fix(cli): prevent automatic updates from switching to less stable channels (#26132)

packages/cli/src/ui/utils/updateCheck.test.ts

@@ -15,6 +15,25 @@ const debugLogger = vi.hoisted(() => ({
 vi.mock('@google/gemini-cli-core', () => ({
   getPackageJson,
   debugLogger,
+  ReleaseChannel: {
+    NIGHTLY: 'nightly',
+    PREVIEW: 'preview',
+    STABLE: 'stable',
+  },
+  getChannelFromVersion: (version: string) => {
+    if (!version || version.includes('nightly')) {
+      return 'nightly';
+    }
+    if (version.includes('preview')) {
+      return 'preview';
+    }
+    return 'stable';
+  },
+  RELEASE_CHANNEL_STABILITY: {
+    nightly: 0,
+    preview: 1,
+    stable: 2,
+  },
 }));
 
 const latestVersion = vi.hoisted(() => vi.fn());
@@ -152,4 +171,68 @@ describe('checkForUpdates', () => {
       expect(result?.update.latest).toBe('1.2.3-nightly.2');
     });
   });
+
+  describe('channel stability', () => {
+    it('should NOT offer nightly update to a stable user even if tagged as latest', async () => {
+      getPackageJson.mockResolvedValue({
+        name: 'test-package',
+        version: '1.0.0',
+      });
+      // latest points to a nightly that is semver-greater
+      latestVersion.mockResolvedValue('1.1.0-nightly.1');
+
+      const result = await checkForUpdates(mockSettings);
+      expect(result).toBeNull();
+    });
+
+    it('should NOT offer preview update to a stable user even if tagged as latest', async () => {
+      getPackageJson.mockResolvedValue({
+        name: 'test-package',
+        version: '1.0.0',
+      });
+      // latest points to a preview that is semver-greater
+      latestVersion.mockResolvedValue('1.1.0-preview.1');
+
+      const result = await checkForUpdates(mockSettings);
+      expect(result).toBeNull();
+    });
+
+    it('should offer stable update to a stable user', async () => {
+      getPackageJson.mockResolvedValue({
+        name: 'test-package',
+        version: '1.0.0',
+      });
+      latestVersion.mockResolvedValue('1.1.0');
+
+      const result = await checkForUpdates(mockSettings);
+      expect(result?.update.latest).toBe('1.1.0');
+    });
+
+    it('should offer stable update to a nightly user', async () => {
+      getPackageJson.mockResolvedValue({
+        name: 'test-package',
+        version: '1.0.0-nightly.1',
+      });
+      latestVersion.mockImplementation(async (name, options) => {
+        if (options?.version === 'nightly') {
+          return '1.0.0-nightly.1'; // No nightly update
+        }
+        return '1.1.0'; // Stable update available
+      });
+
+      const result = await checkForUpdates(mockSettings);
+      expect(result?.update.latest).toBe('1.1.0');
+    });
+
+    it('should offer stable update to a preview user', async () => {
+      getPackageJson.mockResolvedValue({
+        name: 'test-package',
+        version: '1.0.0-preview.1',
+      });
+      latestVersion.mockResolvedValue('1.1.0');
+
+      const result = await checkForUpdates(mockSettings);
+      expect(result?.update.latest).toBe('1.1.0');
+    });
+  });
 });

packages/cli/src/ui/utils/updateCheck.ts

@@ -6,7 +6,12 @@
 
 import latestVersion from 'latest-version';
 import semver from 'semver';
-import { getPackageJson, debugLogger } from '@google/gemini-cli-core';
+import {
+  getPackageJson,
+  debugLogger,
+  getChannelFromVersion,
+  RELEASE_CHANNEL_STABILITY,
+} from '@google/gemini-cli-core';
 import type { LoadedSettings } from '../../config/settings.js';
 import { fileURLToPath } from 'node:url';
 import path from 'node:path';
@@ -65,6 +70,7 @@ export async function checkForUpdates(
     }
 
     const { name, version: currentVersion } = packageJson;
+    const currentChannel = getChannelFromVersion(currentVersion);
     const isNightly = currentVersion.includes('nightly');
 
     if (isNightly) {
@@ -90,8 +96,21 @@ export async function checkForUpdates(
       }
     } else {
       const latestUpdate = await latestVersion(name);
+      if (!latestUpdate) {
+        return null;
+      }
 
-      if (latestUpdate && semver.gt(latestUpdate, currentVersion)) {
+      const targetChannel = getChannelFromVersion(latestUpdate);
+
+      // Only offer updates that are as stable or more stable than the current version
+      if (
+        RELEASE_CHANNEL_STABILITY[targetChannel] <
+        RELEASE_CHANNEL_STABILITY[currentChannel]
+      ) {
+        return null;
+      }
+
+      if (semver.gt(latestUpdate, currentVersion)) {
         const message = `Gemini CLI update available! ${currentVersion} → ${latestUpdate}`;
         const type = semver.diff(latestUpdate, currentVersion) || undefined;
         return {

packages/cli/src/utils/handleAutoUpdate.test.ts

@@ -334,7 +334,8 @@ describe('handleAutoUpdate', () => {
       ...mockUpdateInfo,
       update: {
         ...mockUpdateInfo.update,
-        latest: '2.0.0-nightly',
+        current: '1.0.0-nightly.0',
+        latest: '2.0.0-nightly.1',
       },
     };
     mockGetInstallationInfo.mockReturnValue({
@@ -356,6 +357,26 @@ describe('handleAutoUpdate', () => {
     );
   });
 
+  it('should NOT update if target is less stable than current (defense-in-depth)', async () => {
+    mockUpdateInfo = {
+      ...mockUpdateInfo,
+      update: {
+        ...mockUpdateInfo.update,
+        current: '1.0.0',
+        latest: '1.1.0-nightly.1',
+      },
+    };
+    mockGetInstallationInfo.mockReturnValue({
+      updateCommand: 'npm i -g @google/gemini-cli@latest',
+      isGlobal: false,
+      packageManager: PackageManager.NPM,
+    });
+
+    handleAutoUpdate(mockUpdateInfo, mockSettings, '/root', mockSpawn);
+
+    expect(mockSpawn).not.toHaveBeenCalled();
+  });
+
   it('should emit "update-success" when the update process succeeds', async () => {
     await new Promise<void>((resolve) => {
       mockGetInstallationInfo.mockReturnValue({

packages/cli/src/utils/handleAutoUpdate.ts

@@ -11,7 +11,11 @@ import { updateEventEmitter } from './updateEventEmitter.js';
 import { MessageType, type HistoryItem } from '../ui/types.js';
 import { spawnWrapper } from './spawnWrapper.js';
 import type { spawn } from 'node:child_process';
-import { debugLogger } from '@google/gemini-cli-core';
+import {
+  debugLogger,
+  getChannelFromVersion,
+  RELEASE_CHANNEL_STABILITY,
+} from '@google/gemini-cli-core';
 
 let _updateInProgress = false;
 
@@ -122,6 +126,25 @@ export function handleAutoUpdate(
     return;
   }
 
+  const currentVersion = info.update.current;
+  if (!currentVersion) {
+    debugLogger.warn(
+      'Update check: current version is missing. Skipping automatic update for safety.',
+    );
+    return;
+  }
+
+  const currentChannel = getChannelFromVersion(currentVersion);
+  const targetChannel = getChannelFromVersion(info.update.latest);
+
+  // Defense-in-depth: prevent updates to a less stable channel
+  if (
+    RELEASE_CHANNEL_STABILITY[targetChannel] <
+    RELEASE_CHANNEL_STABILITY[currentChannel]
+  ) {
+    return;
+  }
+
   const isNightly = info.update.latest.includes('nightly');
 
   const updateCommand = installationInfo.updateCommand.replace(