Backend Event-Driven

Purpose

Design event-driven systems with clear event boundaries, reliable delivery, observable flows, and error recovery. Every event is a fact. Every consumer is idempotent. Every failure has a recovery path.

Agent Protocol

Trigger

Exact user phrases: "event-driven", "message queue", "Kafka", "RabbitMQ", "pub/sub", "domain event", "event sourcing", "CQRS", "async messaging", "event bus", "saga", "distributed transaction".

Input Context

Before activating, verify:

• The message broker is known (Kafka, RabbitMQ, NATS, Redis, SQS/SNS) or ask.
• The service boundaries are known (which services produce events, which consume them).
• Whether events are in-process (single service) or cross-service.

Output Artifact

No file output unless requested. Produces event design as text.