[extensions] Add extensions update command (#6878)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/cli/src/commands/extensions.tsx

@@ -8,6 +8,7 @@ import { CommandModule } from 'yargs';
 import { installCommand } from './extensions/install.js';
 import { uninstallCommand } from './extensions/uninstall.js';
 import { listCommand } from './extensions/list.js';
+import { updateCommand } from './extensions/update.js';
 
 export const extensionsCommand: CommandModule = {
   command: 'extensions <command>',
@@ -17,6 +18,7 @@ export const extensionsCommand: CommandModule = {
       .command(installCommand)
       .command(uninstallCommand)
       .command(listCommand)
+      .command(updateCommand)
       .demandCommand(1, 'You need at least one command before continuing.')
       .version(false),
   handler: () => {

packages/cli/src/commands/extensions/update.ts

@@ -0,0 +1,46 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { CommandModule } from 'yargs';
+import { updateExtension } from '../../config/extension.js';
+
+interface UpdateArgs {
+  name: string;
+}
+
+export async function handleUpdate(args: UpdateArgs) {
+  try {
+    // TODO(chrstnb): we should list extensions if the requested extension is not installed.
+    const updatedExtensionInfo = await updateExtension(args.name);
+    if (!updatedExtensionInfo) {
+      console.log(`Extension "${args.name}" failed to update.`);
+      return;
+    }
+    console.log(
+      `Extension "${args.name}" successfully updated: ${updatedExtensionInfo.originalVersion} → ${updatedExtensionInfo.updatedVersion}.`,
+    );
+  } catch (error) {
+    console.error((error as Error).message);
+    process.exit(1);
+  }
+}
+
+export const updateCommand: CommandModule = {
+  command: 'update <name>',
+  describe: 'Updates an extension.',
+  builder: (yargs) =>
+    yargs
+      .positional('name', {
+        describe: 'The name of the extension to update.',
+        type: 'string',
+      })
+      .check((_argv) => true),
+  handler: async (argv) => {
+    await handleUpdate({
+      name: argv['name'] as string,
+    });
+  },
+};

packages/cli/src/config/extension.test.ts

@@ -15,6 +15,7 @@ import {
   installExtension,
   loadExtensions,
   uninstallExtension,
+  updateExtension,
 } from './extension.js';
 import { execSync } from 'child_process';
 import { SimpleGit, simpleGit } from 'simple-git';
@@ -231,7 +232,7 @@ describe('installExtension', () => {
     await expect(
       installExtension({ source: sourceExtDir, type: 'local' }),
     ).rejects.toThrow(
-      'Error: Extension "my-local-extension" is already installed. Please uninstall it first.',
+      'Extension "my-local-extension" is already installed. Please uninstall it first.',
     );
   });
 
@@ -335,7 +336,7 @@ describe('uninstallExtension', () => {
 
   it('should throw an error if the extension does not exist', async () => {
     await expect(uninstallExtension('nonexistent-extension')).rejects.toThrow(
-      'Error: Extension "nonexistent-extension" not found.',
+      'Extension "nonexistent-extension" not found.',
     );
   });
 });
@@ -363,3 +364,77 @@ function createExtension(
   }
   return extDir;
 }
+
+describe('updateExtension', () => {
+  let tempHomeDir: string;
+  let userExtensionsDir: string;
+
+  beforeEach(() => {
+    tempHomeDir = fs.mkdtempSync(
+      path.join(os.tmpdir(), 'gemini-cli-test-home-'),
+    );
+    vi.mocked(os.homedir).mockReturnValue(tempHomeDir);
+    userExtensionsDir = path.join(tempHomeDir, '.gemini', 'extensions');
+    // Clean up before each test
+    fs.rmSync(userExtensionsDir, { recursive: true, force: true });
+    fs.mkdirSync(userExtensionsDir, { recursive: true });
+
+    vi.mocked(execSync).mockClear();
+  });
+
+  afterEach(() => {
+    fs.rmSync(tempHomeDir, { recursive: true, force: true });
+  });
+
+  it('should update a git-installed extension', async () => {
+    // 1. "Install" an extension
+    const gitUrl = 'https://github.com/google/gemini-extensions.git';
+    const extensionName = 'gemini-extensions';
+    const targetExtDir = path.join(userExtensionsDir, extensionName);
+    const metadataPath = path.join(targetExtDir, INSTALL_METADATA_FILENAME);
+
+    // Create the "installed" extension directory and files
+    fs.mkdirSync(targetExtDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(targetExtDir, EXTENSIONS_CONFIG_FILENAME),
+      JSON.stringify({ name: extensionName, version: '1.0.0' }),
+    );
+    fs.writeFileSync(
+      metadataPath,
+      JSON.stringify({ source: gitUrl, type: 'git' }),
+    );
+
+    // 2. Mock the git clone for the update
+    const clone = vi.fn().mockImplementation(async (_, destination) => {
+      fs.mkdirSync(destination, { recursive: true });
+      // This is the "updated" version
+      fs.writeFileSync(
+        path.join(destination, EXTENSIONS_CONFIG_FILENAME),
+        JSON.stringify({ name: extensionName, version: '1.1.0' }),
+      );
+    });
+
+    const mockedSimpleGit = simpleGit as vi.MockedFunction<typeof simpleGit>;
+    mockedSimpleGit.mockReturnValue({
+      clone,
+    } as unknown as SimpleGit);
+
+    // 3. Call updateExtension
+    const updateInfo = await updateExtension(extensionName);
+
+    // 4. Assertions
+    expect(updateInfo).toEqual({
+      originalVersion: '1.0.0',
+      updatedVersion: '1.1.0',
+    });
+
+    // Check that the config file reflects the new version
+    const updatedConfig = JSON.parse(
+      fs.readFileSync(
+        path.join(targetExtDir, EXTENSIONS_CONFIG_FILENAME),
+        'utf-8',
+      ),
+    );
+    expect(updatedConfig.version).toBe('1.1.0');
+  });
+});

packages/cli/src/config/extension.ts

@@ -39,6 +39,11 @@ export interface ExtensionInstallMetadata {
   type: 'git' | 'local';
 }
 
+export interface ExtensionUpdateInfo {
+  originalVersion: string;
+  updatedVersion: string;
+}
+
 export class ExtensionStorage {
   private readonly extensionName: string;
 
@@ -321,7 +326,7 @@ export async function installExtension(
       )
     ) {
       throw new Error(
-        `Error: Extension "${newExtensionName}" is already installed. Please uninstall it first.`,
+        `Extension "${newExtensionName}" is already installed. Please uninstall it first.`,
       );
     }
 
@@ -346,7 +351,7 @@ export async function uninstallExtension(extensionName: string): Promise<void> {
       (installed) => installed.config.name === extensionName,
     )
   ) {
-    throw new Error(`Error: Extension "${extensionName}" not found.`);
+    throw new Error(`Extension "${extensionName}" not found.`);
   }
   const storage = new ExtensionStorage(extensionName);
   return await fs.promises.rm(storage.getExtensionDir(), {
@@ -381,3 +386,45 @@ export function toOutputString(extension: Extension): string {
   }
   return output;
 }
+
+export async function updateExtension(
+  extensionName: string,
+): Promise<ExtensionUpdateInfo | undefined> {
+  const installedExtensions = loadUserExtensions();
+  const extension = installedExtensions.find(
+    (installed) => installed.config.name === extensionName,
+  );
+  if (!extension) {
+    throw new Error(
+      `Extension "${extensionName}" not found. Run gemini extensions list to see available extensions.`,
+    );
+  }
+  if (!extension.installMetadata) {
+    throw new Error(
+      `Extension cannot be updated because it is missing the .gemini-extension.install.json file. To update manually, uninstall and then reinstall the updated version.`,
+    );
+  }
+  const originalVersion = extension.config.version;
+  const tempDir = await ExtensionStorage.createTmpDir();
+  try {
+    await copyExtension(extension.path, tempDir);
+    await uninstallExtension(extensionName);
+    await installExtension(extension.installMetadata);
+
+    const updatedExtension = loadExtension(extension.path);
+    if (!updatedExtension) {
+      throw new Error('Updated extension not found after installation.');
+    }
+    const updatedVersion = updatedExtension.config.version;
+    return {
+      originalVersion,
+      updatedVersion,
+    };
+  } catch (e) {
+    console.error(`Error updating extension, rolling back. ${e}`);
+    await copyExtension(tempDir, extension.path);
+    throw e;
+  } finally {
+    await fs.promises.rm(tempDir, { recursive: true, force: true });
+  }
+}