Fallback to gh CLI credentials if available (#1515)

Adds `gh` CLI as a GitHub credential fallback for users who already have
`gh auth login` configured locally. OpenChamber-owned OAuth credentials
remain the primary source of truth; the `gh` token is only used when no
stored OpenChamber GitHub access token exists and the fallback is not
disabled.

The fallback is implemented as a credential provider only: GitHub features
continue to use the existing Octokit/GitHub API paths for issues, pull
requests, checks, merges, and related operations. The PR does not replace
those endpoints with `gh issue` or `gh pr` CLI commands.

Server changes:
- Add `gh-cli-credential.js` to read `gh auth token` with a bounded timeout.
- Cache the `gh` token lookup for 30 seconds, including negative results,
  to avoid repeated subprocess spawning on status/polling paths.
- Hide the subprocess window on Windows via `windowsHide: true`.
- Clear the gh CLI token cache when the fallback setting changes.
- Update `getOctokitOrNull()` to prefer stored OpenChamber OAuth tokens and
  fall back to the `gh` token only when enabled.
- Add `ghCliDisabled` persistence in the existing settings file with atomic
  writes and `0o600` file permissions.
- Add `POST /api/github/auth/gh-cli` to enable or disable the fallback.
- Extend `/api/github/auth/status` with `ghCli` metadata: availability,
  disabled state, active state, and active user when applicable.

UI/runtime changes:
- Extend `GitHubAuthStatus` and `GitHubAPI` with gh CLI fallback metadata
  and toggle support.
- Add web RuntimeAPI support for toggling the gh CLI fallback through
  `runtimeFetch`, preserving active runtime/remote target behavior.
- Add deterministic VS Code unsupported handling for the gh CLI toggle.
- Update GitHub Settings to show gh CLI availability and active status.
- When gh CLI is the active auth source, show it in the connected account
  card and offer Disable instead of Disconnect.
- Keep Add Account available so users can still connect an OpenChamber OAuth
  account, which then takes priority over gh CLI.
- Add localized gh CLI settings strings across supported settings locales.

Fixes addressed during review:
- Removed unreachable UI branches in the inactive gh CLI card.
- Avoided duplicate and repeated `gh auth token` subprocess calls.
- Hardened settings file permissions for the new persisted flag.
- Routed the gh CLI toggle through the RuntimeAPI/runtimeFetch path instead
  of direct browser `fetch`.
- Added targeted tests for hidden subprocess options and negative-result
  cache behavior.
- Fixed a VS Code webview Response body typing issue that blocked type-check.

packages/web/server/lib/github/auth.js

@@ -305,3 +305,41 @@ export function getGitHubScopes() {
 }
 
 export const GITHUB_AUTH_FILE = STORAGE_FILE;
+
+export function isGhCliDisabled() {
+  try {
+    if (fs.existsSync(SETTINGS_FILE)) {
+      const parsed = JSON.parse(fs.readFileSync(SETTINGS_FILE, 'utf8'));
+      return Boolean(parsed?.ghCliDisabled);
+    }
+  } catch {
+    // ignore
+  }
+  return false;
+}
+
+export function setGhCliDisabled(disabled) {
+  ensureStorageDir();
+  let settings = {};
+  try {
+    if (fs.existsSync(SETTINGS_FILE)) {
+      settings = JSON.parse(fs.readFileSync(SETTINGS_FILE, 'utf8')) || {};
+    }
+  } catch {
+    // ignore
+  }
+  settings.ghCliDisabled = Boolean(disabled);
+  const tmpFile = `${SETTINGS_FILE}.${process.pid}.${Date.now()}.tmp`;
+  fs.writeFileSync(tmpFile, JSON.stringify(settings, null, 2), 'utf8');
+  try {
+    fs.chmodSync(tmpFile, 0o600);
+  } catch {
+    // best-effort
+  }
+  fs.renameSync(tmpFile, SETTINGS_FILE);
+  try {
+    fs.chmodSync(SETTINGS_FILE, 0o600);
+  } catch {
+    // best-effort
+  }
+}

packages/web/server/lib/github/gh-cli-credential.js

@@ -0,0 +1,38 @@
+import { execFileSync } from 'child_process';
+
+const CACHE_TTL_MS = 30_000;
+let cachedToken = null;
+let cachedAt = 0;
+let hasCachedToken = false;
+
+function fetchGhCliToken() {
+  try {
+    const token = execFileSync('gh', ['auth', 'token'], {
+      encoding: 'utf8',
+      stdio: ['pipe', 'pipe', 'pipe'],
+      timeout: 5000,
+      windowsHide: true,
+    }).trim();
+    return token || null;
+  } catch {
+    return null;
+  }
+}
+
+export function getGhCliToken() {
+  const now = Date.now();
+  if (hasCachedToken && now - cachedAt < CACHE_TTL_MS) {
+    return cachedToken;
+  }
+  const token = fetchGhCliToken();
+  cachedToken = token;
+  cachedAt = now;
+  hasCachedToken = true;
+  return token;
+}
+
+export function clearGhCliTokenCache() {
+  cachedToken = null;
+  cachedAt = 0;
+  hasCachedToken = false;
+}

packages/web/server/lib/github/gh-cli-credential.test.js

@@ -0,0 +1,43 @@
+import { beforeEach, describe, expect, mock, test } from 'bun:test';
+
+const execFileSyncMock = mock(() => '');
+
+mock.module('child_process', () => ({
+  execFileSync: execFileSyncMock,
+}));
+
+const { clearGhCliTokenCache, getGhCliToken } = await import('./gh-cli-credential.js');
+
+describe('gh CLI credential lookup', () => {
+  beforeEach(() => {
+    execFileSyncMock.mockReset();
+    clearGhCliTokenCache();
+  });
+
+  test('hides the subprocess window on Windows', () => {
+    execFileSyncMock.mockReturnValueOnce('token\n');
+
+    expect(getGhCliToken()).toBe('token');
+    expect(execFileSyncMock).toHaveBeenCalledWith('gh', ['auth', 'token'], {
+      encoding: 'utf8',
+      stdio: ['pipe', 'pipe', 'pipe'],
+      timeout: 5000,
+      windowsHide: true,
+    });
+  });
+
+  test('caches unavailable gh CLI result until cache is cleared', () => {
+    execFileSyncMock.mockImplementation(() => {
+      throw new Error('gh unavailable');
+    });
+
+    expect(getGhCliToken()).toBeNull();
+    expect(getGhCliToken()).toBeNull();
+    expect(execFileSyncMock).toHaveBeenCalledTimes(1);
+
+    clearGhCliTokenCache();
+
+    expect(getGhCliToken()).toBeNull();
+    expect(execFileSyncMock).toHaveBeenCalledTimes(2);
+  });
+});

packages/web/server/lib/github/index.js

@@ -6,6 +6,8 @@ export {
   clearGitHubAuth,
   getGitHubClientId,
   getGitHubScopes,
+  isGhCliDisabled,
+  setGhCliDisabled,
   GITHUB_AUTH_FILE,
 } from './auth.js';
 

packages/web/server/lib/github/octokit.js

@@ -1,10 +1,12 @@
 import { Octokit } from '@octokit/rest';
-import { getGitHubAuth } from './auth.js';
+import { getGitHubAuth, isGhCliDisabled } from './auth.js';
+import { getGhCliToken } from './gh-cli-credential.js';
 
 export function getOctokitOrNull() {
   const auth = getGitHubAuth();
-  if (!auth?.accessToken) {
+  const token = auth?.accessToken || (!isGhCliDisabled() ? getGhCliToken() : null);
+  if (!token) {
     return null;
   }
-  return new Octokit({ auth: auth.accessToken });
+  return new Octokit({ auth: token });
 }

packages/web/server/lib/github/routes.js

@@ -76,16 +76,25 @@ export function registerGitHubRoutes(app) {
 
   app.get('/api/github/auth/status', async (_req, res) => {
     try {
-      const { getGitHubAuth, getOctokitOrNull, clearGitHubAuth, getGitHubAuthAccounts } = await getGitHubLibraries();
+      const { getGitHubAuth, getOctokitOrNull, clearGitHubAuth, getGitHubAuthAccounts, isGhCliDisabled } = await getGitHubLibraries();
+      const { getGhCliToken } = await import('./gh-cli-credential.js');
+
       const auth = getGitHubAuth();
       const accounts = getGitHubAuthAccounts();
-      if (!auth?.accessToken) {
-        return res.json({ connected: false, accounts });
-      }
+      const ghCliDisabled = isGhCliDisabled();
+      const ghToken = getGhCliToken();
+      const usingOwnToken = Boolean(auth?.accessToken);
+
+      const buildGhCli = (activeUser = null) => ({
+        available: ghToken !== null,
+        disabled: ghCliDisabled,
+        active: !usingOwnToken && ghToken !== null && !ghCliDisabled,
+        ...(activeUser ? { user: activeUser } : {}),
+      });
 
       const octokit = getOctokitOrNull();
       if (!octokit) {
-        return res.json({ connected: false, accounts });
+        return res.json({ connected: false, accounts, ghCli: buildGhCli() });
       }
 
       let user = null;
@@ -93,19 +102,21 @@ export function registerGitHubRoutes(app) {
         user = await getGitHubUserSummary(octokit);
       } catch (error) {
         if (isGitHubAuthInvalid(error)) {
-          clearGitHubAuth();
-          return res.json({ connected: false, accounts: getGitHubAuthAccounts() });
+          if (usingOwnToken) clearGitHubAuth();
+          return res.json({ connected: false, accounts: getGitHubAuthAccounts(), ghCli: buildGhCli() });
         }
       }
 
-      const fallback = auth.user;
+      const fallback = usingOwnToken ? auth.user : null;
       const mergedUser = user || fallback;
+      const ghIsActive = !usingOwnToken && ghToken !== null && !ghCliDisabled;
 
       return res.json({
         connected: true,
         user: mergedUser,
-        scope: auth.scope,
+        scope: usingOwnToken ? auth.scope : undefined,
         accounts,
+        ghCli: buildGhCli(ghIsActive ? mergedUser : null),
       });
     } catch (error) {
       console.error('Failed to get GitHub auth status:', error);
@@ -113,6 +124,20 @@ export function registerGitHubRoutes(app) {
     }
   });
 
+  app.post('/api/github/auth/gh-cli', async (req, res) => {
+    try {
+      const { setGhCliDisabled, isGhCliDisabled } = await getGitHubLibraries();
+      const { clearGhCliTokenCache } = await import('./gh-cli-credential.js');
+      const disabled = Boolean(req.body?.disabled);
+      setGhCliDisabled(disabled);
+      clearGhCliTokenCache();
+      return res.json({ disabled: isGhCliDisabled() });
+    } catch (error) {
+      console.error('Failed to update gh CLI setting:', error);
+      return res.status(500).json({ error: error.message || 'Failed to update gh CLI setting' });
+    }
+  });
+
   app.post('/api/github/auth/start', async (_req, res) => {
     try {
       const { getGitHubClientId, getGitHubScopes, startDeviceFlow } = await getGitHubLibraries();