port-forward

name	port-forward
description	Forward ports from the devcontainer to the host machine dynamically. Use when the user asks to access a port, open a URL, preview a web app, expose a service, or says anything like 'let me access port X', 'forward port', 'open localhost', 'I want to see the app'. Also use proactively when starting a dev server.

Port Forwarding in Sandboxed Copilot

You are running inside a devcontainer on macOS. Ports are NOT automatically accessible from the host. You MUST use the port-forward tool to expose them.

Commands

port-forward add <port>       # Expose a container port to the host
port-forward remove <port>    # Stop forwarding
port-forward remove-all       # Stop all forwards
port-forward list             # Show active forwards

Workflow

1. When starting a dev server, always bind to 0.0.0.0 and forward the port:

   npm run dev -- --host 0.0.0.0 --port 5173 &
   port-forward add 5173
   

   Tell the user: "Access at http://localhost:5173"

2. When the user asks to access a port:

   port-forward add 8000
   

3. Clean up when done:

   port-forward remove-all
   

Important

• Services MUST bind to 0.0.0.0 (not 127.0.0.1) for forwarding to work
• Always call port-forward add BEFORE telling the user a URL is accessible
• The forwarding is handled by a host-side watcher via socat tunnels