antigravityide2api

Export the locally logged-in Antigravity IDE session as an Anthropic-compatible /v1/messages HTTP API, designed for use with Claude Code or any other Anthropic API compatible client.

Prerequisites

1. Antigravity IDE installed and logged in on your local machine;
2. Node.js >= 18;
3. (Recommended) ripgrep (rg): installed and available in $PATH if using fast file search via native tools.

Method 1: Direct Usage via npx (Recommended)

No manual clone or global installation required—run directly using npx.

1. Extract Local IDE Credentials

Ensure Antigravity IDE is open and logged in, then run:

npx @cddchen/antigravityide2api@latest extract-token

Note: This reads OAuth credentials from the local IDE database and stores them safely with 0600 permissions at ~/.antigravityide2api/token.json. You only need to run this on initial setup or when your session expires.

2. Start the Proxy Server

Foreground execution (logs stream directly to the terminal):

npx @cddchen/antigravityide2api@latest
# Or explicitly:
npx @cddchen/antigravityide2api@latest start-fg

Background daemon:

# Start background daemon
npx @cddchen/antigravityide2api@latest start

# Check process status and masked token info
npx @cddchen/antigravityide2api@latest status

# Stop background daemon
npx @cddchen/antigravityide2api@latest stop

3. (Optional) Install Globally

If you prefer calling antigravityide2api directly without npx:

npm i -g @cddchen/antigravityide2api@latest

# Then use the CLI directly:
antigravityide2api extract-token
antigravityide2api start
antigravityide2api status
antigravityide2api stop

Method 2: Run from Source (Development)

Recommended if you want to inspect the source code, develop features, or customize behavior.

1. Clone & Install Dependencies

git clone https://github.com/cddchen/antigravityide2api.git
cd antigravityide2api
npm install

2. Build

# Compile TypeScript to dist/
npm run build

# Or run compiler in watch mode during development
npm run dev

3. Extract Local IDE Credentials

npm run extract-token
# Equivalent to: node dist/cli.js extract-token

4. Start Server

Foreground execution:

npm start
# Equivalent to: node dist/cli.js start-fg

Background daemon:

node dist/cli.js start    # Start background daemon
node dist/cli.js status   # Check status
node dist/cli.js stop     # Stop daemon

Debug mode (with live logcat and prompt inspection):

PORT=4000 DUMP_SYSTEM=1 DEBUG=1 node dist/server.js

Once started, visit http://127.0.0.1:4000/logcat to inspect inbound /v1/messages, outbound Antigravity contents, and each upstream functionCall plus its bridge mapping in real time (same frame; no tokens).

5. Run Tests

npm test

Claude Code Configuration

By default, the server listens at http://127.0.0.1:3000. Configure Claude Code with the following environment variables before starting:

# Point Claude Code to the local proxy
export ANTHROPIC_BASE_URL=http://127.0.0.1:3000

# If no API_KEY is set on the server, any non-empty string satisfies client checks
export ANTHROPIC_AUTH_TOKEN=test

Then start Claude Code:

claude

Session Continuity & Concurrency: Claude Code automatically attaches X-Claude-Code-Session-Id header to requests. The proxy uses this header to maintain the upstream session trajectory (sessionId, cascadeUuid, trajectoryUuid, incrementing stepIndex) across both plain text and tool-use turns. The proxy does not cache conversation history transcripts locally; full request history is faithfully reconstructed on each turn. Non-blocking leases protect against concurrent request races, immediately responding with HTTP 409 if a request is already in progress for that session.

CLI Reference

Commands can be invoked via antigravityide2api <command> or npx @cddchen/antigravityide2api@latest <command>:

| Command | Description | |---------|-------------| | (no args) / start-fg | Start proxy server in the foreground | | start | Start background daemon; stores PID and logs in the token directory | | stop | Stop background daemon | | status | Display token path, masked account count, and process status | | extract-token | Read OAuth credentials from the local Antigravity IDE | | trim-words | List effective filter words (defaults ∪ file ∪ env) | | trim-words add/rm/clear | Persist extra filter words in the config directory | | -h / --help | Show CLI usage help |

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | PORT | 3000 | HTTP listening port | | HOST | 127.0.0.1 | HTTP listening address (defaults to loopback for security) | | API_KEY | Empty | When set, requests must provide matching x-api-key or Bearer token | | TOKEN_FILE | ~/.antigravityide2api/token.json | Path to the credentials file | | DEFAULT_MODEL | gemini-3.6-flash-high | Default upstream model | | WORKSPACE_ROOT | Empty | Allowed directory boundary for file modifications (Write/Edit) | | REQUEST_TIMEOUT | 300000 | Upstream request timeout in milliseconds | | PENDING_TIMEOUT | 600000 | Multi-turn tool execution pending session timeout in milliseconds | | SESSION_IDLE_TIMEOUT | 1800000 | Idle keyed session retention timeout in milliseconds (X-Claude-Code-Session-Id) | | ANTIGRAVITY_BASE | https://daily-cloudcode-pa.googleapis.com | Upstream API base endpoint | | IDE_VERSION | local product.json ideVersion | Metadata and User-Agent version (auto-detected from local IDE) | | ANTIGRAVITY_SYSTEM | trimmed | System prompt strategy: full / trimmed / short | | ANTIGRAVITY_TRIM_WORDS | Empty | Extra filter words (comma-separated or JSON array). Case-insensitive substring match; hits become equal-length zero-width spaces, not deleted as whole lines. Longer phrases win (claude code before claude). Built-in defaults (trimmed mode only) cover file:// and background-task phrases in communication_style. File: trim-words.json next to the token. Restart after changes. | | ANTIGRAVITY_MAX_RETRIES | 3 | Maximum retry attempts upon upstream 429 / 503 errors (0 disables retry) | | ANTIGRAVITY_RETRY_BASE_MS | 1000 | Base delay in milliseconds for exponential backoff | | ANTIGRAVITY_RETRY_MAX_MS | 30000 | Maximum cap for backoff delay in milliseconds |

Verification & API Endpoints

Once the server is running, you can test it directly via curl:

# 1. Health check
curl -s http://127.0.0.1:3000/health

# 2. Dynamic upstream model catalog
curl -s http://127.0.0.1:3000/v1/models | jq '.data[] | {id, display_name}'

# 3. Test non-streaming message
curl -s -X POST http://127.0.0.1:3000/v1/messages \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini-3.6-flash-high","max_tokens":100,"messages":[{"role":"user","content":"Hello"}]}'

Security & Disclaimer

• For personal educational use and interaction with your own authenticated local session only. Use at your own risk.
• Credential extraction is strictly read-only; it never modifies or writes back to the Antigravity IDE database.
• The exported token.json is protected with 0600 file permissions. Never commit or share your token file.