Designed and delivered large-scale, stateful architectures. Implemented robust patterns for coordinating multi-step workflows across services (e.g., two-phase commits, sagas). Experience building reconciled workflows with audit trails and automated recovery. Bake in observability, fault tolerance, and graceful degradation. Understand caching, queueing, rate-limiting, and system tuning for scalability. Break down complex trade-offs into clear plans and document designs. Ship prototypes quickly and iterate based on feedback.