1 files changed, 55 insertions, 44 deletions

diff --git a/packages/core/src/code_assist/oauth2.ts b/packages/core/src/code_assist/oauth2.ts
index 93d0e28b..c2fd0d12 100644
--- a/packages/core/src/code_assist/oauth2.ts
+++ b/packages/core/src/code_assist/oauth2.ts
@@ -44,6 +44,7 @@ const SIGN_IN_FAILURE_URL =
 const GEMINI_DIR = '.gemini';
 const CREDENTIAL_FILENAME = 'oauth_creds.json';
 const GOOGLE_ACCOUNT_ID_FILENAME = 'google_account_id';
+const GOOGLE_ACCOUNT_EMAIL_FILENAME = 'google_account_email';
 
 /**
  * An Authentication URL for updating the credentials of a Oauth2Client
@@ -70,13 +71,10 @@ export async function getOauthClient(
   // If there are cached creds on disk, they always take precedence
   if (await loadCachedCredentials(client)) {
     // Found valid cached credentials.
-    // Check if we need to retrieve Google Account ID
-    if (!getCachedGoogleAccountId()) {
+    // Check if we need to retrieve Google Account ID or Email
+    if (!getCachedGoogleAccountId() || !getCachedGoogleAccountEmail()) {
       try {
-        const googleAccountId = await getRawGoogleAccountId(client);
-        if (googleAccountId) {
-          await cacheGoogleAccountId(googleAccountId);
-        }
+        await fetchAndCacheUserInfo(client);
       } catch {
         // Non-fatal, continue with existing auth.
       }
@@ -163,10 +161,7 @@ async function authWithWeb(client: OAuth2Client): Promise<OauthWebLogin> {
           client.setCredentials(tokens);
           // Retrieve and cache Google Account ID during authentication
           try {
-            const googleAccountId = await getRawGoogleAccountId(client);
-            if (googleAccountId) {
-              await cacheGoogleAccountId(googleAccountId);
-            }
+            await fetchAndCacheUserInfo(client);
           } catch (error) {
             console.error(
               'Failed to retrieve Google Account ID during authentication:',
@@ -275,57 +270,73 @@ export function getCachedGoogleAccountId(): string | null {
   }
 }
 
+function getGoogleAccountEmailCachePath(): string {
+  return path.join(os.homedir(), GEMINI_DIR, GOOGLE_ACCOUNT_EMAIL_FILENAME);
+}
+
+async function cacheGoogleAccountEmail(email: string): Promise<void> {
+  const filePath = getGoogleAccountEmailCachePath();
+  await fs.mkdir(path.dirname(filePath), { recursive: true });
+  await fs.writeFile(filePath, email, 'utf-8');
+}
+
+export function getCachedGoogleAccountEmail(): string | null {
+  try {
+    const filePath = getGoogleAccountEmailCachePath();
+    if (existsSync(filePath)) {
+      return readFileSync(filePath, 'utf-8').trim() || null;
+    }
+    return null;
+  } catch (error) {
+    console.debug('Error reading cached Google Account Email:', error);
+    return null;
+  }
+}
+
 export async function clearCachedCredentialFile() {
   try {
     await fs.rm(getCachedCredentialPath(), { force: true });
     // Clear the Google Account ID cache when credentials are cleared
     await fs.rm(getGoogleAccountIdCachePath(), { force: true });
+    await fs.rm(getGoogleAccountEmailCachePath(), { force: true });
   } catch (_) {
     /* empty */
   }
 }
 
-/**
- * Retrieves the authenticated user's Google Account ID from Google's UserInfo API.
- * @param client - The authenticated OAuth2Client
- * @returns The user's Google Account ID or null if not available
- */
-export async function getRawGoogleAccountId(
-  client: OAuth2Client,
-): Promise<string | null> {
+async function fetchAndCacheUserInfo(client: OAuth2Client): Promise<void> {
   try {
-    // 1. Get a new Access Token including the id_token
-    const refreshedTokens = await new Promise<Credentials | null>(
-      (resolve, reject) => {
-        client.refreshAccessToken((err, tokens) => {
-          if (err) {
-            return reject(err);
-          }
-          resolve(tokens ?? null);
-        });
+    const { token } = await client.getAccessToken();
+    if (!token) {
+      return;
+    }
+
+    const response = await fetch(
+      'https://www.googleapis.com/oauth2/v2/userinfo',
+      {
+        headers: {
+          Authorization: `Bearer ${token}`,
+        },
       },
     );
 
-    if (!refreshedTokens?.id_token) {
-      console.warn('No id_token obtained after refreshing tokens.');
-      return null;
+    if (!response.ok) {
+      console.error(
+        'Failed to fetch user info:',
+        response.status,
+        response.statusText,
+      );
+      return;
     }
 
-    // 2. Verify the ID token to securely get the user's Google Account ID.
-    const ticket = await client.verifyIdToken({
-      idToken: refreshedTokens.id_token,
-      audience: OAUTH_CLIENT_ID,
-    });
-
-    const payload = ticket.getPayload();
-    if (!payload?.sub) {
-      console.warn('Could not extract sub claim from verified ID token.');
-      return null;
+    const userInfo = await response.json();
+    if (userInfo.id) {
+      await cacheGoogleAccountId(userInfo.id);
+    }
+    if (userInfo.email) {
+      await cacheGoogleAccountEmail(userInfo.email);
     }
-
-    return payload.sub;
   } catch (error) {
-    console.error('Error retrieving or verifying Google Account ID:', error);
-    return null;
+    console.error('Error retrieving user info:', error);
   }
 }