Scheduler — the appointment book — How long is a booking? It is decided once

When you book something, the scheduler asks the service how long it takes and writes that onto the booking. From then on the booking is its own authority. That is deliberate, and it is the difference between a schedule you can trust and one you cannot. If a 90-minute massage becomes a 120-minute massage next year, every massage you have ever booked would otherwise grow by half an hour — including the ones already delivered, already invoiced, and sitting in last quarter's reports. Instead: bookings made when it was 90 stay 90, and new ones take 120. It has to be kept somewhere, so the view needs either an end date or a number of minutes on the booking itself. A duration that is looked up through the service does not count — that is the live value this is protecting you from. If there is nowhere to keep it, the scheduler says so above the grid and every booking is drawn the same default length until you pick a field. Typing a number in the booking panel always wins; leaving it blank is what asks the service.