Decoupling a Live App with Domain Events (Part 2)

Phase 1 of decoupling a live app involved applying the RabbitMQ event bus pattern to all Tier 1 services, building 14 Zod schemas, 25 queue handlers, and 79 new tests across CommentService, RecordService, and OccurrenceCrudHelper. A dual-write strategy was used for safety—services emit events while retaining inline side effects, so if the event broker fails, existing logic still handles the work. Event schema design emphasized minimal payloads with only IDs, optional diff fields for updates to prevent race conditions, and distinct events for visibility changes.