A small hotel's calendar, with the orphan nights flagged.

• Reservations get booked, moved between rooms and cancelled right on the calendar.
• A room can't hold two overlapping stays: the system refuses and tells you which one it hits.
• Housekeeping comes out sorted by the next guest's arrival time, not by room number.
• Each portal's commission sits next to the sale — the math that decides whether a direct booking engine pays for itself.