[Bug]: Unbounded Message Listener Duplication on Reconnect

[deepak0x]

The EmbeddedChatApi class fails to clear existing message event listeners when the connect() method is called. The issue occurs because rcClient.onMessage(...) is additive: every invocation registers a new callback without removing previously registered ones.

The close() method currently calls unsubscribeAll() on the SDK client, but this only unsubscribes from server-side DDP streams. It does not clear the internal JavaScript callbacks registered via onMessage on the client instance.

As a result, each reconnect accumulates additional message listeners.

---

UI Masking

This issue is largely hidden in the UI due to message deduplication logic:

• The React frontend uses a store that deduplicates messages by ID.
• useMessageStore relies on an upsertMessage helper that updates existing messages if the ID already exists.

Effect:

• Duplicate message events are processed internally.
• The UI shows only a single message update, masking the underlying duplication.

---

Memory Leak (Linear Growth)

• Each reconnection adds a new closure retaining references to the message handler context.
• Long-lived sessions or unstable network conditions cause unbounded listener growth

Performance Degradation

• CPU Overhead: Each incoming message triggers the processing logic N times.
• Render Thrashing: Even with deduplication, repeated state updates may still trigger reconciliation cycles depending on equality checks.

Side-Effect Duplication

Any non-idempotent side effects tied to message receipt will execute multiple times:

• Sound notifications
• Read receipts
• Analytics or logging
• Desktop notifications

Example: After 5 reconnects, a single incoming message may trigger 5 notification sounds.

---

Reproduction

1. Login and connect.
2. Send Message 1 → Received once.
3. Reconnect (simulate network flap).
4. Send Message 2 → Received twice (proof of leak).

---

Expected behaviour

Ensure message listeners are registered exactly once, or explicitly removed before adding new ones during reconnection.

[deepak0x]

Hi @Spiral-Memory
Pls check and let me know if I can work on this...
Thanks