Write a party

A party is a TypeScript class that handles connections to one room. synkd loads it from synkd.json and serves it at /parties/:party/:room.

Create a party class

import { Server, type Connection } from "@synkd/server";

export class Chat extends Server {
  static options = { hibernate: true };

  onConnect(conn: Connection) {
    conn.send(JSON.stringify({ type: "hello", id: conn.id }));
  }

  onMessage(conn: Connection, message: string | ArrayBuffer) {
    this.broadcast(message, [conn.id]);
  }
}

Register the export in synkd.json:

{
  "parties": {
    "main": {
      "entry": "./src/chat.ts",
      "export": "Chat",
      "className": "ChatDO"
    }
  }
}

className is used when you deploy to a Durable Objects fleet (class name binding).

Room URL

Clients connect to:

/parties/<party-key>/<room-id>

Example: /parties/main/lobby-42.

Useful Server methods

Method	Use
onConnect	New WebSocket joined
onMessage	Client sent data
onClose	Socket left
broadcast	Send to others in the room
this.storage	Per-room durable key/value
this.setAlarm / onAlarm	Delayed work in the room

Enable idle unload with static options = { hibernate: true } when the party can safely wake from storage.

Hot reload

synkd up (and pnpm up in this repo) watches party source files and reloads them. Active sockets close with code 1012 so clients can reconnect.

Disable watching with --no-watch if you need a fixed process for debugging.

Start from a new project

Use the CLI to scaffold a Chat party, then edit src/chat.ts:

pnpm --filter @synkd/cli exec tsx src/bin.ts init ./my-rooms --name my-rooms
pnpm --filter @synkd/cli exec tsx src/bin.ts dev --root ./my-rooms

See CLI for linking, tokens, and deploy.

What to do next

• Connect clients
• Collaborative docs for Yjs
• Packages for import map