[ide-mode] Send the cursor and selected text from the IDE server (#4621)

4 files changed, 27 insertions, 3 deletions

diff --git a/packages/vscode-ide-companion/src/extension.ts b/packages/vscode-ide-companion/src/extension.ts
index 912b9b8f..74bcaf89 100644
--- a/packages/vscode-ide-companion/src/extension.ts
+++ b/packages/vscode-ide-companion/src/extension.ts
@@ -15,7 +15,6 @@ let log: (message: string) => void = () => {};
 export async function activate(context: vscode.ExtensionContext) {
   logger = vscode.window.createOutputChannel('Gemini CLI IDE Companion');
   log = createLogger(context, logger);
-
   log('Extension activated');
   ideServer = new IDEServer(log);
   try {
diff --git a/packages/vscode-ide-companion/src/ide-server.ts b/packages/vscode-ide-companion/src/ide-server.ts
index 75828485..aad86a08 100644
--- a/packages/vscode-ide-companion/src/ide-server.ts
+++ b/packages/vscode-ide-companion/src/ide-server.ts
@@ -18,6 +18,7 @@ import { RecentFilesManager } from './recent-files-manager.js';
 
 const MCP_SESSION_ID_HEADER = 'mcp-session-id';
 const IDE_SERVER_PORT_ENV_VAR = 'GEMINI_CLI_IDE_SERVER_PORT';
+const MAX_SELECTED_TEXT_LENGTH = 16384; // 16 KiB limit
 
 function sendOpenFilesChangedNotification(
   transport: StreamableHTTPServerTransport,
@@ -29,6 +30,19 @@ function sendOpenFilesChangedNotification(
     editor && editor.document.uri.scheme === 'file'
       ? editor.document.uri.fsPath
       : '';
+  const selection = editor?.selection;
+  const cursor = selection
+    ? {
+        // This value is a zero-based index, but the vscode IDE is one-based.
+        line: selection.active.line + 1,
+        character: selection.active.character,
+      }
+    : undefined;
+  let selectedText = editor?.document.getText(selection) ?? undefined;
+  if (selectedText && selectedText.length > MAX_SELECTED_TEXT_LENGTH) {
+    selectedText =
+      selectedText.substring(0, MAX_SELECTED_TEXT_LENGTH) + '... [TRUNCATED]';
+  }
   const notification: JSONRPCNotification = {
     jsonrpc: '2.0',
     method: 'ide/openFilesChanged',
@@ -37,6 +51,8 @@ function sendOpenFilesChangedNotification(
       recentOpenFiles: recentFilesManager.recentFiles.filter(
         (file) => file.filePath !== filePath,
       ),
+      cursor,
+      selectedText,
     },
   };
   log(
@@ -69,7 +85,7 @@ export class IDEServer {
     const mcpServer = createMcpServer();
 
     const recentFilesManager = new RecentFilesManager(context);
-    const disposable = recentFilesManager.onDidChange(() => {
+    const onDidChangeSubscription = recentFilesManager.onDidChange(() => {
       for (const transport of Object.values(transports)) {
         sendOpenFilesChangedNotification(
           transport,
@@ -78,7 +94,7 @@ export class IDEServer {
         );
       }
     });
-    context.subscriptions.push(disposable);
+    context.subscriptions.push(onDidChangeSubscription);
 
     app.post('/mcp', async (req: Request, res: Response) => {
       const sessionId = req.headers[MCP_SESSION_ID_HEADER] as
diff --git a/packages/vscode-ide-companion/src/recent-files-manager.test.ts b/packages/vscode-ide-companion/src/recent-files-manager.test.ts
index 97f19f30..9d56a10d 100644
--- a/packages/vscode-ide-companion/src/recent-files-manager.test.ts
+++ b/packages/vscode-ide-companion/src/recent-files-manager.test.ts
@@ -28,6 +28,7 @@ vi.mock('vscode', () => ({
   }),
   window: {
     onDidChangeActiveTextEditor: vi.fn(),
+    onDidChangeTextEditorSelection: vi.fn(),
   },
   workspace: {
     onDidDeleteFiles: vi.fn(),
diff --git a/packages/vscode-ide-companion/src/recent-files-manager.ts b/packages/vscode-ide-companion/src/recent-files-manager.ts
index cbe7e9a9..317cc903 100644
--- a/packages/vscode-ide-companion/src/recent-files-manager.ts
+++ b/packages/vscode-ide-companion/src/recent-files-manager.ts
@@ -47,11 +47,19 @@ export class RecentFilesManager {
         this.add(newUri);
       }
     });
+
+    const selectionWatcher = vscode.window.onDidChangeTextEditorSelection(
+      () => {
+        this.fireWithDebounce();
+      },
+    );
+
     context.subscriptions.push(
       editorWatcher,
       deleteWatcher,
       closeWatcher,
       renameWatcher,
+      selectionWatcher,
     );
   }