Anshuman
Rout.

FastAPI backend exposes a send_email endpoint that enqueues tasks directly into Redis

Dramatiq workers poll the Redis queue, execute tasks, and publish results via Redis Pub/Sub

SSE endpoint fans out Pub/Sub messages to connected clients in real-time — zero HTTP round-trips

Clean separation between producer, consumer, and delivery layers for resilience and scalability

Per-user buckets created on first request, stored and queried from a fast in-memory store

Refill computed dynamically using elapsed time × token rate — no background jobs needed

Mutex locks prevent race conditions when concurrent tabs or clients consume tokens simultaneously

Clean middleware interface — drop it in front of any FastAPI route with a single decorator