pi-antigravity-acp-provider

A first-class Pi provider for Google Antigravity through its official ACP server.

Important: this package no longer uses @google/gemini-cli. The Gemini CLI individual Code Assist login path was retired and is not a supported authentication route. Antigravity/agy is the target runtime.

Features

• Registers antigravity-acp/* models backed by Google Antigravity.
• Uses ACP protocol v1 and the official TypeScript SDK.
• Collapses Antigravity's effort-qualified IDs into one entry per model; Pi's Shift+Tab reasoning control selects low/medium/high dynamically.
• Supports Pi streaming, cancellation, usage/quota metadata, lifecycle cleanup, and persisted ACP session restoration across Pi restarts.
• Routes compatible Pi tools through an authenticated loopback MCP bridge.
• Supports persisted default, auto-edit, and yolo Antigravity permission modes. The requested default is yolo; switching to a prompting mode retains the single-use, fail-closed Pi permission broker.
• Advertises no ACP filesystem or terminal client capabilities.
• Provides setup, auth-health, logout/account-switching, qualification, quota, and runtime-update commands.
• Automatically checks for newer managed ACP runtimes once per day, with automatic, notify, and manual update modes.
• Uses an Ed25519-signed runtime catalog with exact Google artifact URLs, archive hashes and sizes, strict two-file extraction, pre-activation ACP identity/version validation, immutable releases, rollback retention, musl rejection, macOS quarantine cleanup, and Windows process-tree handling.

New-user setup

Install from the official Pi package gallery/npm:

pi install npm:pi-antigravity-acp-provider
pi

To run from source instead:

git clone https://github.com/zacbemis/pi-antigravity-acp-provider.git
cd pi-antigravity-acp-provider
npm install
pi --no-extensions -e ./extensions/index.ts

In Pi:

1. Optionally run /antigravity-acp setup for a runtime/auth preflight.
2. Run /login.
3. Choose Sign in with an account.
4. Choose Google Antigravity (ACP).
5. If needed, wait for the official ACP server download and extraction. Progress is shown; the Linux build observed during development expands to about 1.8 GB.
6. Complete the Google login in the browser.
7. Run /antigravity-acp setup again to perform a network auth probe and model discovery.
8. Run /model and select one of the antigravity-acp models.
9. Press Shift+Tab to choose the reasoning effort. Flash models expose low, medium, and high; Pro exposes only the tiers advertised by Antigravity.
10. Send a prompt. The default permission mode is yolo, so Antigravity-native commands and edits can run without confirmation.

The provider first looks at AGY_ACP_BIN, then its verified managed ~/.local/opt/agy-acp/current/ release, ~/.local/bin/agy_acp_server.par, and PATH. Set AGY_ACP_BIN to explicitly prefer an externally managed runtime. If absent, it installs the platform build published in the ACP registry. A global agy or gemini command is not required.

SSH and headless Google login

When Pi is running over SSH, or on Linux without DISPLAY/WAYLAND_DISPLAY, /login automatically uses a manual browser relay:

1. Pi prints the Google authorization URL instead of trying to launch a browser on the server.
2. Open that URL in a browser on your local machine and finish Google sign-in.
3. Google redirects to an Antigravity loopback URL. The page may show a connection error because 127.0.0.1 refers to your local machine; copy the complete final URL from the browser address bar.
4. Paste that URL into Pi. The provider validates its host, port, path, and OAuth state, then relays it to Antigravity's loopback listener on the server. An SSH port-forward is not required.

Set PI_ANTIGRAVITY_ACP_OAUTH_MODE=manual to force this flow, or PI_ANTIGRAVITY_ACP_OAUTH_MODE=browser to force normal browser launch. OAuth URLs and callback codes are kept in a private temporary directory only for the duration of login and are never logged or persisted by this package.

For API-key authentication, choose Enter an API key and then Antigravity Gemini API key in /login, or set GEMINI_API_KEY before starting Pi.

Antigravity owns OAuth tokens under ~/.gemini/antigravity-acp/; Pi stores only a non-secret configured marker. Existing agy CLI credentials and Gemini CLI credentials should not be assumed to authenticate this separate ACP server.

Commands

/antigravity-acp setup
/antigravity-acp doctor
/antigravity-acp doctor --verbose
/antigravity-acp status
/antigravity-acp quota
/antigravity-acp update
/antigravity-acp updates [automatic|notify|manual]
/antigravity-acp qualify
/antigravity-acp logout
/antigravity-acp account
/antigravity-acp permissions
/antigravity-acp permissions default
/antigravity-acp permissions auto-edit
/antigravity-acp permissions yolo

Permission and runtime-update modes are saved in ~/.pi/agent/antigravity-acp-provider/config.json. Runtime updates default to automatic; only provider-managed installations are replaced. ACP session bindings are saved beside the config in sessions.json.

logout/account clears local Antigravity credentials and saved ACP sessions. Run Pi's /logout afterward to remove the Pi credential marker, then /login for the new account. update checks the official registry and installs its newest release only after matching it to the provider's signed runtime catalog. See docs/RUNTIME-UPDATES.md.

Development

npm run check
npm run test:real-acp  # initializes the installed Antigravity ACP server
npm run test:live      # sends a real authenticated prompt
npm run test:qualify   # live cancel, restore, MCP, model, and permission qualification
npm run test:packed
npm audit --audit-level=high

# Maintainer-only runtime catalog refresh/signing
npm run refresh:runtime-manifest
ACP_RUNTIME_MANIFEST_PRIVATE_KEY_PATH=/secure/key.pem npm run sign:runtime-manifest

Security boundary

This launches a full coding agent with the user's OS privileges. The default yolo mode permits Antigravity-native commands and edits without confirmation. Use /antigravity-acp permissions default for confirmation prompts. Disabling ACP filesystem/terminal client callbacks is not a sandbox for Antigravity-native tools. Pi hooks govern tools routed through the pi_ MCP namespace; Antigravity-native tools remain governed by Antigravity policy and ACP permission requests.

Compatibility

The implementation is pinned to Pi 0.85.0, ACP SDK 0.19.1, and ACP protocol 1. The bundled signed catalog bootstraps Antigravity ACP 1.1.1 and can accept newer signed catalog releases without an npm update. ACP session setup allows up to two minutes for slow first-run initialization, while transport shutdown rejects pending requests immediately. The official registry currently provides Linux x64/ARM64, Windows x64/ARM64, and macOS ARM64 artifacts. Intel macOS has no pinned artifact, and Alpine/musl is rejected because Google's Linux build targets glibc.

During browser authentication, Chromium may write Opening in existing browser session. to the ACP process's inherited stdout. The transport ignores only that exact known compatibility line and reports its count in doctor; all other non-JSON stdout remains a fatal protocol error.

Managed installations also repair executable permissions for both the ACP server and its localharness_external helper. This repairs installations created by 0.1.3 and earlier, where OAuth could succeed but session creation failed with an opaque ACP Internal error because the extracted helper was not executable.

Earlier repository documents analyzing @google/[email protected] describe the superseded implementation and are retained only as historical research. See docs/ANTIGRAVITY-MIGRATION.md.

License

MIT