System design interview question
Design a Real-Time Collaborative Document Editor with Conflict Resolution (like Google Docs at scale)
Design a distributed system that enables real-time collaborative document editing across 200M users globally, supporting 50K concurrent active editing sessions with sub-500ms latency for operational transforms. The system must handle 100K operations/second, persist changes durably, maintain document consistency across regions, support offline editing with eventual consistency, and provide audit trails. Users expect CRDT-like behavior without actual CRDTs, instant local echo, conflict-free merging, and ability to view historical versions at any point in time. Consider multi-region deployment, network partitions, and graceful degradation when connectivity is poor.
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