Google Antigravity v0.1.16

0.1.16 August 31, 2026 Default Gemini 3.8 Flash model upgrade, lightweight agent configuration, and Vertex AI Express mode The 0.1.16 release updates the default model for new agents to gemini-3.8-flash for enhanced reasoning capabilities, introduces a .lightweight() method on agent configs for small and local models, adds Vertex AI Express mode with API keys, and expands tool runner support for callable classes and dataclass functors. Improvements (8) Default Model Update to Gemini 3.8 Flash : The default model for new agents and configurations has been updated to gemini-3.8-flash , delivering higher reasoning quality and stronger task performance. Developers can override this default by specifying model in their configuration: Optimized Lightweight Agent Configuration : New .lightweight() method on agent configurations (including LocalAgentConfig and LiteRTAgentConfig ) applies preset optimizations for smaller, local-running models by configuring minimal tool sets, minimal prompting, and disabling background subagents: Vertex AI Express Mode (API Key Support) : Developers can now connect to Vertex AI using Express mode by providing an API key directly on LocalAgentConfig(vertex=True, api_key="...") , simplifying authentication without needing full GCP project/location ADC setup: Support for Callable Class and Dataclass Tools : The SDK's ToolRunner now inspects and executes tools defined as callable class instances (functors) and dataclass methods, enhancing flexibility for custom tool implementations: OS Sandbox Opt-in for Commands : Added an enable_sandbox field to RunCommandConfig to allow developers to execute terminal commands within an OS-level sandbox environment: Tool Invocation Argument Flexibility : ToolWithSchema and public callable proxies now accept both positional ( args ) and keyword arguments ( *kwargs ), matching standard Python function calling conventions. Support for genai.Content Media : Introduced a structconverter to support media blocks from