Antigravity

opencode-antigravity is an OpenCode plugin that lets OpenCode talk directly to Google Antigravity / Cloud Code Assist models — Gemini, plus the Claude and GPT-OSS models Antigravity also advertises. Sign in with Google, pick a model, and go. Under the hood it handles OAuth login, native SSE streaming, model routing, and quota diagnostics itself, so it never shells out to an external Antigravity CLI.

Using Pi Coding Agent instead of OpenCode? Install the companion extension pi-antigravity.

Unofficial integration. This project is not affiliated with or endorsed by Google. Use it only with an account and services you are authorized to access, and review its source before granting OAuth permissions.

Contents

• Requirements
• Install
• Quick start
• Authentication and credential safety
• Commands and tools
• Models and routing
• Configuration
• Troubleshooting
• Development

Requirements

• OpenCode
• A Google account that can use the relevant Cloud Code Assist / Antigravity services
• A browser to complete Google sign-in. Same-machine is best (the browser hits the local callback automatically); on a remote/headless machine, see Troubleshooting.

Install

Add the plugin to your global OpenCode config (~/.config/opencode/opencode.json):

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["@rahularya01/opencode-antigravity"]
}

Or add the same plugin entry to a project's opencode.json. OpenCode downloads the package from npm at startup.

Optional global install:

npm install -g --ignore-scripts @rahularya01/opencode-antigravity
# or
bun add -g --ignore-scripts @rahularya01/opencode-antigravity

To load a local checkout after bun run build:

{
  "plugin": ["file:///absolute/path/to/opencode-antigravity/dist/plugin.js"]
}

Restart OpenCode after changing plugin config.

Quick start

1. Add the plugin (see Install) and restart OpenCode.
2. Run opencode auth login, select provider antigravity, then Google account (Antigravity browser login).
3. Complete Google sign-in in your browser.
4. Pick a model, for example antigravity/gemini-3.8-flash.
5. Start working. If a request fails on quota, run /antigravity-usage.

Authentication and credential safety

The plugin uses the OAuth 2.0 Authorization Code flow with PKCE, so credentials are only ever exchanged with Google — never typed into OpenCode.

1. opencode auth login opens Google sign-in and starts a temporary callback listener at http://localhost:51121/oauth-callback.
2. After you approve access, OpenCode exchanges the callback code for tokens and stores them in OpenCode's auth store (normally ~/.local/share/opencode/auth.json).
3. OpenCode refreshes access tokens automatically when they expire — you shouldn't need to sign in again unless a token is revoked.

You can also paste a ya29… OAuth access token at the API-token prompt, or set ANTIGRAVITY_ACCESS_TOKEN / GOOGLE_ACCESS_TOKEN.

The callback listener binds only to a loopback host, so it isn't reachable from outside your machine. The auth file it writes to contains sensitive access and refresh tokens: do not commit it, paste it into issues, or share its contents.

Signing in requests these Google OAuth scopes:

Scope	Why it's needed
aicode	Access to the Cloud Code Assist / Antigravity model catalog and endpoints
cloud-platform	General Cloud Code Assist API access
userinfo.email, userinfo.profile	Identify the signed-in Google account
cclog	Cloud Code Assist logging/telemetry endpoints used by the API
experimentsandconfigs	Server-side experiment and config flags for the API

Review these permissions before approving access. If your credentials expire or are revoked, just re-run opencode auth login for provider antigravity.

Commands and tools

Command / tool	Description
opencode auth login	Sign in to Google and configure the provider.
/antigravity-usage	Show the server-reported shared quota groups and reset times (antigravity_usage tool).
/antigravity-models	List available runtime models, remaining shared-pool quota, and capabilities (antigravity_models).
/antigravity-image	Generate an image via Antigravity (generate_image tool).
/antigravity-search	Search the web using Google Search Grounding via Antigravity (google_search tool).
/antigravity-doctor	Show sanitized provider diagnostics, endpoints, and resolved model (antigravity_doctor tool).

The plugin also registers tools the model can call directly:

Tool	Description
generate_image	Create an image and save it under .opencode/generated-images/ unless path is set. Optional aspectRatio and model.
google_search	Real-time web search and URL analysis using Google Search Grounding powered by Gemini 3 Flash.
antigravity_usage	Shared quota pools and reset times. Free-tier accounts may not get the aggregate summary; per-model remaining % still works.
antigravity_models	Runtime models with remaining shared-pool quota. Set all=true to include tab/chat models.
antigravity_doctor	Show sanitized Antigravity provider diagnostics, including the endpoint, status, and resolved runtime model.

Model availability, entitlement, quota groups, and resets are returned by the service and can differ by account. The quota percentage shown for a model can represent a shared pool, not a private per-model allowance.

Image models such as gemini-3-pro-image are account-dependent; generation falls back to other advertised Gemini image IDs on 404.

Models and routing

plugin.config() registers a static catalog at OpenCode startup (no network). After you sign in, provider.models refreshes the list from Antigravity (fetchAvailableModels) and groups runtime thinking variants into public OpenCode model IDs. Newly enabled models — for example a new Gemini Flash generation — become selectable after that refresh without waiting for a plugin release. Static routing for known IDs always wins over the discovered overlay.

Use /antigravity-models to see live availability and quota for your account. Unspecified thinking effort maps to high.

Why Claude and GPT-OSS appear

Antigravity / Cloud Code Assist exposes a multi-provider catalog. Depending on your account, its Google-authenticated API can advertise Google Gemini models alongside Claude models served through Anthropic Vertex and GPT-OSS served through OpenAI Vertex. This plugin exposes those advertised Claude and GPT-OSS models through the single antigravity provider; they are not separate OpenCode providers and do not use a separate Anthropic or OpenAI login.

The backend's display labels do not always match its runtime IDs. For example, gemini-3.5-flash-extra-low, gemini-3.5-flash-low, and gemini-3-flash-agent can be displayed as Gemini 3.5 Flash Low, Medium, and High. Gemini 3.8 and 3.7 Flash send thinkingLevel on a *-tiered runtime id; Gemini 3.6 Flash uses per-effort runtime IDs; Gemini 3.5 Flash and 3.1 Pro send thinkingBudget.

Public model ID	Input	Thinking levels shown	Max output tokens	Request routing
gemini-3.8-flash	Text, image	Low, Medium, High	65,536	all efforts → gemini-3.8-flash-tiered
gemini-3.7-flash	Text, image	Low, Medium, High	65,536	all efforts → gemini-3.7-flash-tiered
gemini-3.6-flash	Text, image	Low, Medium, High	65,536	low → gemini-3.6-flash-low; medium → gemini-3.6-flash-medium; high → gemini-3.6-flash-high
gemini-3.5-flash	Text, image	Low, Medium, High	65,536	low → gemini-3.5-flash-extra-low; medium → gemini-3.5-flash-low; high → gemini-3-flash-agent
gemini-3.1-pro	Text, image	Low, High	65,535	low → gemini-3.1-pro-low; high → gemini-pro-agent
claude-sonnet-4-6	Text, image	High	64,000	high → claude-sonnet-4-6
claude-opus-4-6	Text, image	High	64,000	high → claude-opus-4-6-thinking
gpt-oss-120b	Text	Medium	32,768	medium → gpt-oss-120b-medium

OpenCode owns the chat UI, tools (read, write, edit, bash, …), permissions, sessions, and compaction. This plugin owns streaming, thinking translation, Gemini schema conversion, and token refresh. Tool calls from Gemini / Claude are surfaced as standard AI SDK tool calls so OpenCode executes them locally under your permission rules.

Configuration

Lookup order is OPENCODE_ANTIGRAVITY_*, then ANTIGRAVITY_*, then the legacy NOAGY_* prefix.

Variable	Purpose
ANTIGRAVITY_ACCESS_TOKEN	Direct OAuth access token override. GOOGLE_ACCESS_TOKEN is also accepted.
ANTIGRAVITY_BASE_URL	Override the API base URL. It must be HTTPS, contain no URL credentials, and target an allowed Google APIs host.
ANTIGRAVITY_PROJECT_ID	Use a specific Cloud Code Assist project ID instead of discovery or the managed fallback.
ANTIGRAVITY_CALLBACK_HOST	Bind OAuth callback to 127.0.0.1, ::1, or localhost only. Defaults to 127.0.0.1.
ANTIGRAVITY_USER_AGENT	Override the request user-agent.
ANTIGRAVITY_CLIENT_ID	Use a custom Google OAuth client ID.
ANTIGRAVITY_CLIENT_SECRET	Use a custom Google OAuth client secret. Keep it out of source control and shell history.
ANTIGRAVITY_NO_PREWARM	Set to 1 to skip the TLS pre-warm request made when the provider loads.
ANTIGRAVITY_NO_EXTRA_TOOLS	Set to 1 to disable both google_search and generate_image extra tools.
ANTIGRAVITY_NO_SEARCH_TOOL	Set to 1 to disable the google_search tool (e.g. to avoid clashing with other search providers).
ANTIGRAVITY_NO_IMAGE_TOOL	Set to 1 to disable the generate_image tool.

By default, the plugin tries https://cloudcode-pa.googleapis.com, then the daily host, then the sandbox host. Prefer the built-in OAuth client unless you have a reason to use your own credentials.

Setting ANTIGRAVITY_PROJECT_ID removes the project-discovery round-trip when credentials do not already carry a project ID.

Troubleshooting

• No credentials / 401 / 403: Run opencode auth login for provider antigravity again.
• Remote/headless machine — browser can't reach localhost:51121: The callback binds to loopback only. From the machine with the browser, run ssh -N -L 51121:127.0.0.1:51121 <user>@<server> and keep it open, then run opencode auth login on the server.
• OAuth callback will not start: Ensure port 51121 is free and ANTIGRAVITY_CALLBACK_HOST is a permitted loopback address.
• Model is unavailable: Run /antigravity-models; availability is account- and service-dependent.
• Quota or rate limit: Run /antigravity-usage. A 429 response usually indicates quota or rate limiting; changing models may still draw from the same shared pool.

Development

This repo uses Bun for install, tests, and the bundle. Tests mock fetch and do not call live Google APIs.

bun install
bun run typecheck
bun test
bun run build

The OpenCode plugin entry is src/entries/plugin.ts (id + server). ./sdk exports createAntigravity for use as a Vercel AI SDK LanguageModelV3 provider.

Support the project

If opencode-antigravity is useful to you, consider sponsoring the project on GitHub.

License

MIT