Google Antigravity Python SDK — v0.1.11 Release Notes

[NTaylorMullen]

The 0.1.11 release updates the default model to gemini-3.7-flash, introduces session-level budget enforcement and turn termination stop reasons, Vertex AI Express Mode authentication and a new agent behavior setting that toggles betweein interactive and autonomous (the default). It also expands tool hook metadata, resolves string annotation coercion for postponed evaluation, and improves MCP server and subagent stability.

🌟 Key Highlights

• Default Model Upgrade to Gemini 3.7 Flash: Upgraded the default inference model to gemini-3.7-flash.
• Session Budget Enforcement & Stop Reasons: Added BudgetConfig to define session-level usage limits (model invocations, tool invocations, and token budgets) and StopReason enum (MAX_MODEL_CALLS_EXCEEDED, MAX_TOOL_CALLS_EXCEEDED, MAX_TOTAL_TOKENS_EXCEEDED, QUOTA_EXHAUSTED, etc.) to inspect turn termination causes.
• Vertex AI Express Mode Support: Added native support for Express Mode authentication via VertexEndpoint(api_key=...) and LocalAgentConfig(vertex=true, api_key=...), simplifying headless and non-GCP deployments.
• Autonomous Agent Behavior Mode: Control the agent's behavior with AgentBehavior. By default the SDK now has a AgentBehavior.AUTONOMOUS mode (used to be AgentBehavior.INTERACTIVE) to streamline scripting, background and headless interactions modes.
• Multi-Interface Hook Registration: Enabled single-instance registration across multiple hook interfaces (PreToolHook, PostToolHook, PreTurnHook), allowing for cross functional instrumentation.

🔧 Detailed Changes

New Features

• Budget Enforcement: Introduced BudgetConfig(max_model_calls, max_tool_calls, max_input_tokens, max_output_tokens, max_total_tokens) and exposed stop reason metadata on turn responses.
• Express Mode API Key Auth: Added api_key support across VertexEndpoint and local agent configurations.
• Multi-Interface Hooks: Supported registering composite hook classes without duplicate invocation.
• PreToolArgs Metadata: Exposed step_id on tool hook payloads for chat thread context tracing.

Model & Default Changes

• Default Model Upgrade: Updated the default model from gemini-3.6-flash to gemini-3.7-flash.
• Agent Behavior: Introduced the ability to control AgentBehavior. Now defaults to autonomous (form interactive) to avoid unexpected interactive pause states during script execution. Override by setting CapabilitiesConfig(agent_behavior=AgentBehavior.INTERACTIVE).

Bug Fixes & Maintenance

• ToolRunner String Annotation Coercion: When using from __future__ import annotations, tool argument coercion failed on stringified types; resolved by resolving type annotations via typing.get_type_hints before type adaptation.
• MCP Server Example Port Binding: Ephemeral port race conditions in test and example server startup were resolved by binding directly to port 0.
• Subagent Deadlock Prevention: Handled subagent fatal errors in the localagent executor to prevent deadlocks when subagents terminate abnormally.
• Empty Input Validation: Added input validation to prevent SDK unresponsiveness on empty or whitespace-only prompts.