AG (Antigravity) Local Bridge

Exposes your running Antigravity instance as a local OpenAI-compatible API on localhost:11435.

Use your Antigravity subscription with any tool that speaks OpenAI — opencode, aider, continue.dev, or plain curl.

How it Works

Your tool → HTTP :11435 → VS Code extension → Antigravity sidecar (ConnectRPC) → Cloud AI

The extension runs inside Antigravity's VS Code process, discovers the sidecar via process inspection, intercepts CSRF tokens from Antigravity's own traffic, and proxies your requests through the same authenticated channel Antigravity uses internally.

Features

• OpenAI-compatible API — drop-in replacement for any tool expecting OpenAI format
• Image support — paste screenshots or attach images from OpenAI clients; images are saved to temp files and referenced in the message so the agent can view them
• Workspace-aware — automatically detects and sets the correct project context via x-workspace-dir / x-workspace-uri headers
• Conversation multiplexing — reuses Cascade conversations for efficiency, with automatic retry on capacity errors
• Streaming & non-streaming — both modes supported

Available Models

Model ID	Description
antigravity-claude-sonnet-4-6	Claude Sonnet 4.6 with Thinking (default)
antigravity-claude-opus-4-6-thinking	Claude Opus 4.6 with Thinking
antigravity-gemini-3-flash	Gemini 3 Flash
antigravity-gemini-3.1-pro-high	Gemini 3.1 Pro — High thinking
antigravity-gemini-3.1-pro-low	Gemini 3.1 Pro — Low thinking
antigravity-gpt-oss-120b	GPT-OSS 120B Medium

Installation

From Open VSX (recommended)

1. Open Antigravity
2. Go to Extensions (Ctrl+Shift+X)
3. Search for "AG Local Bridge" by marcodiniz
4. Click Install
5. Reload Antigravity (Ctrl+Shift+P → Developer: Reload Window)

Manual install

1. Clone into your Antigravity extensions directory:

   # Windows
   git clone https://github.com/marcodiniz/ag-local-bridge "%USERPROFILE%\.antigravity\extensions\ag-local-bridge-1.0.0-universal"
   
   # macOS / Linux
   git clone https://github.com/marcodiniz/ag-local-bridge ~/.antigravity/extensions/ag-local-bridge-1.0.0-universal

2. Reload Antigravity (Ctrl+Shift+P → Developer: Reload Window)

Verify

Look for "AG Local Bridge" in the Output panel — you should see:

✅ Server running on http://localhost:11435

Usage

With opencode

Add to ~/.config/opencode/opencode.json:

{
  "provider": {
    "ag-local-bridge": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "AG Local Bridge",
      "options": {
        "baseURL": "http://localhost:11435/v1",
        "apiKey": "local"
      },
      "models": {
        "antigravity-claude-sonnet-4-6": {
          "name": "Claude Sonnet 4.6 (Antigravity)",
          "modalities": { "input": ["text", "image"], "output": ["text"] },
          "limit": { "context": 200000, "output": 64000 }
        },
        "antigravity-claude-opus-4-6-thinking": {
          "name": "Claude Opus 4.6 Thinking (Antigravity)",
          "modalities": { "input": ["text", "image"], "output": ["text"] },
          "limit": { "context": 200000, "output": 64000 }
        },
        "antigravity-gemini-3.1-pro-high": {
          "name": "Gemini 3.1 Pro High (Antigravity)",
          "modalities": { "input": ["text", "image"], "output": ["text"] },
          "limit": { "context": 1048576, "output": 65535 }
        },
        "antigravity-gemini-3.1-pro-low": {
          "name": "Gemini 3.1 Pro Low (Antigravity)",
          "modalities": { "input": ["text", "image"], "output": ["text"] },
          "limit": { "context": 1048576, "output": 65535 }
        },
        "antigravity-gemini-3-flash": {
          "name": "Gemini 3 Flash (Antigravity)",
          "modalities": { "input": ["text", "image"], "output": ["text"] },
          "limit": { "context": 1048576, "output": 65536 }
        },
        "antigravity-gpt-oss-120b": {
          "name": "GPT-OSS 120B Medium (Antigravity)",
          "modalities": { "input": ["text", "image"], "output": ["text"] },
          "limit": { "context": 128000, "output": 16384 }
        }
      }
    }
  }
}

Then select ag-local-bridge/antigravity-claude-sonnet-4-6 as your model.

Image support: The modalities field enables image input (clipboard paste, file attach). Images are saved to temp files and the agent views them with its built-in file tools.

With curl

# List models
curl http://localhost:11435/v1/models

# Chat completion
curl http://localhost:11435/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "antigravity-claude-sonnet-4-6",
    "messages": [{"role": "user", "content": "Hello!"}],
    "stream": false
  }'

# Streaming
curl http://localhost:11435/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "antigravity-gemini-3.1-pro-high",
    "messages": [{"role": "user", "content": "Hello!"}],
    "stream": true
  }'

# With image (base64 data URL)
curl http://localhost:11435/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "antigravity-claude-sonnet-4-6",
    "messages": [{"role": "user", "content": [
      {"type": "text", "text": "What do you see?"},
      {"type": "image_url", "image_url": {"url": "data:image/png;base64,iVBOR..."}}
    ]}],
    "stream": false
  }'

With any OpenAI-compatible client

Base URL: http://localhost:11435/v1
API Key:  anything (not validated)

API Endpoints

Method	Path	Description
GET	/v1/models	List available models
POST	/v1/chat/completions	Chat completion (streaming & non-streaming)
POST	/v1/proxy	Forward arbitrary RPC to sidecar
GET	/v1/debug	Debug info (sidecar ports, CSRF, captures)

Image Support

Images sent via the OpenAI image_url content type are handled as follows:

1. Base64 data URLs (data:image/png;base64,...) — decoded and saved to a temp file
2. Remote URLs (https://...) — downloaded, then saved to a temp file
3. File URIs (file:///C:/path/to/image.png) — read directly from disk

The image file path is prepended to the message text so the Antigravity agent can use its view_file tool to inspect the image.

Workspace Context

Pass workspace context via HTTP headers:

Header	Description
x-workspace-dir	Absolute filesystem path (e.g. C:\code\myproject)
x-workspace-uri	File URI (e.g. file:///C:/code/myproject)

When set, the bridge switches the active VS Code workspace folder before creating a Cascade, ensuring the agent operates in the correct project context.

Architecture

The extension uses a 2-tier fallback strategy:

1. Tier 1 — Sidecar ConnectRPC (preferred): Discovers the Antigravity sidecar process, connects via HTTP/2 with CSRF authentication, and uses the Cascade API (StartCascade → SendUserCascadeMessage → poll GetCascadeTrajectory). Conversations are multiplexed and the active workspace is auto-detected.

2. Tier 2 — Command Dispatch: Last resort — fires the message through antigravity.executeCascadeAction.

Commands

Command	Description
AG Local Bridge: Start Server	Start the HTTP server
AG Local Bridge: Stop Server	Stop the HTTP server
AG Local Bridge: Show Status	Display connection status
AG Local Bridge: Probe Sidecar	Test sidecar connectivity
AG Local Bridge: List Available LM Models	List configured models and sidecar status
AG Local Bridge: List Available Chat Commands (Debug)	List chat commands available for debugging

Configuration

Setting	Default	Description
agLocalBridge.port	11435	HTTP server port
agLocalBridge.logRequests	false	Log request/response details

Requirements

• Antigravity installed and running
• Active Antigravity subscription (Free/Pro/Teams/Enterprise)

Contributing

We use a beta → master release flow:

Branch	Role	Publishes as
beta	Default / development	Pre-release
master	Stable releases only	Stable

1. Fork & branch off beta (the default branch).
2. Open your PR against beta — GitHub will target it automatically.
3. Once merged, a pre-release is published to Open VSX for beta testers.
4. When a beta build is ready for general availability, the maintainer merges beta → master to cut a stable release.

Note: master is protected — direct pushes are not allowed. All changes flow through beta first.

License

MIT