ test('test generateWorkspaceEdits', async () => {
     );
 });
 
-function applyWorkspaceEditToService(service: AnalyzerService, edits: WorkspaceEdit, filesChanged: Set<string>) {
+function applyWorkspaceEditToService(service: AnalyzerService, edits: WorkspaceEdit, filesChanged: Map<string, Uri>) {
     const program = service.backgroundAnalysisProgram.program;
     applyWorkspaceEdit(program, edits, filesChanged);
 }
diff --git a/packages/pyright-internal/src/tests/zipfs.test.ts b/packages/pyright-internal/src/tests/zipfs.test.ts
index 439f0bcee..326ef03fd 100644
--- a/packages/pyright-internal/src/tests/zipfs.test.ts
+++ b/packages/pyright-internal/src/tests/zipfs.test.ts
@@ -6,13 +6,12 @@
 
 import * as assert from 'assert';
 import * as path from 'path';
-
-import { combinePaths } from '../common/pathUtils';
 import { createFromRealFileSystem } from '../common/realFileSystem';
 import { compareStringsCaseSensitive } from '../common/stringUtils';
+import { Uri } from '../common/uri/uri';
 
 function runTests(p: string): void {
-    const zipRoot = path.resolve(path.dirname(module.filename), p);
+    const zipRoot = Uri.file(path.resolve(path.dirname(module.filename), p));
     const fs = createFromRealFileSystem();
 
     test('stat root', () => {
@@ -39,13 +38,13 @@ function runTests(p: string): void {
     });
 
     test('stat EGG-INFO', () => {
-        const stats = fs.statSync(combinePaths(zipRoot, 'EGG-INFO'));
+        const stats = fs.statSync(zipRoot.combinePaths('EGG-INFO'));
         assert.strictEqual(stats.isDirectory(), true);
         assert.strictEqual(stats.isFile(), false);
     });
 
     test('readdirEntriesSync root', () => {
-        const entries = fs.readdirEntriesSync(combinePaths(zipRoot, 'EGG-INFO'));
+        const entries = fs.readdirEntriesSync(zipRoot.combinePaths('EGG-INFO'));
         assert.strictEqual(entries.length, 5);
 
         entries.sort((a, b) => compareStringsCaseSensitive(a.name, b.name));
@@ -72,24 +71,24 @@ function runTests(p: string): void {
     });
 
     test('read file', () => {
-        const contents = fs.readFileSync(combinePaths(zipRoot, 'EGG-INFO', 'top_level.txt'), 'utf-8');
+        const contents = fs.readFileSync(zipRoot.combinePaths('EGG-INFO', 'top_level.txt'), 'utf-8');
         assert.strictEqual(contents.trim(), 'test');
     });
 
     test('read file async', async () => {
-        const contents = await fs.readFileText(combinePaths(zipRoot, 'EGG-INFO', 'top_level.txt'), 'utf-8');
+        const contents = await fs.readFileText(zipRoot.combinePaths('EGG-INFO', 'top_level.txt'), 'utf-8');
         assert.strictEqual(contents.trim(), 'test');
     });
 
     test('unlink fails', async () => {
         expect(() => {
-            fs.unlinkSync(combinePaths(zipRoot, 'EGG-INFO', 'top_level.txt'));
+            fs.unlinkSync(zipRoot.combinePaths('EGG-INFO', 'top_level.txt'));
         }).toThrow(/read-only filesystem/);
     });
 
     test('isInZip', () => {
-        assert.strictEqual(fs.isInZip(combinePaths(zipRoot, 'EGG-INFO', 'top_level.txt')), true);
-        assert.strictEqual(fs.isInZip(module.filename), false);
+        assert.strictEqual(fs.isInZip(zipRoot.combinePaths('EGG-INFO', 'top_level.txt')), true);
+        assert.strictEqual(fs.isInZip(Uri.file(module.filename)), false);
     });
 }
 
@@ -98,7 +97,7 @@ describe('egg', () => runTests('./samples/zipfs/basic.egg'));
 describe('jar', () => runTests('./samples/zipfs/basic.jar'));
 
 function runBadTests(p: string): void {
-    const zipRoot = path.resolve(path.dirname(module.filename), p);
+    const zipRoot = Uri.file(path.resolve(path.dirname(module.filename), p));
     const fs = createFromRealFileSystem();
 
     test('stat root', () => {
@@ -108,7 +107,7 @@ function runBadTests(p: string): void {
     });
 
     test('isInZip', () => {
-        assert.strictEqual(fs.isInZip(combinePaths(zipRoot, 'EGG-INFO', 'top_level.txt')), false);
+        assert.strictEqual(fs.isInZip(zipRoot.combinePaths('EGG-INFO', 'top_level.txt')), false);
     });
 }
 
diff --git a/packages/pyright-internal/src/workspaceFactory.ts b/packages/pyright-internal/src/workspaceFactory.ts
index 7d5666508..f78ac2a54 100644
--- a/packages/pyright-internal/src/workspaceFactory.ts
+++ b/packages/pyright-internal/src/workspaceFactory.ts
@@ -9,7 +9,7 @@ import { InitializeParams, WorkspaceFoldersChangeEvent } from 'vscode-languagese
 import { AnalyzerService } from './analyzer/service';
 import { ConsoleInterface } from './common/console';
 import { createDeferred } from './common/deferred';
-import { UriParser } from './common/uriParser';
+import { Uri } from './common/uri/uri';
 
 let WorkspaceFactoryIdCounter = 0;
 
@@ -75,16 +75,15 @@ export function createInitStatus(): InitStatus {
 // rootPath will always point to the folder that contains the workspace.
 export interface Workspace {
     workspaceName: string;
-    rootPath: string;
-    uri: string;
+    rootUri: Uri;
     kinds: string[];
     service: AnalyzerService;
     disableLanguageServices: boolean;
     disableOrganizeImports: boolean;
     disableWorkspaceSymbol: boolean;
     isInitialized: InitStatus;
-    searchPathsToWatch: string[];
-    pythonPath: string | undefined;
+    searchPathsToWatch: Uri[];
+    pythonPath: Uri | undefined;
     pythonPathKind: WorkspacePythonPathKind;
     pythonEnvironmentName: string | undefined;
 }
@@ -93,20 +92,14 @@ export class WorkspaceFactory {
     private _defaultWorkspacePath = '<default>';
     private _map = new Map<string, Workspace>();
     private _id = WorkspaceFactoryIdCounter++;
-
     constructor(
         private readonly _console: ConsoleInterface,
-        private readonly _uriParser: UriParser,
         private readonly _isWeb: boolean,
-        private readonly _createService: (
-            name: string,
-            rootPath: string,
-            uri: string,
-            kinds: string[]
-        ) => AnalyzerService,
-        private readonly _isPythonPathImmutable: (path: string) => boolean,
+        private readonly _createService: (name: string, rootPath: Uri, kinds: string[]) => AnalyzerService,
+        private readonly _isPythonPathImmutable: (uri: Uri) => boolean,
         private readonly _onWorkspaceCreated: (workspace: Workspace) => void,
-        private readonly _onWorkspaceRemoved: (workspace: Workspace) => void
+        private readonly _onWorkspaceRemoved: (workspace: Workspace) => void,
+        private readonly _isCaseSensitive: boolean
     ) {
         this._console.log(`WorkspaceFactory ${this._id} created`);
     }
@@ -115,48 +108,49 @@ export class WorkspaceFactory {
         // Create a service instance for each of the workspace folders.
         if (params.workspaceFolders) {
             params.workspaceFolders.forEach((folder) => {
-                const path = this._uriParser.decodeTextDocumentUri(folder.uri);
-                this._add(folder.uri, path, folder.name, undefined, WorkspacePythonPathKind.Mutable, [
-                    WellKnownWorkspaceKinds.Regular,
-                ]);
+                this._add(
+                    Uri.parse(folder.uri, this._isCaseSensitive),
+                    folder.name,
+                    undefined,
+                    WorkspacePythonPathKind.Mutable,
+                    [WellKnownWorkspaceKinds.Regular]
+                );
             });
         } else if (params.rootPath) {
-            this._add(params.rootUri || '', params.rootPath, '', undefined, WorkspacePythonPathKind.Mutable, [
-                WellKnownWorkspaceKinds.Regular,
-            ]);
+            this._add(
+                Uri.file(params.rootPath, this._isCaseSensitive),
+                '',
+                undefined,
+                WorkspacePythonPathKind.Mutable,
+                [WellKnownWorkspaceKinds.Regular]
+            );
         }
     }
 
     handleWorkspaceFoldersChanged(params: WorkspaceFoldersChangeEvent) {
         params.removed.forEach((workspaceInfo) => {
-            const rootPath = this._uriParser.decodeTextDocumentUri(workspaceInfo.uri);
+            const uri = Uri.parse(workspaceInfo.uri, this._isCaseSensitive);
             // Delete all workspaces for this folder. Even the ones generated for notebook kernels.
-            const workspaces = this.getNonDefaultWorkspaces().filter((w) => w.rootPath === rootPath);
+            const workspaces = this.getNonDefaultWorkspaces().filter((w) => w.rootUri.equals(uri));
             workspaces.forEach((w) => {
                 this._remove(w);
             });
         });
 
         params.added.forEach((workspaceInfo) => {
-            const rootPath = this._uriParser.decodeTextDocumentUri(workspaceInfo.uri);
-
+            const uri = Uri.parse(workspaceInfo.uri, this._isCaseSensitive);
             // If there's a workspace that contains this folder, we need to mimic files from this workspace to
             // to the new one. Otherwise the subfolder won't have the changes for the files in it.
-            const containing = this.items().filter((w) => rootPath.startsWith(w.rootPath))[0];
+            const containing = this.items().filter((w) => uri.startsWith(w.rootUri))[0];
 
             // Add the new workspace.
-            const newWorkspace = this._add(
-                workspaceInfo.uri,
-                rootPath,
-                workspaceInfo.name,
-                undefined,
-                WorkspacePythonPathKind.Mutable,
-                [WellKnownWorkspaceKinds.Regular]
-            );
+            const newWorkspace = this._add(uri, workspaceInfo.name, undefined, WorkspacePythonPathKind.Mutable, [
+                WellKnownWorkspaceKinds.Regular,
+            ]);
 
             // Move files from the containing workspace to the new one that are in the new folder.
             if (containing) {
-                this._mimicOpenFiles(containing, newWorkspace, (f) => f.startsWith(rootPath));
+                this._mimicOpenFiles(containing, newWorkspace, (f) => f.startsWith(uri));
             }
         });
     }
@@ -165,7 +159,7 @@ export class WorkspaceFactory {
         return Array.from(this._map.values());
     }
 
-    applyPythonPath(workspace: Workspace, newPythonPath: string | undefined): string | undefined {
+    applyPythonPath(workspace: Workspace, newPythonPath: Uri | undefined): Uri | undefined {
         // See if were allowed to apply the new python path
         if (workspace.pythonPathKind === WorkspacePythonPathKind.Mutable && newPythonPath) {
             const originalPythonPath = workspace.pythonPath;
@@ -181,7 +175,7 @@ export class WorkspaceFactory {
             }
 
             // If the python path has changed, we may need to move the immutable files to the correct workspace.
-            if (originalPythonPath && newPythonPath !== originalPythonPath && workspaceInMap) {
+            if (originalPythonPath && !newPythonPath.equals(originalPythonPath) && workspaceInMap) {
                 // Potentially move immutable files from one workspace to another.
                 this._moveImmutableFilesToCorrectWorkspace(originalPythonPath, workspaceInMap);
             }
@@ -219,16 +213,14 @@ export class WorkspaceFactory {
         return false;
     }
 
-    getContainingWorkspace(filePath: string, pythonPath?: string) {
+    getContainingWorkspace(filePath: Uri, pythonPath?: Uri) {
         return this._getBestRegularWorkspace(
-            this.getNonDefaultWorkspaces(WellKnownWorkspaceKinds.Regular).filter((w) =>
-                filePath.startsWith(w.rootPath)
-            ),
+            this.getNonDefaultWorkspaces(WellKnownWorkspaceKinds.Regular).filter((w) => filePath.startsWith(w.rootUri)),
             pythonPath
         );
     }
 
-    moveFiles(filePaths: string[], fromWorkspace: Workspace, toWorkspace: Workspace) {
+    moveFiles(filePaths: Uri[], fromWorkspace: Workspace, toWorkspace: Workspace) {
         if (fromWorkspace === toWorkspace) {
             return;
         }
@@ -241,21 +233,13 @@ export class WorkspaceFactory {
                     const version = fileInfo.sourceFile.getClientVersion() ?? null;
                     const content = fileInfo.sourceFile.getFileContent() || '';
                     const ipythonMode = fileInfo.sourceFile.getIPythonMode();
-                    const chainedSourceFile = fileInfo.chainedSourceFile?.sourceFile.getFilePath();
-                    const realFilePath = fileInfo.sourceFile.getRealFilePath();
+                    const chainedSourceFile = fileInfo.chainedSourceFile?.sourceFile.getUri();
 
                     // Remove the file from the old workspace first (closing will propagate to the toWorkspace automatically).
                     fromWorkspace.service.setFileClosed(f, /* isTracked */ false);
 
                     // Then open it in the toWorkspace so that it is marked tracked there.
-                    toWorkspace.service.setFileOpened(
-                        f,
-                        version,
-                        content,
-                        ipythonMode,
-                        chainedSourceFile,
-                        realFilePath
-                    );
+                    toWorkspace.service.setFileOpened(f, version, content, ipythonMode, chainedSourceFile);
                 }
             });
 
@@ -269,7 +253,7 @@ export class WorkspaceFactory {
     getNonDefaultWorkspaces(kind?: string): Workspace[] {
         const workspaces: Workspace[] = [];
         this._map.forEach((workspace) => {
-            if (!workspace.rootPath) {
+            if (!workspace.rootUri) {
                 return;
             }
 
@@ -285,13 +269,13 @@ export class WorkspaceFactory {
 
     // Returns the best workspace for a file. Waits for the workspace to be finished handling other events before
     // returning the appropriate workspace.
-    async getWorkspaceForFile(filePath: string, pythonPath: string | undefined): Promise<Workspace> {
+    async getWorkspaceForFile(uri: Uri, pythonPath: Uri | undefined): Promise<Workspace> {
         // Wait for all workspaces to be initialized before attempting to find the best workspace. Otherwise
         // the list of files won't be complete and the `contains` check might fail.
         await Promise.all(this.items().map((w) => w.isInitialized.promise));
 
         // Find or create best match.
-        const workspace = await this._getOrCreateBestWorkspaceForFile(filePath, pythonPath);
+        const workspace = await this._getOrCreateBestWorkspaceForFile(uri, pythonPath);
 
         // The workspace may have just been created. Wait for it to be initialized before returning it.
         await workspace.isInitialized.promise;
@@ -299,12 +283,12 @@ export class WorkspaceFactory {
         return workspace;
     }
 
-    getWorkspaceForFileSync(filePath: string, pythonPath: string | undefined): Workspace {
+    getWorkspaceForFileSync(filePath: Uri, pythonPath: Uri | undefined): Workspace {
         // Find or create best match.
         return this._getOrCreateBestWorkspaceFileSync(filePath, pythonPath);
     }
 
-    async getContainingWorkspacesForFile(filePath: string): Promise<Workspace[]> {
+    async getContainingWorkspacesForFile(filePath: Uri): Promise<Workspace[]> {
         // Wait for all workspaces to be initialized before attempting to find the best workspace. Otherwise
         // the list of files won't be complete and the `contains` check might fail.
         await Promise.all(this.items().map((w) => w.isInitialized.promise));
@@ -318,17 +302,17 @@ export class WorkspaceFactory {
         return workspaces;
     }
 
-    getContainingWorkspacesForFileSync(filePath: string): Workspace[] {
+    getContainingWorkspacesForFileSync(fileUri: Uri): Workspace[] {
         // All workspaces that track the file should be considered.
-        let workspaces = this.items().filter((w) => w.service.isTracked(filePath));
+        let workspaces = this.items().filter((w) => w.service.isTracked(fileUri));
 
         // If that list is empty, get the best workspace
         if (workspaces.length === 0) {
-            workspaces.push(this._getOrCreateBestWorkspaceFileSync(filePath, undefined));
+            workspaces.push(this._getOrCreateBestWorkspaceFileSync(fileUri, undefined));
         }
 
         // If the file is immutable, then only return that workspace.
-        if (this._isPythonPathImmutable(filePath)) {
+        if (this._isPythonPathImmutable(fileUri)) {
             workspaces = workspaces.filter((w) => w.pythonPathKind === WorkspacePythonPathKind.Immutable);
         }
 
@@ -346,21 +330,18 @@ export class WorkspaceFactory {
         }
     }
 
-    private async _moveImmutableFilesToCorrectWorkspace(oldPythonPath: string, mutableWorkspace: Workspace) {
+    private async _moveImmutableFilesToCorrectWorkspace(oldPythonPath: Uri, mutableWorkspace: Workspace) {
         // If the python path changes we may need to move some immutable files around.
         // For example, if a notebook had the old python path, we need to create a new workspace
         // for the notebook.
         // If a notebook has the new python path but is currently in a workspace with the path hardcoded, we need to move it to
         // this workspace.
-        const oldPathFiles = Array.from(
-            new Set<string>(mutableWorkspace.service.getOpenFiles().filter((f) => this._isPythonPathImmutable(f)))
-        );
+        const oldPathFiles = mutableWorkspace.service.getOpenFiles().filter((f) => this._isPythonPathImmutable(f));
         const exitingWorkspaceWithSamePath = this.items().find(
             (w) => w.pythonPath === mutableWorkspace.pythonPath && w !== mutableWorkspace
         );
-        const newPathFiles = new Set<string>(
-            exitingWorkspaceWithSamePath?.service.getOpenFiles().filter((f) => this._isPythonPathImmutable(f))
-        );
+        const newPathFiles =
+            exitingWorkspaceWithSamePath?.service.getOpenFiles().filter((f) => this._isPythonPathImmutable(f)) ?? [];
 
         // Immutable files that were in this mutableWorkspace have to be moved
         // to a (potentially) new workspace (with the old path).
@@ -376,39 +357,37 @@ export class WorkspaceFactory {
         // Immutable files from a different workspace (with the same path as the new path)
         // have to be moved to the mutable workspace (which now has the new path)
         if (exitingWorkspaceWithSamePath) {
-            this.moveFiles(Array.from(newPathFiles), exitingWorkspaceWithSamePath!, mutableWorkspace);
+            this.moveFiles(newPathFiles, exitingWorkspaceWithSamePath!, mutableWorkspace);
             this.removeUnused(exitingWorkspaceWithSamePath);
         }
     }
 
     private _add(
-        rootUri: string,
-        rootPath: string,
+        rootUri: Uri,
         name: string,
-        pythonPath: string | undefined,
+        pythonPath: Uri | undefined,
         pythonPathKind: WorkspacePythonPathKind,
         kinds: string[]
     ) {
         // Update the kind based if the uri is local or not
-        if (!kinds.includes(WellKnownWorkspaceKinds.Default) && (!this._uriParser.isLocal(rootUri) || this._isWeb)) {
+        if (!kinds.includes(WellKnownWorkspaceKinds.Default) && (!rootUri.isLocal() || this._isWeb)) {
             // Web based workspace should be limited.
             kinds = [...kinds, WellKnownWorkspaceKinds.Limited];
         }
 
         const result: Workspace = {
             workspaceName: name,
-            rootPath,
-            uri: rootUri,
+            rootUri,
             kinds,
             pythonPath,
             pythonPathKind,
-            service: this._createService(name, rootPath, rootUri, kinds),
+            service: this._createService(name, rootUri, kinds),
             disableLanguageServices: false,
             disableOrganizeImports: false,
             disableWorkspaceSymbol: false,
             isInitialized: createInitStatus(),
             searchPathsToWatch: [],
-            pythonEnvironmentName: pythonPath,
+            pythonEnvironmentName: pythonPath?.toString(),
         };
 
         // Stick in our map
@@ -441,7 +420,7 @@ export class WorkspaceFactory {
         }
     }
 
-    private _getDefaultWorkspaceKey(pythonPath: string | undefined) {
+    private _getDefaultWorkspaceKey(pythonPath: Uri | undefined) {
         return `${this._defaultWorkspacePath}:${
             pythonPath !== undefined ? pythonPath : WorkspacePythonPathKind.Mutable
         }`;
@@ -452,7 +431,7 @@ export class WorkspaceFactory {
         // without a root path
         const rootPath = value.kinds.includes(WellKnownWorkspaceKinds.Default)
             ? this._defaultWorkspacePath
-            : value.rootPath;
+            : value.rootUri;
 
         // Key is defined by the rootPath and the pythonPath. We might include platform in this, but for now
         // platform is only used by the import resolver.
@@ -461,37 +440,34 @@ export class WorkspaceFactory {
         }`;
     }
 
-    private async _getOrCreateBestWorkspaceForFile(
-        filePath: string,
-        pythonPath: string | undefined
-    ): Promise<Workspace> {
+    private async _getOrCreateBestWorkspaceForFile(uri: Uri, pythonPath: Uri | undefined): Promise<Workspace> {
         // Find the current best workspace (without creating a new one)
-        let bestInstance = this._getBestWorkspaceForFile(filePath, pythonPath);
+        let bestInstance = this._getBestWorkspaceForFile(uri, pythonPath);
 
         // Make sure the best instance is initialized so that it has its pythonPath.
         await bestInstance.isInitialized.promise;
 
         // If this best instance doesn't match the pythonPath, then we need to create a new one.
-        if (pythonPath !== undefined && bestInstance.pythonPath !== pythonPath) {
+        if (pythonPath !== undefined && !bestInstance.pythonPath?.equals(pythonPath)) {
             bestInstance = this._createImmutableCopy(bestInstance, pythonPath);
         }
 
         return bestInstance;
     }
 
-    private _getOrCreateBestWorkspaceFileSync(filePath: string, pythonPath: string | undefined) {
+    private _getOrCreateBestWorkspaceFileSync(uri: Uri, pythonPath: Uri | undefined) {
         // Find the current best workspace (without creating a new one)
-        let bestInstance = this._getBestWorkspaceForFile(filePath, pythonPath);
+        let bestInstance = this._getBestWorkspaceForFile(uri, pythonPath);
 
         // If this best instance doesn't match the pythonPath, then we need to create a new one.
-        if (pythonPath !== undefined && bestInstance.pythonPath !== pythonPath) {
+        if (pythonPath !== undefined && !bestInstance.pythonPath?.equals(pythonPath)) {
             bestInstance = this._createImmutableCopy(bestInstance, pythonPath);
         }
 
         return bestInstance;
     }
 
-    private _mimicOpenFiles(source: Workspace, dest: Workspace, predicate: (f: string) => boolean) {
+    private _mimicOpenFiles(source: Workspace, dest: Workspace, predicate: (f: Uri) => boolean) {
         // All mutable open files in the first workspace should be opened in the new workspace.
         // Immutable files should stay where they are since they're tied to a specific workspace.
         const files = source.service.getOpenFiles().filter((f) => !this._isPythonPathImmutable(f));
@@ -505,17 +481,15 @@ export class WorkspaceFactory {
                     sourceFile.getClientVersion() || null,
                     fileContents || '',
                     sourceFile.getIPythonMode(),
-                    sourceFileInfo.chainedSourceFile?.sourceFile.getFilePath(),
-                    sourceFile.getRealFilePath()
+                    sourceFileInfo.chainedSourceFile?.sourceFile.getUri()
                 );
             }
         }
     }
 
-    private _createImmutableCopy(workspace: Workspace, pythonPath: string): Workspace {
+    private _createImmutableCopy(workspace: Workspace, pythonPath: Uri): Workspace {
         const result = this._add(
-            workspace.uri,
-            workspace.rootPath,
+            workspace.rootUri,
             workspace.workspaceName,
             pythonPath,
             WorkspacePythonPathKind.Immutable,
@@ -528,7 +502,7 @@ export class WorkspaceFactory {
         return result;
     }
 
-    private _getBestWorkspaceForFile(filePath: string, pythonPath: string | undefined): Workspace {
+    private _getBestWorkspaceForFile(uri: Uri, pythonPath: Uri | undefined): Workspace {
         let bestInstance: Workspace | undefined;
 
         // The order of how we find the best matching workspace for the given file is
@@ -543,7 +517,7 @@ export class WorkspaceFactory {
 
         // First find the workspaces that are tracking the file
         const regularWorkspaces = this.getNonDefaultWorkspaces(WellKnownWorkspaceKinds.Regular);
-        const trackingWorkspaces = this.items().filter((w) => w.service.isTracked(filePath));
+        const trackingWorkspaces = this.items().filter((w) => w.service.isTracked(uri));
 
         // Then find the best in all of those that actually matches the pythonPath.
         bestInstance = this._getBestRegularWorkspace(trackingWorkspaces, pythonPath);
@@ -552,7 +526,9 @@ export class WorkspaceFactory {
         // length root path
         if (
             bestInstance === undefined &&
-            regularWorkspaces.every((w) => w.rootPath.length === regularWorkspaces[0].rootPath.length)
+            regularWorkspaces.every(
+                (w) => w.rootUri.getRootPathLength() === regularWorkspaces[0].rootUri.getRootPathLength()
+            )
         ) {
             bestInstance = this._getBestRegularWorkspace(regularWorkspaces, pythonPath);
         }
@@ -562,7 +538,7 @@ export class WorkspaceFactory {
         if (bestInstance === undefined || bestInstance.pythonPath !== pythonPath) {
             bestInstance =
                 this._getBestRegularWorkspace(
-                    regularWorkspaces.filter((w) => w.service.hasSourceFile(filePath)),
+                    regularWorkspaces.filter((w) => w.service.hasSourceFile(uri)),
                     pythonPath
                 ) || bestInstance;
         }
@@ -575,15 +551,14 @@ export class WorkspaceFactory {
         return bestInstance;
     }
 
-    private _getOrCreateDefaultWorkspace(pythonPath: string | undefined): Workspace {
+    private _getOrCreateDefaultWorkspace(pythonPath: Uri | undefined): Workspace {
         // Default key depends upon the pythonPath
         let defaultWorkspace = this._map.get(this._getDefaultWorkspaceKey(pythonPath));
         if (!defaultWorkspace) {
             // Create a default workspace for files that are outside
             // of all workspaces.
             defaultWorkspace = this._add(
-                '',
-                '',
+                Uri.empty(),
                 this._defaultWorkspacePath,
                 pythonPath,
                 pythonPath !== undefined ? WorkspacePythonPathKind.Immutable : WorkspacePythonPathKind.Mutable,
@@ -597,18 +572,18 @@ export class WorkspaceFactory {
     private _getLongestPathWorkspace(workspaces: Workspace[]): Workspace {
         const longestPath = workspaces.reduce((previousPath, currentWorkspace) => {
             if (!previousPath) {
-                return currentWorkspace.rootPath;
+                return currentWorkspace.rootUri;
             }
-            if (currentWorkspace.rootPath.length > previousPath.length) {
-                return currentWorkspace.rootPath;
+            if (currentWorkspace.rootUri.getPathLength() > previousPath.getPathLength()) {
+                return currentWorkspace.rootUri;
             }
 
             return previousPath;
-        }, '');
-        return workspaces.find((w) => w.rootPath === longestPath)!;
+        }, Uri.empty());
+        return workspaces.find((w) => w.rootUri === longestPath)!;
     }
 
-    private _getBestRegularWorkspace(workspaces: Workspace[], pythonPath?: string): Workspace | undefined {
+    private _getBestRegularWorkspace(workspaces: Workspace[], pythonPath?: Uri): Workspace | undefined {
         if (workspaces.length === 0) {
             return undefined;
         }
diff --git a/tsconfig.json b/tsconfig.json
index a612a1d41..171104dc5 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -17,6 +17,7 @@
         "noImplicitReturns": true,
         "noImplicitOverride": true,
         "checkJs": true,
+        "experimentalDecorators": true
     },
     "exclude": [
         "node_modules",