Data Consistency and Distributed Transactions Questions

Maintaining correctness of state across services and replicas: eventual consistency, conflict resolution (last-write-wins, CRDTs, vector clocks), the saga pattern, two-phase commit, and idempotency keys for exactly-once effects. Covers when to trade strict consistency for availability and how to reason about read-your-writes and monotonic guarantees. Focuses on the application/service layer rather than storage-engine internals.