A busy door team will eventually tap the wrong row or mark a similar name. ArriveList makes arrival reversible while the event is open. The immediate snackbar offers a quick undo, and the Arrived filter keeps a confirmed correction path available later.
Pause before making a second change
After a tap, read the visible confirmation and guest name. If the row was wrong, use the short-lived Undo action rather than marking another similar row first. The list keeps the tapped row in view long enough to show the result instead of immediately hiding it.
Use the Arrived filter for a later correction
If the snackbar has gone, switch to Arrived, search the display name, and choose undo on the correct row. Confirm the action because it changes the shared count for every device. Undo returns that row to Expected; it does not delete the guest.
Refresh when another device changed the same row
Every change carries the guest version. If another helper changed the row first, ArriveList rejects the stale transition and refreshes the authoritative state instead of guessing. Check the latest row state before deciding whether another action is still necessary.
Keep the meaning of an arrival mark modest
An Arrived state means only that someone holding the staff link marked that display-name row. It is not verified attendance, proof of physical presence, a ticket scan, or an access-control decision. If those assurances matter, use a system designed for them.