Opencode Antigravity OAuth Auth Plugin

Opencode plugin (v1.9.7) enabling OAuth authentication against Google's Antigravity (IDE) and Gemini CLI quotas for access to models like gemini-3.1-pro and gemini-3-flash. Supports multi-account auto-rotation, dual quota systems, Google Search grounding, and extended thinking for Gemini models. Includes automatic session recovery and tool failure handling. Violates Google ToS — accounts may be banned. Requires Node >=20 and TypeScript ^5 as peer dependency. Ships TypeScript types.