Realtime: persistent WebSocket and message-driven subscriptions

Appwrite Realtime now keeps a single WebSocket per client session and applies incremental, message-based subscription changes instead of encoding subscription state mainly in the connection URL and reconnecting for every add or remove.

Previously, subscription details were often encoded in the WebSocket URL query string. That tied you to URL length limits in browsers, proxies, and servers, which capped how many channels you could combine and how much metadata you could send on one connection. It also squeezed Realtime queries for server-side filtering, because every extra filter still had to fit in the same limited URL. Channels and queries are now carried over the open socket, so you are not constrained by query-string size the same way.

In client SDKs, you can now:

• Per-subscription lifecycle: Call unsubscribe() on a subscription handle to stop that listener only; other subscriptions on the same Realtime instance keep running.
• update(): Change channels and queries on an existing subscription in place, without recreating the client.
• disconnect(): Close the WebSocket and drop every active subscription in one call when your app is done with Realtime (for example on component unmount).

Together, the Realtime protocol change and matching SDK APIs reduce unnecessary reconnects, make UI-driven subscription changes easier to reason about, and move subscription state off the WebSocket URL onto incremental messages over the open connection.

Read the announcement on the blog for context and examples, and see the Realtime documentation for how this maps to your platform.