# Antigravity Proxy

OpenAI-compatible proxy that intercepts and relays requests to Google's Antigravity language server, impersonating the real Electron webview.

## Quick Start

```bash
# Build
cargo build --release

# Run (language server must be running)
RUST_LOG=info ./target/release/antigravity-proxy

# Custom port
RUST_LOG=info ./target/release/antigravity-proxy --port 9000
```

Default port: **8741**

## Endpoints

| Method   | Path                   | Description                                                 |
| -------- | ---------------------- | ----------------------------------------------------------- |
| `POST`   | `/v1/responses`        | **Responses API** (primary) — supports `stream: true/false` |
| `POST`   | `/v1/chat/completions` | Chat Completions API (OpenAI compat shim)                   |
| `GET`    | `/v1/models`           | List available models                                       |
| `GET`    | `/v1/sessions`         | List active sessions                                        |
| `DELETE` | `/v1/sessions/:id`     | Delete a session                                            |
| `POST`   | `/v1/token`            | Set OAuth token at runtime                                  |
| `GET`    | `/v1/usage`            | MITM-intercepted token usage stats                          |
| `GET`    | `/v1/quota`            | LS quota — credits, per-model rate limits, reset timers     |
| `GET`    | `/health`              | Health check                                                |

## Available Models

| Name                | Label                                    |
| ------------------- | ---------------------------------------- |
| `opus-4.6`          | Claude Opus 4.6 (Thinking) — **default** |
| `opus-4.5`          | Claude Opus 4.5 (Thinking)               |
| `gemini-3-pro-high` | Gemini 3 Pro (High)                      |
| `gemini-3-pro`      | Gemini 3 Pro (Low)                       |
| `gemini-3-flash`    | Gemini 3 Flash                           |

## Example: Responses API

### Sync

```bash
curl -s http://localhost:8741/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3-flash",
    "input": "Say hello in exactly 3 words",
    "stream": false,
    "timeout": 60
  }' | jq .
```

### Streaming

```bash
curl -N http://localhost:8741/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3-flash",
    "input": "Say hello in exactly 3 words",
    "stream": true,
    "timeout": 60
  }'
```

### Multi-turn (session reuse)

```bash
# First message
curl -s http://localhost:8741/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3-flash",
    "input": "What is 2+2?",
    "conversation": "my-session-1",
    "stream": false
  }' | jq .

# Follow-up in same cascade
curl -s http://localhost:8741/v1/responses \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3-flash",
    "input": "Now multiply that by 10",
    "conversation": "my-session-1",
    "stream": false
  }' | jq .
```

## Authentication

The proxy needs an OAuth token. Three ways to provide it:

1. **Environment variable**: `export ANTIGRAVITY_OAUTH_TOKEN=ya29.xxx`
2. **Token file**: `echo 'ya29.xxx' > ~/.config/antigravity-proxy-token`
3. **Runtime API**: `curl -X POST http://localhost:8741/v1/token -d '{"token":"ya29.xxx"}'`

## Stealth Features

- **TLS fingerprint**: BoringSSL with Chrome 142 JA3/JA4 + H2 fingerprint via `wreq`
- **Protobuf**: Hand-rolled encoder producing byte-exact match to real webview traffic
- **Warmup**: Mimics real webview startup RPC calls
- **Heartbeat**: Periodic keep-alive matching real webview lifecycle
- **Jitter**: Randomized polling intervals to avoid automation fingerprint
- **Session reuse**: Cascades are reused for multi-turn, matching real webview behavior
- **Version detection**: Auto-detects Antigravity/Chrome/Electron versions from installed app

## MITM Proxy

Built-in TLS-intercepting proxy captures real token usage from LS ↔ Google/Anthropic traffic. Disabled with `--no-mitm`.

### Setup

```bash
# 1. Start proxy (generates CA cert automatically)
RUST_LOG=info ./target/release/antigravity-proxy

# 2. Install wrapper (patches LS binary to route through MITM)
sudo ./scripts/mitm-wrapper.sh install

# 3. Restart Antigravity — done!

# Check status
./scripts/mitm-wrapper.sh status

# Uninstall
sudo ./scripts/mitm-wrapper.sh uninstall
```

### Usage Stats

```bash
curl -s http://localhost:8741/v1/usage | jq .
```

## Standalone Language Server

Launch an isolated LS instance for experimentation:

```bash
# Basic test (starts, checks quota, exits)
./scripts/standalone-ls.sh

# Foreground mode (stays alive)
./scripts/standalone-ls.sh --fg

# With MITM traffic interception
./scripts/standalone-ls.sh --mitm

# Capture a clean traffic snapshot
./scripts/standalone-ls.sh --snapshot

# Snapshot with custom prompt
./scripts/standalone-ls.sh --snapshot --prompt "Explain quantum computing"
```

The standalone LS shares the main Antigravity app's OAuth (via its extension server) but has its own port, data directory, and cascades.

### Traffic Snapshots

The `--snapshot` flag captures all HTTP/2 traffic and formats it into a clean, color-coded report:

```
══════════════════════════════════════════════════════════════════════
  STANDALONE LS TRAFFIC SNAPSHOT
══════════════════════════════════════════════════════════════════════

▸ Outbound Connections
  → antigravity-unleash.goog    (Feature Flags)
  → play.googleapis.com         (Telemetry)

══════════════════════════════════════════════════════════════════════
  antigravity-unleash.goog — Feature Flags
══════════════════════════════════════════════════════════════════════

  → POST /api/client/register
    authorization: *:production.e4455...
    unleash-appname: codeium-language-server
    Body (561 bytes, JSON):
      {"appName":"codeium-language-server","instanceId":"..."}
```

## Architecture

```mermaid
graph LR
    A[Your App<br/>OpenAI SDK] -->|HTTP| B[Proxy<br/>:8741]
    B -->|gRPC| C[Language<br/>Server]
    C -->|HTTPS| D[Google /<br/>Anthropic]
    E[MITM Proxy<br/>:8742] -.->|intercept| D
    C -.->|routed via| E
```

## CLI Flags

```
antigravity-proxy [OPTIONS]

Options:
  --port <PORT>          API server port (default: 8741)
  --no-mitm              Disable MITM proxy
  --mitm-port <PORT>     Override MITM proxy port (default: auto)
```

## License

Private. Do not distribute.