Topics, publish, and presence helpers

Subscribe and publish

await client.connect();

const off = await client.subscribe("orders", (message) => {
  if (message.type === "publish") {
    // handle application events
  }
});

await client.publish("orders", "created", { orderId: "o1" });

off();

subscribe returns an unsubscribe function. When the last handler for a topic is removed, the client sends an unsubscribe envelope automatically.

Presence helpers

• client.clientCount(topic) — async call that asks the channel for the current member count.
• client.onPresenceChange(topic, ({ clientCount }) => { ... }) — listens to SDK topicPresence events filtered for a single topic.

Observing shared state

• client.onStateUpdated(topic, handler) — convenience wrapper that listens for envelopes where event === "state_updated" on the given topic.