Antigravity API key account test uses invalid upstream paths against cloudcode-pa.googleapis.com

[isjiajia01]

Summary

When creating an antigravity account with type=apikey and base_url=https://cloudcode-pa.googleapis.com, the admin "Test account" flow hits upstream paths that return Google 404 pages.

Reproduction

1. Create an account in admin UI:
   • platform: Antigravity
   • type: API Key
   • base_url: https://cloudcode-pa.googleapis.com
   • api_key: valid key
2. Click Test account
3. Test with either:
   • default / Claude-style model
   • Gemini-style model such as gemini-3-pro-high

Actual behavior

Two invalid path patterns were observed during testing:

1. Claude-style test path:
   • /antigravity/v1/messages?beta=true
2. Gemini-style test path:
   • /antigravity/v1beta/models/gemini-3-pro-high:streamGenerateContent?alt=sse

Both returned Google HTML 404 pages.

Expected behavior

If cloudcode-pa.googleapis.com is a supported upstream for Antigravity API key accounts, the test flow should construct the correct upstream path and auth style.

If it is not a supported upstream for API key accounts, the admin test flow and/or account creation UI should reject this configuration explicitly instead of sending requests to invalid paths.

Notes

• Runtime service remained healthy; the issue is in the admin test flow / upstream compatibility assumption.
• The UI can mislead operators into thinking https://cloudcode-pa.googleapis.com is a valid API key upstream for Antigravity.
• It may be worth clarifying whether Antigravity over cloudcode-pa.googleapis.com is intended to support only OAuth / Code Assist style auth rather than API key auth.