Add API for component groups (#3286)

RELEASES.md

@@ -12,6 +12,9 @@
 - Updated to
   [GraalVM 21.3.0](https://github.com/graalvm/graalvm-ce-builds/releases/tag/vm-21.3.0)
   ([#3258](https://github.com/enso-org/enso/pull/3258)).
+- Extended language server API to allow accessing the package definition, and to
+  get the available component groups
+  [#3286](https://github.com/enso-org/enso/pull/3286).
 
 ## Interpreter/Runtime
 

docs/language-server/protocol-language-server.md

@@ -62,6 +62,12 @@ transport formats, please look [here](./protocol-architecture).
   - [`LibraryVersion`](#libraryversion)
   - [`Contact`](#contact)
   - [`EditionReference`](#editionreference)
+  - [`ComponentGroups`](#componentgroups)
+  - [`ComponentGroup`](#componentgroup)
+  - [`ExtendedComponentGroup`](#extendedcomponentgroup)
+  - [`ModuleReference`](#modulereference)
+  - [`Component`](#component)
+  - [`LibraryComponentGroup`](#librarycomponentgroup)
 - [Connection Management](#connection-management)
   - [`session/initProtocolConnection`](#sessioninitprotocolconnection)
   - [`session/initBinaryConnection`](#sessioninitbinaryconnection)
@@ -156,10 +162,12 @@ transport formats, please look [here](./protocol-architecture).
   - [`editions/setProjectParentEdition`](#editionssetprojectparentedition)
   - [`editions/setProjectLocalLibrariesPreference`](#editionssetprojectlocallibrariespreference)
   - [`editions/listDefinedLibraries`](#editionslistdefinedlibraries)
+  - [`editions/listDefinedComponents`](#editionslistdefinedcomponents)
   - [`library/listLocal`](#librarylistlocal)
   - [`library/create`](#librarycreate)
   - [`library/getMetadata`](#librarygetmetadata)
   - [`library/setMetadata`](#librarysetmetadata)
+  - [`library/getPackage`](#librarygetpackage)
   - [`library/publish`](#librarypublish)
   - [`library/preinstall`](#librarypreinstall)
 - [Errors](#errors-75)
@@ -204,6 +212,7 @@ transport formats, please look [here](./protocol-architecture).
   - [`LibraryNotResolved`](#librarynotresolved)
   - [`InvalidLibraryName`](#invalidlibraryname)
   - [`DependencyDiscoveryError`](#dependencydiscoveryerror)
+  - [`InvalidSemverVersion`](#invalidsemverversion)
 
 <!-- /MarkdownTOC -->
 
@@ -1418,6 +1427,114 @@ interface NamedEdition {
 }
 ```
 
+### `ComponentGroups`
+
+The description of component groups provided by the package. Object fields can
+be omitted if the corresponding list is empty.
+
+```typescript
+interface ComponentGroups {
+  /** The list of component groups provided by the package. */
+  newGroups?: ComponentGroup[];
+
+  /** The list of component groups that this package extends.*/
+  extendedGroups?: ExtendedComponentGroup[];
+}
+```
+
+### `ComponentGroup`
+
+The definition of a single component group.
+
+```typescript
+interface ComponentGroup {
+  /** The module name containing the declared componennts. */
+  module: string;
+
+  color?: string;
+
+  icon?: string;
+
+  /** The list of components provided by this component group. */
+  exports: Component[];
+}
+```
+
+### `ExtendedComponentGroup`
+
+The definition of a component group that extends an existing one.
+
+```typescript
+interface ExtendedComponentGroup {
+  /** The reference to the component group module being extended. */
+  module: ModuleReference;
+
+  /** The list of components provided by this component group. */
+  exports: Component[];
+}
+```
+
+### `ModuleReference`
+
+The reference to a module.
+
+```typescript
+interface ModuleReference {
+  /**
+   * A string consisting of a namespace and a lirary name separated by the dot
+   * <namespace>.<library name>, i.e. `Standard.Base`.
+   */
+  libraryName: string;
+
+  /** The module name without the library name prefix.
+   *  E.g. given the `Standard.Base.Data.Vector` module reference,
+   * the `moduleName` field contains `Data.Vector`.
+   */
+  moduleName: string;
+}
+```
+
+### `Component`
+
+A single component of a component group.
+
+```typescript
+interface Component {
+  /** The component name. */
+  name: string;
+
+  /** The component shortcut. */
+  shortcut?: string;
+}
+```
+
+### `LibraryComponentGroup`
+
+The component group provided by a library.
+
+```typescript
+interface LibraryComponentGroup {
+  /**
+   * A string consisting of a namespace and a lirary name separated by the dot
+   * <namespace>.<library name>, i.e. `Standard.Base`.
+   */
+  library: string;
+
+  /** The module name without the library name prefix.
+   *  E.g. given the `Standard.Base.Data.Vector` module reference,
+   * the `module` field contains `Data.Vector`.
+   */
+  module: string;
+
+  color?: string;
+
+  icon?: string;
+
+  /** The list of components provided by this component group. */
+  exports: Component[];
+}
+```
+
 ## Connection Management
 
 In order to properly set-up and tear-down the language server connection, we
@@ -4305,6 +4422,33 @@ To get local libraries that are not directly referenced in the edition, use
 
 #### Errors
 
+- [`EditionNotFoundError`](#editionnotfounderror) indicates that the requested
+  edition, or an edition referenced in one of its parents, could not be found.
+- [`FileSystemError`](#filesystemerror) to signal a generic, unrecoverable
+  file-system error.
+
+### `editions/listDefinedComponents`
+
+Lists all the component groups defined in an edition.
+
+#### Parameters
+
+```typescript
+{
+  edition: EditionReference;
+}
+```
+
+#### Result
+
+```typescript
+{
+  availableComponents: LibraryComponentGroup[];
+}
+```
+
+#### Errors
+
 - [`EditionNotFoundError`](#editionnotfounderror) indicates that the requested
   edition, or an edition referenced in one of its parents, could not be found.
 - [`FileSystemError`](#filesystemerror) to signal a generic, unrecoverable
@@ -4412,6 +4556,8 @@ All returned fields are optional, as they may be missing.
 
 - [`LocalLibraryNotFound`](#locallibrarynotfound) to signal that a local library
   with the given name does not exist on the local libraries path.
+- [`InvalidSemverVersion`](#invalidsemverversion) to signal that the provided
+  version string is not a valid semver version.
 - [`FileSystemError`](#filesystemerror) to signal a generic, unrecoverable
   file-system error.
 
@@ -4446,6 +4592,47 @@ null;
 - [`FileSystemError`](#filesystemerror) to signal a generic, unrecoverable
   file-system error.
 
+### `library/getPackage`
+
+Gets the package config associated with a specific library version.
+
+If the version is `LocalLibraryVersion`, it will try to read the package file of
+the local library and return an empty result if the manifest does not exist.
+
+If the version is `PublishedLibraryVersion`, it will fetch the package config
+from the library repository. A cached package config may also be used, if it is
+available.
+
+All returned fields are optional, as they may be missing.
+
+#### Parameters
+
+```typescript
+{
+  namespace: String;
+  name: String;
+  version: LibraryVersion;
+}
+```
+
+#### Results
+
+```typescript
+{
+  license?: String;
+  componentGroups?: ComponentGroups;
+}
+```
+
+#### Errors
+
+- [`LocalLibraryNotFound`](#locallibrarynotfound) to signal that a local library
+  with the given name does not exist on the local libraries path.
+- [`InvalidSemverVersion`](#invalidsemverversion) to signal that the provided
+  version string is not a valid semver version.
+- [`FileSystemError`](#filesystemerror) to signal a generic, unrecoverable
+  file-system error.
+
 ### `library/publish`
 
 Publishes a library located in the local libraries directory to the main Enso
@@ -5083,3 +5270,18 @@ dependencies of the requested library.
   "message" : "Error occurred while discovering dependencies: <reason>."
 }
 ```
+
+### `InvalidSemverVersion`
+
+Signals that the provided version string is not a valid semver version. The
+message contains the invalid version in the payload.
+
+```typescript
+"error" : {
+  "code" : 8011,
+  "message" : "[<invalid-version>] is not a valid semver version.",
+  "payload" : {
+    "version" : "<invalid-version>"
+  }
+}
+```

engine/language-server/src/main/scala/org/enso/languageserver/libraries/ComponentGroupsResolver.scala

@@ -0,0 +1,196 @@
+package org.enso.languageserver.libraries
+
+import org.enso.editions.LibraryName
+import org.enso.pkg.{
+  ComponentGroup,
+  ComponentGroups,
+  Config,
+  ExtendedComponentGroup,
+  ModuleReference
+}
+
+import scala.collection.immutable.ListMap
+import scala.collection.{mutable, View}
+
+/** The module allowing to resolve the dependencies between the component groups
+  * of different packages.
+  */
+final class ComponentGroupsResolver {
+
+  /** Run the component groups resolution algorithm.
+    *
+    * A package can define a new component group or extend an existing one. The
+    * resolving algorithm takes the component groups defined by the packages and
+    * applies the available extensions.
+    *
+    * @param packages the list of package configs
+    * @return the list of component groups with the dependencies resolved
+    */
+  def run(packages: Iterable[Config]): Vector[LibraryComponentGroup] = {
+    val libraryComponents = packages
+      .map { config =>
+        LibraryName(config.namespace, config.name) -> config.componentGroups
+      }
+      .collect { case (libraryName, Right(componentGroups)) =>
+        libraryName -> componentGroups
+      }
+    val libraryComponentsMap =
+      ComponentGroupsResolver
+        .toMapKeepFirst(libraryComponents)
+        .to(ListMap)
+    resolveComponentGroups(libraryComponentsMap)
+  }
+
+  /** Resolve the component groups. Utility method that takes a list of
+    * component groups associated with the library name.
+    *
+    * @param libraryComponents the associated list of component groups
+    * @return the list of component groups with dependencies resolved
+    */
+  private def resolveComponentGroups(
+    libraryComponents: Map[LibraryName, ComponentGroups]
+  ): Vector[LibraryComponentGroup] = {
+    val newLibraryComponentGroups: View[LibraryComponentGroup] =
+      libraryComponents.view
+        .flatMap { case (libraryName, componentGroups) =>
+          componentGroups.newGroups.map(toLibraryComponentGroup(libraryName, _))
+        }
+    val newLibraryComponentGroupsMap
+      : Map[ModuleReference, LibraryComponentGroup] =
+      ComponentGroupsResolver
+        .groupByKeepFirst(newLibraryComponentGroups) { libraryComponentGroup =>
+          ModuleReference(
+            libraryComponentGroup.library,
+            libraryComponentGroup.module
+          )
+        }
+
+    val extendedComponentGroups: View[ExtendedComponentGroup] =
+      libraryComponents.view
+        .flatMap { case (_, componentGroups) =>
+          componentGroups.extendedGroups
+        }
+    val extendedComponentGroupsMap
+      : Map[ModuleReference, Vector[ExtendedComponentGroup]] =
+      ComponentGroupsResolver
+        .groupByKeepOrder(extendedComponentGroups)(_.module)
+
+    applyExtendedComponentGroups(
+      newLibraryComponentGroupsMap,
+      extendedComponentGroupsMap
+    )
+  }
+
+  /** Applies the extended component groups to the existing ones.
+    *
+    * @param libraryComponentGroups the list of component groups defined by
+    * packages
+    * @param extendedComponentGroups the list of component groups extending
+    * existing ones
+    * @return the list of component groups after extended component groups being
+    * applied
+    */
+  private def applyExtendedComponentGroups(
+    libraryComponentGroups: Map[ModuleReference, LibraryComponentGroup],
+    extendedComponentGroups: Map[ModuleReference, Seq[ExtendedComponentGroup]]
+  ): Vector[LibraryComponentGroup] =
+    libraryComponentGroups.map { case (module, libraryComponentGroup) =>
+      extendedComponentGroups
+        .get(module)
+        .fold(libraryComponentGroup) { extendedComponentGroups =>
+          extendedComponentGroups
+            .foldLeft(libraryComponentGroup)(applyExtendedComponentGroup)
+        }
+    }.toVector
+
+  /** Applies the extended component group to the target component group.
+    *
+    * @param libraryComponentGroup the target component group
+    * @param extendedComponentGroup the component group to apply
+    * @return the resulting component group
+    */
+  private def applyExtendedComponentGroup(
+    libraryComponentGroup: LibraryComponentGroup,
+    extendedComponentGroup: ExtendedComponentGroup
+  ): LibraryComponentGroup =
+    libraryComponentGroup.copy(
+      exports = libraryComponentGroup.exports :++ extendedComponentGroup.exports
+    )
+
+  /** Convert [[ComponentGroup]] to [[LibraryComponentGroup]] representation.
+    *
+    * @param libraryName the library name defining this component group
+    * @param componentGroup the component group to convert
+    * @return the [[LibraryComponentGroup]] representation of this component
+    * group
+    */
+  private def toLibraryComponentGroup(
+    libraryName: LibraryName,
+    componentGroup: ComponentGroup
+  ): LibraryComponentGroup = {
+    LibraryComponentGroup(
+      libraryName,
+      componentGroup.module,
+      componentGroup.color,
+      componentGroup.icon,
+      componentGroup.exports
+    )
+  }
+
+}
+
+object ComponentGroupsResolver {
+
+  /** Partitions this collection into a map according to some discriminator
+    * function, dropping duplicated keys, and preserving the order of elements.
+    * E.g. if the discriminator function produces same keys for different
+    * values, the resulting map will contain only the first encountered
+    * key-value pair for that key.
+    *
+    * @param xs the source collection
+    * @param f the discriminator function
+    * @return the grouped collection preserving the order of elements
+    */
+  private def groupByKeepFirst[K, V](xs: Iterable[V])(f: V => K): Map[K, V] =
+    xs
+      .foldLeft(mutable.LinkedHashMap.empty[K, V]) { (m, v) =>
+        val k = f(v)
+        if (m.contains(k)) m
+        else m += k -> v
+      }
+      .toMap
+
+  /** Partitions this collection into a map according to some discriminator
+    * function and preserving the order of elements.
+    *
+    * @param xs the source collection
+    * @param f the discriminator function
+    * @return the grouped collection that preserves the order of elements
+    */
+  private def groupByKeepOrder[K, V](
+    xs: Iterable[V]
+  )(f: V => K): Map[K, Vector[V]] =
+    xs
+      .foldLeft(mutable.LinkedHashMap.empty[K, Vector[V]]) { (m, v) =>
+        m.updateWith(f(v)) {
+          case Some(xs) => Some(xs :+ v)
+          case None     => Some(Vector(v))
+        }
+        m
+      }
+      .toMap
+
+  /** Convert the collection of key-value pairs into a map, dropping duplicated
+    * keys, and preserving the order of elements.
+    *
+    * @param xs the collection of key-value pairs
+    * @return the map preserving the order of elements
+    */
+  private def toMapKeepFirst[K, V](xs: Iterable[(K, V)]): Map[K, V] =
+    xs
+      .foldLeft(mutable.LinkedHashMap.empty[K, V]) { case (m, (k, v)) =>
+        if (m.contains(k)) m
+        else m += k -> v
+      }
+      .toMap
+}

engine/language-server/src/main/scala/org/enso/languageserver/libraries/ComponentGroupsValidator.scala

@@ -0,0 +1,149 @@
+package org.enso.languageserver.libraries
+
+import org.enso.editions.LibraryName
+import org.enso.pkg.{ComponentGroup, Config, ModuleReference}
+
+import scala.collection.mutable
+
+/** Validate the component groups of provided packages. */
+final class ComponentGroupsValidator {
+
+  import ComponentGroupsValidator.ValidationError
+
+  /** Run the validation.
+    *
+    * The algorithm checks that the provided component groups are consistent:
+    * - Package configs have valid component groups structure
+    * - Packages don't define duplicate component groups
+    * - Packages override existing component groups
+    *
+    * @param packages the list of package configs
+    * @return the validation result for each package
+    */
+  def validate(
+    packages: Iterable[Config]
+  ): Iterable[Either[ValidationError, Config]] = {
+    val init: Iterable[Right[ValidationError, Config]]           = packages.map(Right(_))
+    val modulesMap: mutable.Map[ModuleReference, ComponentGroup] = mutable.Map()
+
+    runValidation(init)(
+      validateInvalidComponentGroups,
+      validateDuplicateComponentGroups(modulesMap),
+      validateComponentGroupExtendsNothing(modulesMap)
+    )
+  }
+
+  private def validateInvalidComponentGroups
+    : Config => Either[ValidationError, Config] = { config =>
+    val libraryName = LibraryName(config.namespace, config.name)
+    config.componentGroups match {
+      case Right(_) =>
+        Right(config)
+      case Left(e) =>
+        Left(
+          ValidationError.InvalidComponentGroups(libraryName, e.getMessage())
+        )
+    }
+  }
+
+  private def validateDuplicateComponentGroups(
+    modulesMap: mutable.Map[ModuleReference, ComponentGroup]
+  ): Config => Either[ValidationError, Config] = { config =>
+    val libraryName = LibraryName(config.namespace, config.name)
+    config.componentGroups.toOption
+      .flatMap { componentGroups =>
+        componentGroups.newGroups
+          .map { componentGroup =>
+            val moduleReference =
+              ModuleReference(libraryName, componentGroup.module)
+            if (modulesMap.contains(moduleReference)) {
+              Left(
+                ValidationError
+                  .DuplicatedComponentGroup(libraryName, moduleReference)
+              )
+            } else {
+              modulesMap += moduleReference -> componentGroup
+              Right(config)
+            }
+          }
+          .find(_.isLeft)
+      }
+      .getOrElse(Right(config))
+  }
+
+  private def validateComponentGroupExtendsNothing(
+    modulesMap: mutable.Map[ModuleReference, ComponentGroup]
+  ): Config => Either[ValidationError, Config] = { config =>
+    val libraryName = LibraryName(config.namespace, config.name)
+    config.componentGroups.toOption
+      .flatMap { componentGroups =>
+        componentGroups.extendedGroups
+          .map { extendedComponentGroup =>
+            if (modulesMap.contains(extendedComponentGroup.module)) {
+              Right(config)
+            } else {
+              Left(
+                ValidationError.ComponentGroupExtendsNothing(
+                  libraryName,
+                  extendedComponentGroup.module
+                )
+              )
+            }
+          }
+          .find(_.isLeft)
+      }
+      .getOrElse(Right(config))
+  }
+
+  private def runValidation[A, E](xs: Iterable[Either[E, A]])(
+    fs: A => Either[E, A]*
+  ): Iterable[Either[E, A]] =
+    fs.foldLeft(xs) { (xs, f) =>
+      xs.map {
+        case Right(a) => f(a)
+        case Left(e)  => Left(e)
+      }
+    }
+}
+
+object ComponentGroupsValidator {
+
+  /** Base trait for validation results. */
+  sealed trait ValidationError
+  object ValidationError {
+
+    /** An error indicating that the package config defines duplicate component
+      * group.
+      *
+      * @param libraryName the library defining duplicate component group
+      * @param moduleReference the duplicated module reference
+      */
+    case class DuplicatedComponentGroup(
+      libraryName: LibraryName,
+      moduleReference: ModuleReference
+    ) extends ValidationError
+
+    /** An error indicating that the package config has invalid component groups
+      * format.
+      *
+      * @param libraryName the library name defining invalid component groups
+      * @param message the error message
+      */
+    case class InvalidComponentGroups(
+      libraryName: LibraryName,
+      message: String
+    ) extends ValidationError
+
+    /** An error indicating that the library defines a component group extension
+      * that extends non-existent component group.
+      *
+      * @param libraryName the library defining problematic component group
+      *                    extension
+      * @param moduleReference the module reference to non-existent module
+      */
+    case class ComponentGroupExtendsNothing(
+      libraryName: LibraryName,
+      moduleReference: ModuleReference
+    ) extends ValidationError
+  }
+}

engine/language-server/src/main/scala/org/enso/languageserver/libraries/LibraryApi.scala

@@ -1,10 +1,10 @@
 package org.enso.languageserver.libraries
 
-import io.circe.Json
+import io.circe.{Json, JsonObject}
 import io.circe.literal.JsonStringContext
 import org.enso.editions.{LibraryName, LibraryVersion}
 import org.enso.jsonrpc.{Error, HasParams, HasResult, Method, Unused}
-import org.enso.pkg.Contact
+import org.enso.pkg.{ComponentGroups, Contact}
 
 object LibraryApi {
   case object EditionsListAvailable extends Method("editions/listAvailable") {
@@ -98,6 +98,21 @@ object LibraryApi {
     }
   }
 
+  case object EditionsListDefinedComponents
+      extends Method("editions/listDefinedComponents") { self =>
+
+    case class Params(edition: EditionReference)
+
+    case class Result(availableComponents: Seq[LibraryComponentGroup])
+
+    implicit val hasParams = new HasParams[this.type] {
+      type Params = self.Params
+    }
+    implicit val hasResult = new HasResult[this.type] {
+      type Result = self.Result
+    }
+  }
+
   case object LibraryListLocal extends Method("library/listLocal") { self =>
 
     case class Result(localLibraries: Seq[LibraryEntry])
@@ -163,6 +178,30 @@ object LibraryApi {
     }
   }
 
+  case object LibraryGetPackage extends Method("library/getPackage") { self =>
+
+    case class Params(
+      namespace: String,
+      name: String,
+      version: LibraryEntry.LibraryVersion
+    )
+
+    // TODO[DB]: raw package was added to response as a temporary field and
+    //  should be removed when the integration with IDE is finished
+    case class Result(
+      license: Option[String],
+      componentGroups: Option[ComponentGroups],
+      raw: JsonObject
+    )
+
+    implicit val hasParams = new HasParams[this.type] {
+      type Params = self.Params
+    }
+    implicit val hasResult = new HasResult[this.type] {
+      type Result = self.Result
+    }
+  }
+
   case object LibraryPublish extends Method("library/publish") { self =>
 
     case class Params(
@@ -256,4 +295,12 @@ object LibraryApi {
         8010,
         s"Error occurred while discovering dependencies: $reason."
       )
+
+  case class InvalidSemverVersion(version: String)
+      extends Error(8011, s"[$version] is not a valid semver version.") {
+
+    override def payload: Option[Json] = Some(
+      json"""{ "version" : $version }"""
+    )
+  }
 }

engine/language-server/src/main/scala/org/enso/languageserver/libraries/LibraryComponentGroup.scala

@@ -0,0 +1,59 @@
+package org.enso.languageserver.libraries
+
+import io.circe._
+import io.circe.syntax._
+import org.enso.editions.LibraryName
+import org.enso.pkg.{Component, ModuleName}
+
+/** The component group definition of a library.
+  *
+  * @param library the library name
+  * @param module the module name
+  * @param color the component group color
+  * @param icon the component group icon
+  * @param exports the list of components provided by this component group
+  */
+case class LibraryComponentGroup(
+  library: LibraryName,
+  module: ModuleName,
+  color: Option[String],
+  icon: Option[String],
+  exports: Seq[Component]
+)
+object LibraryComponentGroup {
+
+  /** Fields for use when serializing the [[LibraryComponentGroup]]. */
+  private object Fields {
+    val Library = "library"
+    val Module  = "module"
+    val Color   = "color"
+    val Icon    = "icon"
+    val Exports = "exports"
+  }
+
+  /** [[Encoder]] instance for the [[LibraryComponentGroup]]. */
+  implicit val encoder: Encoder[LibraryComponentGroup] = { componentGroup =>
+    val color = componentGroup.color.map(Fields.Color -> _.asJson)
+    val icon  = componentGroup.icon.map(Fields.Icon -> _.asJson)
+    val exports = Option.unless(componentGroup.exports.isEmpty)(
+      Fields.Exports -> componentGroup.exports.asJson
+    )
+    Json.obj(
+      (Fields.Library -> componentGroup.library.asJson) +:
+      (Fields.Module  -> componentGroup.module.asJson) +:
+      (color.toSeq ++ icon.toSeq ++ exports.toSeq): _*
+    )
+  }
+
+  /** [[Decoder]] instance for the [[LibraryComponentGroup]]. */
+  implicit val decoder: Decoder[LibraryComponentGroup] = { json =>
+    for {
+      library <- json.get[LibraryName](Fields.Library)
+      module  <- json.get[ModuleName](Fields.Module)
+      color   <- json.get[Option[String]](Fields.Color)
+      icon    <- json.get[Option[String]](Fields.Icon)
+      exports <- json.getOrElse[List[Component]](Fields.Exports)(List())
+    } yield LibraryComponentGroup(library, module, color, icon, exports)
+  }
+
+}

engine/language-server/src/main/scala/org/enso/languageserver/libraries/LocalLibraryManager.scala

@@ -2,7 +2,6 @@ package org.enso.languageserver.libraries
 
 import akka.actor.Props
 import com.typesafe.scalalogging.LazyLogging
-import org.enso.distribution.FileSystem.PathSyntax
 import org.enso.distribution.{DistributionManager, FileSystem}
 import org.enso.editions.{Editions, LibraryName}
 import org.enso.languageserver.libraries.LocalLibraryManagerProtocol._
@@ -12,11 +11,12 @@ import org.enso.librarymanager.local.{
 }
 import org.enso.librarymanager.published.repository.LibraryManifest
 import org.enso.pkg.validation.NameValidation
-import org.enso.pkg.{Contact, PackageManager}
+import org.enso.pkg.{Config, Contact, Package, PackageManager}
 import org.enso.yaml.YamlHelper
 
 import java.io.File
 import java.nio.file.{Files, Path}
+
 import scala.util.{Success, Try}
 
 /** An Actor that manages local libraries. */
@@ -41,6 +41,8 @@ class LocalLibraryManager(
             tagLine     = request.tagLine
           )
         )
+      case GetPackage(libraryName) =>
+        startRequest(getPackage(libraryName))
       case ListLocalLibraries =>
         startRequest(listLocalLibraries())
       case Create(libraryName, authors, maintainers, license) =>
@@ -190,6 +192,28 @@ class LocalLibraryManager(
     _ = saveManifest(manifestPath, updatedManifest)
   } yield EmptyResponse()
 
+  /** Loads the package config for a local library. */
+  private def getPackage(libraryName: LibraryName): Try[GetPackageResponse] =
+    for {
+      libraryRootPath <- localLibraryProvider
+        .findLibrary(libraryName)
+        .toRight(LocalLibraryNotFoundError(libraryName))
+        .toTry
+      configPath = libraryRootPath / Package.configFileName
+      config <- loadPackageConfig(configPath)
+    } yield {
+      if (config.componentGroups.isLeft) {
+        logger.error(
+          s"Failed to parse library [$libraryName] component groups."
+        )
+      }
+      GetPackageResponse(
+        license         = config.license,
+        componentGroups = config.componentGroups.toOption,
+        rawPackage      = config.originalJson
+      )
+    }
+
   /** Tries to load the manifest.
     *
     * If the file does not exist, an empty manifest is returned. Any other
@@ -206,6 +230,10 @@ class LocalLibraryManager(
     manifest: LibraryManifest
   ): Unit = FileSystem.writeTextFile(manifestPath, YamlHelper.toYaml(manifest))
 
+  /** Load the package config. */
+  private def loadPackageConfig(packagePath: Path): Try[Config] =
+    YamlHelper.load[Config](packagePath)
+
   /** Finds the edition associated with the current project, if specified in its
     * config.
     */

engine/language-server/src/main/scala/org/enso/languageserver/libraries/LocalLibraryManagerFailureMapper.scala

@@ -0,0 +1,21 @@
+package org.enso.languageserver.libraries
+
+import org.enso.jsonrpc
+
+/** The object mapping the [[LocalLibraryManagerProtocol]] failures into the
+  * corresponding JSONRPC error messages.
+  */
+object LocalLibraryManagerFailureMapper {
+
+  /** Convert the [[LocalLibraryManagerProtocol.Failure]] into the corresponding
+    * JSONRPC error message.
+    *
+    * @param error the failure object
+    * @return the JSONRPC error message
+    */
+  def mapFailure(error: LocalLibraryManagerProtocol.Failure): jsonrpc.Error =
+    error match {
+      case LocalLibraryManagerProtocol.InvalidSemverVersionError(version) =>
+        LibraryApi.InvalidSemverVersion(version)
+    }
+}

engine/language-server/src/main/scala/org/enso/languageserver/libraries/LocalLibraryManagerProtocol.scala

@@ -1,9 +1,9 @@
 package org.enso.languageserver.libraries
 
+import io.circe.JsonObject
 import org.enso.editions.LibraryName
-import org.enso.pkg.Contact
+import org.enso.librarymanager.resolved.LibraryRoot
-
+import org.enso.pkg.{ComponentGroups, Contact}
-import java.nio.file.Path
 
 object LocalLibraryManagerProtocol {
 
@@ -26,6 +26,16 @@ object LocalLibraryManagerProtocol {
     tagLine: Option[String]
   ) extends Request
 
+  /** A request to get the library package. */
+  case class GetPackage(libraryName: LibraryName) extends Request
+
+  /** A response to the [[GetPackage]] request. */
+  case class GetPackageResponse(
+    license: String,
+    componentGroups: Option[ComponentGroups],
+    rawPackage: JsonObject
+  )
+
   /** A request to list local libraries. */
   case object ListLocalLibraries extends Request
 
@@ -44,7 +54,7 @@ object LocalLibraryManagerProtocol {
   case class FindLibrary(libraryName: LibraryName) extends Request
 
   /** A response to [[FindLibrary]]. */
-  case class FindLibraryResponse(libraryRoot: Option[Path])
+  case class FindLibraryResponse(libraryRoot: Option[LibraryRoot])
 
   /** Indicates that a library with the given name was not found among local
     * libraries.
@@ -59,4 +69,14 @@ object LocalLibraryManagerProtocol {
     * Sent as a reply to [[Create]] and [[SetMetadata]].
     */
   case class EmptyResponse()
+
+  /** A base trait for failures. */
+  sealed trait Failure
+
+  /** An error indicating that the provided version is not a valid semver
+    * version.
+    *
+    * @version invalid version string
+    */
+  case class InvalidSemverVersionError(version: String) extends Failure
 }

engine/language-server/src/main/scala/org/enso/languageserver/libraries/handler/EditionsListDefinedComponentsHandler.scala

@@ -0,0 +1,165 @@
+package org.enso.languageserver.libraries.handler
+
+import akka.actor.{Actor, ActorRef, Props, Status}
+import akka.pattern.pipe
+import com.typesafe.scalalogging.LazyLogging
+import org.enso.editions.{LibraryName, LibraryVersion}
+import org.enso.jsonrpc.{Id, Request, ResponseError, ResponseResult}
+import org.enso.languageserver.filemanager.FileManagerApi.FileSystemError
+import org.enso.languageserver.libraries.LibraryApi._
+import org.enso.languageserver.libraries.{
+  BlockingOperation,
+  ComponentGroupsResolver,
+  ComponentGroupsValidator,
+  EditionReferenceResolver,
+  LibraryComponentGroup
+}
+import org.enso.languageserver.util.UnhandledLogging
+import org.enso.librarymanager.local.LocalLibraryProvider
+import org.enso.librarymanager.published.PublishedLibraryCache
+import org.enso.pkg.Config
+
+/** A request handler for the `editions/listDefinedComponents` endpoint.
+  *
+  * @param editionReferenceResolver an [[EditionReferenceResolver]] instance
+  * @param localLibraryProvider     a provider of local libraries
+  * @param publishedLibraryCache    a cache of published libraries
+  * @param componentGroupsResolver  a module resolving the dependencies between
+  *                                 component groups
+  */
+class EditionsListDefinedComponentsHandler(
+  editionReferenceResolver: EditionReferenceResolver,
+  localLibraryProvider: LocalLibraryProvider,
+  publishedLibraryCache: PublishedLibraryCache,
+  componentGroupsResolver: ComponentGroupsResolver,
+  componentGroupsValidator: ComponentGroupsValidator
+) extends Actor
+    with LazyLogging
+    with UnhandledLogging {
+
+  import context.dispatcher
+
+  override def receive: Receive = requestStage
+
+  private def requestStage: Receive = {
+    case Request(
+          EditionsListDefinedComponents,
+          id,
+          EditionsListDefinedComponents.Params(reference)
+        ) =>
+      BlockingOperation
+        .run {
+          val edition = editionReferenceResolver.resolveEdition(reference).get
+          val definedLibraries = edition.getAllDefinedLibraries.view
+            .map { case (name, version) =>
+              readLocalPackage(name, version)
+            }
+            .collect { case Some(config) =>
+              config
+            }
+          val validationResults = componentGroupsValidator
+            .validate(definedLibraries)
+
+          validationResults
+            .collect { case Left(error) => error }
+            .foreach(logValidationError)
+
+          val validatedLibraries = validationResults
+            .collect { case Right(config) => config }
+          componentGroupsResolver.run(validatedLibraries)
+        }
+        .map(EditionsListDefinedComponentsHandler.Result) pipeTo self
+
+      context.become(responseStage(id, sender()))
+  }
+
+  private def logValidationError(
+    error: ComponentGroupsValidator.ValidationError
+  ): Unit =
+    error match {
+      case ComponentGroupsValidator.ValidationError
+            .InvalidComponentGroups(libraryName, message) =>
+        logger.warn(
+          s"Validation error. Failed to read library [$libraryName] " +
+          s"component groups (reason: $message)."
+        )
+      case ComponentGroupsValidator.ValidationError
+            .DuplicatedComponentGroup(libraryName, moduleReference) =>
+        logger.warn(
+          s"Validation error. Library [$libraryName] defines duplicate " +
+          s"component group [$moduleReference]."
+        )
+      case ComponentGroupsValidator.ValidationError
+            .ComponentGroupExtendsNothing(libraryName, moduleReference) =>
+        logger.warn(
+          s"Validation error. Library [$libraryName] component group " +
+          s"[$moduleReference] extends nothing."
+        )
+    }
+
+  private def responseStage(id: Id, replyTo: ActorRef): Receive = {
+    case EditionsListDefinedComponentsHandler.Result(components) =>
+      replyTo ! ResponseResult(
+        EditionsListDefinedComponents,
+        id,
+        EditionsListDefinedComponents.Result(components)
+      )
+      context.stop(self)
+
+    case Status.Failure(exception) =>
+      replyTo ! ResponseError(
+        Some(id),
+        FileSystemError(exception.getMessage)
+      )
+      context.stop(self)
+  }
+
+  private def readLocalPackage(
+    libraryName: LibraryName,
+    libraryVersion: LibraryVersion
+  ): Option[Config] = {
+    val libraryPathOpt = libraryVersion match {
+      case LibraryVersion.Local =>
+        localLibraryProvider.findLibrary(libraryName)
+      case LibraryVersion.Published(version, _) =>
+        publishedLibraryCache.findCachedLibrary(libraryName, version)
+    }
+    libraryPathOpt.flatMap { libraryPath =>
+      libraryPath.getReadAccess.readPackage().toOption
+    }
+  }
+}
+
+object EditionsListDefinedComponentsHandler {
+
+  private case class Result(components: Seq[LibraryComponentGroup])
+
+  /** Creates a configuration object to create
+    * [[EditionsListDefinedComponentsHandler]].
+    *
+    * @param editionReferenceResolver an [[EditionReferenceResolver]] instance
+    * @param localLibraryProvider     a provider of local libraries
+    * @param publishedLibraryCache    a cache of published libraries
+    * @param componentGroupsResolver  a module resolving the dependencies
+    *                                 between component groups
+    * @param componentGroupsValidator a module that checks component groups for
+    *                                 consistency
+    */
+  def props(
+    editionReferenceResolver: EditionReferenceResolver,
+    localLibraryProvider: LocalLibraryProvider,
+    publishedLibraryCache: PublishedLibraryCache,
+    componentGroupsResolver: ComponentGroupsResolver =
+      new ComponentGroupsResolver,
+    componentGroupsValidator: ComponentGroupsValidator =
+      new ComponentGroupsValidator
+  ): Props = Props(
+    new EditionsListDefinedComponentsHandler(
+      editionReferenceResolver,
+      localLibraryProvider,
+      publishedLibraryCache,
+      componentGroupsResolver,
+      componentGroupsValidator
+    )
+  )
+}

engine/language-server/src/main/scala/org/enso/languageserver/libraries/handler/LibraryGetMetadataHandler.scala

@@ -1,6 +1,8 @@
 package org.enso.languageserver.libraries.handler
 
 import akka.actor.{Actor, ActorRef, Cancellable, Props, Status}
+
+import scala.util.{Success, Try}
 import akka.pattern.pipe
 import com.typesafe.scalalogging.LazyLogging
 import nl.gn0s1s.bump.SemVer
@@ -11,23 +13,27 @@ import org.enso.languageserver.filemanager.FileManagerApi.FileSystemError
 import org.enso.languageserver.libraries.LibraryApi._
 import org.enso.languageserver.libraries.{
   LibraryEntry,
+  LocalLibraryManagerFailureMapper,
   LocalLibraryManagerProtocol
 }
 import org.enso.languageserver.requesthandler.RequestTimeout
 import org.enso.languageserver.util.UnhandledLogging
+import org.enso.librarymanager.published.PublishedLibraryCache
 import org.enso.librarymanager.published.repository.RepositoryHelper.RepositoryMethods
 
 import scala.concurrent.Future
 import scala.concurrent.duration.FiniteDuration
 
-/** A request handler for the `library/create` endpoint.
+/** A request handler for the `library/getMetadata` endpoint.
   *
   * @param timeout request timeout
   * @param localLibraryManager reference to the local library manager actor
+  * @param publishedLibraryCache the cache of published libraries
   */
 class LibraryGetMetadataHandler(
   timeout: FiniteDuration,
-  localLibraryManager: ActorRef
+  localLibraryManager: ActorRef,
+  publishedLibraryCache: PublishedLibraryCache
 ) extends Actor
     with LazyLogging
     with UnhandledLogging {
@@ -48,11 +54,18 @@ class LibraryGetMetadataHandler(
             libraryName
           )
         case LibraryEntry.PublishedLibraryVersion(version, repositoryUrl) =>
-          fetchPublishedMetadata(
+          SemVer(version) match {
+            case Some(semVerVersion) =>
+              getOrFetchPublishedMetadata(
                 libraryName,
-            version,
+                semVerVersion,
                 repositoryUrl
               ) pipeTo self
+            case None =>
+              self ! LocalLibraryManagerProtocol.InvalidSemverVersionError(
+                version
+              )
+          }
       }
 
       val cancellable =
@@ -82,33 +95,59 @@ class LibraryGetMetadataHandler(
       cancellable.cancel()
       context.stop(self)
 
+    case failure: LocalLibraryManagerProtocol.Failure =>
+      replyTo ! LocalLibraryManagerFailureMapper.mapFailure(failure)
+      cancellable.cancel()
+      context.stop(self)
+
     case Status.Failure(exception) =>
       replyTo ! ResponseError(Some(id), FileSystemError(exception.getMessage))
       cancellable.cancel()
       context.stop(self)
   }
 
-  // TODO [RW] Once the manifests of downloaded libraries are being cached,
+  private def getOrFetchPublishedMetadata(
-  //  it may be worth to try resolving the local cache first to avoid
+    libraryName: LibraryName,
-  //  downloading the manifest again. This should be done before the issues
+    version: SemVer,
-  //  #1772 or #1775 are completed.
+    repositoryUrl: String
+  ): Future[LocalLibraryManagerProtocol.GetMetadataResponse] =
+    getCachedMetadata(libraryName, version) match {
+      case Some(response) =>
+        response.fold(Future.failed, Future.successful)
+      case None =>
+        fetchPublishedMetadata(libraryName, version, repositoryUrl)
+    }
+
+  private def getCachedMetadata(
+    libraryName: LibraryName,
+    version: SemVer
+  ): Option[Try[LocalLibraryManagerProtocol.GetMetadataResponse]] =
+    publishedLibraryCache
+      .findCachedLibrary(libraryName, version)
+      .map { libraryPath =>
+        libraryPath.getReadAccess
+          .readManifest()
+          .map { manifestAttempt =>
+            manifestAttempt.map(manifest =>
+              LocalLibraryManagerProtocol.GetMetadataResponse(
+                manifest.description,
+                manifest.tagLine
+              )
+            )
+          }
+          .getOrElse(
+            Success(LocalLibraryManagerProtocol.GetMetadataResponse(None, None))
+          )
+      }
+
   private def fetchPublishedMetadata(
     libraryName: LibraryName,
-    version: String,
+    version: SemVer,
     repositoryUrl: String
   ): Future[LocalLibraryManagerProtocol.GetMetadataResponse] = for {
-    semver <- Future.fromTry(
-      SemVer(version)
-        .toRight(
-          new IllegalStateException(
-            s"Library version [$version] is not a valid semver string."
-          )
-        )
-        .toTry
-    )
     manifest <- Repository(repositoryUrl)
-      .accessLibrary(libraryName, semver)
+      .accessLibrary(libraryName, version)
-      .downloadManifest()
+      .fetchManifest()
       .toFuture
   } yield LocalLibraryManagerProtocol.GetMetadataResponse(
     description = manifest.description,
@@ -122,7 +161,18 @@ object LibraryGetMetadataHandler {
     *
     * @param timeout request timeout
     * @param localLibraryManager reference to the local library manager actor
+    * @param publishedLibraryCache the cache of published libraries
     */
-  def props(timeout: FiniteDuration, localLibraryManager: ActorRef): Props =
+  def props(
-    Props(new LibraryGetMetadataHandler(timeout, localLibraryManager))
+    timeout: FiniteDuration,
+    localLibraryManager: ActorRef,
+    publishedLibraryCache: PublishedLibraryCache
+  ): Props =
+    Props(
+      new LibraryGetMetadataHandler(
+        timeout,
+        localLibraryManager,
+        publishedLibraryCache
+      )
+    )
 }

engine/language-server/src/main/scala/org/enso/languageserver/libraries/handler/LibraryGetPackageHandler.scala

@@ -0,0 +1,179 @@
+package org.enso.languageserver.libraries.handler
+
+import akka.actor.{Actor, ActorRef, Cancellable, Props, Status}
+import akka.pattern.pipe
+import com.typesafe.scalalogging.LazyLogging
+import nl.gn0s1s.bump.SemVer
+import org.enso.editions.Editions.Repository
+import org.enso.editions.LibraryName
+import org.enso.jsonrpc._
+import org.enso.languageserver.filemanager.FileManagerApi.FileSystemError
+import org.enso.languageserver.libraries.LibraryApi._
+import org.enso.languageserver.libraries.{
+  LibraryEntry,
+  LocalLibraryManagerFailureMapper,
+  LocalLibraryManagerProtocol
+}
+import org.enso.languageserver.requesthandler.RequestTimeout
+import org.enso.languageserver.util.UnhandledLogging
+import org.enso.librarymanager.published.PublishedLibraryCache
+import org.enso.librarymanager.published.repository.RepositoryHelper.RepositoryMethods
+
+import scala.concurrent.Future
+import scala.concurrent.duration.FiniteDuration
+import scala.util.Try
+
+/** A request handler for the `library/getPackage` endpoint.
+  *
+  * @param timeout request timeout
+  * @param localLibraryManager reference to the local library manager actor
+  * @param publishedLibraryCache the cache of published libraries
+  */
+class LibraryGetPackageHandler(
+  timeout: FiniteDuration,
+  localLibraryManager: ActorRef,
+  publishedLibraryCache: PublishedLibraryCache
+) extends Actor
+    with LazyLogging
+    with UnhandledLogging {
+  import context.dispatcher
+
+  override def receive: Receive = requestStage
+
+  private def requestStage: Receive = {
+    case Request(
+          LibraryGetPackage,
+          id,
+          LibraryGetPackage.Params(namespace, name, version)
+        ) =>
+      val libraryName = LibraryName(namespace, name)
+      version match {
+        case LibraryEntry.LocalLibraryVersion =>
+          localLibraryManager ! LocalLibraryManagerProtocol.GetPackage(
+            libraryName
+          )
+        case LibraryEntry.PublishedLibraryVersion(version, repositoryUrl) =>
+          SemVer(version) match {
+            case Some(semVerVersion) =>
+              getOrFetchPublishedPackage(
+                libraryName,
+                semVerVersion,
+                repositoryUrl
+              ) pipeTo self
+            case None =>
+              self ! LocalLibraryManagerProtocol.InvalidSemverVersionError(
+                version
+              )
+          }
+      }
+
+      val cancellable =
+        context.system.scheduler.scheduleOnce(timeout, self, RequestTimeout)
+      context.become(responseStage(id, sender(), cancellable))
+  }
+
+  private def responseStage(
+    id: Id,
+    replyTo: ActorRef,
+    cancellable: Cancellable
+  ): Receive = {
+    case RequestTimeout =>
+      logger.error("Request [{}] timed out.", id)
+      replyTo ! ResponseError(Some(id), Errors.RequestTimeout)
+      context.stop(self)
+
+    case LocalLibraryManagerProtocol.GetPackageResponse(
+          license,
+          componentGroups,
+          rawPackage
+        ) =>
+      replyTo ! ResponseResult(
+        LibraryGetPackage,
+        id,
+        LibraryGetPackage.Result(
+          Option.unless(license.isEmpty)(license),
+          componentGroups,
+          rawPackage
+        )
+      )
+      cancellable.cancel()
+      context.stop(self)
+
+    case failure: LocalLibraryManagerProtocol.Failure =>
+      replyTo ! LocalLibraryManagerFailureMapper.mapFailure(failure)
+      cancellable.cancel()
+      context.stop(self)
+
+    case Status.Failure(exception) =>
+      replyTo ! ResponseError(Some(id), FileSystemError(exception.getMessage))
+      cancellable.cancel()
+      context.stop(self)
+  }
+
+  private def getOrFetchPublishedPackage(
+    libraryName: LibraryName,
+    version: SemVer,
+    repositoryUrl: String
+  ): Future[LocalLibraryManagerProtocol.GetPackageResponse] =
+    getCachedPackage(libraryName, version) match {
+      case Some(response) =>
+        response.fold(Future.failed, Future.successful)
+      case None =>
+        fetchPublishedPackage(libraryName, version, repositoryUrl)
+    }
+
+  private def getCachedPackage(
+    libraryName: LibraryName,
+    version: SemVer
+  ): Option[Try[LocalLibraryManagerProtocol.GetPackageResponse]] =
+    publishedLibraryCache
+      .findCachedLibrary(libraryName, version)
+      .map { libraryPath =>
+        libraryPath.getReadAccess
+          .readPackage()
+          .map(config =>
+            LocalLibraryManagerProtocol.GetPackageResponse(
+              config.license,
+              config.componentGroups.toOption,
+              config.originalJson
+            )
+          )
+      }
+
+  private def fetchPublishedPackage(
+    libraryName: LibraryName,
+    version: SemVer,
+    repositoryUrl: String
+  ): Future[LocalLibraryManagerProtocol.GetPackageResponse] = for {
+    config <- Repository(repositoryUrl)
+      .accessLibrary(libraryName, version)
+      .fetchPackageConfig()
+      .toFuture
+  } yield LocalLibraryManagerProtocol.GetPackageResponse(
+    license         = config.license,
+    componentGroups = config.componentGroups.toOption,
+    rawPackage      = config.originalJson
+  )
+}
+
+object LibraryGetPackageHandler {
+
+  /** Creates a configuration object to create [[LibraryGetPackageHandler]].
+    *
+    * @param timeout request timeout
+    * @param localLibraryManager reference to the local library manager actor
+    * @param publishedLibraryCache the cache of published libraries
+    */
+  def props(
+    timeout: FiniteDuration,
+    localLibraryManager: ActorRef,
+    publishedLibraryCache: PublishedLibraryCache
+  ): Props =
+    Props(
+      new LibraryGetPackageHandler(
+        timeout,
+        localLibraryManager,
+        publishedLibraryCache
+      )
+    )
+}

engine/language-server/src/main/scala/org/enso/languageserver/libraries/handler/LibraryPublishHandler.scala

@@ -107,7 +107,7 @@ class LibraryPublishHandler(
           new CompilerBasedDependencyExtractor(logLevel)
         LibraryUploader(dependencyExtractor)
           .uploadLibrary(
-            libraryRoot,
+            libraryRoot.location,
             uploadUrl,
             token,
             progressReporter

engine/language-server/src/main/scala/org/enso/languageserver/protocol/json/JsonConnectionController.scala

@@ -73,6 +73,7 @@ import org.enso.polyglot.runtime.Runtime.Api
 import org.enso.polyglot.runtime.Runtime.Api.ProgressNotification
 
 import java.util.UUID
+
 import scala.concurrent.duration._
 
 /** An actor handling communications between a single client and the language
@@ -506,18 +507,33 @@ class JsonConnectionController(
         .props(requestTimeout, projectSettingsManager),
       EditionsSetLocalLibrariesPreference -> EditionsSetProjectLocalLibrariesPreferenceHandler
         .props(requestTimeout, projectSettingsManager),
+      EditionsListDefinedComponents -> EditionsListDefinedComponentsHandler
+        .props(
+          libraryConfig.editionReferenceResolver,
+          libraryConfig.localLibraryProvider,
+          libraryConfig.publishedLibraryCache
+        ),
       LibraryCreate -> LibraryCreateHandler
         .props(requestTimeout, libraryConfig.localLibraryManager),
       LibraryListLocal -> LibraryListLocalHandler
         .props(requestTimeout, libraryConfig.localLibraryManager),
       LibraryGetMetadata -> LibraryGetMetadataHandler
-        .props(requestTimeout, libraryConfig.localLibraryManager),
+        .props(
+          requestTimeout,
+          libraryConfig.localLibraryManager,
+          libraryConfig.publishedLibraryCache
+        ),
       LibraryPreinstall -> LibraryPreinstallHandler
         .props(libraryConfig.editionReferenceResolver, libraryConfig),
       LibraryPublish -> LibraryPublishHandler
         .props(requestTimeout, libraryConfig.localLibraryManager),
       LibrarySetMetadata -> LibrarySetMetadataHandler
-        .props(requestTimeout, libraryConfig.localLibraryManager)
+        .props(requestTimeout, libraryConfig.localLibraryManager),
+      LibraryGetPackage -> LibraryGetPackageHandler.props(
+        requestTimeout,
+        libraryConfig.localLibraryManager,
+        libraryConfig.publishedLibraryCache
+      )
     )
   }
 

engine/language-server/src/main/scala/org/enso/languageserver/protocol/json/JsonRpc.scala

@@ -76,10 +76,12 @@ object JsonRpc {
     .registerRequest(EditionsSetParentEdition)
     .registerRequest(EditionsSetLocalLibrariesPreference)
     .registerRequest(EditionsListDefinedLibraries)
+    .registerRequest(EditionsListDefinedComponents)
     .registerRequest(LibraryListLocal)
     .registerRequest(LibraryCreate)
     .registerRequest(LibraryGetMetadata)
     .registerRequest(LibrarySetMetadata)
+    .registerRequest(LibraryGetPackage)
     .registerRequest(LibraryPublish)
     .registerRequest(LibraryPreinstall)
     .registerNotification(TaskStarted)

engine/language-server/src/test/scala/org/enso/languageserver/libraries/ComponentGroupsResolverSpec.scala

@@ -0,0 +1,316 @@
+package org.enso.languageserver.libraries
+
+import org.enso.editions.LibraryName
+import org.enso.pkg.{
+  Component,
+  ComponentGroup,
+  ComponentGroups,
+  Config,
+  ExtendedComponentGroup,
+  ModuleName,
+  ModuleReference
+}
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+
+class ComponentGroupsResolverSpec extends AnyWordSpec with Matchers {
+
+  import ComponentGroupsResolverSpec._
+
+  "ComponentGroupsResolver" should {
+
+    "return a list of defined component groups preserving the order" in {
+      val resolver = new ComponentGroupsResolver
+      val testPackages = Vector(
+        config("Foo", "Bar"),
+        config(
+          "Foo",
+          "Baz",
+          ComponentGroups(List(newComponentGroup("Mod1", "one", "two")), List())
+        ),
+        config(
+          "Foo",
+          "Quux",
+          ComponentGroups(List(newComponentGroup("Mod2", "one")), List())
+        )
+      )
+
+      resolver.run(testPackages) shouldEqual Vector(
+        libraryComponentGroup("Foo", "Baz", "Mod1", "one", "two"),
+        libraryComponentGroup("Foo", "Quux", "Mod2", "one")
+      )
+    }
+
+    "drop duplicated library definitions" in {
+      val resolver = new ComponentGroupsResolver
+      val testPackages = Vector(
+        config("Foo", "Bar"),
+        config(
+          "Foo",
+          "Baz",
+          ComponentGroups(
+            List(newComponentGroup("Mod1", "one", "two")),
+            List()
+          )
+        ),
+        config(
+          "Foo",
+          "Baz",
+          ComponentGroups(List(newComponentGroup("Mod1", "one")), List())
+        ),
+        config(
+          "Foo",
+          "Quux",
+          ComponentGroups(List(newComponentGroup("Mod2", "one")), List())
+        )
+      )
+
+      resolver.run(testPackages) shouldEqual Vector(
+        libraryComponentGroup("Foo", "Baz", "Mod1", "one", "two"),
+        libraryComponentGroup("Foo", "Quux", "Mod2", "one")
+      )
+    }
+
+    "drop duplicated component group definitions" in {
+      val resolver = new ComponentGroupsResolver
+      val testPackages = Vector(
+        config("Foo", "Bar"),
+        config(
+          "Foo",
+          "Baz",
+          ComponentGroups(
+            List(
+              newComponentGroup("Mod1", "one", "two"),
+              newComponentGroup("Mod1", "three")
+            ),
+            List()
+          )
+        ),
+        config(
+          "Foo",
+          "Quux",
+          ComponentGroups(List(newComponentGroup("Mod2", "one")), List())
+        )
+      )
+
+      resolver.run(testPackages) shouldEqual Vector(
+        libraryComponentGroup("Foo", "Baz", "Mod1", "one", "two"),
+        libraryComponentGroup("Foo", "Quux", "Mod2", "one")
+      )
+    }
+
+    "apply extended component groups" in {
+      val resolver = new ComponentGroupsResolver
+      val testPackages = Vector(
+        config(
+          "user",
+          "Unnamed",
+          ComponentGroups(
+            List(newComponentGroup("Main", "main")),
+            List(
+              extendedComponentGroup("Standard", "Base", "Data.Vector", "quux")
+            )
+          )
+        ),
+        config(
+          "Standard",
+          "Base",
+          ComponentGroups(
+            List(newComponentGroup("Data.Vector", "one", "two")),
+            List()
+          )
+        ),
+        config(
+          "user",
+          "Vector_Utils",
+          ComponentGroups(
+            List(),
+            List(
+              extendedComponentGroup("Standard", "Base", "Data.Vector", "three")
+            )
+          )
+        )
+      )
+
+      resolver.run(testPackages) shouldEqual Vector(
+        libraryComponentGroup("user", "Unnamed", "Main", "main"),
+        libraryComponentGroup(
+          "Standard",
+          "Base",
+          "Data.Vector",
+          "one",
+          "two",
+          "quux",
+          "three"
+        )
+      )
+    }
+
+    "apply mutually extended component groups" in {
+      val resolver = new ComponentGroupsResolver
+      val testPackages = Vector(
+        config(
+          "Standard",
+          "Table",
+          ComponentGroups(
+            List(newComponentGroup("Data.Table", "first")),
+            List(
+              extendedComponentGroup("Standard", "Base", "Data.Vector", "quux")
+            )
+          )
+        ),
+        config(
+          "Standard",
+          "Base",
+          ComponentGroups(
+            List(newComponentGroup("Data.Vector", "one", "two")),
+            List(
+              extendedComponentGroup(
+                "Standard",
+                "Table",
+                "Data.Table",
+                "second"
+              )
+            )
+          )
+        ),
+        config(
+          "user",
+          "Vector_Utils",
+          ComponentGroups(
+            List(),
+            List(
+              extendedComponentGroup("Standard", "Base", "Data.Vector", "three")
+            )
+          )
+        )
+      )
+
+      resolver.run(testPackages) shouldEqual Vector(
+        libraryComponentGroup(
+          "Standard",
+          "Table",
+          "Data.Table",
+          "first",
+          "second"
+        ),
+        libraryComponentGroup(
+          "Standard",
+          "Base",
+          "Data.Vector",
+          "one",
+          "two",
+          "quux",
+          "three"
+        )
+      )
+    }
+
+    "skip component groups extending nothing" in {
+      val resolver = new ComponentGroupsResolver
+      val testPackages = Vector(
+        config(
+          "user",
+          "Unnamed",
+          ComponentGroups(List(newComponentGroup("Main", "main")), List())
+        ),
+        config(
+          "Standard",
+          "Base",
+          ComponentGroups(
+            List(newComponentGroup("Data.Vector", "one", "two")),
+            List()
+          )
+        ),
+        config(
+          "user",
+          "Vector_Utils",
+          ComponentGroups(
+            List(),
+            List(
+              extendedComponentGroup("Custom", "Lib", "Vector", "three")
+            )
+          )
+        ),
+        config(
+          "user",
+          "Other_Utils",
+          ComponentGroups(
+            List(),
+            List(
+              extendedComponentGroup("Standard", "Base", "Data.List", "four")
+            )
+          )
+        )
+      )
+
+      resolver.run(testPackages) shouldEqual Vector(
+        libraryComponentGroup("user", "Unnamed", "Main", "main"),
+        libraryComponentGroup("Standard", "Base", "Data.Vector", "one", "two")
+      )
+    }
+  }
+}
+
+object ComponentGroupsResolverSpec {
+
+  /** Create a new config. */
+  def config(
+    namespace: String,
+    name: String,
+    componentGroups: ComponentGroups = ComponentGroups.empty
+  ): Config =
+    Config(
+      name                 = name,
+      namespace            = namespace,
+      version              = "0.0.1",
+      license              = "",
+      authors              = Nil,
+      maintainers          = Nil,
+      edition              = None,
+      preferLocalLibraries = true,
+      componentGroups      = Right(componentGroups)
+    )
+
+  /** Create a new component group. */
+  def newComponentGroup(
+    module: String,
+    exports: String*
+  ): ComponentGroup =
+    ComponentGroup(
+      module  = ModuleName(module),
+      color   = None,
+      icon    = None,
+      exports = exports.map(Component(_, None))
+    )
+
+  /** Create a new extended component group. */
+  def extendedComponentGroup(
+    extendedLibraryNamespace: String,
+    extendedLibraryName: String,
+    extendedModule: String,
+    exports: String*
+  ): ExtendedComponentGroup =
+    ExtendedComponentGroup(
+      module = ModuleReference(
+        LibraryName(extendedLibraryNamespace, extendedLibraryName),
+        ModuleName(extendedModule)
+      ),
+      exports = exports.map(Component(_, None))
+    )
+
+  /** Create a new library component group. */
+  def libraryComponentGroup(
+    namespace: String,
+    name: String,
+    module: String,
+    exports: String*
+  ): LibraryComponentGroup =
+    LibraryComponentGroup(
+      library = LibraryName(namespace, name),
+      module  = ModuleName(module),
+      color   = None,
+      icon    = None,
+      exports = exports.map(Component(_, None))
+    )
+}

engine/language-server/src/test/scala/org/enso/languageserver/libraries/ComponentGroupsValidatorSpec.scala

@@ -0,0 +1,145 @@
+package org.enso.languageserver.libraries
+
+import io.circe.DecodingFailure
+import org.enso.editions.LibraryName
+import org.enso.pkg.{ComponentGroups, Config, ModuleName, ModuleReference}
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+
+class ComponentGroupsValidatorSpec extends AnyWordSpec with Matchers {
+
+  import ComponentGroupsValidator._
+  import ComponentGroupsValidatorSpec._
+  import ComponentGroupsResolverSpec._
+
+  "ComponentGroupsValidator" should {
+
+    "validate invalid component groups" in {
+      val validator = new ComponentGroupsValidator
+      val testPackages = Vector(
+        config("Foo", "Bar"),
+        config(
+          "Foo",
+          "Baz",
+          ComponentGroups(List(newComponentGroup("Mod1", "one", "two")), List())
+        ),
+        configError(
+          "Foo",
+          "Quux",
+          "Error message"
+        )
+      )
+
+      validator.validate(testPackages) shouldEqual testPackages.map { config =>
+        config.componentGroups match {
+          case Right(_) =>
+            Right(config)
+          case Left(error) =>
+            Left(
+              ValidationError.InvalidComponentGroups(
+                libraryName(config),
+                error.getMessage()
+              )
+            )
+        }
+      }
+    }
+
+    "validate duplicate component groups" in {
+      val validator = new ComponentGroupsValidator
+      val testPackages = Vector(
+        config(
+          "Foo",
+          "Bar",
+          ComponentGroups(List(newComponentGroup("Mod1", "a", "b")), List())
+        ),
+        config(
+          "Foo",
+          "Bar",
+          ComponentGroups(List(newComponentGroup("Mod1", "one", "two")), List())
+        ),
+        config(
+          "Baz",
+          "Quux",
+          ComponentGroups(List(newComponentGroup("Mod1", "one", "two")), List())
+        )
+      )
+
+      validator
+        .validate(testPackages) shouldEqual Vector(
+        Right(testPackages(0)),
+        Left(
+          ValidationError.DuplicatedComponentGroup(
+            libraryName(testPackages(1)),
+            ModuleReference(LibraryName("Foo", "Bar"), ModuleName("Mod1"))
+          )
+        ),
+        Right(testPackages(2))
+      )
+    }
+
+    "validate non-existent extensions" in {
+      val validator = new ComponentGroupsValidator
+      val testPackages = Vector(
+        config(
+          "Foo",
+          "Bar",
+          ComponentGroups(List(newComponentGroup("Mod1", "a", "b")), List())
+        ),
+        config(
+          "Foo",
+          "Baz",
+          ComponentGroups(
+            List(),
+            List(extendedComponentGroup("Foo", "Bar", "Mod1", "c", "d"))
+          )
+        ),
+        config(
+          "Baz",
+          "Quux",
+          ComponentGroups(
+            List(),
+            List(extendedComponentGroup("Foo", "Baz", "Mod1", "quuux"))
+          )
+        )
+      )
+
+      validator
+        .validate(testPackages) shouldEqual Vector(
+        Right(testPackages(0)),
+        Right(testPackages(1)),
+        Left(
+          ValidationError.ComponentGroupExtendsNothing(
+            libraryName(testPackages(2)),
+            ModuleReference(LibraryName("Foo", "Baz"), ModuleName("Mod1"))
+          )
+        )
+      )
+    }
+  }
+}
+
+object ComponentGroupsValidatorSpec {
+
+  /** Create a new config with containing a component groups error. */
+  def configError(
+    namespace: String,
+    name: String,
+    message: String
+  ): Config =
+    Config(
+      name                 = name,
+      namespace            = namespace,
+      version              = "0.0.1",
+      license              = "",
+      authors              = Nil,
+      maintainers          = Nil,
+      edition              = None,
+      preferLocalLibraries = true,
+      componentGroups      = Left(DecodingFailure.apply(message, List()))
+    )
+
+  /** Create a library name from config. */
+  def libraryName(config: Config): LibraryName =
+    LibraryName(config.namespace, config.name)
+}

engine/language-server/src/test/scala/org/enso/languageserver/websocket/json/LibrariesTest.scala

@@ -13,7 +13,19 @@ import org.enso.librarymanager.published.repository.{
   ExampleRepository,
   LibraryManifest
 }
-import org.enso.pkg.{Contact, PackageManager}
+import org.enso.pkg.{
+  Component,
+  ComponentGroup,
+  ComponentGroups,
+  Config,
+  Contact,
+  ExtendedComponentGroup,
+  ModuleName,
+  ModuleReference,
+  Package,
+  PackageManager,
+  Shortcut
+}
 import org.enso.yaml.YamlHelper
 
 import java.nio.file.Files
@@ -215,6 +227,96 @@ class LibrariesTest extends BaseServerTest {
           """)
     }
 
+    "get the package config" in {
+      val client = getInitialisedWsClient()
+      val testComponentGroups = ComponentGroups(
+        newGroups = List(
+          ComponentGroup(
+            module = ModuleName("Foo"),
+            color  = Some("#32a852"),
+            icon   = None,
+            exports = Seq(
+              Component("foo", Some(Shortcut("abc"))),
+              Component("bar", None)
+            )
+          )
+        ),
+        extendedGroups = List(
+          ExtendedComponentGroup(
+            module = ModuleReference(
+              LibraryName("Standard", "Base"),
+              ModuleName("Data")
+            ),
+            exports = List(
+              Component("bar", None)
+            )
+          )
+        )
+      )
+
+      client.send(json"""
+          { "jsonrpc": "2.0",
+            "method": "library/create",
+            "id": 0,
+            "params": {
+              "namespace": "user",
+              "name": "Get_Package_Test_Lib",
+              "authors": [],
+              "maintainers": [],
+              "license": ""
+            }
+          }
+          """)
+      client.expectJson(json"""
+          { "jsonrpc": "2.0",
+            "id": 0,
+            "result": null
+          }
+          """)
+
+      val libraryRoot = getTestDirectory
+        .resolve("test_home")
+        .resolve("libraries")
+        .resolve("user")
+        .resolve("Get_Package_Test_Lib")
+      val packageFile = libraryRoot.resolve(Package.configFileName)
+      val packageConfig =
+        YamlHelper
+          .load[Config](packageFile)
+          .get
+          .copy(
+            componentGroups = Right(testComponentGroups)
+          )
+      Files.writeString(packageFile, packageConfig.toYaml)
+
+      client.send(json"""
+          { "jsonrpc": "2.0",
+            "method": "library/getPackage",
+            "id": 1,
+            "params": {
+              "namespace": "user",
+              "name": "Get_Package_Test_Lib",
+              "version": {
+                "type": "LocalLibraryVersion"
+              }
+            }
+          }
+          """)
+      val response = client.expectSomeJson()
+
+      response.hcursor
+        .downField("result")
+        .downField("license")
+        .as[Option[String]]
+        .rightValue shouldEqual None
+
+      response.hcursor
+        .downField("result")
+        .downField("componentGroups")
+        .as[ComponentGroups]
+        .rightValue shouldEqual testComponentGroups
+    }
+
     "create, publish a library and fetch its manifest from the server" in {
       val client = getInitialisedWsClient()
       client.send(json"""
@@ -475,14 +577,16 @@ class LibrariesTest extends BaseServerTest {
           .value
 
         val pkg =
-          PackageManager.Default.loadPackage(cachedLibraryRoot.toFile).get
+          PackageManager.Default
+            .loadPackage(cachedLibraryRoot.location.toFile)
+            .get
         pkg.name shouldEqual "Bar"
         pkg.listSources.map(
           _.file.getName
         ) should contain theSameElementsAs Seq("Main.enso")
 
         assert(
-          Files.exists(cachedLibraryRoot.resolve(LibraryManifest.filename)),
+          Files.exists(cachedLibraryRoot / LibraryManifest.filename),
           "The manifest file of a downloaded library should be saved in the cache too."
         )
       }
@@ -609,6 +713,55 @@ class LibrariesTest extends BaseServerTest {
     }
   }
 
+  "editions/listDefinedComponents" should {
+    "include expected components in the list" in {
+      val client = getInitialisedWsClient()
+      client.send(json"""
+          { "jsonrpc": "2.0",
+            "method": "editions/listDefinedComponents",
+            "id": 0,
+            "params": {
+              "edition": {
+                "type": "CurrentProjectEdition"
+              }
+            }
+          }
+          """)
+
+      client.expectJson(json"""
+          { "jsonrpc": "2.0",
+            "id": 0,
+            "result": {
+              "availableComponents" : [ ]
+            }
+          }
+          """)
+
+      val currentEditionName = buildinfo.Info.currentEdition
+      client.send(json"""
+          { "jsonrpc": "2.0",
+            "method": "editions/listDefinedComponents",
+            "id": 0,
+            "params": {
+              "edition": {
+                "type": "NamedEdition",
+                "editionName": $currentEditionName
+              }
+            }
+          }
+          """)
+
+      client.expectJson(json"""
+          { "jsonrpc": "2.0",
+            "id": 0,
+            "result": {
+              "availableComponents" : [ ]
+            }
+          }
+          """)
+    }
+  }
+
   "editions/resolve" should {
     "resolve the engine version associated with an edition" in {
       val currentVersion = buildinfo.Info.ensoVersion

engine/runtime/src/main/scala/org/enso/compiler/PackageRepository.scala

@@ -10,6 +10,7 @@ import org.enso.interpreter.instrument.NotificationHandler
 import org.enso.interpreter.runtime.builtin.Builtins
 import org.enso.interpreter.runtime.util.TruffleFileSystem
 import org.enso.interpreter.runtime.{Context, Module}
+import org.enso.librarymanager.resolved.LibraryRoot
 import org.enso.librarymanager.{
   DefaultLibraryProvider,
   ResolvingLibraryProvider
@@ -23,6 +24,7 @@ import org.enso.pkg.{
   PackageManager,
   QualifiedName
 }
+
 import java.nio.file.Path
 
 import scala.util.Try
@@ -247,14 +249,14 @@ object PackageRepository {
     private def loadPackage(
       libraryName: LibraryName,
       libraryVersion: LibraryVersion,
-      root: Path
+      root: LibraryRoot
     ): Either[Error, Package[TruffleFile]] = Try {
       logger.debug(
         s"Loading library $libraryName from " +
-        s"[${MaskedPath(root).applyMasking()}]."
+        s"[${MaskedPath(root.location).applyMasking()}]."
       )
       val rootFile = context.getEnvironment.getInternalTruffleFile(
-        root.toAbsolutePath.normalize.toString
+        root.location.toAbsolutePath.normalize.toString
       )
       val pkg = packageManager.loadPackage(rootFile).get
       registerPackageInternal(
@@ -362,7 +364,7 @@ object PackageRepository {
           case Right(resolved) =>
             logger.info(
               s"Found library ${resolved.name} @ ${resolved.version} " +
-              s"at [${MaskedPath(resolved.location).applyMasking()}]."
+              s"at [${MaskedPath(resolved.root.location).applyMasking()}]."
             )
         }
 
@@ -373,7 +375,7 @@ object PackageRepository {
           else
             resolvedLibrary
               .flatMap { library =>
-                loadPackage(library.name, library.version, library.location)
+                loadPackage(library.name, library.version, library.root)
               }
               .flatMap(resolveComponentGroups)
               .left

engine/runtime/src/test/scala/org/enso/interpreter/test/instrument/RuntimeComponentsTest.scala

@@ -62,8 +62,6 @@ class RuntimeComponentsTest
                 LibraryName("Standard", "Base"),
                 ModuleName("Group2")
               ),
-              color   = None,
-              icon    = None,
               exports = List(Component("foo", None))
             )
           )

lib/scala/library-manager-test/src/test/scala/org/enso/librarymanager/published/repository/LibraryDownloadTest.scala

@@ -41,13 +41,14 @@ class LibraryDownloadTest
               )
               .get
           }
-          val pkg = PackageManager.Default.loadPackage(libPath.toFile).get
+          val pkg =
+            PackageManager.Default.loadPackage(libPath.location.toFile).get
           pkg.name shouldEqual "Bar"
           val sources = pkg.listSources
           sources should have size 1
           sources.head.file.getName shouldEqual "Main.enso"
           assert(
-            Files.notExists(libPath.resolve("LICENSE.md")),
+            Files.notExists(libPath / "LICENSE.md"),
             "The license file should not exist as it was not provided " +
             "in the repository."
           )

lib/scala/library-manager-test/src/test/scala/org/enso/libraryupload/LibraryUploadTest.scala

@@ -80,7 +80,9 @@ class LibraryUploadTest
           )
           val installedRoot =
             cache.findOrInstallLibrary(libraryName, libraryVersion, repo).get
-          val pkg = PackageManager.Default.loadPackage(installedRoot.toFile).get
+          val pkg = PackageManager.Default
+            .loadPackage(installedRoot.location.toFile)
+            .get
           pkg.name shouldEqual libraryName.name
           val sources = pkg.listSources
           sources should have size 1

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/ResolvedLibrary.scala

@@ -1,12 +1,32 @@
 package org.enso.librarymanager
 
 import org.enso.editions.{LibraryName, LibraryVersion}
+import org.enso.librarymanager.resolved.{
+  FilesystemLibraryReadAccess,
+  LibraryReadAccess,
+  LibraryRoot
+}
 
-import java.nio.file.Path
+/** Represents a resolved library that is located somewhere on the filesystem.
-
+  *
-/** Represents a resolved library that is located somewhere on the filesystem. */
+  * @param name the library name
+  * @param version the library version
+  * @param root the library location on the filesystem
+  */
 case class ResolvedLibrary(
   name: LibraryName,
   version: LibraryVersion,
-  location: Path
+  root: LibraryRoot
 )
+object ResolvedLibrary {
+
+  /** Extension methods of [[ResolvedLibrary]]. */
+  implicit class ResolvedLibraryMethods(val resolvedLibrary: ResolvedLibrary)
+      extends AnyVal {
+
+    /** Provides read methods to access the library files. */
+    def getReadAccess: LibraryReadAccess =
+      new FilesystemLibraryReadAccess(resolvedLibrary.root)
+  }
+
+}

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/dependencies/DependencyResolver.scala

@@ -8,10 +8,8 @@ import org.enso.librarymanager.published.repository.LibraryManifest
 import org.enso.librarymanager.published.repository.RepositoryHelper.RepositoryMethods
 import org.enso.libraryupload.DependencyExtractor
 import org.enso.pkg.PackageManager
-import org.enso.yaml.YamlHelper
 
 import java.io.File
-import java.nio.file.Files
 import scala.util.Try
 
 /** A helper class that allows to find all transitive dependencies of a specific
@@ -61,7 +59,7 @@ class DependencyResolver(
         case LibraryVersion.Local =>
           val libraryPath = localLibraryProvider.findLibrary(libraryName)
           val libraryPackage = libraryPath.map(path =>
-            PackageManager.Default.loadPackage(path.toFile).get
+            PackageManager.Default.loadPackage(path.location.toFile).get
           )
 
           val dependencies = libraryPackage match {
@@ -99,16 +97,11 @@ class DependencyResolver(
   ): LibraryManifest = {
     val cachedManifest = publishedLibraryProvider
       .findCachedLibrary(libraryName, version.version)
-      .flatMap { libraryPath =>
+      .flatMap(_.getReadAccess.readManifest().flatMap(_.toOption))
-        val manifestPath = libraryPath.resolve(LibraryManifest.filename)
-        if (Files.exists(manifestPath))
-          YamlHelper.load[LibraryManifest](manifestPath).toOption
-        else None
-      }
     cachedManifest.getOrElse {
       version.repository
         .accessLibrary(libraryName, version.version)
-        .downloadManifest()
+        .fetchManifest()
         .force()
     }
   }

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/local/DefaultLocalLibraryProvider.scala

@@ -3,9 +3,11 @@ package org.enso.librarymanager.local
 import com.typesafe.scalalogging.Logger
 import org.enso.editions.LibraryName
 import org.enso.librarymanager.LibraryLocations
+import org.enso.librarymanager.resolved.LibraryRoot
 import org.enso.logger.masking.MaskedPath
 
 import java.nio.file.{Files, Path}
+
 import scala.annotation.tailrec
 
 /** A default implementation of [[LocalLibraryProvider]]. */
@@ -15,13 +17,13 @@ class DefaultLocalLibraryProvider(searchPaths: List[Path])
   private val logger = Logger[DefaultLocalLibraryProvider]
 
   /** @inheritdoc */
-  override def findLibrary(libraryName: LibraryName): Option[Path] =
+  override def findLibrary(libraryName: LibraryName): Option[LibraryRoot] = {
-    findLibraryHelper(
+    findLibraryHelper(libraryName, searchPaths)
-      libraryName,
+      .map(LibraryRoot(_))
-      searchPaths
+  }
-    )
 
-  /** Searches through the available library paths, checking if any one of them contains the requested library.
+  /** Searches through the available library paths, checking if any one of them
+    * contains the requested library.
     *
     * The first path on the list takes precedence.
     */

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/local/LocalLibraryProvider.scala

@@ -2,16 +2,19 @@ package org.enso.librarymanager.local
 
 import org.enso.distribution.FileSystem.PathSyntax
 import org.enso.editions.LibraryName
+import org.enso.librarymanager.resolved.LibraryRoot
 
 import java.nio.file.Path
 
 /** A provider for local libraries. */
 trait LocalLibraryProvider {
 
-  /** Returns the path to a local instance of the requested library, if it is
+  /** Find the local library by name.
-    * available.
+    *
+    * @param libraryName the library name
+    * @return the location of the requested library, if it is available.
     */
-  def findLibrary(libraryName: LibraryName): Option[Path]
+  def findLibrary(libraryName: LibraryName): Option[LibraryRoot]
 }
 
 object LocalLibraryProvider {

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/CachedLibraryProvider.scala

@@ -1,27 +1,24 @@
 package org.enso.librarymanager.published
 
 import nl.gn0s1s.bump.SemVer
-import org.enso.editions.{Editions, LibraryName}
+import org.enso.editions.LibraryName
-import org.enso.librarymanager.LibraryResolutionError
 import org.enso.librarymanager.published.cache.ReadOnlyLibraryCache
+import org.enso.librarymanager.resolved.LibraryRoot
 
-import java.nio.file.Path
 import scala.annotation.tailrec
-import scala.util.Try
 
-/** A [[PublishedLibraryProvider]] that just provides libraries which are
+/** A [[PublishedLibraryCache]] that just provides libraries which are
   * already available in the cache.
   */
 class CachedLibraryProvider(caches: List[ReadOnlyLibraryCache])
-    extends PublishedLibraryProvider
+    extends PublishedLibraryCache {
-    with PublishedLibraryCache {
 
   @tailrec
   private def findCachedHelper(
     libraryName: LibraryName,
     version: SemVer,
     caches: List[ReadOnlyLibraryCache]
-  ): Option[Path] = caches match {
+  ): Option[LibraryRoot] = caches match {
     case head :: tail =>
       head.findCachedLibrary(libraryName, version) match {
         case Some(found) => Some(found)
@@ -34,21 +31,8 @@ class CachedLibraryProvider(caches: List[ReadOnlyLibraryCache])
   override def findCachedLibrary(
     libraryName: LibraryName,
     version: SemVer
-  ): Option[Path] = findCachedHelper(libraryName, version, caches)
+  ): Option[LibraryRoot] =
-
+    findCachedHelper(libraryName, version, caches)
-  /** @inheritdoc */
-  override def findLibrary(
-    libraryName: LibraryName,
-    version: SemVer,
-    recommendedRepository: Editions.Repository
-  ): Try[Path] =
-    findCachedLibrary(libraryName, version)
-      .toRight(
-        LibraryResolutionError(
-          s"Library [$libraryName:$version] was not found in the cache."
-        )
-      )
-      .toTry
 
   /** @inheritdoc */
   override def isLibraryCached(

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/DefaultPublishedLibraryProvider.scala

@@ -7,8 +7,8 @@ import org.enso.librarymanager.published.cache.{
   LibraryCache,
   ReadOnlyLibraryCache
 }
+import org.enso.librarymanager.resolved.LibraryRoot
 
-import java.nio.file.Path
 import scala.util.{Success, Try}
 
 /** A default implementation of [[PublishedLibraryProvider]] which uses one
@@ -18,7 +18,8 @@ import scala.util.{Success, Try}
 class DefaultPublishedLibraryProvider(
   primaryCache: LibraryCache,
   auxiliaryCaches: List[ReadOnlyLibraryCache]
-) extends CachedLibraryProvider(caches = primaryCache :: auxiliaryCaches) {
+) extends CachedLibraryProvider(caches = primaryCache :: auxiliaryCaches)
+    with PublishedLibraryProvider {
   private val logger = Logger[DefaultPublishedLibraryProvider]
 
   /** @inheritdoc */
@@ -26,9 +27,9 @@ class DefaultPublishedLibraryProvider(
     libraryName: LibraryName,
     version: SemVer,
     recommendedRepository: Editions.Repository
-  ): Try[Path] = {
+  ): Try[LibraryRoot] = {
-    val cached = findCachedLibrary(libraryName, version)
+    val cachedLibrary = findCachedLibrary(libraryName, version)
-    cached.map(Success(_)).getOrElse {
+    cachedLibrary.map(Success(_)).getOrElse {
       logger.trace(
         s"$libraryName was not found in any caches, it will need to be " +
         s"downloaded."

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/PublishedLibraryCache.scala

@@ -4,6 +4,7 @@ import nl.gn0s1s.bump.SemVer
 import org.enso.editions.LibraryName
 import org.enso.librarymanager.LibraryLocations
 import org.enso.librarymanager.published.bundles.LocalReadOnlyRepository
+import org.enso.librarymanager.resolved.LibraryRoot
 
 import java.nio.file.Path
 
@@ -18,7 +19,10 @@ trait PublishedLibraryCache {
   def isLibraryCached(libraryName: LibraryName, version: SemVer): Boolean
 
   /** Tries to locate a cached version of the requested library. */
-  def findCachedLibrary(libraryName: LibraryName, version: SemVer): Option[Path]
+  def findCachedLibrary(
+    libraryName: LibraryName,
+    version: SemVer
+  ): Option[LibraryRoot]
 }
 
 object PublishedLibraryCache {

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/PublishedLibraryProvider.scala

@@ -3,8 +3,8 @@ package org.enso.librarymanager.published
 import nl.gn0s1s.bump.SemVer
 import org.enso.editions.Editions.Repository
 import org.enso.editions.LibraryName
+import org.enso.librarymanager.resolved.LibraryRoot
 
-import java.nio.file.Path
 import scala.util.Try
 
 /** A provider of published libraries.
@@ -24,5 +24,5 @@ trait PublishedLibraryProvider {
     libraryName: LibraryName,
     version: SemVer,
     recommendedRepository: Repository
-  ): Try[Path]
+  ): Try[LibraryRoot]
 }

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/bundles/LocalReadOnlyRepository.scala

@@ -7,6 +7,7 @@ import org.enso.librarymanager.published.cache.{
   LibraryCache,
   ReadOnlyLibraryCache
 }
+import org.enso.librarymanager.resolved.LibraryRoot
 import org.enso.logger.masking.MaskedPath
 
 import java.nio.file.{Files, Path}
@@ -31,13 +32,13 @@ class LocalReadOnlyRepository(root: Path) extends ReadOnlyLibraryCache {
   override def findCachedLibrary(
     libraryName: LibraryName,
     version: SemVer
-  ): Option[Path] = {
+  ): Option[LibraryRoot] = {
     val path = LibraryCache.resolvePath(root, libraryName, version)
     if (Files.exists(path)) {
       logger.trace(
         s"$libraryName found at [${MaskedPath(path).applyMasking()}]."
       )
-      Some(path)
+      Some(LibraryRoot(path))
     } else {
       logger.trace(
         s"Did not find $libraryName at [${MaskedPath(path).applyMasking()}]."

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/cache/DownloadingLibraryCache.scala

@@ -18,11 +18,13 @@ import org.enso.librarymanager.published.repository.RepositoryHelper.{
   LibraryAccess,
   RepositoryMethods
 }
+import org.enso.librarymanager.resolved.LibraryRoot
 import org.enso.logger.masking.MaskedPath
 import org.enso.pkg.PackageManager
 import org.enso.yaml.YamlHelper
 
 import java.nio.file.{Files, Path}
+
 import scala.util.control.NonFatal
 import scala.util.{Success, Try}
 
@@ -50,7 +52,7 @@ class DownloadingLibraryCache(
   override def findCachedLibrary(
     libraryName: LibraryName,
     version: SemVer
-  ): Option[Path] = {
+  ): Option[LibraryRoot] = {
     val path = LibraryCache.resolvePath(cacheRoot, libraryName, version)
     resourceManager.withResource(
       lockUserInterface,
@@ -62,7 +64,7 @@ class DownloadingLibraryCache(
           s"Library [$libraryName:$version] found cached at " +
           s"[${MaskedPath(path).applyMasking()}]."
         )
-        Some(path)
+        Some(LibraryRoot(path))
       } else None
     }
   }
@@ -72,7 +74,7 @@ class DownloadingLibraryCache(
     libraryName: LibraryName,
     version: SemVer,
     recommendedRepository: Editions.Repository
-  ): Try[Path] = {
+  ): Try[LibraryRoot] = {
     val cached = findCachedLibrary(libraryName, version)
     cached match {
       case Some(result) => Success(result)
@@ -95,7 +97,7 @@ class DownloadingLibraryCache(
     libraryName: LibraryName,
     version: SemVer,
     recommendedRepository: Editions.Repository
-  ): Try[Path] = Try {
+  ): Try[LibraryRoot] = Try {
     logger.trace(s"Trying to install [$libraryName:$version].")
     resourceManager.withResource(
       lockUserInterface,
@@ -108,7 +110,7 @@ class DownloadingLibraryCache(
         logger.info(
           s"Another process has just installed [$libraryName:$version]."
         )
-        cachedLibraryPath
+        LibraryRoot(cachedLibraryPath)
       } else {
         val access   = recommendedRepository.accessLibrary(libraryName, version)
         val manifest = downloadManifest(libraryName, access)
@@ -129,7 +131,7 @@ class DownloadingLibraryCache(
             destination = cachedLibraryPath
           )
 
-          cachedLibraryPath
+          LibraryRoot(cachedLibraryPath)
         } catch {
           case NonFatal(exception) =>
             logger.error(
@@ -149,7 +151,7 @@ class DownloadingLibraryCache(
     libraryName: LibraryName,
     access: LibraryAccess
   ): LibraryManifest = {
-    val manifestDownload = access.downloadManifest()
+    val manifestDownload = access.fetchManifest()
     progressReporter.trackProgress(
       s"Downloading library manifest of [$libraryName].",
       manifestDownload

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/cache/LibraryCache.scala

@@ -2,8 +2,10 @@ package org.enso.librarymanager.published.cache
 
 import nl.gn0s1s.bump.SemVer
 import org.enso.editions.{Editions, LibraryName, LibraryVersion}
+import org.enso.librarymanager.resolved.LibraryRoot
 
 import java.nio.file.Path
+
 import scala.util.Try
 
 /** A library cache that is also capable of downloading missing libraries (which
@@ -26,7 +28,7 @@ trait LibraryCache extends ReadOnlyLibraryCache {
   override def findCachedLibrary(
     libraryName: LibraryName,
     version: SemVer
-  ): Option[Path]
+  ): Option[LibraryRoot]
 
   /** If the cache contains the library, it is returned immediately, otherwise,
     * it tries to download the missing library.
@@ -46,7 +48,7 @@ trait LibraryCache extends ReadOnlyLibraryCache {
     libraryName: LibraryName,
     version: SemVer,
     recommendedRepository: Editions.Repository
-  ): Try[Path]
+  ): Try[LibraryRoot]
 
   /** Ensures that the given library and all of its dependencies are installed.
     *

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/cache/ReadOnlyLibraryCache.scala

@@ -2,8 +2,7 @@ package org.enso.librarymanager.published.cache
 
 import nl.gn0s1s.bump.SemVer
 import org.enso.editions.LibraryName
-
+import org.enso.librarymanager.resolved.LibraryRoot
-import java.nio.file.Path
 
 /** A read-only cache may contain some pre-defined set of libraries, but it does
   * not necessarily install any additional libraries.
@@ -15,5 +14,8 @@ trait ReadOnlyLibraryCache {
   /** Locates the library in the cache and returns the path to its root if it
     * has been found.
     */
-  def findCachedLibrary(libraryName: LibraryName, version: SemVer): Option[Path]
+  def findCachedLibrary(
+    libraryName: LibraryName,
+    version: SemVer
+  ): Option[LibraryRoot]
 }

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/published/repository/RepositoryHelper.scala

@@ -6,10 +6,10 @@ import org.enso.distribution.FileSystem.PathSyntax
 import org.enso.downloader.http.{HTTPDownload, URIBuilder}
 import org.enso.editions.Editions.Repository
 import org.enso.editions.LibraryName
-import org.enso.pkg.Package
+import org.enso.pkg.{Config, Package}
 import org.enso.yaml.YamlHelper
-
 import java.nio.file.Path
+
 import scala.util.Failure
 
 /** A class that manages the HTTP API of the Library Repository.
@@ -52,15 +52,15 @@ object RepositoryHelper {
     libraryRoot: URIBuilder
   ) {
 
-    /** Downloads and parses the manifest file.
+    /** Fetches the contents of manifest file and parses it.
       *
       * If the repository responds with 404 status code, it returns a special
       * [[LibraryNotFoundException]] indicating that the repository does not
       * provide that library. Any other failures are indicated with the more
       * generic [[LibraryDownloadFailure]].
       */
-    def downloadManifest(): TaskProgress[LibraryManifest] = {
+    def fetchManifest(): TaskProgress[LibraryManifest] = {
-      val url = (libraryRoot / manifestFilename).build()
+      val url = (libraryRoot / LibraryManifest.filename).build()
       HTTPDownload.fetchString(url).flatMap { response =>
         response.statusCode match {
           case 200 =>
@@ -80,6 +80,34 @@ object RepositoryHelper {
       }
     }
 
+    /** Fetches the contents of package config file and parses it.
+      *
+      * If the repository responds with 404 status code, it returns a special
+      * [[LibraryNotFoundException]] indicating that the repository does not
+      * provide that library. Any other failures are indicated with the more
+      * generic [[LibraryDownloadFailure]].
+      */
+    def fetchPackageConfig(): TaskProgress[Config] = {
+      val url = (libraryRoot / Package.configFileName).build()
+      HTTPDownload.fetchString(url).flatMap { response =>
+        response.statusCode match {
+          case 200 =>
+            YamlHelper.parseString[Config](response.content).toTry
+          case 404 =>
+            Failure(
+              LibraryNotFoundException(libraryName, version, url.toString)
+            )
+          case code =>
+            Failure(
+              new LibraryDownloadFailure(
+                s"Could not download the package config: The repository responded " +
+                s"with $code status code."
+              )
+            )
+        }
+      }
+    }
+
     /** A helper that downloads an artifact to a specific location. */
     private def downloadArtifact(
       artifactName: String,
@@ -108,9 +136,6 @@ object RepositoryHelper {
     ): TaskProgress[Unit] = downloadArtifact(archiveName, destinationDirectory)
   }
 
-  /** Name of the manifest file. */
-  val manifestFilename = "manifest.yaml"
-
   /** Name of the attached license file. */
   val licenseFilename = "LICENSE.md"
 

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/resolved/FilesystemLibraryReadAccess.scala

@@ -0,0 +1,32 @@
+package org.enso.librarymanager.resolved
+
+import org.enso.librarymanager.published.repository.LibraryManifest
+import org.enso.pkg.{Config, Package}
+import org.enso.yaml.YamlHelper
+
+import java.nio.file.Files
+
+import scala.util.Try
+
+/** Default filesystem read access to libraries.
+  *
+  * @param libraryPath the library location on the filesystem
+  */
+class FilesystemLibraryReadAccess(libraryPath: LibraryRoot)
+    extends LibraryReadAccess {
+
+  /** @inheritdoc */
+  override def readManifest(): Option[Try[LibraryManifest]] = {
+    val manifestPath = libraryPath.location.resolve(LibraryManifest.filename)
+    Option.when(Files.exists(manifestPath)) {
+      YamlHelper.load[LibraryManifest](manifestPath)
+    }
+  }
+
+  /** @inheritdoc */
+  override def readPackage(): Try[Config] = {
+    val configPath = libraryPath.location.resolve(Package.configFileName)
+    YamlHelper.load[Config](configPath)
+  }
+
+}

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/resolved/LibraryReadAccess.scala

@@ -0,0 +1,22 @@
+package org.enso.librarymanager.resolved
+
+import org.enso.librarymanager.published.repository.LibraryManifest
+import org.enso.pkg.Config
+
+import scala.util.Try
+
+/** Base trait allowing to read the library files on a filesystem. */
+trait LibraryReadAccess {
+
+  /** Read the library manifest file.
+    *
+    * @return the library manifest, if the manifest file exists and `None` otherwise.
+    */
+  def readManifest(): Option[Try[LibraryManifest]]
+
+  /** Read the library package config.
+    *
+    * @return the parsed library config.
+    */
+  def readPackage(): Try[Config]
+}

lib/scala/library-manager/src/main/scala/org/enso/librarymanager/resolved/LibraryRoot.scala

@@ -0,0 +1,28 @@
+package org.enso.librarymanager.resolved
+
+import java.nio.file.Path
+
+/** The path to the library on a filesystem.
+  *
+  * @param location the library location on a filesystem
+  */
+case class LibraryRoot(location: Path)
+object LibraryRoot {
+
+  /** Extension methods of [[LibraryRoot]]. */
+  implicit class LibraryRootMethods(val libraryPath: LibraryRoot)
+      extends AnyVal {
+
+    /** Get the read access to the library files. */
+    def getReadAccess: LibraryReadAccess =
+      new FilesystemLibraryReadAccess(libraryPath)
+  }
+
+  /** Syntax allowing to write nested paths in a more readable and concise way.
+    */
+  implicit class LibraryRootSyntax(val libraryRoot: LibraryRoot)
+      extends AnyVal {
+    def /(other: String): Path = libraryRoot.location.resolve(other)
+    def /(other: Path): Path   = libraryRoot.location.resolve(other)
+  }
+}

lib/scala/library-manager/src/test/scala/org/enso/librarymanager/LibraryResolverSpec.scala

@@ -4,6 +4,7 @@ import nl.gn0s1s.bump.SemVer
 import org.enso.editions.Editions.Repository
 import org.enso.editions.{Editions, LibraryName, LibraryVersion}
 import org.enso.librarymanager.local.LocalLibraryProvider
+import org.enso.librarymanager.resolved.LibraryRoot
 import org.enso.testkit.EitherValue
 import org.scalatest.Inside
 import org.scalatest.matchers.should.Matchers
@@ -57,8 +58,14 @@ class LibraryResolverSpec
 
     case class FakeLocalLibraryProvider(fixtures: Map[LibraryName, Path])
         extends LocalLibraryProvider {
-      override def findLibrary(libraryName: LibraryName): Option[Path] =
+
-        fixtures.get(libraryName)
+      /** @inheritdoc */
+      override def findLibrary(
+        libraryName: LibraryName
+      ): Option[LibraryRoot] =
+        fixtures
+          .get(libraryName)
+          .map(LibraryRoot(_))
     }
 
     val localLibraries = Map(

lib/scala/pkg/src/main/scala/org/enso/pkg/ComponentGroup.scala

@@ -102,14 +102,10 @@ object ComponentGroup {
 /** The definition of a component group that extends an existing one.
   *
   * @param module the reference to the extended component group
-  * @param color the component group color
-  * @param icon the component group icon
   * @param exports the list of components provided by this component group
   */
 case class ExtendedComponentGroup(
   module: ModuleReference,
-  color: Option[String],
-  icon: Option[String],
   exports: Seq[Component]
 )
 object ExtendedComponentGroup {
@@ -117,22 +113,17 @@ object ExtendedComponentGroup {
   /** Fields for use when serializing the [[ExtendedComponentGroup]]. */
   private object Fields {
     val Module  = "module"
-    val Color   = "color"
-    val Icon    = "icon"
     val Exports = "exports"
   }
 
   /** [[Encoder]] instance for the [[ExtendedComponentGroup]]. */
   implicit val encoder: Encoder[ExtendedComponentGroup] = {
     extendedComponentGroup =>
-      val color = extendedComponentGroup.color.map(Fields.Color -> _.asJson)
-      val icon  = extendedComponentGroup.icon.map(Fields.Icon -> _.asJson)
       val exports = Option.unless(extendedComponentGroup.exports.isEmpty)(
         Fields.Exports -> extendedComponentGroup.exports.asJson
       )
       Json.obj(
-        (Fields.Module -> extendedComponentGroup.module.asJson) +:
+        (Fields.Module -> extendedComponentGroup.module.asJson) +: exports.toSeq: _*
-        (color.toSeq ++ icon.toSeq ++ exports.toSeq): _*
       )
   }
 
@@ -145,10 +136,8 @@ object ExtendedComponentGroup {
           Fields.Module,
           json
         )
-      color   <- json.get[Option[String]](Fields.Color)
-      icon    <- json.get[Option[String]](Fields.Icon)
       exports <- json.getOrElse[List[Component]](Fields.Exports)(List())
-    } yield ExtendedComponentGroup(reference, color, icon, exports)
+    } yield ExtendedComponentGroup(reference, exports)
   }
 }
 
@@ -219,7 +208,18 @@ object Shortcut {
 case class ModuleReference(
   libraryName: LibraryName,
   moduleName: ModuleName
-)
+) {
+
+  /** The qualified name of the library consists of its prefix and name
+    * separated with a dot.
+    */
+  def qualifiedName: String =
+    s"$libraryName${LibraryName.separator}${moduleName.name}"
+
+  /** @inheritdoc */
+  override def toString: String = qualifiedName
+
+}
 object ModuleReference {
 
   private def toModuleString(moduleReference: ModuleReference): String = {

lib/scala/pkg/src/test/scala/org/enso/pkg/ConfigSpec.scala

@@ -134,8 +134,6 @@ class ConfigSpec
               LibraryName("Standard", "Base"),
               ModuleName("Group 2")
             ),
-            color   = None,
-            icon    = None,
             exports = List(Component("bax", None))
           )
         )