antigravity-sdklisted

# Antigravity SDK Use `google-antigravity` when embedding the Antigravity harness itself provides value. [google-adk](../google-adk/SKILL.md) remains the default agent framework; [python-stack](../python-stack/SKILL.md) owns project conventions. ## Workflow 1. **Verify the installed SDK**: inspect the uv dependency and source before using its evolving API; distinguish the local SDK from the interactive `agy` CLI and hosted Interactions agent. 1. **Choose authentication**: Gemini API key (`ANTIGRAVITY_SDK_API_KEY` or `GEMINI_API_KEY`) or Vertex ADC through gcloud; read [setup and configuration](references/sdk-usage.md). The SDK uses Gemini API billing, not the CLI/IDE subscription. 1. **Bound the run**: explicitly select tools, policies, token/call budgets, subagent roster and depth, and result schemas; custom tools must enforce their own side-effect constraints. 1. **Implement the smallest topology**: adapt [orchestrator.py](references/orchestrator.py) only when independent workers are needed; follow the matching SDK skill for detailed APIs. 1. **Verify and observe**: use local fakes first, then authorized live access; record calls, denials, failures, usage, and termination. Do not infer completion from a running or detached process. ## Gotchas - **`BuiltinTools.read_only()` omits `START_SUBAGENT`**: passing it verbatim as `enabled_tools` silently disables delegation, and the config then rejects `max_subagent_depth` at validation. Append `types.BuiltinTools.START_SUBAGEN