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Reconnect and Heartbeat ​

Problem ​

A realtime session must recover from network loss without opening duplicate sockets or replaying application messages before its channel and room state exists.

Solution ​

Enable reconnect and heartbeat, create scopes before connecting, and react to the status readable.

ts
import { createPulse } from '@vielzeug/pulse';
import { effect } from '@vielzeug/ripple';

type Channels = {
  chat: {
    client: { send: { text: string } };
    server: { message: { text: string } };
  };
};

const pulse = createPulse<{}, {}, Channels>('wss://api.example.com/ws', {
  heartbeat: { interval: 20_000, timeout: 8_000 },
  onError: console.error,
  reconnect: { delay: (attempt) => Math.min(500 * 2 ** attempt, 30_000), maxAttempts: 8 },
});
const chat = pulse.channel('chat');

effect(() => {
  console.log('Pulse status:', pulse.status.value);
});

try {
  await pulse.connect();
  chat.on('message', ({ text }) => console.log(text));
} catch (error) {
  console.error('Pulse connection failed:', error);
}

Pitfalls ​

  • disconnect() cancels retry immediately. It never leaves a scheduled reconnect behind.
  • Restoration is ordered. Pulse resubscribes channels, rejoins rooms, then restores the last successfully published local presence state.
  • status is transport state. Wait for the server's own restored-room data before acting on room membership.