ACP Proxy Server

A WebSocket proxy server that bridges Chrome extensions to ACP (Agent Client Protocol) agents.

Part of the chrome-acp monorepo.

Installation

$3

``bash
npm install -g @chrome-acp/proxy-server
`

$3

`bash


From monorepo root


bun install
`

Usage

$3

`bash
npx @chrome-acp/proxy-server /path/to/agent
`

$3

`bash
acp-proxy /path/to/agent
`

$3

`bash
bun src/cli/bin.ts /path/to/agent
`

$3

`bash


Basic usage

acp-proxy /path/to/agent

With custom port

acp-proxy --port 9000 /path/to/agent

With debug logging

acp-proxy --debug /path/to/agent

Pass arguments to the agent (use -- to separate)

acp-proxy /path/to/agent -- --verbose --model gpt-4
`

CLI Reference

`
USAGE
acp-proxy [--port value] [--debug] ...
acp-proxy --help
acp-proxy --version

FLAGS
[--port] Port to listen on [default = 9315]
[--debug] Enable debug logging
-h --help Print help information and exit
-v --version Print version information and exit

ARGUMENTS
command... Agent command followed by its arguments
`

How It Works

The proxy server:
1. Listens for WebSocket connections from the Chrome extension
2. When a "connect" message is received, spawns the configured ACP agent as a subprocess
3. Bridges messages between the WebSocket (extension) and stdin/stdout (agent)
4. Exposes browser tools to agents via MCP (Model Context Protocol)

This allows Chrome extensions to communicate with ACP agents despite not being able to spawn subprocesses directly.

Browser Tools (via MCP)

The proxy server exposes an MCP endpoint at http://localhost:{port}/mcp with these tools:

| Tool | Description |
|------|-------------|
| browser_tabs | List all open tabs (returns id, url, title, active status) |
| browser_read | Read content of a specific tab (requires tabId from browser_tabs) |
| browser_execute` | Execute JavaScript in a specific tab (requires tabId from browser_tabs) |

License

MIT