Offline check-in and duplicate dashcard detection

If your check-in system needs the internet to work, you're one bad carrier signal away from a queue of frustrated entrants backing up to the main road. It's not a hypothetical — it happens at almost every large outdoor show. A car park full of vehicles, everyone on their phones, and suddenly nobody's getting three bars.

Old-school solutions (a printed spreadsheet, a clipboard) are reliable but give you nothing useful at the end of the day — no timestamp, no cross-reference, no digital record. And typing everything up later defeats the point of running a digital show.

When a gate volunteer opens the check-in screen on their phone, Car Show Expert automatically downloads and caches the full entry list for that show. Every registered entrant — their name, car number, vehicle details, class, and payment status — is stored locally on the device.

From that point on, searching for an entrant and marking them as checked in works entirely offline. No spinner, no timeout, no "cannot connect to server" error. The volunteer taps check in, the entry is marked, and the gate keeps moving.

Check-in records include an exact timestamp, so even if ten minutes of actions sync all at once, you know precisely when each vehicle arrived. That matters for judging windows, for late-entry disputes, and for your own end-of-day records.

A dashcard is the numbered placard you place on a vehicle's dashboard so judges and attendees can identify it. At a well-run show they're printed and handed out at check-in.

The scam is simple: an entrant prints or photocopies an extra dashcard and gives it to a friend. The friend drives a different vehicle into the show without paying the entry fee. With a busy paper-based gate, nobody checks whether car number 47 has already been checked in.

The same thing can happen accidentally — a volunteer checks in a car, loses their place, and checks in the same car again. Either way, you end up with two "checked in" records for one entry, and you have no idea which vehicle is the legitimate one.

Car Show Expert tracks check-in status locally on every device. The moment a volunteer tries to check in an entry that is already marked as checked in, the system stops them with a full-screen alert — a deliberate interruption that demands attention.

The alert shows the original check-in time, so staff immediately know how long ago the legitimate vehicle came through. If something looks wrong, they tap "Flag as suspicious". The entry is marked in the system and synced to the organiser's dashboard the moment connectivity returns.

Flagged entries appear in the registrations table with a red badge, including the exact time the flag was raised. Organisers can review them at any point during or after the show.

Large shows often run multiple gate lanes. Each device maintains its own local cache and sync queue. When any device syncs, the server record is updated — so if lane 1 checks in car #47 and lane 2 tries to check in the same car later, lane 2 will get the duplicate alert as soon as it next syncs (which happens automatically every few seconds when online).

This means the fraud detection is most effective when devices have at least intermittent connectivity. In practice, a brief connection every minute or two is enough to keep all gates in sync. Even without any connectivity, the duplicate guard works within a single device — so a volunteer can't accidentally check in the same car twice on their own phone regardless of signal.