PiLink

An OAuth-protected MCP server that exposes the Pi Agent coding-tool harness over Streamable HTTP (and legacy SSE). It is designed for a single trusted owner connecting a remote MCP client such as ChatGPT to a local development machine.

See the complete getting-started guide for first-time setup and ChatGPT OAuth configuration.

Quick start

Prerequisite: Node.js 22.19+. On Linux, the first start automatically downloads the selected hosting binary (official Cloudflare cloudflared for a Quick Tunnel or Caddy for direct nip.io HTTPS) to the private PiLink configuration directory. On macOS and Windows, install the selected hosting binary yourself first.

npx pilink start --allow-unsafe-full-access

The first run creates ~/.config/pilink/.env with mode 0600, asks how to expose PiLink publicly, then guides you through ChatGPT's user-defined OAuth setup and waits for its callback URL. pilink init creates the private configuration without starting the server. pilink serve starts without public hosting for reverse-proxy or local use.

Set PI_CLOUDFLARED_PATH when your preferred cloudflared binary is outside PATH.

Public hosting choices

The first pilink start asks which public hosting mode to save. pilink start --setup deletes all PiLink-generated state (configuration, OAuth clients, managed hosting binaries, and Caddy TLS state), then runs the complete first-time setup again. It does not delete your repository or workspace:

• Cloudflare Quick Tunnel is the default and needs no account, router change, or additional setup. Its hostname changes every restart. ChatGPT treats each hostname as a new connector, so create a new connector and OAuth client with pilink start --setup after every Quick Tunnel restart.
• Direct nip.io HTTPS hosting keeps a hostname such as https://pilink-203-0-113-10.nip.io while your public IPv4 address remains unchanged. PiLink downloads and runs Caddy on Linux to provide trusted HTTPS automatically, then, with explicit confirmation, tries UPnP and NAT-PMP to create temporary router mappings for public TCP 80 and 443. It renews them while running and removes them on shutdown. This exposes your computer to the Internet; do not enable unsafe full access unless every authorized client is fully trusted.

If Linux uses firewalld, allow Caddy's forwarded ports before starting direct hosting: sudo firewall-cmd --permanent --add-port=8080/tcp, sudo firewall-cmd --permanent --add-port=8443/tcp, then sudo firewall-cmd --reload.

Automatic mapping cannot bypass CGNAT, ISP port blocking, or routers that disable UPnP/NAT-PMP. PiLink falls back to manual port-forwarding instructions in those cases. If your public IP changes, its nip.io hostname changes too and ChatGPT needs a new connector.

Security model

The default mode is deliberately restrictive: file tools are jailed to PI_WORK_DIR (including symlink-escape checks) and bash is unavailable. This is appropriate for a public tunnel.

--allow-unsafe-full-access enables unrestricted shell and filesystem access for every authorized MCP client. It is remote code execution by design; only use it with a private configuration, a trusted ChatGPT profile, and a machine/account you are willing to expose. PiLink cannot make arbitrary shell commands safe without an OS-level sandbox.

Client registration requires the generated PI_BOOTSTRAP_SECRET as an RFC 7591 registration access token:

curl -X POST "$SERVER_URL/oauth/register" \
  -H "Authorization: Bearer $PI_BOOTSTRAP_SECRET" \
  -H 'Content-Type: application/json' \
  -d '{"client_name":"trusted-client","grant_types":["client_credentials"],"scope":"mcp:tools"}'

Keep that secret out of ChatGPT prompts, logs, source control, and public configuration. A client must support registration access tokens (or be pre-registered) to use the protected dynamic-registration endpoint.

Configuration

pilink init documents the generated values. See .env.example for manual or deployment configuration. The server rejects startup if JWT_SECRET or PI_BOOTSTRAP_SECRET is missing or shorter than 32 characters. SERVER_URL must be the externally visible HTTPS URL when using a reverse proxy or tunnel.

OAuth tokens are audience/issuer-bound, expire after TOKEN_EXPIRY seconds (default 3600), and preserve their scopes for the lifetime of an MCP session. mcp:read permits only read/search tools, mcp:write permits mutation (and bash when unsafe mode is explicitly enabled), and mcp:tools permits all tools subject to the harness mode.

Development and publishing

npm ci
npm test

Run a local checkout as pilink

From the repository root, run the local CLI without a global installation:

npm exec -- pilink start --setup

To make pilink available in your shell permanently without sudo, configure npm to use a directory owned by your user, add it to PATH, then link this checkout:

npm config set prefix "$HOME/.local"
printf '\nexport PATH="$HOME/.local/bin:$PATH"\n' >> ~/.bashrc
source ~/.bashrc
npm link

After that, pilink start --setup works from any directory. The default npm global prefix may be /usr, where npm link fails with EACCES for non-root users; do not use sudo to work around that error.

The package contains only dist, this README, and the MIT license.

Credits & Acknowledgments

PiLink builds upon the excellent Pi Agent ecosystem:

• Pi Agent (@earendil-works/pi-coding-agent): The powerful underlying coding-agent tool harness providing structured file operations, grep search, symbol analysis, and command execution capability.