🌌 Antigravity Bridge

Standalone Google OAuth bridge for Gemini Code Assist / Antigravity. Multi-account. No OpenCode required.

Built for agents and clients that do not support Google OAuth directly: Hermes, Open WebUI, Continue, Boba, BetterGPT, and any other OpenAI-compatible tool.

📖 Table of contents

TL;DR
What is it?
Quick install
Architecture
- Single-account (simple)
- Multi-account
Configuration
Account management (admin API)
OAuth login
Agent setup
API reference
Supported features
API quick tests
Troubleshooting
Disclaimer
License

⚡ TL;DR

git clone https://github.com/lomeliDev/antigravity-bridge.git
cd antigravity-bridge
chmod +x install.sh
./install.sh

The installer handles Python venv, OAuth login (opens your browser), and installs the service. One command.

No OpenCode, no agy CLI, no npm packages. Just Python + a Google account.

✨ What is it?

A Flask bridge that uses Google OAuth refresh_tokens to access Gemini Code Assist (Antigravity). It talks the OpenAI-compatible HTTP API so any client that works with OpenAI can work with Gemini Code Assist — including Claude and GPT models proxied through Google's platform.

┌─────────────┐   OpenAI API     ┌────────────────────┐   HTTPS    ┌─────────────────────────┐
│   Hermes    │ ────────────────► │  Antigravity       │ ─────────► │  cloudcode-pa.google    │
│  Open WebUI │  /v1/chat/...    │  Bridge :PORT       │  Bearer   │  Gemini · Claude · GPT  │
│  LiteLLM    │                  │                     │  + OAuth  │  14 models              │
└─────────────┘                  └────────────────────┘           └─────────────────────────┘

14 models across 3 providers through a single bridge: Gemini (2.5, 3, 3.1, 3.5), Claude (Sonnet, Opus), GPT.

🚀 Quick install

git clone https://github.com/lomeliDev/antigravity-bridge.git
cd antigravity-bridge
chmod +x install.sh
./install.sh

What the installer does:

Checks Python 3.10+ and creates a .venv.
Installs flask + requests.
OAuth login — opens your browser, you authorize Google, paste the redirect URL.
Asks for port and optional API key.
Installs a systemd (Linux) or launchd (macOS) service.
Runs health + models + chat validation.

Manual run

source .env
.venv/bin/python3 server.py --host 0.0.0.0 --port 52847

🏗️ Architecture

Single-account (simple)

Default setup with env vars — good for personal use:

.env:
  BRIDGE_REFRESH_TOKEN=1//...    ← one Google account
  BRIDGE_API_KEY=sk-...          ← optional client auth

→ All requests go through that one account.

Multi-account

One bridge process → unlimited Google accounts → one API key per account:

accounts.json:
{
  "accounts": {
    "sk-account-one-xxxxxxxxxxxx": {
      "label": "Miguel Personal",
      "refresh_token": "1//...",
      "client_id": "...",
      "client_secret": "..."
    },
    "sk-account-two-yyyyyyyyyyyy": {
      "label": "Work Account", 
      "refresh_token": "1//..."
    }
  }
}

Authorization: Bearer <your-account-key>  → Miguel's account
Authorization: Bearer <your-work-key>      → Work account

Each account gets its own access token cache in auth_cache/, its own rate limits, and its own model access. Perfect for teams, agencies, or power users.

⚙️ Configuration

Variable	Default	Purpose
`HOST`	`0.0.0.0`	Listen host
`PORT`	`52847`	Listen port
`BRIDGE_REFRESH_TOKEN`	—	OAuth refresh_token (single-account mode)
`BRIDGE_API_KEY`	—	Client API key (deprecated — use accounts.json for multi-account)
`BRIDGE_ADMIN_KEY`	—	Protects `/admin/*` endpoints. If empty → open access (dev mode)
`BRIDGE_ACCOUNTS_FILE`	`./accounts.json`	Path to multi-account config
`BRIDGE_AUTH_CACHE_DIR`	`./auth_cache/`	Per-account token cache directory
`ANTIGRAVITY_CLIENT_ID`	(hardcoded)	Google OAuth client ID
`ANTIGRAVITY_CLIENT_SECRET`	(hardcoded)	Google OAuth client secret

👥 Account management (admin API)

Protected by BRIDGE_ADMIN_KEY (set in .env). All admin calls require Authorization: Bearer <admin_key>.

Create an account

curl -X POST http://127.0.0.1:52848/admin/accounts \
  -H "Authorization: Bearer <admin_key>" \
  -H "Content-Type: application/json" \
  -d '{"api_key": "sk-my-new-account", "label": "My New Account"}'

Response: {"ok": true, "api_key": "sk-my-new-account"}

Start OAuth login for the new account

curl -X POST http://127.0.0.1:52848/admin/accounts/sk-my-new-account/login \
  -H "Authorization: Bearer <admin_key>"

Returns an auth_url — open it in your browser, authorize Google, and the bridge captures the code automatically (localhost callback). Or use manual mode:

# After authorizing in browser, copy the redirect URL and:
curl -X POST http://127.0.0.1:52848/auth/login/manual \
  -H "Content-Type: application/json" \
  -d '{"code": "..."}'

List all accounts

curl http://127.0.0.1:52848/admin/accounts \
  -H "Authorization: Bearer <admin_key>"

Remove an account

curl -X DELETE http://127.0.0.1:52848/admin/accounts/sk-my-new-account \
  -H "Authorization: Bearer <admin_key>"

Use the account

curl http://127.0.0.1:52848/v1/chat/completions \
  -H "Authorization: Bearer sk-my-new-account" \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini-2.5-flash","messages":[{"role":"user","content":"hello"}]}'

Full flow from scratch

POST /admin/accounts          → create account (empty, no token yet)
POST /admin/accounts/X/login  → get auth_url
→ user opens URL in browser
→ authorizes Google
→ localhost:51121 captures code automatically
POST /auth/login/callback     → exchanges code for tokens
✅ Account ready — refresh_token saved to accounts.json

🔑 OAuth login

Interactive (browser)

python3 auth-login.py

Opens your browser, captures the OAuth redirect on localhost:51121.

Web UI

Open http://YOUR_HOST:PORT/login in your browser — dual mode (auto callback + manual code paste).

Manual (remote servers)

# 1. Get auth URL
curl -X POST http://YOUR_HOST:52848/auth/login

# 2. Open the returned auth_url in a browser, authorize

# 3. Copy the redirect URL and exchange:
curl -X POST http://YOUR_HOST:52848/auth/login/manual \
  -H "Content-Type: application/json" \
  -d '{"code": "PASTE_FULL_REDIRECT_URL_HERE"}'

🤖 Agent setup

Hermes

./scripts/add-to-hermes.sh gemini-2.5-flash antigravity-bridge

LiteLLM

Add to litellm_config.yaml:

model_list:
  - model_name: gemini-2.5-flash
    litellm_params:
      model: openai/gemini-2.5-flash
      api_base: http://127.0.0.1:52848/v1
      api_key: sk-your-account-key
  - model_name: claude-sonnet-4-6
    litellm_params:
      model: openai/claude-sonnet-4-6
      api_base: http://127.0.0.1:52848/v1
      api_key: sk-your-account-key

Open WebUI

Admin Panel → Settings → Connections → Add OpenAI API.
URL: http://YOUR_SERVER:52848/v1
Key: your account API key (from accounts.json).

Generic OpenAI client

Field	Value
Base URL	`http://YOUR_SERVER:52848/v1`
API key	Account key (`sk-...`) from `accounts.json`
Models	Fetched via `GET /v1/models`

📡 API reference

Method	Endpoint	Auth	Description
`GET`	`/`	—	Bridge info + account count
`GET`	`/health`	—	Health + credential status
`GET`	`/v1/models`	—	List all models
`GET`	`/v1/models/{id}`	—	Single model info
`POST`	`/v1/chat/completions`	Account key	Chat (stream + non-stream)
`GET`	`/v1/usage`	—	Per-model usage stats
`GET`	`/v1/billing/subscription`	—	Billing stub (Hermes compat)
`GET`	`/admin/accounts`	Admin key	List accounts
`POST`	`/admin/accounts`	Admin key	Create account
`DELETE`	`/admin/accounts/{key}`	Admin key	Remove account
`POST`	`/admin/accounts/{key}/login`	Admin key	Start OAuth for account
`POST`	`/auth/login`	—	Start OAuth (default account)
`POST`	`/auth/login/callback`	—	Exchange captured code
`POST`	`/auth/login/manual`	—	Exchange pasted code
`GET`	`/auth/login/status`	—	Auth status
`GET`	`/login`	—	Web UI login page

🧩 Supported features

POST /v1/chat/completions — blocking and SSE streaming
Multi-turn conversations with tool calls (tools, tool_choice, role: "tool")
Vision — image_url with base64 data URI or public URL (7/8 models tested ✅)
response_format — json_object and json_schema
seed, max_tokens, max_completion_tokens, n, stop, temperature, top_p
stream_options.include_usage
Hermes Dashboard compatibility: /v1/usage, /v1/billing/subscription
Automatic token refresh — access tokens refreshed transparently
Auto-clear on invalid_grant — revoked tokens are detected and cleaned
PKCE (S256) OAuth security
Multi-account — one bridge, N Google accounts, N API keys
Admin API with optional BRIDGE_ADMIN_KEY protection

🧪 API quick tests

BASE=http://127.0.0.1:52848

# Health
curl -s "$BASE/health" | jq

# Models
curl -s "$BASE/v1/models" | jq '.data[].id'

# Chat (no key, single-account mode)
curl -s "$BASE/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini-2.5-flash","messages":[{"role":"user","content":"hi"}]}' | jq

# Chat (with account key, multi-account mode)
curl -s "$BASE/v1/chat/completions" \
  -H "Authorization: Bearer sk-your-account" \
  -H "Content-Type: application/json" \
  -d '{"model":"claude-sonnet-4-6","messages":[{"role":"user","content":"hi"}]}' | jq

# Streaming
curl -N "$BASE/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini-2.5-flash","stream":true,"messages":[{"role":"user","content":"tell me a joke"}]}'

# Usage
curl -s "$BASE/v1/usage" | jq

# Vision (image URL)
curl -s "$BASE/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini-2.5-flash","messages":[{"role":"user","content":[{"type":"text","text":"What do you see?"},{"type":"image_url","image_url":{"url":"https://example.com/photo.jpg"}}]}]}' | jq

🛠️ Troubleshooting

Problem	Solution
Bridge fails to start	Run manually: `source .env && .venv/bin/python3 server.py`
`Missing OAuth credentials`	Account has no refresh_token. Run OAuth login for that account.
`401 Invalid API key`	The account key doesn't match any in `accounts.json`. Check with `GET /admin/accounts`.
`invalid_grant` from Google	Token revoked. The bridge auto-clears it. Run login again.
Models list is empty	Token refresh failed. Check `GET /health` for credential status.
Admin `401`	Set `BRIDGE_ADMIN_KEY` in `.env` and pass it as `Authorization: Bearer <admin_key>`.

⚠️ Disclaimer

This is an unofficial, experimental project. Not affiliated with Google, Antigravity, or Gemini Code Assist.

Use at your own risk. See DISCLAIMER.md.

📄 License

Made with 💜 so you can use Antigravity everywhere.

Name		Name	Last commit message	Last commit date
scripts		scripts
.env.example		.env.example
.gitignore		.gitignore
DISCLAIMER.md		DISCLAIMER.md
LICENSE		LICENSE
README.md		README.md
accounts.json.example		accounts.json.example
antigravity-bridge.service		antigravity-bridge.service
auth-login.py		auth-login.py
install.sh		install.sh
requirements.txt		requirements.txt
server.py		server.py

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🌌 Antigravity Bridge

📖 Table of contents

⚡ TL;DR

✨ What is it?

🚀 Quick install

Manual run

🏗️ Architecture

Single-account (simple)

Multi-account

⚙️ Configuration

👥 Account management (admin API)

Create an account

Start OAuth login for the new account

List all accounts

Remove an account

Use the account

Full flow from scratch

🔑 OAuth login

Interactive (browser)

Web UI

Manual (remote servers)

🤖 Agent setup

Hermes

LiteLLM

Open WebUI

Generic OpenAI client

📡 API reference

🧩 Supported features

🧪 API quick tests

🛠️ Troubleshooting

⚠️ Disclaimer

📄 License

About

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🌌 Antigravity Bridge

📖 Table of contents

⚡ TL;DR

✨ What is it?

🚀 Quick install

Manual run

🏗️ Architecture

Single-account (simple)

Multi-account

⚙️ Configuration

👥 Account management (admin API)

Create an account

Start OAuth login for the new account

List all accounts

Remove an account

Use the account

Full flow from scratch

🔑 OAuth login

Interactive (browser)

Web UI

Manual (remote servers)

🤖 Agent setup

Hermes

LiteLLM

Open WebUI

Generic OpenAI client

📡 API reference

🧩 Supported features

🧪 API quick tests

🛠️ Troubleshooting

⚠️ Disclaimer

📄 License

About

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