Google Cloud now offers Claude Opus 5.5 and Claude Sonnet 5.5 through Antigravity, providing developers with more model choices. Claude Opus 5.5 excels at complex tasks, while Sonnet 5.5 offers speed and cost-effectiveness. Administrators can enable these models alongside Google's Gemini models within Antigravity. Developers can then select their preferred models directly from the model picker across various Antigravity tools. This integration enables a unified billing and security environment for model selection. The platform supports multi-model engineering patterns to enhance code quality and manage costs. One pattern involves using different models for implementation and validation to prevent model-specific biases. Developers can assign Claude Opus 5.5 or Gemini 4 Argon for implementation and a different model for validation. Another pattern pairs powerful reasoning models with faster "Flash" subagents for efficiency. Subagents can be configured to use specific model tiers, like Gemini Flash, for high-volume tasks. This allows for optimized workflows by delegating tasks to specialized models. Administrators can configure billing and authorize partner models for their organizations. Developers should update their Antigravity tools to access these new model capabilities.