google--adk-python/contributing/samples/integrations/antigravity_agent

Antigravity SDK Game Developer Agent

Overview

This sample wraps a pre-configured Google Antigravity SDK agent as a native ADK agent using AntigravityAgent, configured as a game developer that writes small, runnable browser games into the game_repo/ workspace as single self-contained HTML files. Each turn is delegated to the Antigravity runner, and its trajectory steps (model text, tool calls, and tool responses) are streamed back as standard ADK events recorded in the session.

AntigravityAgent must be used as a standalone root agent (the SDK currently only supports local mode). See the package README for the full setup, limitations, and API details.

Prerequisites

• Install the SDK: pip install "google-adk[antigravity]"
• Set a Gemini API key: export GEMINI_API_KEY="your-api-key" (required by the Antigravity SDK, which drives the model)

The agent writes generated games into a game_repo/ directory and persists conversation trajectories (for cross-turn resumption) into a trajectories/ directory, both next to agent.py and created automatically on import.

Sample Inputs

• Create a playable Snake game.

  The agent writes a self-contained HTML implementation into game_repo/ (e.g. game_repo/snake.html, with inline CSS and JavaScript) using the built-in create_file tool, then explains how to open it in a browser.

• Create a 2-player turn-based Artillery game with adjustable angle and power.

  The agent writes another self-contained HTML game (e.g. game_repo/artillery.html) with canvas rendering and projectile physics.

• Create a Brick Breaker game.

  The agent writes a self-contained HTML implementation (e.g. game_repo/brick_breaker.html) with a paddle, ball, and breakable bricks.

Graph

Each turn, the wrapper delegates to the SDK agent's local Go harness and maps the trajectory steps it streams back into ADK events:

graph LR
    Runner[ADK Runner] -->|prompt| Wrapper[AntigravityAgent]
    Wrapper -->|send| SDK[Antigravity SDK Agent]
    SDK -->|local mode| Harness[Go localharness]
    Harness -->|steps| SDK
    SDK -->|steps| Wrapper
    Wrapper -->|ADK events| Runner

How To

The wrapper takes a google.antigravity.LocalAgentConfig via the config argument:

root_agent = AntigravityAgent(
    name="antigravity_game_developer",
    description="...",
    config=_sdk_config,
)

The SDK agent enables its built-in file tools by default; the policy.workspace_only([...]) policy keeps all file reads and writes contained to game_repo/. Internally, AntigravityAgent._run_async_impl deep-copies the config per turn (the SDK's AsyncExitStack is single-use), enters a fresh SDK Agent, sends the latest user prompt, and converts each streamed Step into ADK events.

The root-only restriction is enforced at construction time: giving the agent sub_agents, or adopting it under a parent agent, raises a ValueError.