Google Agentic Architect - Subconcept 3.2: Concurrent State Mutation Safety

Focus exclusively on the critical concurrency challenges in multi-agent architectures where parallel worker nodes attempt to update a shared session state. Deep dive into the implementation of Optimistic Concurrency Control (OCC) using Cloud Firestore update preconditions. Explain how to design agents to check version counters or update timestamps (e.g., using Firestore transaction preconditions) so that parallel, conflicting writes are detected. Detail the retry patterns required to catch OCC errors, automatically re-hydrate the agent's state with the latest database snapshot, and replay the state mutation safely.