Read-only mode for controllers (#6259)

Closes #6181

- Added a read-only flag for the project model (now controlled by a temporary shortcut).
- Renaming the project, editing the code, connecting and disconnecting nodes, and collapsing, and navigating through collapsed nodes are forbidden and will result in the error message in the console.
- Some of the above actions produce undesired effects on the IDE, which will be fixed later. This PR is focused on restricting actual AST modifications.
- Moving nodes (and updating metadata in general) no longer causes reevaluation


https://user-images.githubusercontent.com/6566674/231616408-4f334bb7-1985-43ba-9953-4c0998338a9b.mp4

app/gui/controller/engine-protocol/src/language_server.rs

@@ -113,7 +113,7 @@ trait API {
     /// have permission to edit the resources for which edits are sent. This failure may be partial,
     /// in that some edits are applied and others are not.
     #[MethodInput=ApplyTextFileEditInput, rpc_name="text/applyEdit"]
-    fn apply_text_file_edit(&self, edit: FileEdit) -> ();
+    fn apply_text_file_edit(&self, edit: FileEdit, execute: bool) -> ();
 
     /// Create a new execution context. Return capabilities executionContext/canModify and
     /// executionContext/receivesUpdates containing freshly created ContextId

app/gui/controller/engine-protocol/src/language_server/tests.rs

@@ -547,7 +547,7 @@ fn test_execution_context() {
     let path = main.clone();
     let edit = FileEdit { path, edits, old_version, new_version };
     test_request(
-        |client| client.apply_text_file_edit(&edit),
+        |client| client.apply_text_file_edit(&edit, &true),
         "text/applyEdit",
         json!({
             "edit" : {
@@ -572,7 +572,8 @@ fn test_execution_context() {
                 ],
                 "oldVersion" : "d3ee9b1ba1990fecfd794d2f30e0207aaa7be5d37d463073096d86f8",
                 "newVersion" : "6a33e22f20f16642697e8bd549ff7b759252ad56c05a1b0acc31dc69"
-            }
+            },
+            "execute": true
         }),
         unit_json.clone(),
         (),

app/gui/src/controller/graph/executed.rs

@@ -44,6 +44,10 @@ pub struct NotEvaluatedYet(double_representation::node::Id);
 #[fail(display = "The node {} does not resolve to a method call.", _0)]
 pub struct NoResolvedMethod(double_representation::node::Id);
 
+#[allow(missing_docs)]
+#[derive(Debug, Fail, Clone, Copy)]
+#[fail(display = "Operation is not permitted in read only mode")]
+pub struct ReadOnly;
 
 
 // ====================
@@ -216,8 +220,13 @@ impl Handle {
     /// This will cause pushing a new stack frame to the execution context and changing the graph
     /// controller to point to a new definition.
     ///
-    /// Fails if method graph cannot be created (see `graph_for_method` documentation).
+    /// ### Errors
+    /// - Fails if method graph cannot be created (see `graph_for_method` documentation).
+    /// - Fails if the project is in read-only mode.
     pub async fn enter_method_pointer(&self, local_call: &LocalCall) -> FallibleResult {
+        if self.project.read_only() {
+            Err(ReadOnly.into())
+        } else {
             debug!("Entering node {}.", local_call.call);
             let method_ptr = &local_call.definition;
             let graph = controller::Graph::new_method(&self.project, method_ptr);
@@ -230,6 +239,7 @@ impl Handle {
 
             Ok(())
         }
+    }
 
     /// Attempts to get the computed value of the specified node.
     ///
@@ -246,9 +256,14 @@ impl Handle {
 
     /// Leave the current node. Reverse of `enter_node`.
     ///
-    /// Fails if this execution context is already at the stack's root or if the parent graph
+    /// ### Errors
+    /// - Fails if this execution context is already at the stack's root or if the parent graph
     /// cannot be retrieved.
+    /// - Fails if the project is in read-only mode.
     pub async fn exit_node(&self) -> FallibleResult {
+        if self.project.read_only() {
+            Err(ReadOnly.into())
+        } else {
             let frame = self.execution_ctx.pop().await?;
             let method = self.execution_ctx.current_method();
             let graph = controller::Graph::new_method(&self.project, &method).await?;
@@ -256,6 +271,7 @@ impl Handle {
             self.notifier.publish(Notification::SteppedOutOfNode(frame.call)).await;
             Ok(())
         }
+    }
 
     /// Interrupt the program execution.
     pub async fn interrupt(&self) -> FallibleResult {
@@ -264,10 +280,17 @@ impl Handle {
     }
 
     /// Restart the program execution.
+    ///
+    /// ### Errors
+    /// - Fails if the project is in read-only mode.
     pub async fn restart(&self) -> FallibleResult {
+        if self.project.read_only() {
+            Err(ReadOnly.into())
+        } else {
             self.execution_ctx.restart().await?;
             Ok(())
         }
+    }
 
     /// Get the current call stack frames.
     pub fn call_stack(&self) -> Vec<LocalCall> {
@@ -308,16 +331,30 @@ impl Handle {
     }
 
     /// Create connection in graph.
+    ///
+    /// ### Errors
+    /// - Fails if the project is in read-only mode.
     pub fn connect(&self, connection: &Connection) -> FallibleResult {
+        if self.project.read_only() {
+            Err(ReadOnly.into())
+        } else {
             self.graph.borrow().connect(connection, self)
         }
+    }
 
     /// Remove the connections from the graph. Returns an updated edge destination endpoint for
     /// disconnected edge, in case it is still used as destination-only edge. When `None` is
     /// returned, no update is necessary.
+    ///
+    /// ### Errors
+    /// - Fails if the project is in read-only mode.
     pub fn disconnect(&self, connection: &Connection) -> FallibleResult<Option<span_tree::Crumbs>> {
+        if self.project.read_only() {
+            Err(ReadOnly.into())
+        } else {
             self.graph.borrow().disconnect(connection, self)
         }
+    }
 }
 
 
@@ -368,6 +405,8 @@ pub mod tests {
     use crate::model::execution_context::ExpressionId;
     use crate::test;
 
+    use crate::test::mock::Fixture;
+    use controller::graph::SpanTree;
     use engine_protocol::language_server::types::test::value_update_with_type;
     use wasm_bindgen_test::wasm_bindgen_test;
     use wasm_bindgen_test::wasm_bindgen_test_configure;
@@ -454,4 +493,95 @@ pub mod tests {
 
         notifications.expect_pending();
     }
+
+    // Test that moving nodes is possible in read-only mode.
+    #[wasm_bindgen_test]
+    fn read_only_mode_does_not_restrict_moving_nodes() {
+        use model::module::Position;
+
+        let fixture = crate::test::mock::Unified::new().fixture();
+        let Fixture { executed_graph, graph, .. } = fixture;
+
+        let nodes = executed_graph.graph().nodes().unwrap();
+        let node = &nodes[0];
+
+        let pos1 = Position::new(500.0, 250.0);
+        let pos2 = Position::new(300.0, 150.0);
+
+        graph.set_node_position(node.id(), pos1).unwrap();
+        assert_eq!(graph.node(node.id()).unwrap().position(), Some(pos1));
+        graph.set_node_position(node.id(), pos2).unwrap();
+        assert_eq!(graph.node(node.id()).unwrap().position(), Some(pos2));
+    }
+
+    // Test that certain actions are forbidden in read-only mode.
+    #[wasm_bindgen_test]
+    fn read_only_mode() {
+        fn run(code: &str, f: impl FnOnce(&Handle)) {
+            let mut data = crate::test::mock::Unified::new();
+            data.set_code(code);
+            let fixture = data.fixture();
+            fixture.read_only.set(true);
+            let Fixture { executed_graph, .. } = fixture;
+            f(&executed_graph);
+        }
+
+
+        // === Editing the node. ===
+
+        let default_code = r#"
+main =
+    foo = 2 * 2
+"#;
+        run(default_code, |executed| {
+            let nodes = executed.graph().nodes().unwrap();
+            let node = &nodes[0];
+            assert!(executed.graph().set_expression(node.info.id(), "5 * 20").is_err());
+        });
+
+
+        // === Collapsing nodes. ===
+
+        let code = r#"
+main =
+    foo = 2
+    bar = foo + 6
+    baz = 2 + foo + bar
+    caz = baz / 2 * baz
+"#;
+        run(code, |executed| {
+            let nodes = executed.graph().nodes().unwrap();
+            // Collapse two middle nodes.
+            let nodes_range = vec![nodes[1].id(), nodes[2].id()];
+            assert!(executed.graph().collapse(nodes_range, "extracted").is_err());
+        });
+
+
+        // === Connecting nodes. ===
+
+        let code = r#"
+main =
+    2 + 2
+    5 * 5
+"#;
+        run(code, |executed| {
+            let nodes = executed.graph().nodes().unwrap();
+            let sum_node = &nodes[0];
+            let product_node = &nodes[1];
+
+            assert_eq!(sum_node.expression().to_string(), "2 + 2");
+            assert_eq!(product_node.expression().to_string(), "5 * 5");
+
+            let context = &span_tree::generate::context::Empty;
+            let sum_tree = SpanTree::<()>::new(&sum_node.expression(), context).unwrap();
+            let sum_input =
+                sum_tree.root_ref().leaf_iter().find(|n| n.is_argument()).unwrap().crumbs;
+            let connection = Connection {
+                source:      controller::graph::Endpoint::new(product_node.id(), []),
+                destination: controller::graph::Endpoint::new(sum_node.id(), sum_input),
+            };
+
+            assert!(executed.connect(&connection).is_err());
+        });
+    }
 }

app/gui/src/controller/module.rs

@@ -173,7 +173,7 @@ impl Handle {
     ) -> FallibleResult<Self> {
         let ast = parser.parse(code.to_string(), id_map).try_into()?;
         let metadata = default();
-        let model = Rc::new(model::module::Plain::new(path, ast, metadata, repository));
+        let model = Rc::new(model::module::Plain::new(path, ast, metadata, repository, default()));
         Ok(Handle { model, language_server, parser })
     }
 

app/gui/src/controller/searcher.rs

@@ -97,6 +97,7 @@ pub struct CannotCommitExpression {
 }
 
 
+
 // =====================
 // === Notifications ===
 // =====================

app/gui/src/model/module.rs

@@ -744,7 +744,9 @@ pub mod test {
             repository: Rc<model::undo_redo::Repository>,
         ) -> Module {
             let ast = parser.parse_module(&self.code, self.id_map.clone()).unwrap();
-            let module = Plain::new(self.path.clone(), ast, self.metadata.clone(), repository);
+            let path = self.path.clone();
+            let metadata = self.metadata.clone();
+            let module = Plain::new(path, ast, metadata, repository, default());
             Rc::new(module)
         }
     }

app/gui/src/model/module/plain.rs

@@ -26,6 +26,17 @@ use std::collections::hash_map::Entry;
 
 
 
+// ==============
+// === Errors ===
+// ==============
+
+#[allow(missing_docs)]
+#[derive(Debug, Clone, Copy, Fail)]
+#[fail(display = "Attempt to edit a read-only module")]
+pub struct EditInReadOnly;
+
+
+
 // ==============
 // === Module ===
 // ==============
@@ -41,6 +52,7 @@ pub struct Module {
     content:       RefCell<Content>,
     notifications: notification::Publisher<Notification>,
     repository:    Rc<model::undo_redo::Repository>,
+    read_only:     Rc<Cell<bool>>,
 }
 
 impl Module {
@@ -50,26 +62,33 @@ impl Module {
         ast: ast::known::Module,
         metadata: Metadata,
         repository: Rc<model::undo_redo::Repository>,
+        read_only: Rc<Cell<bool>>,
     ) -> Self {
         Module {
             content: RefCell::new(ParsedSourceFile { ast, metadata }),
             notifications: default(),
             path,
             repository,
+            read_only,
         }
     }
 
     /// Replace the module's content with the new value and emit notification of given kind.
     ///
-    /// Fails if the `new_content` is so broken that it cannot be serialized to text. In such case
+    /// ### Errors
+    /// - Fails if the `new_content` is so broken that it cannot be serialized to text. In such case
     /// the module's state is guaranteed to remain unmodified and the notification will not be
     /// emitted.
+    /// - Fails if the module is read-only. Metadata-only changes are allowed in read-only mode.
     #[profile(Debug)]
     fn set_content(&self, new_content: Content, kind: NotificationKind) -> FallibleResult {
         if new_content == *self.content.borrow() {
             debug!("Ignoring spurious update.");
             return Ok(());
         }
+        if self.read_only.get() && kind != NotificationKind::MetadataChanged {
+            Err(EditInReadOnly.into())
+        } else {
             trace!("Updating module's content: {kind:?}. New content:\n{new_content}");
             let transaction = self.repository.transaction("Setting module's content");
             transaction.fill_content(self.id(), self.content.borrow().clone());
@@ -81,6 +100,7 @@ impl Module {
             self.notifications.notify(notification);
             Ok(())
         }
+    }
 
     /// Use `f` to update the module's content.
     ///

app/gui/src/model/module/synchronized.rs

@@ -165,6 +165,7 @@ impl Module {
         language_server: Rc<language_server::Connection>,
         parser: Parser,
         repository: Rc<model::undo_redo::Repository>,
+        read_only: Rc<Cell<bool>>,
     ) -> FallibleResult<Rc<Self>> {
         let file_path = path.file_path().clone();
         info!("Opening module {file_path}");
@@ -176,7 +177,9 @@ impl Module {
         let source = parser.parse_with_metadata(opened.content);
         let digest = opened.current_version;
         let summary = ContentSummary { digest, end_of_file };
-        let model = model::module::Plain::new(path, source.ast, source.metadata, repository);
+        let metadata = source.metadata;
+        let ast = source.ast;
+        let model = model::module::Plain::new(path, ast, metadata, repository, read_only);
         let this = Rc::new(Module { model, language_server });
         let content = this.model.serialized_content()?;
         let first_invalidation = this.full_invalidation(&summary, content);
@@ -238,7 +241,7 @@ impl Module {
         self.content().replace(parsed_source);
         let summary = ContentSummary::new(&content);
         let change = TextEdit::from_prefix_postfix_differences(&content, &source.content);
-        self.notify_language_server(&summary, &source, vec![change]).await?;
+        self.notify_language_server(&summary, &source, vec![change], true).await?;
         let notification = Notification::new(source, NotificationKind::Reloaded);
         self.notify(notification);
         Ok(())
@@ -423,7 +426,8 @@ impl Module {
                     };
                     //id_map goes first, because code change may alter its position.
                     let edits = vec![id_map_change, code_change];
-                    let notify_ls = self.notify_language_server(&summary.summary, &new_file, edits);
+                    let summary = &summary.summary;
+                    let notify_ls = self.notify_language_server(summary, &new_file, edits, true);
                     profiler::await_!(notify_ls, _profiler)
                 }
                 NotificationKind::MetadataChanged => {
@@ -431,7 +435,8 @@ impl Module {
                         range: summary.metadata_engine_range().into(),
                         text:  new_file.metadata_slice().to_string(),
                     }];
-                    let notify_ls = self.notify_language_server(&summary.summary, &new_file, edits);
+                    let summary = &summary.summary;
+                    let notify_ls = self.notify_language_server(summary, &new_file, edits, false);
                     profiler::await_!(notify_ls, _profiler)
                 }
                 NotificationKind::Reloaded => Ok(ParsedContentSummary::from_source(&new_file)),
@@ -450,7 +455,7 @@ impl Module {
         debug!("Handling full invalidation: {ls_content:?}.");
         let range = Range::new(Location::default(), ls_content.end_of_file);
         let edits = vec![TextEdit { range: range.into(), text: new_file.content.clone() }];
-        self.notify_language_server(ls_content, &new_file, edits)
+        self.notify_language_server(ls_content, &new_file, edits, true)
     }
 
     fn edit_for_snipped(
@@ -518,7 +523,7 @@ impl Module {
         .into_iter()
         .flatten()
         .collect_vec();
-        self.notify_language_server(&ls_content.summary, &new_file, edits)
+        self.notify_language_server(&ls_content.summary, &new_file, edits, true)
     }
 
     /// This is a helper function with all common logic regarding sending the update to
@@ -529,6 +534,7 @@ impl Module {
         ls_content: &ContentSummary,
         new_file: &SourceFile,
         edits: Vec<TextEdit>,
+        execute: bool,
     ) -> impl Future<Output = FallibleResult<ParsedContentSummary>> + 'static {
         let summary = ParsedContentSummary::from_source(new_file);
         let edit = FileEdit {
@@ -538,7 +544,7 @@ impl Module {
             new_version: Sha3_224::new(new_file.content.as_bytes()),
         };
         debug!("Notifying LS with edit: {edit:#?}.");
-        let ls_future_reply = self.language_server.client.apply_text_file_edit(&edit);
+        let ls_future_reply = self.language_server.client.apply_text_file_edit(&edit, &execute);
         async move {
             ls_future_reply.await?;
             Ok(summary)
@@ -634,7 +640,7 @@ pub mod test {
             f: impl FnOnce(&FileEdit) -> json_rpc::Result<()> + 'static,
         ) {
             let this = self.clone();
-            client.expect.apply_text_file_edit(move |edits| {
+            client.expect.apply_text_file_edit(move |edits, _execute| {
                 let content_so_far = this.current_ls_content.get();
                 let result = f(edits);
                 let new_content = apply_edits(content_so_far, edits);
@@ -755,9 +761,11 @@ pub mod test {
         // * there is an initial invalidation after opening the module
         // * replacing AST causes invalidation
         // * localized text edit emits similarly localized synchronization updates.
+        // * modifying the code fails if the read-only mode is enabled.
         let initial_code = "main =\n    println \"Hello World!\"";
         let mut data = crate::test::mock::Unified::new();
         data.set_code(initial_code);
+        let read_only: Rc<Cell<bool>> = default();
         // We do actually care about sharing `data` between `test` invocations, as it stores the
         // Parser which is time-consuming to construct.
         let test = |runner: &mut Runner| {
@@ -784,19 +792,33 @@ pub mod test {
                     Ok(())
                 });
             });
+            fixture.read_only.set(read_only.get());
 
             let parser = data.parser.clone();
             let module = fixture.synchronized_module();
 
             let new_content = "main =\n    println \"Test\"";
             let new_ast = parser.parse_module(new_content, default()).unwrap();
-            module.update_ast(new_ast).unwrap();
+            let res = module.update_ast(new_ast);
+            if read_only.get() {
+                assert!(res.is_err());
+            } else {
+                assert!(res.is_ok());
+            }
             runner.perhaps_run_until_stalled(&mut fixture);
             let change = TextChange { range: (20..24).into(), text: "Test 2".to_string() };
-            module.apply_code_change(change, &Parser::new(), default()).unwrap();
+            let res = module.apply_code_change(change, &Parser::new(), default());
+            if read_only.get() {
+                assert!(res.is_err());
+            } else {
+                assert!(res.is_ok());
+            }
             runner.perhaps_run_until_stalled(&mut fixture);
         };
 
+        read_only.set(false);
+        Runner::run(test);
+        read_only.set(true);
         Runner::run(test);
     }
 

app/gui/src/model/project.rs

@@ -39,6 +39,15 @@ pub trait API: Debug {
     /// Project's qualified name
     fn qualified_name(&self) -> project::QualifiedName;
 
+    /// Whether the read-only mode is enabled for the project.
+    ///
+    /// Read-only mode forbids certain operations, like renaming the project or editing the code
+    /// through the IDE.
+    fn read_only(&self) -> bool;
+
+    /// Set the read-only mode for the project.
+    fn set_read_only(&self, read_only: bool);
+
     /// Get Language Server JSON-RPC Connection for this project.
     fn json_rpc(&self) -> Rc<language_server::Connection>;
 
@@ -267,4 +276,8 @@ pub mod test {
             path.qualified_module_name(name.clone())
         });
     }
+
+    pub fn expect_read_only(project: &mut MockAPI, read_only: Rc<Cell<bool>>) {
+        project.expect_read_only().returning_st(move || read_only.get());
+    }
 }

app/gui/src/model/project/synchronized.rs

@@ -224,6 +224,11 @@ async fn update_modules_on_file_change(
 #[fail(display = "Project Manager is unavailable.")]
 pub struct ProjectManagerUnavailable;
 
+#[allow(missing_docs)]
+#[derive(Clone, Copy, Debug, Fail)]
+#[fail(display = "Project renaming is not available in read-only mode.")]
+pub struct RenameInReadOnly;
+
 /// A wrapper for an error with information that user tried to open project with unsupported
 /// engine's version (which is likely the cause of the problems).
 #[derive(Debug, Fail)]
@@ -295,6 +300,7 @@ pub struct Project {
     pub parser:              Parser,
     pub notifications:       notification::Publisher<model::project::Notification>,
     pub urm:                 Rc<model::undo_redo::Manager>,
+    pub read_only:           Rc<Cell<bool>>,
 }
 
 impl Project {
@@ -339,6 +345,7 @@ impl Project {
             parser,
             notifications,
             urm,
+            read_only: default(),
         };
 
         let binary_handler = ret.binary_event_handler();
@@ -620,13 +627,13 @@ impl Project {
         &self,
         path: module::Path,
     ) -> impl Future<Output = FallibleResult<Rc<module::Synchronized>>> {
-        let language_server = self.language_server_rpc.clone_ref();
+        let ls = self.language_server_rpc.clone_ref();
         let parser = self.parser.clone_ref();
         let urm = self.urm();
-        let repository = urm.repository.clone_ref();
+        let repo = urm.repository.clone_ref();
+        let read_only = self.read_only.clone_ref();
         async move {
-            let module =
+            let module = module::Synchronized::open(path, ls, parser, repo, read_only).await?;
-                module::Synchronized::open(path, language_server, parser, repository).await?;
             urm.module_opened(module.clone());
             Ok(module)
         }
@@ -702,10 +709,14 @@ impl model::project::API for Project {
     }
 
     fn rename_project(&self, name: String) -> BoxFuture<FallibleResult> {
+        if self.read_only() {
+            std::future::ready(Err(RenameInReadOnly.into())).boxed_local()
+        } else {
             async move {
                 let old_name = self.properties.borrow_mut().name.project.clone_ref();
                 let referent_name = name.to_im_string();
-            let project_manager = self.project_manager.as_ref().ok_or(ProjectManagerUnavailable)?;
+                let project_manager =
+                    self.project_manager.as_ref().ok_or(ProjectManagerUnavailable)?;
                 let project_id = self.properties.borrow().id;
                 let project_name = ProjectName::new_unchecked(name);
                 project_manager.rename_project(&project_id, &project_name).await?;
@@ -715,6 +726,7 @@ impl model::project::API for Project {
             }
             .boxed_local()
         }
+    }
 
     fn project_content_root_id(&self) -> Uuid {
         self.language_server_rpc.project_root().id()
@@ -727,6 +739,14 @@ impl model::project::API for Project {
     fn urm(&self) -> Rc<model::undo_redo::Manager> {
         self.urm.clone_ref()
     }
+
+    fn read_only(&self) -> bool {
+        self.read_only.get()
+    }
+
+    fn set_read_only(&self, read_only: bool) {
+        self.read_only.set(read_only);
+    }
 }
 
 
@@ -864,7 +884,7 @@ mod test {
         let write_capability = Some(write_capability);
         let open_response = response::OpenTextFile { content, current_version, write_capability };
         expect_call!(client.open_text_file(path=path.clone()) => Ok(open_response));
-        client.expect.apply_text_file_edit(|_| Ok(()));
+        client.expect.apply_text_file_edit(|_, _| Ok(()));
         expect_call!(client.close_text_file(path) => Ok(()));
     }
 

app/gui/src/model/registry.rs

@@ -165,9 +165,10 @@ mod test {
     use super::*;
 
     use crate::executor::test_utils::TestWithLocalPoolExecutor;
+    use model::module::Plain;
 
     type ModulePath = model::module::Path;
-    type Registry = super::Registry<ModulePath, model::module::Plain>;
+    type Registry = super::Registry<ModulePath, Plain>;
 
     #[test]
     fn getting_module() {
@@ -177,7 +178,7 @@ mod test {
             let ast = ast::Ast::one_line_module(line).try_into().unwrap();
             let path = ModulePath::from_mock_module_name("Test");
             let urm = default();
-            let state = Rc::new(model::module::Plain::new(path.clone(), ast, default(), urm));
+            let state = Rc::new(Plain::new(path.clone(), ast, default(), urm, default()));
             let registry = Registry::default();
             let expected = state.clone_ref();
 
@@ -198,7 +199,7 @@ mod test {
         let path1 = ModulePath::from_mock_module_name("Test");
         let path2 = path1.clone();
         let urm = default();
-        let state1 = Rc::new(model::module::Plain::new(path1.clone_ref(), ast, default(), urm));
+        let state1 = Rc::new(Plain::new(path1.clone_ref(), ast, default(), urm, default()));
         let state2 = state1.clone_ref();
         let registry1 = Rc::new(Registry::default());
         let registry2 = registry1.clone_ref();

app/gui/src/presenter/project.rs

@@ -199,6 +199,12 @@ impl Model {
         self.ide_controller.set_component_browser_private_entries_visibility(!visibility);
     }
 
+    fn toggle_read_only(&self) {
+        let read_only = self.controller.model.read_only();
+        self.controller.model.set_read_only(!read_only);
+        info!("New read only state: {}.", self.controller.model.read_only());
+    }
+
     fn restore_project_snapshot(&self) {
         let controller = self.controller.clone_ref();
         let breadcrumbs = self.view.graph().model.breadcrumbs.clone_ref();
@@ -374,6 +380,8 @@ impl Project {
             eval_ view.execution_context_interrupt(model.execution_context_interrupt());
 
             eval_ view.execution_context_restart(model.execution_context_restart());
+
+            eval_ view.toggle_read_only(model.toggle_read_only());
         }
 
         let graph_controller = self.model.graph_controller.clone_ref();

app/gui/src/presenter/searcher.rs

@@ -134,7 +134,7 @@ impl Model {
         match self.suggestion_for_entry_id(entry_id) {
             Ok(suggestion) =>
                 if let Err(error) = self.controller.preview_suggestion(suggestion) {
-                    warn!("Failed to preview suggestion {entry_id:?} because of error: {error:?}.");
+                    warn!("Failed to preview suggestion {entry_id:?} because of error: {error}.");
                 },
             Err(err) => warn!("Error while previewing suggestion: {err}."),
         }

app/gui/src/test.rs

@@ -135,6 +135,7 @@ pub mod mock {
         pub suggestions:  HashMap<suggestion_database::entry::Id, suggestion_database::Entry>,
         pub context_id:   model::execution_context::Id,
         pub parser:       parser::Parser,
+        pub read_only:    Rc<Cell<bool>>,
         code:             String,
         id_map:           ast::IdMap,
         metadata:         crate::model::module::Metadata,
@@ -172,6 +173,7 @@ pub mod mock {
                 context_id: CONTEXT_ID,
                 root_definition: definition_name(),
                 parser: parser::Parser::new(),
+                read_only: default(),
             }
         }
 
@@ -184,8 +186,14 @@ pub mod mock {
             let path = self.module_path.clone();
             let metadata = self.metadata.clone();
             let repository = urm.repository.clone_ref();
-            let module = Rc::new(model::module::Plain::new(path, ast, metadata, repository));
+            let module = Rc::new(model::module::Plain::new(
-            urm.module_opened(module.clone());
+                path,
+                ast,
+                metadata,
+                repository,
+                self.read_only.clone_ref(),
+            ));
+            urm.module_opened(module.clone_ref());
             module
         }
 
@@ -242,6 +250,7 @@ pub mod mock {
             // Root ID is needed to generate module path used to get the module.
             model::project::test::expect_root_id(&mut project, crate::test::mock::data::ROOT_ID);
             model::project::test::expect_suggestion_db(&mut project, suggestion_database);
+            model::project::test::expect_read_only(&mut project, self.read_only.clone_ref());
             let json_rpc = language_server::Connection::new_mock_rc(json_client);
             model::project::test::expect_json_rpc(&mut project, json_rpc);
             let binary_rpc = binary::Connection::new_mock_rc(binary_client);
@@ -301,6 +310,7 @@ pub mod mock {
                 position_in_code,
             )
             .unwrap();
+            let read_only = self.read_only.clone_ref();
             executor.run_until_stalled();
             Fixture {
                 executor,
@@ -313,6 +323,7 @@ pub mod mock {
                 project,
                 searcher,
                 ide,
+                read_only,
             }
         }
 
@@ -360,6 +371,7 @@ pub mod mock {
         pub executed_graph: controller::ExecutedGraph,
         pub suggestion_db:  Rc<model::SuggestionDatabase>,
         pub project:        model::Project,
+        pub read_only:      Rc<Cell<bool>>,
         pub ide:            controller::Ide,
         pub searcher:       controller::Searcher,
         #[deref]
@@ -384,7 +396,8 @@ pub mod mock {
             let path = self.data.module_path.clone();
             let ls = self.project.json_rpc();
             let repository = self.project.urm().repository.clone_ref();
-            let module_future = model::module::Synchronized::open(path, ls, parser, repository);
+            let ro = self.read_only.clone_ref();
+            let module_future = model::module::Synchronized::open(path, ls, parser, repository, ro);
             // We can `expect_ready`, because in fact this is synchronous in test conditions.
             // (there's no real asynchronous connection beneath, just the `MockClient`)
             let module = module_future.boxed_local().expect_ready().unwrap();

app/gui/tests/language_server.rs

@@ -240,7 +240,7 @@ async fn ls_text_protocol_test() {
     let new_version = Sha3_224::new(b"Hello, world!");
     let path = move_path.clone();
     let edit = FileEdit { path, edits, old_version, new_version: new_version.clone() };
-    client.apply_text_file_edit(&edit).await.expect("Couldn't apply edit.");
+    client.apply_text_file_edit(&edit, &true).await.expect("Couldn't apply edit.");
 
     let saving_result = client.save_text_file(&move_path, &new_version).await;
     saving_result.expect("Couldn't save file.");

app/gui/view/src/project.rs

@@ -103,6 +103,7 @@ ensogl::define_endpoints! {
         execution_context_interrupt(),
         /// Restart the program execution.
         execution_context_restart(),
+        toggle_read_only(),
     }
 
     Output {
@@ -689,6 +690,8 @@ impl application::View for View {
             (Press, "debug_mode", DEBUG_MODE_SHORTCUT, "disable_debug_mode"),
             (Press, "", "cmd shift t", "execution_context_interrupt"),
             (Press, "", "cmd shift r", "execution_context_restart"),
+            // TODO(#6179): Remove this temporary shortcut when Play button is ready.
+            (Press, "", "ctrl shift b", "toggle_read_only"),
         ]
         .iter()
         .map(|(a, b, c, d)| Self::self_shortcut_when(*a, *c, *d, *b))