Antigravity SDK 0.1.11

[Improvements] Default model upgrade to Gemini 3.7 Flash: Upgraded the default inference model to gemini-3.7-flash.

[Improvements] Session budget enforcement and stop reasons: Added BudgetConfig to define session-level usage limits (total tokens, turns, and cost) and StopReason enum (BUDGET_EXCEEDED, TURN_LIMIT, USER_CANCELLED, etc.) to inspect turn termination causes.

[Improvements] Vertex AI Express Mode support: Added native support for Express Mode authentication using VertexEndpoint(api_key=...) and LocalAgentConfig(vertex=true, api_key=...), simplifying headless and non-GCP deployments.

[Improvements] Autonomous agent behavior mode: Control the agent's behavior with AgentBehavior. By default the SDK now has an AgentBehavior.AUTONOMOUS mode (previously AgentBehavior.INTERACTIVE) to streamline scripting, background, and headless interaction modes. Override by setting CapabilitiesConfig(agent_behavior=AgentBehavior.INTERACTIVE).

[Improvements] Multi-interface hook registration: Enabled single-instance registration across multiple hook interfaces (PreToolHook, PostToolHook, PreTurnHook), allowing for cross-functional instrumentation without duplicate invocations.

[Improvements] PreToolArgs metadata: Exposed trajectory_id and step_index on tool hook payloads for chat thread context tracing.

[Fixes] ToolRunner string annotation coercion: When using from __future__ import annotations, tool argument coercion failed on stringified types; resolved by resolving type annotations using typing.get_type_hints before type adaptation.

[Fixes] Subagent deadlock prevention: Handled subagent fatal errors in the localagent executor to prevent deadlocks when subagents terminate abnormally.

[Fixes] Empty input validation: Added input validation to prevent SDK unresponsiveness on empty or whitespace-only prompts.

[Fixes] MCP server example port binding: Ephemeral port race conditions in test and example server startup were resolved by binding directly to port 0.