Add simple extensions release flow support (#8498)

docs/extension-releasing.md

@@ -0,0 +1,78 @@
+# Extension Releasing
+
+Gemini CLI extensions can be distributed as pre-built binaries through GitHub Releases. This provides a faster and more reliable installation experience for users, as it avoids the need to clone the repository and build the extension from source.
+
+## Asset naming convention
+
+To ensure Gemini CLI can automatically find the correct release asset for each platform, you should follow this naming convention. The CLI will search for assets in the following order:
+
+1.  **Platform and Architecture-Specific:** `{platform}.{arch}.{name}.{extension}`
+2.  **Platform-Specific:** `{platform}.{name}.{extension}`
+3.  **Generic:** If only one asset is provided, it will be used as a generic fallback.
+
+- `{name}`: The name of your extension.
+- `{platform}`: The operating system. Supported values are:
+  - `darwin` (macOS)
+  - `linux`
+  - `win32` (Windows)
+- `{arch}`: The architecture. Supported values are:
+  - `x64`
+  - `arm64`
+- `{extension}`: The file extension of the archive (e.g., `.tar.gz` or `.zip`).
+
+**Examples:**
+
+- `darwin.arm64.my-tool.tar.gz` (specific to Apple Silicon Macs)
+- `darwin.my-tool.tar.gz` (for all Macs)
+- `linux.x64.my-tool.tar.gz`
+- `win32.my-tool.zip`
+
+If your extension is platform-independent, you can provide a single generic asset. In this case, there should be only one asset attached to the release.
+
+## Archive structure
+
+The `gemini-extension.json` file must be at the root of the archive.
+
+## Example GitHub Actions workflow
+
+Here is an example of a GitHub Actions workflow that builds and releases a Gemini CLI extension for multiple platforms:
+
+```yaml
+name: Release Extension
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '20'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build extension
+        run: npm run build
+
+      - name: Create release assets
+        run: |
+          npm run package -- --platform=darwin --arch=arm64
+          npm run package -- --platform=linux --arch=x64
+          npm run package -- --platform=win32 --arch=x64
+
+      - name: Create GitHub Release
+        uses: softprops/action-gh-release@v1
+        with:
+          files: |
+            release/darwin.arm64.my-tool.tar.gz
+            release/linux.arm64.my-tool.tar.gz
+            release/win32.arm64.my-tool.zip
+```

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

@@ -5,10 +5,8 @@
  */
 
 import type { CommandModule } from 'yargs';
-import {
+import { installExtension } from '../../config/extension.js';
-  installExtension,
+import type { ExtensionInstallMetadata } from '@google/gemini-cli-core';
-  type ExtensionInstallMetadata,
-} from '../../config/extension.js';
 
 import { getErrorMessage } from '../../utils/errors.js';
 

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

@@ -5,10 +5,8 @@
  */
 
 import type { CommandModule } from 'yargs';
-import {
+import { installExtension } from '../../config/extension.js';
-  installExtension,
+import type { ExtensionInstallMetadata } from '@google/gemini-cli-core';
-  type ExtensionInstallMetadata,
-} from '../../config/extension.js';
 
 import { getErrorMessage } from '../../utils/errors.js';
 

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

@@ -13,7 +13,6 @@ import {
   INSTALL_METADATA_FILENAME,
   annotateActiveExtensions,
   checkForAllExtensionUpdates,
-  checkForExtensionUpdate,
   disableExtension,
   enableExtension,
   installExtension,
@@ -23,7 +22,6 @@ import {
   uninstallExtension,
   updateExtension,
   type Extension,
-  type ExtensionInstallMetadata,
 } from './extension.js';
 import {
   GEMINI_DIR,
@@ -32,6 +30,7 @@ import {
   ClearcutLogger,
   type Config,
   ExtensionUninstallEvent,
+  type ExtensionInstallMetadata,
 } from '@google/gemini-cli-core';
 import { execSync } from 'node:child_process';
 import { SettingScope } from './settings.js';
@@ -1140,118 +1139,6 @@ describe('extension tests', () => {
     });
   });
 
-  describe('checkForExtensionUpdate', () => {
-    it('should return UpdateAvailable for a git extension with updates', async () => {
-      const extensionDir = createExtension({
-        extensionsDir: userExtensionsDir,
-        name: 'test-extension',
-        version: '1.0.0',
-        installMetadata: {
-          source: 'https://some.git/repo',
-          type: 'git',
-        },
-      });
-      const extension = annotateActiveExtensions(
-        [
-          loadExtension({
-            extensionDir,
-            workspaceDir: tempWorkspaceDir,
-          })!,
-        ],
-        [],
-        process.cwd(),
-      )[0];
-
-      mockGit.getRemotes.mockResolvedValue([
-        { name: 'origin', refs: { fetch: 'https://some.git/repo' } },
-      ]);
-      mockGit.listRemote.mockResolvedValue('remoteHash	HEAD');
-      mockGit.revparse.mockResolvedValue('localHash');
-
-      const result = await checkForExtensionUpdate(extension);
-      expect(result).toBe(ExtensionUpdateState.UPDATE_AVAILABLE);
-    });
-
-    it('should return UpToDate for a git extension with no updates', async () => {
-      const extensionDir = createExtension({
-        extensionsDir: userExtensionsDir,
-        name: 'test-extension',
-        version: '1.0.0',
-        installMetadata: {
-          source: 'https://some.git/repo',
-          type: 'git',
-        },
-      });
-      const extension = annotateActiveExtensions(
-        [
-          loadExtension({
-            extensionDir,
-            workspaceDir: tempWorkspaceDir,
-          })!,
-        ],
-        [],
-        process.cwd(),
-      )[0];
-
-      mockGit.getRemotes.mockResolvedValue([
-        { name: 'origin', refs: { fetch: 'https://some.git/repo' } },
-      ]);
-      mockGit.listRemote.mockResolvedValue('sameHash	HEAD');
-      mockGit.revparse.mockResolvedValue('sameHash');
-
-      const result = await checkForExtensionUpdate(extension);
-      expect(result).toBe(ExtensionUpdateState.UP_TO_DATE);
-    });
-
-    it('should return NotUpdatable for a non-git extension', async () => {
-      const extensionDir = createExtension({
-        extensionsDir: userExtensionsDir,
-        name: 'local-extension',
-        version: '1.0.0',
-      });
-      const extension = annotateActiveExtensions(
-        [
-          loadExtension({
-            extensionDir,
-            workspaceDir: tempWorkspaceDir,
-          })!,
-        ],
-        [],
-        process.cwd(),
-      )[0];
-
-      const result = await checkForExtensionUpdate(extension);
-      expect(result).toBe(ExtensionUpdateState.NOT_UPDATABLE);
-    });
-
-    it('should return Error when git check fails', async () => {
-      const extensionDir = createExtension({
-        extensionsDir: userExtensionsDir,
-        name: 'error-extension',
-        version: '1.0.0',
-        installMetadata: {
-          source: 'https://some.git/repo',
-          type: 'git',
-        },
-      });
-      const extension = annotateActiveExtensions(
-        [
-          loadExtension({
-            extensionDir,
-            workspaceDir: tempWorkspaceDir,
-          })!,
-        ],
-        [],
-        process.cwd(),
-      )[0];
-
-      mockGit.getRemotes.mockRejectedValue(new Error('Git error'));
-
-      const result = await checkForExtensionUpdate(extension);
-      expect(result).toBe(ExtensionUpdateState.ERROR);
-    });
-  });
-
   describe('disableExtension', () => {
     it('should disable an extension at the user scope', () => {
       disableExtension('my-extension', SettingScope.User);

packages/cli/src/config/extension.ts

@@ -7,6 +7,7 @@
 import type {
   MCPServerConfig,
   GeminiCLIExtension,
+  ExtensionInstallMetadata,
 } from '@google/gemini-cli-core';
 import {
   GEMINI_DIR,
@@ -19,7 +20,6 @@ import {
 import * as fs from 'node:fs';
 import * as path from 'node:path';
 import * as os from 'node:os';
-import { simpleGit } from 'simple-git';
 import { SettingScope, loadSettings } from '../config/settings.js';
 import { getErrorMessage } from '../utils/errors.js';
 import { recursivelyHydrateStrings } from './extensions/variables.js';
@@ -27,6 +27,11 @@ import { isWorkspaceTrusted } from './trustedFolders.js';
 import { resolveEnvVarsInObject } from '../utils/envVarResolver.js';
 import { randomUUID } from 'node:crypto';
 import { ExtensionUpdateState } from '../ui/state/extensions.js';
+import {
+  cloneFromGit,
+  checkForExtensionUpdate,
+  downloadFromGitHubRelease,
+} from './extensions/github.js';
 import type { LoadExtensionContext } from './extensions/variableSchema.js';
 import { ExtensionEnablementManager } from './extensions/extensionEnablement.js';
 
@@ -50,12 +55,6 @@ export interface ExtensionConfig {
   excludeTools?: string[];
 }
 
-export interface ExtensionInstallMetadata {
-  source: string;
-  type: 'git' | 'local' | 'link';
-  ref?: string;
-}
-
 export interface ExtensionUpdateInfo {
   name: string;
   originalVersion: string;
@@ -301,7 +300,6 @@ export function annotateActiveExtensions(
   const manager = new ExtensionEnablementManager(
     ExtensionStorage.getUserExtensionsDir(),
   );
-
   const annotatedExtensions: GeminiCLIExtension[] = [];
   if (enabledExtensionNames.length === 0) {
     return extensions.map((extension) => ({
@@ -309,9 +307,7 @@ export function annotateActiveExtensions(
       version: extension.config.version,
       isActive: manager.isEnabled(extension.config.name, workspaceDir),
       path: extension.path,
-      source: extension.installMetadata?.source,
+      installMetadata: extension.installMetadata,
-      type: extension.installMetadata?.type,
-      ref: extension.installMetadata?.ref,
     }));
   }
 
@@ -328,9 +324,7 @@ export function annotateActiveExtensions(
       version: extension.config.version,
       isActive: false,
       path: extension.path,
-      source: extension.installMetadata?.source,
+      installMetadata: extension.installMetadata,
-      type: extension.installMetadata?.type,
-      ref: extension.installMetadata?.ref,
     }));
   }
 
@@ -349,6 +343,7 @@ export function annotateActiveExtensions(
       version: extension.config.version,
       isActive,
       path: extension.path,
+      installMetadata: extension.installMetadata,
     });
   }
 
@@ -359,43 +354,6 @@ export function annotateActiveExtensions(
   return annotatedExtensions;
 }
 
-/**
- * Clones a Git repository to a specified local path.
- * @param installMetadata The metadata for the extension to install.
- * @param destination The destination path to clone the repository to.
- */
-async function cloneFromGit(
-  installMetadata: ExtensionInstallMetadata,
-  destination: string,
-): Promise<void> {
-  try {
-    const git = simpleGit(destination);
-    await git.clone(installMetadata.source, './', ['--depth', '1']);
-
-    const remotes = await git.getRemotes(true);
-    if (remotes.length === 0) {
-      throw new Error(
-        `Unable to find any remotes for repo ${installMetadata.source}`,
-      );
-    }
-
-    const refToFetch = installMetadata.ref || 'HEAD';
-
-    await git.fetch(remotes[0].name, refToFetch);
-
-    // After fetching, checkout FETCH_HEAD to get the content of the fetched ref.
-    // This results in a detached HEAD state, which is fine for this purpose.
-    await git.checkout('FETCH_HEAD');
-  } catch (error) {
-    throw new Error(
-      `Failed to clone Git repository from ${installMetadata.source}`,
-      {
-        cause: error,
-      },
-    );
-  }
-}
-
 /**
  * Asks users a prompt and awaits for a y/n response
  * @param prompt A yes/no prompt to ask the user
@@ -445,9 +403,22 @@ export async function installExtension(
 
     let tempDir: string | undefined;
 
-    if (installMetadata.type === 'git') {
+    if (
+      installMetadata.type === 'git' ||
+      installMetadata.type === 'github-release'
+    ) {
       tempDir = await ExtensionStorage.createTmpDir();
-      await cloneFromGit(installMetadata, tempDir);
+      try {
+        const tagName = await downloadFromGitHubRelease(
+          installMetadata,
+          tempDir,
+        );
+        updateExtensionVersion(tempDir, tagName);
+        installMetadata.type = 'github-release';
+      } catch (_error) {
+        await cloneFromGit(installMetadata, tempDir);
+        installMetadata.type = 'git';
+      }
       localSourcePath = tempDir;
     } else if (
       installMetadata.type === 'local' ||
@@ -488,7 +459,11 @@ export async function installExtension(
       }
       await fs.promises.mkdir(destinationPath, { recursive: true });
 
-      if (installMetadata.type === 'local' || installMetadata.type === 'git') {
+      if (
+        installMetadata.type === 'local' ||
+        installMetadata.type === 'git' ||
+        installMetadata.type === 'github-release'
+      ) {
         await copyExtension(localSourcePath, destinationPath);
       }
 
@@ -536,6 +511,21 @@ export async function installExtension(
   }
 }
 
+async function updateExtensionVersion(
+  extensionDir: string,
+  extensionVersion: string,
+) {
+  const configFilePath = path.join(extensionDir, EXTENSIONS_CONFIG_FILENAME);
+  if (fs.existsSync(configFilePath)) {
+    const configContent = await fs.promises.readFile(configFilePath, 'utf-8');
+    const config = JSON.parse(configContent);
+    config.version = extensionVersion;
+    await fs.promises.writeFile(
+      configFilePath,
+      JSON.stringify(config, null, 2),
+    );
+  }
+}
 async function requestConsent(extensionConfig: ExtensionConfig) {
   const mcpServerEntries = Object.entries(extensionConfig.mcpServers || {});
   if (mcpServerEntries.length) {
@@ -662,13 +652,15 @@ export async function updateExtension(
   cwd: string = process.cwd(),
   setExtensionUpdateState: (updateState: ExtensionUpdateState) => void,
 ): Promise<ExtensionUpdateInfo> {
-  if (!extension.type) {
+  const installMetadata = loadInstallMetadata(extension.path);
+
+  if (!installMetadata?.type) {
     setExtensionUpdateState(ExtensionUpdateState.ERROR);
     throw new Error(
       `Extension ${extension.name} cannot be updated, type is unknown.`,
     );
   }
-  if (extension.type === 'link') {
+  if (installMetadata?.type === 'link') {
     setExtensionUpdateState(ExtensionUpdateState.UP_TO_DATE);
     throw new Error(`Extension is linked so does not need to be updated`);
   }
@@ -679,15 +671,7 @@ export async function updateExtension(
   try {
     await copyExtension(extension.path, tempDir);
     await uninstallExtension(extension.name, cwd);
-    await installExtension(
+    await installExtension(installMetadata, false, cwd);
-      {
-        source: extension.source!,
-        type: extension.type,
-        ref: extension.ref,
-      },
-      false,
-      cwd,
-    );
 
     const updatedExtensionStorage = new ExtensionStorage(extension.name);
     const updatedExtension = loadExtension({
@@ -786,61 +770,15 @@ export async function checkForAllExtensionUpdates(
 ): Promise<Map<string, ExtensionUpdateState>> {
   const finalState = new Map<string, ExtensionUpdateState>();
   for (const extension of extensions) {
-    finalState.set(extension.name, await checkForExtensionUpdate(extension));
+    if (!extension.installMetadata) {
+      finalState.set(extension.name, ExtensionUpdateState.NOT_UPDATABLE);
+      continue;
+    }
+    finalState.set(
+      extension.name,
+      await checkForExtensionUpdate(extension.installMetadata),
+    );
   }
   setExtensionsUpdateState(finalState);
   return finalState;
 }
-
-export async function checkForExtensionUpdate(
-  extension: GeminiCLIExtension,
-): Promise<ExtensionUpdateState> {
-  if (extension.type !== 'git') {
-    return ExtensionUpdateState.NOT_UPDATABLE;
-  }
-
-  try {
-    const git = simpleGit(extension.path);
-    const remotes = await git.getRemotes(true);
-    if (remotes.length === 0) {
-      console.error('No git remotes found.');
-      return ExtensionUpdateState.ERROR;
-    }
-    const remoteUrl = remotes[0].refs.fetch;
-    if (!remoteUrl) {
-      console.error(`No fetch URL found for git remote ${remotes[0].name}.`);
-      return ExtensionUpdateState.ERROR;
-    }
-
-    // Determine the ref to check on the remote.
-    const refToCheck = extension.ref || 'HEAD';
-
-    const lsRemoteOutput = await git.listRemote([remoteUrl, refToCheck]);
-
-    if (typeof lsRemoteOutput !== 'string' || lsRemoteOutput.trim() === '') {
-      console.error(`Git ref ${refToCheck} not found.`);
-      return ExtensionUpdateState.ERROR;
-    }
-
-    const remoteHash = lsRemoteOutput.split('\t')[0];
-    const localHash = await git.revparse(['HEAD']);
-
-    if (!remoteHash) {
-      console.error(
-        `Unable to parse hash from git ls-remote output "${lsRemoteOutput}"`,
-      );
-      return ExtensionUpdateState.ERROR;
-    } else if (remoteHash === localHash) {
-      return ExtensionUpdateState.UP_TO_DATE;
-    } else {
-      return ExtensionUpdateState.UPDATE_AVAILABLE;
-    }
-  } catch (error) {
-    console.error(
-      `Failed to check for updates for extension "${
-        extension.name
-      }": ${getErrorMessage(error)}`,
-    );
-    return ExtensionUpdateState.ERROR;
-  }
-}

packages/cli/src/config/extensions/github.test.ts

@@ -0,0 +1,234 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import {
+  checkForExtensionUpdate,
+  cloneFromGit,
+  findReleaseAsset,
+} from './github.js';
+import { simpleGit, type SimpleGit } from 'simple-git';
+import { ExtensionUpdateState } from '../../ui/state/extensions.js';
+import type * as os from 'node:os';
+import type { ExtensionInstallMetadata } from '@google/gemini-cli-core';
+
+const mockPlatform = vi.hoisted(() => vi.fn());
+const mockArch = vi.hoisted(() => vi.fn());
+vi.mock('node:os', async (importOriginal) => {
+  const actual = await importOriginal<typeof os>();
+  return {
+    ...actual,
+    platform: mockPlatform,
+    arch: mockArch,
+  };
+});
+
+vi.mock('simple-git');
+
+describe('git extension helpers', () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  describe('cloneFromGit', () => {
+    const mockGit = {
+      clone: vi.fn(),
+      getRemotes: vi.fn(),
+      fetch: vi.fn(),
+      checkout: vi.fn(),
+    };
+
+    beforeEach(() => {
+      vi.mocked(simpleGit).mockReturnValue(mockGit as unknown as SimpleGit);
+    });
+
+    it('should clone, fetch and checkout a repo', async () => {
+      const installMetadata = {
+        source: 'http://my-repo.com',
+        ref: 'my-ref',
+        type: 'git' as const,
+      };
+      const destination = '/dest';
+      mockGit.getRemotes.mockResolvedValue([
+        { name: 'origin', refs: { fetch: 'http://my-repo.com' } },
+      ]);
+
+      await cloneFromGit(installMetadata, destination);
+
+      expect(mockGit.clone).toHaveBeenCalledWith('http://my-repo.com', './', [
+        '--depth',
+        '1',
+      ]);
+      expect(mockGit.getRemotes).toHaveBeenCalledWith(true);
+      expect(mockGit.fetch).toHaveBeenCalledWith('origin', 'my-ref');
+      expect(mockGit.checkout).toHaveBeenCalledWith('FETCH_HEAD');
+    });
+
+    it('should use HEAD if ref is not provided', async () => {
+      const installMetadata = {
+        source: 'http://my-repo.com',
+        type: 'git' as const,
+      };
+      const destination = '/dest';
+      mockGit.getRemotes.mockResolvedValue([
+        { name: 'origin', refs: { fetch: 'http://my-repo.com' } },
+      ]);
+
+      await cloneFromGit(installMetadata, destination);
+
+      expect(mockGit.fetch).toHaveBeenCalledWith('origin', 'HEAD');
+    });
+
+    it('should throw if no remotes are found', async () => {
+      const installMetadata = {
+        source: 'http://my-repo.com',
+        type: 'git' as const,
+      };
+      const destination = '/dest';
+      mockGit.getRemotes.mockResolvedValue([]);
+
+      await expect(cloneFromGit(installMetadata, destination)).rejects.toThrow(
+        'Failed to clone Git repository from http://my-repo.com',
+      );
+    });
+
+    it('should throw on clone error', async () => {
+      const installMetadata = {
+        source: 'http://my-repo.com',
+        type: 'git' as const,
+      };
+      const destination = '/dest';
+      mockGit.clone.mockRejectedValue(new Error('clone failed'));
+
+      await expect(cloneFromGit(installMetadata, destination)).rejects.toThrow(
+        'Failed to clone Git repository from http://my-repo.com',
+      );
+    });
+  });
+
+  describe('checkForExtensionUpdate', () => {
+    const mockGit = {
+      getRemotes: vi.fn(),
+      listRemote: vi.fn(),
+      revparse: vi.fn(),
+    };
+
+    beforeEach(() => {
+      vi.mocked(simpleGit).mockReturnValue(mockGit as unknown as SimpleGit);
+    });
+
+    it('should return NOT_UPDATABLE for non-git extensions', async () => {
+      const installMetadata: ExtensionInstallMetadata = {
+        type: 'local',
+        source: '',
+      };
+      const result = await checkForExtensionUpdate(installMetadata);
+      expect(result).toBe(ExtensionUpdateState.NOT_UPDATABLE);
+    });
+
+    it('should return ERROR if no remotes found', async () => {
+      const installMetadata: ExtensionInstallMetadata = {
+        type: 'git',
+        source: '',
+      };
+      mockGit.getRemotes.mockResolvedValue([]);
+      const result = await checkForExtensionUpdate(installMetadata);
+      expect(result).toBe(ExtensionUpdateState.ERROR);
+    });
+
+    it('should return UPDATE_AVAILABLE when remote hash is different', async () => {
+      const installMetadata: ExtensionInstallMetadata = {
+        type: 'git',
+        source: '/ext',
+      };
+      mockGit.getRemotes.mockResolvedValue([
+        { name: 'origin', refs: { fetch: 'http://my-repo.com' } },
+      ]);
+      mockGit.listRemote.mockResolvedValue('remote-hash\tHEAD');
+      mockGit.revparse.mockResolvedValue('local-hash');
+
+      const result = await checkForExtensionUpdate(installMetadata);
+      expect(result).toBe(ExtensionUpdateState.UPDATE_AVAILABLE);
+    });
+
+    it('should return UP_TO_DATE when remote and local hashes are the same', async () => {
+      const installMetadata: ExtensionInstallMetadata = {
+        type: 'git',
+        source: '/ext',
+      };
+      mockGit.getRemotes.mockResolvedValue([
+        { name: 'origin', refs: { fetch: 'http://my-repo.com' } },
+      ]);
+      mockGit.listRemote.mockResolvedValue('same-hash\tHEAD');
+      mockGit.revparse.mockResolvedValue('same-hash');
+
+      const result = await checkForExtensionUpdate(installMetadata);
+      expect(result).toBe(ExtensionUpdateState.UP_TO_DATE);
+    });
+
+    it('should return ERROR on git error', async () => {
+      const installMetadata: ExtensionInstallMetadata = {
+        type: 'git',
+        source: '/ext',
+      };
+      mockGit.getRemotes.mockRejectedValue(new Error('git error'));
+      const result = await checkForExtensionUpdate(installMetadata);
+      expect(result).toBe(ExtensionUpdateState.ERROR);
+    });
+  });
+
+  describe('findReleaseAsset', () => {
+    const assets = [
+      { name: 'darwin.arm64.extension.tar.gz', browser_download_url: 'url1' },
+      { name: 'darwin.x64.extension.tar.gz', browser_download_url: 'url2' },
+      { name: 'linux.x64.extension.tar.gz', browser_download_url: 'url3' },
+      { name: 'win32.x64.extension.tar.gz', browser_download_url: 'url4' },
+      { name: 'extension-generic.tar.gz', browser_download_url: 'url5' },
+    ];
+
+    it('should find asset matching platform and architecture', () => {
+      mockPlatform.mockReturnValue('darwin');
+      mockArch.mockReturnValue('arm64');
+      const result = findReleaseAsset(assets);
+      expect(result).toEqual(assets[0]);
+    });
+
+    it('should find asset matching platform if arch does not match', () => {
+      mockPlatform.mockReturnValue('linux');
+      mockArch.mockReturnValue('arm64');
+      const result = findReleaseAsset(assets);
+      expect(result).toEqual(assets[2]);
+    });
+
+    it('should return undefined if no matching asset is found', () => {
+      mockPlatform.mockReturnValue('sunos');
+      mockArch.mockReturnValue('x64');
+      const result = findReleaseAsset(assets);
+      expect(result).toBeUndefined();
+    });
+
+    it('should find generic asset if it is the only one', () => {
+      const singleAsset = [
+        { name: 'extension.tar.gz', browser_download_url: 'url' },
+      ];
+      mockPlatform.mockReturnValue('darwin');
+      mockArch.mockReturnValue('arm64');
+      const result = findReleaseAsset(singleAsset);
+      expect(result).toEqual(singleAsset[0]);
+    });
+
+    it('should return undefined if multiple generic assets exist', () => {
+      const multipleGenericAssets = [
+        { name: 'extension-1.tar.gz', browser_download_url: 'url1' },
+        { name: 'extension-2.tar.gz', browser_download_url: 'url2' },
+      ];
+      mockPlatform.mockReturnValue('darwin');
+      mockArch.mockReturnValue('arm64');
+      const result = findReleaseAsset(multipleGenericAssets);
+      expect(result).toBeUndefined();
+    });
+  });
+});

packages/cli/src/config/extensions/github.ts

@@ -0,0 +1,346 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { simpleGit } from 'simple-git';
+import { getErrorMessage } from '../../utils/errors.js';
+import type { ExtensionInstallMetadata } from '@google/gemini-cli-core';
+import { ExtensionUpdateState } from '../../ui/state/extensions.js';
+import * as os from 'node:os';
+import * as https from 'node:https';
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import { execSync } from 'node:child_process';
+
+function getGitHubToken(): string | undefined {
+  return process.env['GITHUB_TOKEN'];
+}
+
+/**
+ * Clones a Git repository to a specified local path.
+ * @param installMetadata The metadata for the extension to install.
+ * @param destination The destination path to clone the repository to.
+ */
+export async function cloneFromGit(
+  installMetadata: ExtensionInstallMetadata,
+  destination: string,
+): Promise<void> {
+  try {
+    const git = simpleGit(destination);
+    let sourceUrl = installMetadata.source;
+    const token = getGitHubToken();
+    if (token) {
+      try {
+        const parsedUrl = new URL(sourceUrl);
+        if (
+          parsedUrl.protocol === 'https:' &&
+          parsedUrl.hostname === 'github.com'
+        ) {
+          if (!parsedUrl.username) {
+            parsedUrl.username = token;
+          }
+          sourceUrl = parsedUrl.toString();
+        }
+      } catch {
+        // If source is not a valid URL, we don't inject the token.
+        // We let git handle the source as is.
+      }
+    }
+    await git.clone(sourceUrl, './', ['--depth', '1']);
+
+    const remotes = await git.getRemotes(true);
+    if (remotes.length === 0) {
+      throw new Error(
+        `Unable to find any remotes for repo ${installMetadata.source}`,
+      );
+    }
+
+    const refToFetch = installMetadata.ref || 'HEAD';
+
+    await git.fetch(remotes[0].name, refToFetch);
+
+    // After fetching, checkout FETCH_HEAD to get the content of the fetched ref.
+    // This results in a detached HEAD state, which is fine for this purpose.
+    await git.checkout('FETCH_HEAD');
+  } catch (error) {
+    throw new Error(
+      `Failed to clone Git repository from ${installMetadata.source}`,
+      {
+        cause: error,
+      },
+    );
+  }
+}
+
+function parseGitHubRepo(source: string): { owner: string; repo: string } {
+  // The source should be "owner/repo" or a full GitHub URL.
+  const parts = source.split('/');
+  if (!source.includes('://') && parts.length !== 2) {
+    throw new Error(
+      `Invalid GitHub repository source: ${source}. Expected "owner/repo".`,
+    );
+  }
+  const owner = parts.at(-2);
+  const repo = parts.at(-1)?.replace('.git', '');
+
+  if (!owner || !repo) {
+    throw new Error(`Invalid GitHub repository source: ${source}`);
+  }
+  return { owner, repo };
+}
+
+async function fetchFromGithub(
+  owner: string,
+  repo: string,
+  ref?: string,
+): Promise<{ assets: Asset[]; tag_name: string }> {
+  const endpoint = ref ? `releases/tags/${ref}` : 'releases/latest';
+  const url = `https://api.github.com/repos/${owner}/${repo}/${endpoint}`;
+  return await fetchJson(url);
+}
+
+export async function checkForExtensionUpdate(
+  installMetadata: ExtensionInstallMetadata,
+): Promise<ExtensionUpdateState> {
+  if (
+    installMetadata.type !== 'git' &&
+    installMetadata.type !== 'github-release'
+  ) {
+    return ExtensionUpdateState.NOT_UPDATABLE;
+  }
+  try {
+    if (installMetadata.type === 'git') {
+      const git = simpleGit(installMetadata.source);
+      const remotes = await git.getRemotes(true);
+      if (remotes.length === 0) {
+        console.error('No git remotes found.');
+        return ExtensionUpdateState.ERROR;
+      }
+      const remoteUrl = remotes[0].refs.fetch;
+      if (!remoteUrl) {
+        console.error(`No fetch URL found for git remote ${remotes[0].name}.`);
+        return ExtensionUpdateState.ERROR;
+      }
+
+      // Determine the ref to check on the remote.
+      const refToCheck = installMetadata.ref || 'HEAD';
+
+      const lsRemoteOutput = await git.listRemote([
+        remotes[0].name,
+        refToCheck,
+      ]);
+
+      if (typeof lsRemoteOutput !== 'string' || lsRemoteOutput.trim() === '') {
+        console.error(`Git ref ${refToCheck} not found.`);
+        return ExtensionUpdateState.ERROR;
+      }
+
+      const remoteHash = lsRemoteOutput.split('\t')[0];
+      const localHash = await git.revparse(['HEAD']);
+
+      if (!remoteHash) {
+        console.error(
+          `Unable to parse hash from git ls-remote output "${lsRemoteOutput}"`,
+        );
+        return ExtensionUpdateState.ERROR;
+      }
+      if (remoteHash === localHash) {
+        return ExtensionUpdateState.UP_TO_DATE;
+      }
+      return ExtensionUpdateState.UPDATE_AVAILABLE;
+    } else {
+      const { source, ref } = installMetadata;
+      if (!source) {
+        return ExtensionUpdateState.ERROR;
+      }
+      const { owner, repo } = parseGitHubRepo(source);
+
+      const releaseData = await fetchFromGithub(
+        owner,
+        repo,
+        installMetadata.ref,
+      );
+      if (releaseData.tag_name !== ref) {
+        return ExtensionUpdateState.UPDATE_AVAILABLE;
+      }
+      return ExtensionUpdateState.UP_TO_DATE;
+    }
+  } catch (error) {
+    console.error(
+      `Failed to check for updates for extension "${installMetadata.source}": ${getErrorMessage(error)}`,
+    );
+    return ExtensionUpdateState.ERROR;
+  }
+}
+
+export async function downloadFromGitHubRelease(
+  installMetadata: ExtensionInstallMetadata,
+  destination: string,
+): Promise<string> {
+  const { source, ref } = installMetadata;
+  const { owner, repo } = parseGitHubRepo(source);
+
+  try {
+    const releaseData = await fetchFromGithub(owner, repo, ref);
+    if (
+      !releaseData ||
+      !releaseData.assets ||
+      releaseData.assets.length === 0
+    ) {
+      throw new Error(
+        `No release assets found for ${owner}/${repo} at tag ${ref}`,
+      );
+    }
+
+    const asset = findReleaseAsset(releaseData.assets);
+    if (!asset) {
+      throw new Error(
+        `No suitable release asset found for platform ${os.platform()}-${os.arch()}`,
+      );
+    }
+
+    const downloadedAssetPath = path.join(
+      destination,
+      path.basename(asset.browser_download_url),
+    );
+    await downloadFile(asset.browser_download_url, downloadedAssetPath);
+
+    extractFile(downloadedAssetPath, destination);
+
+    const files = await fs.promises.readdir(destination);
+    const extractedDirName = files.find((file) => {
+      const filePath = path.join(destination, file);
+      return fs.statSync(filePath).isDirectory();
+    });
+
+    if (extractedDirName) {
+      const extractedDirPath = path.join(destination, extractedDirName);
+      const extractedDirFiles = await fs.promises.readdir(extractedDirPath);
+      for (const file of extractedDirFiles) {
+        await fs.promises.rename(
+          path.join(extractedDirPath, file),
+          path.join(destination, file),
+        );
+      }
+      await fs.promises.rmdir(extractedDirPath);
+    }
+
+    await fs.promises.unlink(downloadedAssetPath);
+    return releaseData.tag_name;
+  } catch (error) {
+    throw new Error(
+      `Failed to download release from ${installMetadata.source}: ${getErrorMessage(error)}`,
+    );
+  }
+}
+
+interface Asset {
+  name: string;
+  browser_download_url: string;
+}
+
+export function findReleaseAsset(assets: Asset[]): Asset | undefined {
+  const platform = os.platform();
+  const arch = os.arch();
+
+  const platformArchPrefix = `${platform}.${arch}.`;
+  const platformPrefix = `${platform}.`;
+
+  // Check for platform + architecture specific asset
+  const platformArchAsset = assets.find((asset) =>
+    asset.name.toLowerCase().startsWith(platformArchPrefix),
+  );
+  if (platformArchAsset) {
+    return platformArchAsset;
+  }
+
+  // Check for platform specific asset
+  const platformAsset = assets.find((asset) =>
+    asset.name.toLowerCase().startsWith(platformPrefix),
+  );
+  if (platformAsset) {
+    return platformAsset;
+  }
+
+  // Check for generic asset if only one is available
+  const genericAsset = assets.find(
+    (asset) =>
+      !asset.name.toLowerCase().includes('darwin') &&
+      !asset.name.toLowerCase().includes('linux') &&
+      !asset.name.toLowerCase().includes('win32'),
+  );
+  if (assets.length === 1) {
+    return genericAsset;
+  }
+
+  return undefined;
+}
+
+async function fetchJson(
+  url: string,
+): Promise<{ assets: Asset[]; tag_name: string }> {
+  const headers: { 'User-Agent': string; Authorization?: string } = {
+    'User-Agent': 'gemini-cli',
+  };
+  const token = getGitHubToken();
+  if (token) {
+    headers.Authorization = `token ${token}`;
+  }
+  return new Promise((resolve, reject) => {
+    https
+      .get(url, { headers }, (res) => {
+        if (res.statusCode !== 200) {
+          return reject(
+            new Error(`Request failed with status code ${res.statusCode}`),
+          );
+        }
+        const chunks: Buffer[] = [];
+        res.on('data', (chunk) => chunks.push(chunk));
+        res.on('end', () => {
+          const data = Buffer.concat(chunks).toString();
+          resolve(JSON.parse(data) as { assets: Asset[]; tag_name: string });
+        });
+      })
+      .on('error', reject);
+  });
+}
+
+async function downloadFile(url: string, dest: string): Promise<void> {
+  const headers: { 'User-agent': string; Authorization?: string } = {
+    'User-agent': 'gemini-cli',
+  };
+  const token = getGitHubToken();
+  if (token) {
+    headers.Authorization = `token ${token}`;
+  }
+  return new Promise((resolve, reject) => {
+    https
+      .get(url, { headers }, (res) => {
+        if (res.statusCode === 302 || res.statusCode === 301) {
+          downloadFile(res.headers.location!, dest).then(resolve).catch(reject);
+          return;
+        }
+        if (res.statusCode !== 200) {
+          return reject(
+            new Error(`Request failed with status code ${res.statusCode}`),
+          );
+        }
+        const file = fs.createWriteStream(dest);
+        res.pipe(file);
+        file.on('finish', () => file.close(resolve as () => void));
+      })
+      .on('error', reject);
+  });
+}
+
+function extractFile(file: string, dest: string) {
+  if (file.endsWith('.tar.gz')) {
+    execSync(`tar -xzf ${file} -C ${dest}`);
+  } else if (file.endsWith('.zip')) {
+    execSync(`unzip ${file} -d ${dest}`);
+  } else {
+    throw new Error(`Unsupported file extension for extraction: ${file}`);
+  }
+}

packages/core/src/config/config.ts

@@ -117,8 +117,12 @@ export interface GeminiCLIExtension {
   version: string;
   isActive: boolean;
   path: string;
-  source?: string;
+  installMetadata?: ExtensionInstallMetadata;
-  type?: 'git' | 'local' | 'link';
+}
+
+export interface ExtensionInstallMetadata {
+  source: string;
+  type: 'git' | 'local' | 'link' | 'github-release';
   ref?: string;
 }