Course Analytics "Ghost" Sessions

[codeCraft-Ritik]

Summary

User presence signals do not always clean up correctly upon browser closure, leading to inflated "Online" user counts in the presenceService.

Full Description

The presence.svelte.ts service tracks users in a course. If a user closes their laptop or loses connection, the Supabase record may persist until a server-side timeout. Adding a client-side "Last Will" ensures more accurate real-time data.

How to Resolve

Use the beforeunload browser event in the root layout.
Call a cleanup function in presence.svelte.ts to explicitly leave the channel.

Code Fix In src/lib/ui/TutorsShell.svelte:

<script>
  import { onMount } from "svelte";
  import { presenceService } from "$lib/services/community/services/presence.svelte";

  onMount(() => {
    const handleUnload = () => {
      presenceService.leaveCourse(); // Explicitly clear presence
    };
    window.addEventListener("beforeunload", handleUnload);
    return () => window.removeEventListener("beforeunload", handleUnload);
  });
</script>

In presence.svelte.ts:

export const presenceService = {
  // ... existing code
  leaveCourse() {
    if (this.channel) {
      this.channel.unsubscribe();
      this.channel = null;
    }
  }
};