Backend Message Queue

Purpose

Design consistent, production-grade message-driven systems. Every message flow must follow the same conventions for broker selection, topic/queue topology, message schema, delivery guarantees, consumer idempotency, retry, and dead-letter handling.

Agent Protocol

Trigger

Exact user phrases: "message queue", "Kafka", "RabbitMQ", "SQS", "pub-sub", "event bus", "consumer group", "topic", "queue", "at-least-once", "exactly-once", "idempotent consumer", "event sourcing", "dead letter queue", "DLQ", "message broker", "producer", "consumer", "event-driven", "async processing", "design a message flow".

Input Context

Before activating, verify:

• The business event or asynchronous task is known.
• The delivery guarantee requirement (at-most-once / at-least-once / exactly-once) is known. If not, ask: "What delivery guarantee do you need?"
• The throughput requirement is known.
• The broker preference (Kafka / RabbitMQ / SQS) is known. If not, ask: "Which broker? Kafka (high throughput, replay), RabbitMQ (routing, flexibility), or SQS (managed, simple)?"

Output Artifact

No file output unless the user requests it. Produces messaging topology specs as text.