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Design Real-Time Mobile Data Sync

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Your question is Design Real-Time Mobile Data Sync. Take a moment with it on the right.

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Problem

Design a mobile app architecture that keeps data fresh in near real time while still supporting offline use. Explain how the client receives updates, stores local state, handles concurrent edits, and recovers from network failures.

What to Cover

  • How the app gets real-time updates from the server
  • How local storage acts as the UI source of truth
  • How offline writes are queued and replayed
  • How conflicts are detected and resolved
  • How to avoid race conditions in the sync layer

Design Constraints

  • Minimize battery and network usage
  • Support intermittent connectivity
  • Prevent stale data from overwriting newer updates
  • Keep the UI responsive during sync
  • Handle duplicate, delayed, or out-of-order events