Event Sourcing over CRUD for Audit Trails

Decision: Replace standard CRUD in PostgreSQL with Event Sourcing for financial transaction audit compliance. Context: Compliance requires full history of transaction state changes. Alternatives: Database triggers rejected (no business context - triggers only see row changes without user intent). Adopted: Event Sourcing - immutable domain events in Kafka, materialized views in Postgres. Reference: Martin Fowler Event Sourcing Pattern article. Implementation: src/services/transactionService.ts (event producers), src/events/eventStore.ts (consumer/store logic).