Improve RabbitMQ

Operation

Implement the requested coherent change at the owning source and update directly affected consumers. An earlier audit is optional when the user and repository already establish the target. Validate the changed behavior, then stop when the requested scope is complete.

Goal

Implement one selected, evidence-backed RabbitMQ improvement at the authoritative owner. Complete the directly affected contract without broad cleanup or redesign.

Domain rules

• Make topology changes compatible and staged; avoid changing immutable queue arguments in place without migration/drain strategy.
• Use confirms plus unroutable-return handling for required delivery assurance and keep publish retry idempotent.
• Place ack/nack after the real processing boundary, bound requeue loops, and route terminal failures with complete diagnostic context.
• Tune prefetch from work cost/downstream capacity rather than using concurrency as an unbounded throughput lever.
• Own connection/channel lifecycle explicitly and re-declare/re-subscribe only through the established recovery mechanism.

Validation

• Run topology declaration and integration tests against a supported RabbitMQ version and policy profile.
• Exercise unroutable publish, confirm ambiguity, consumer crash, repeated redelivery, connection/channel recovery, blocked broker, and graceful shutdown.
• Verify queue depth/age, unacked count, duplicates, ordering scope, DLQ metadata, and recovery without destructive production testing.