Realtime

const unsubscribe = await cb.collection("posts").subscribe("*", (event) => {
  console.log(event.action, event.record); // "create" | "update" | "delete"
});

// later
unsubscribe();

topic is "*" (the whole collection) or a bare record id — matching the topic grammar described in Realtime. The third argument, SubscribeOptions (filter, fields, expand), scopes the subscription server-side:

await cb.collection("posts").subscribe(
  "*",
  (event) => console.log(event.record.title),
  { filter: "published = true" },
);

No EventSource polyfill

The SDK’s realtime transport is built on fetch and a streamed ReadableStream response, not EventSource. That means:

• No polyfill needed in any environment fetch runs in, including Node/SSR — subscriptions work outside the browser, unlike EventSource, which is browser-only without a shim.
• The stream carries whatever auth the client already uses — bearer token or session cookie — since it’s an ordinary authenticated fetch request, not EventSource’s cookie-only, header-less connection.

Subscriptions are still filtered server-side by the collection’s listRule, so a subscriber never receives an event for a record it couldn’t otherwise read.