Clarify why authentication failures might be happening and direct users to documentation (#1478)

Co-authored-by: Scott Densmore <scottdensmore@mac.com>
Co-authored-by: matt korwel <matt.korwel@gmail.com>

docs/cli/authentication.md

@@ -22,10 +22,16 @@ The Gemini CLI requires you to authenticate with Google's AI services. On initia
         source ~/.bashrc
         ```
 
-3.  **Login with Google Workspace**
+3.  **<a id="workspace-gca"></a>Login with Google (Gemini Code Assist for Workspace or licensed Code Assist users):**
 
-    - Use this option to log in with the **Google Workspace Accounts**. This is a paid service for businesses and organizations that provides a suite of productivity tools, including a custom email domain (e.g. your-name@your-company.com), enhanced security features, and administrative controls. These accounts are often managed by an employer or school.
+    (For more information, see: https://developers.google.com/gemini-code-assist/resources/faqs#gcp-project-requirement)
-      - Google Workspace Account must first configure a Google Cloud Project Id to use, [enable the Gemini for Cloud API](https://cloud.google.com/gemini/docs/discover/set-up-gemini#enable-api) and [configure access permissions](https://cloud.google.com/gemini/docs/discover/set-up-gemini#grant-iam). You can temporarily set the environment variable in your current shell session using the following command:
+
+    - Use this option if:
+
+      1. You have a Google Workspace account. Google Workspace is a paid service for businesses and organizations that provides a suite of productivity tools, including a custom email domain (e.g. your-name@your-company.com), enhanced security features, and administrative controls. These accounts are often managed by an employer or school.
+      2. You are a licensed Code Assist user. This can happen if you have previously purchased a Code Assist license or have acquired one through Google Developer Program.
+
+    - If you fall into one of these categories, you must first configure a Google Cloud Project Id to use, [enable the Gemini for Cloud API](https://cloud.google.com/gemini/docs/discover/set-up-gemini#enable-api) and [configure access permissions](https://cloud.google.com/gemini/docs/discover/set-up-gemini#grant-iam). You can temporarily set the environment variable in your current shell session using the following command:
       ```bash
       export GOOGLE_CLOUD_PROJECT="YOUR_PROJECT_ID"
       ```

packages/cli/src/ui/components/AuthDialog.tsx

@@ -35,7 +35,7 @@ export function AuthDialog({
     },
     { label: 'Gemini API Key', value: AuthType.USE_GEMINI },
     {
-      label: 'Login with Google Workspace',
+      label: 'Login with Google (for Workspace or licensed Code Assist users)',
       value: AuthType.LOGIN_WITH_GOOGLE_ENTERPRISE,
     },
     { label: 'Vertex AI', value: AuthType.USE_VERTEX_AI },

packages/cli/src/ui/hooks/useAuthCommand.ts

@@ -49,7 +49,7 @@ export const useAuthCommand = (
         const errorMessage =
           settings.merged.selectedAuthType ===
           AuthType.LOGIN_WITH_GOOGLE_PERSONAL
-            ? `Failed to login. Ensure your Google account is not a Workspace account.
+            ? `Failed to login. Ensure the Google account you are using is not a Workspace account and that you are not a licensed Code Assist user (see https://goo.gle/gemini-cli-auth-docs#workspace-gca).
 Message: ${getErrorMessage(e)}`
             : `Failed to login. Message: ${getErrorMessage(e)}`;
         setAuthError(errorMessage);