[ide-mode] Support multi-folder workspaces (#6177)

2 files changed, 106 insertions, 26 deletions

diff --git a/packages/core/src/ide/ide-client.test.ts b/packages/core/src/ide/ide-client.test.ts
new file mode 100644
index 00000000..6955e495
--- /dev/null
+++ b/packages/core/src/ide/ide-client.test.ts
@@ -0,0 +1,68 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect } from 'vitest';
+import { IdeClient } from './ide-client.js';
+
+describe('IdeClient.validateWorkspacePath', () => {
+  it('should return valid if cwd is a subpath of the IDE workspace path', () => {
+    const result = IdeClient.validateWorkspacePath(
+      '/Users/person/gemini-cli',
+      'VS Code',
+      '/Users/person/gemini-cli/sub-dir',
+    );
+    expect(result.isValid).toBe(true);
+  });
+
+  it('should return invalid if GEMINI_CLI_IDE_WORKSPACE_PATH is undefined', () => {
+    const result = IdeClient.validateWorkspacePath(
+      undefined,
+      'VS Code',
+      '/Users/person/gemini-cli/sub-dir',
+    );
+    expect(result.isValid).toBe(false);
+    expect(result.error).toContain('Failed to connect');
+  });
+
+  it('should return invalid if GEMINI_CLI_IDE_WORKSPACE_PATH is empty', () => {
+    const result = IdeClient.validateWorkspacePath(
+      '',
+      'VS Code',
+      '/Users/person/gemini-cli/sub-dir',
+    );
+    expect(result.isValid).toBe(false);
+    expect(result.error).toContain('please open a workspace folder');
+  });
+
+  it('should return invalid if cwd is not within the IDE workspace path', () => {
+    const result = IdeClient.validateWorkspacePath(
+      '/some/other/path',
+      'VS Code',
+      '/Users/person/gemini-cli/sub-dir',
+    );
+    expect(result.isValid).toBe(false);
+    expect(result.error).toContain('Directory mismatch');
+  });
+
+  it('should handle multiple workspace paths and return valid', () => {
+    const result = IdeClient.validateWorkspacePath(
+      '/some/other/path:/Users/person/gemini-cli',
+      'VS Code',
+      '/Users/person/gemini-cli/sub-dir',
+    );
+    expect(result.isValid).toBe(true);
+  });
+
+  it('should return invalid if cwd is not in any of the multiple workspace paths', () => {
+    const result = IdeClient.validateWorkspacePath(
+      '/some/other/path:/another/path',
+      'VS Code',
+      '/Users/person/gemini-cli/sub-dir',
+    );
+    expect(result.isValid).toBe(false);
+    expect(result.error).toContain('Directory mismatch');
+  });
+});
diff --git a/packages/core/src/ide/ide-client.ts b/packages/core/src/ide/ide-client.ts
index 94107f21..810e82e0 100644
--- a/packages/core/src/ide/ide-client.ts
+++ b/packages/core/src/ide/ide-client.ts
@@ -5,6 +5,7 @@
  */
 
 import * as fs from 'node:fs';
+import { isSubpath } from '../utils/paths.js';
 import { detectIde, DetectedIde, getIdeInfo } from '../ide/detect-ide.js';
 import {
   ideContext,
@@ -93,7 +94,14 @@ export class IdeClient {
 
     this.setState(IDEConnectionStatus.Connecting);
 
-    if (!this.validateWorkspacePath()) {
+    const { isValid, error } = IdeClient.validateWorkspacePath(
+      process.env['GEMINI_CLI_IDE_WORKSPACE_PATH'],
+      this.currentIdeDisplayName,
+      process.cwd(),
+    );
+
+    if (!isValid) {
+      this.setState(IDEConnectionStatus.Disconnected, error, true);
       return;
     }
 
@@ -245,37 +253,41 @@ export class IdeClient {
     }
   }
 
-  private validateWorkspacePath(): boolean {
-    const ideWorkspacePath = process.env['GEMINI_CLI_IDE_WORKSPACE_PATH'];
+  static validateWorkspacePath(
+    ideWorkspacePath: string | undefined,
+    currentIdeDisplayName: string | undefined,
+    cwd: string,
+  ): { isValid: boolean; error?: string } {
     if (ideWorkspacePath === undefined) {
-      this.setState(
-        IDEConnectionStatus.Disconnected,
-        `Failed to connect to IDE companion extension for ${this.currentIdeDisplayName}. Please ensure the extension is running and try refreshing your terminal. To install the extension, run /ide install.`,
-        true,
-      );
-      return false;
+      return {
+        isValid: false,
+        error: `Failed to connect to IDE companion extension for ${currentIdeDisplayName}. Please ensure the extension is running and try refreshing your terminal. To install the extension, run /ide install.`,
+      };
     }
+
     if (ideWorkspacePath === '') {
-      this.setState(
-        IDEConnectionStatus.Disconnected,
-        `To use this feature, please open a single workspace folder in ${this.currentIdeDisplayName} and try again.`,
-        true,
-      );
-      return false;
+      return {
+        isValid: false,
+        error: `To use this feature, please open a workspace folder in ${currentIdeDisplayName} and try again.`,
+      };
     }
 
-    const idePath = getRealPath(ideWorkspacePath).toLocaleLowerCase();
-    const cwd = getRealPath(process.cwd()).toLocaleLowerCase();
-    const rel = path.relative(idePath, cwd);
-    if (rel.startsWith('..') || path.isAbsolute(rel)) {
-      this.setState(
-        IDEConnectionStatus.Disconnected,
-        `Directory mismatch. Gemini CLI is running in a different location than the open workspace in ${this.currentIdeDisplayName}. Please run the CLI from the same directory as your project's root folder.`,
-        true,
-      );
-      return false;
+    const ideWorkspacePaths = ideWorkspacePath.split(':');
+    const realCwd = getRealPath(cwd);
+    const isWithinWorkspace = ideWorkspacePaths.some((workspacePath) => {
+      const idePath = getRealPath(workspacePath);
+      return isSubpath(idePath, realCwd);
+    });
+
+    if (!isWithinWorkspace) {
+      return {
+        isValid: false,
+        error: `Directory mismatch. Gemini CLI is running in a different location than the open workspace in ${currentIdeDisplayName}. Please run the CLI from one of the following directories: ${ideWorkspacePaths.join(
+          ', ',
+        )}`,
+      };
     }
-    return true;
+    return { isValid: true };
   }
 
   private getPortFromEnv(): string | undefined {