Frontend & browser·Storage and platform APIs
the app opened and worked on a train with no signal, then synced when the connection came back.
Offline-first
Also calledoffline support
Treating the network as an enhancement: reads come from local storage and writes queue until they can be sent. It is genuinely valuable for field and mobile use and it drags in a distributed systems problem — conflicting edits, ordering, and what to show when a queued write is finally rejected. Most implementations get the caching right and the conflict resolution wrong.