Queue a multi-path update to run when the client disconnects.
tsx
import { ref } from "firebase/database";
import { useOnDisconnectUpdateMutation } from "@tanstack-query-firebase/react/database";
const userRef = ref(database, `users/${uid}`);
const { mutate } = useOnDisconnectUpdateMutation(userRef);
mutate({ status: "offline", lastSeen: Date.now() });