Notification System - Improvements #15
Description
No end-to-end enforcement of promotion expiry
If messages are not dropped or canceled at each stage based on TTL or end time, stale promos will be delivered, damaging user trust and potentially violating compliance or business policies.
Missing idempotency and per-user ordering
At-least-once retries without deduplication yield duplicates, and lack of partitioning by user/device leads to out-of-order deliveries. Both confuse users and complicate reconciliation and support.