"I Pointed Claude Code at Google's Antigravity — Here's the 5-Minute OAuth Setup"

The thing that finally pushed me over the edge was a 401 at 1am. Anthropic key rotated. Claude Code dead. Three terminals open, a half-finished refactor, and now I'm digging through a password manager looking for the right ANTHROPIC_API_KEY to paste into a shell config so my CLI tool can keep talking to a model. Then it hit me: I was already logged into Google's Antigravity in another tab. And Antigravity hands out claude-sonnet-4-6 and claude-opus-4-6 like it's nothing. So why was I paying Anth