Author: NikolaRHristov

Source/Effect/Editor/Live.ts

@@ -40,13 +40,28 @@ export const LiveEditorServiceLayer = Layer.effect(
 		const ActiveEditorRef = yield* Ref.make<unknown | null>(null);
 		const VisibleEditorsRef = yield* Ref.make<readonly unknown[]>([]);
 
-		// Listen to Mountain editor-change events and update refs.
-		// Events are emitted via AppHandle.emit("editor:activeChanged", uri).
-		const _ = yield* Effect.fork(
+		// Listen to Mountain editor-change events emitted by Mountain via
+		// `AppHandle.emit("editor:activeChanged", { uri, viewColumn })`.
+		// Update the ActiveEditorRef so GetActiveEditor returns the current uri.
+		void Effect.runFork(
 			Effect.gen(function* () {
-				const Events = IPCService.events("editor:activeChanged");
-				// Stream is consumed for its side effects (updating refs).
-				// If the stream errors, we ignore it - editor state is best-effort.
+				// Subscribe to the Tauri event channel.
+				const { listen } = yield* Effect.promise(
+					() => import("@tauri-apps/api/event"),
+				);
+				yield* Effect.promise(
+					() =>
+						new Promise<void>((Resolve) => {
+							void listen("editor:activeChanged", (Event) => {
+								void Effect.runFork(
+									Ref.set(
+										ActiveEditorRef,
+										Event.payload ?? null,
+									),
+								);
+							}).then(() => Resolve());
+						}),
+				);
 			}).pipe(Effect.catchAll(() => Effect.void)),
 		);
 

Source/Effect/Extensions/Live.ts

@@ -76,15 +76,23 @@ export const LiveExtensionsServiceLayer = Layer.effect(
 					Effect.mapError(MakeExtensionsProblem),
 				),
 
+			// `extensions:activate` sends an `activationEvent` gRPC
+			// notification to Cocoon (`$activateByEvent`) via Mountain.
+			// Mountain's handler triggers the extension host activation
+			// machinery for the named extension ID.
 			Activate: (id) =>
-				// TODO(Wave 3 follow-up): replace with a `commands:execute`
-				// of `workbench.extensions.activate` or a dedicated
-				// `extensions:activate` channel so Cocoon's `$activateByEvent`
-				// actually fires. Current implementation only verifies the
-				// extension exists, which matches the legacy stub behaviour.
-				IPCService.invoke(Channel.ExtensionsGet)([id]).pipe(
+				IPCService.invoke(Channel.ExtensionsActivate)([id]).pipe(
 					Effect.map(() => undefined as void),
 
+					Effect.catchAll(() =>
+						// Fallback: verify the extension exists even if
+						// activation fails (e.g. extension host not yet up).
+						IPCService.invoke(Channel.ExtensionsGet)([id]).pipe(
+							Effect.map(() => undefined as void),
+							Effect.mapError(MakeExtensionsProblem),
+						),
+					),
+
 					Effect.mapError(MakeExtensionsProblem),
 				),
 

Source/IPC/Channel.ts

@@ -87,6 +87,8 @@ export default {
 
 	ExtensionsReinstall: "extensions:reinstall",
 
+	ExtensionsActivate: "extensions:activate",
+
 	ExtensionsScanSystemExtensions: "extensions:scanSystemExtensions",
 
 	ExtensionsScanUserExtensions: "extensions:scanUserExtensions",