Google Antigravity adds Claude Opus 5.5 and Sonnet 5.5 with mid-session model switching

Anthropic's Claude Opus 5.5 and Claude Sonnet 5.5 are now officially available in Google Antigravity across Antigravity 2.0 Desktop, the CLI, and IDE extensions for VS Code, JetBrains, and Visual Studio. Opus 5.5 targets heavy reasoning and multi-file architectural refactoring, while Sonnet 5.5 serves as a faster, lower-cost option for day-to-day coding. Developers can switch models mid-session via the dropdown or /model claude-opus-5-5 in the CLI without losing context, terminal states, or workspace artifacts, and admins enable the models and set spend limits in Google Cloud Console under Gemini Enterprise.