LINE Webhook + Remote MCP for Render

This service has two public endpoints:

• POST /callback — LINE Messaging API webhook, protected by LINE_CHANNEL_SECRET.
• GET, POST, DELETE /mcp — Streamable HTTP MCP endpoint, protected by MCP_API_KEY as a bearer token.

What it can do

• Send LINE text messages to a User ID (U...) or Group ID (C...).
• Send LINE Flex Messages.
• Report message quota.
• Receive a group webhook and expose Group IDs received since the service started.

Deploy to Render

1. Push this directory to a private GitHub repository. Do not commit .env.
2. In Render, select New > Blueprint, choose the repository, and create the service from render.yaml.
3. In the Render service's Environment tab, set:
   • CHANNEL_ACCESS_TOKEN
   • LINE_CHANNEL_SECRET
   • DESTINATION_ID (optional)
   • keep the generated MCP_API_KEY private.
4. After the deploy succeeds, copy the public URL. It will look like https://line-render-mcp.onrender.com.
5. In LINE Developers Console > Messaging API:
   • set Webhook URL to https://line-render-mcp.onrender.com/callback;
   • click Verify;
   • turn on Use webhook;
   • enable Allow bot to join group chats if you need group delivery.
6. In a ChatGPT Business workspace, create a custom app with the endpoint: https://line-render-mcp.onrender.com/mcp Configure it to send Authorization: Bearer <MCP_API_KEY> and only enable the tools you want.

Local test

npm install
Copy-Item .env.example .env
# Fill the values in .env, then:
npm run dev

For a webhook test, use a public HTTPS tunnel only during development. Use the Render URL in production.

Security notes

• Never put the LINE access token or MCP_API_KEY into source code, an issue, or a public repository.
• Keep the Render repository private.
• MCP_API_KEY grants the ability to send LINE messages. Rotate it immediately if exposed.
• get_known_groups currently stores IDs in process memory only. Use a database before relying on it across redeploys or multiple service instances.