Bookings — Repeats, classes, and things booked by the night

A repeat is stored as a rule, not as a thousand rows. “Every Tuesday, forever” is literally true: no hidden end date, no cap. Change one and you are asked how far it should reach — just this one, this and every later one, or the whole repeat — and the middle answer leaves everything before today exactly as it was. A class is not a double-booking. Twenty people at one yoga session is twenty rows at the same time with the same instructor. Tell the view how many the session holds and it counts seats instead, so only the real problems are left: a full class, and an instructor booked into two different rooms. Some things are booked by the night. Cottages, rooms, boats, hire cars. Give the view a start date and an end date with no time of day and it becomes a chart with a row per unit and a column per day. The end date is the day the unit comes free again, so a guest leaving on the 8th and one arriving on the 8th sit side by side rather than reading as a clash.