pi-agy-bridge

Use Antigravity models in Pi without changing how Pi works.

Use Antigravity models with Pi Coding Agent through Google's official ACP server. Keep your Pi tools, extensions, skills, and session history. An optional CLI driver is also available.

Architecture

Pi runs the agent. Antigravity provides the models.

Pi Coding Agent
  |  Prompts and session context
  v
pi-agy-bridge (ACP or CLI)
  |
  v
Antigravity models
  |
  |  Tool requests
  v
Local MCP bridge
  |
  v
Pi tools -> Results return to the model

The bridge connects Antigravity models to Pi. Pi manages the conversation and executes registered tools. The selected driver controls how the bridge communicates with Antigravity.

Features

• Native Pi Experience — Keep Pi tools, extensions, skills, and session history.
• Pi Tool Integration — Run registered tool requests through Pi with its applicable permissions.
• Two Drivers — Use the managed ACP server or your installed agy CLI.
• Session Continuity — Reuse compatible sessions. Restore context from Pi history when needed.
• Image Support — Read images through Pi tools, with automatic image injection for ACP.
• Automatic ACP Setup — Download and verify the pinned ACP server.
• Diagnostics — Check your setup with /agy-bridge:doctor.

Requirements

Quick Start

1. Install the Extension

Install the extension with Pi:

pi install npm:@ackneal/pi-agy-bridge

Or install it from GitHub:

pi install git:github.com/ackneal/pi-agy-bridge

2. Sign In

1. Run:

   /login

2. Select Antigravity [pi-agy-bridge] from the provider list.
3. Complete sign-in in your browser.

Startup checks and diagnostics do not open a sign-in browser. Use /login to sign in.

3. Select a Model

1. Open the model selector:

   /model

2. Type agy to find Antigravity models. Available models depend on the selected driver.
3. Select a model and start using Pi.

Command Reference

Driver and doctor results are user-only notifications, not model conversation messages. Without a UI, results are written to stderr.

How It Works

Tool Execution

Antigravity models request tools through the bridge. Pi runs registered tool requests and returns the results. The bridge limits native tool capabilities through the selected driver.

Choose a Driver

Use /agy-bridge:driver to change the driver. Use /model to see its available models. On startup, the bridge uses the driver recorded in its saved authentication. If no saved authentication or valid driver is present, it defaults to ACP.

Images: Both drivers support tool-based image reads. ACP also uses an image observer for eligible offloaded images. The observer returns text and may add latency and model usage.

For images referenced in user messages, ACP can automatically inject image blocks into the model prompt. Tool-based reads remain available for images in history and other locations.

Usage: ACP and CLI report usage at different levels. Do not compare their values as billing totals. The bridge does not calculate monetary costs.

Sessions

The bridge reuses a native session when it matches Pi's history. If Pi branches or compacts a conversation, the bridge can rebuild the model context from Pi's saved messages.

Configuration

Environment Variables

For a custom ACP distribution, keep both files in the same directory and set:

export AGY_ACP_DIR="$HOME/path/to/agy-acp-server"

Managed ACP Server Details

• Version: Antigravity ACP Server 1.4.5 (macOS and Linux, x64 and ARM64).
• Registry: src/extension/drivers/acp/registry.json.
• Storage: <Pi Agent Home>/pi-agy-bridge/acp/<archive-name>/ (typically ~/.pi/agent/pi-agy-bridge/acp/).
• Verification: SHA-256 checksums are verified before extraction.

Troubleshooting

Run /agy-bridge:doctor to check the installation, connection, and sign-in status.

Common Problems

• ACP download or extraction fails: Check your network, disk space, and permissions under ~/.pi/agent/. Downloads are about 93–307 MiB. Linux extraction can require about 1 GiB.
• Signed out: Run /login and select Antigravity [pi-agy-bridge].
• No models appear: Sign in and run /agy-bridge:doctor. When offline, the bridge can use a cached model catalog.
• Custom ACP server fails: Check that AGY_ACP_DIR is an absolute directory path containing executable agy_acp_server.par and localharness_external files. Unset AGY_ACP_DIR to use the managed server.
• Enable debug logs:

  export AGY_BRIDGE_DEBUG=1
  pi

Development

Use Bun to install dependencies. Use Node.js to run tests:

# Install dependencies
bun install

# Verify version alignment
bun run check:version

# Run TypeScript type check
bun run typecheck

# Run test suite
bun run test