I been doing the same, saying Hi or hello and no response. It’s been down for a whole 24 hours for me now. So I just been using the gemini CLI which works fine, I set it to my project folder and everything is fine, but I would like Antigravity to work.
IT’S WORKING, I POSTED A SOLUTION here IT’S WORKING - Antigravity AI Chat Models - Gemini API - Google AI Developers Forum
I also experienced it yesterday, when I tried to use “Anthropic models”. It was working fine with other models like “Flash” or “Gemini 3.1” but showing errors with Opus model.
I’ve posted the fix.