Offline-first, not offline-eventually
No connection.
What matters is still here.
Itinerary, tickets, and notes live on each phone. Your day works without signal — visible, editable, complete.
You edit on the plane while she edits in Rome. Or both of you with no signal at all. When you reconnect, the changes meet without spinners and without fighting: the most recent edit wins, the rest fall into place.
A queue is table stakes — every offline app has one. The trick is the radio in your pocket. When neither phone has signal, the change hops directly between you — like AirDrop, but only between phones that already know each other.
For now the beta lives entirely on your phones, no account. Online mode — cloud backup and sync at a distance — comes later: always on top of the offline core, never in its place.