Official · Product & backend · intermediate
Sync inspections from offline field teams
Reconcile conflicting edits and large photo uploads without losing submitted inspections.
The question
Design an offline-capable field-inspection service. Inspectors edit a checklist and attach photos on mobile; supervisors can correct the same inspection in the web app. Define which conflicts are safe to merge and which need a human decision.
- 12,000 inspectors each complete up to 20 inspections/day with eight 3 MB photos per inspection.
- Devices can remain offline for 48 hours and may have unreliable clocks.
- After a supervisor accepts an inspection, historical signed-off content must remain auditable even if a correction is requested.
What to cover
Define client operations, server acknowledgements, cursors, retries and tombstone retention.
Work through same-field edits, attachment additions and a correction after sign-off.
Describe revision history, authorization and staged/resumable photo attachment.
Calculate daily photo volume and an offline reconnect burst; state quotas and recovery behavior.
How your practice is reviewed
- Convergence and durable retries (30 points): Defines operation identity, acknowledgements, retention and recovery without relying on correct client clocks.
- Conflict and audit semantics (30 points): Distinguishes mergeable actions from conflicts and preserves accepted history.
- Media and authorization lifecycle (20 points): Connects resumable uploads to authorized records with safe cleanup and visibility rules.
- Quantified operating plan (20 points): Explains storage/transfer arithmetic, reconnect load and observable failure recovery.
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