The gauntlet is what turns a lossy feed into a safe schedule. Order matters: promotion of synthetic rows runs before the duplicate guards, the merged-widen check runs before the 30-night owner-closure skip, and the missing-booking engine runs only after the event loop and only if the feed had any events at all. Lemon documents every guard with the incident that produced it, and a regression test replays that incident's feed so the guard cannot be quietly removed.
The practical consequence for a host is that a Booking.com or Airbnb event never reaches a cleaner's phone on the strength of one fetch. It has to be present, plausible in length, not a reshape of something already tracked, not a duplicate across feeds, and not inside a hold before a job exists; and it has to be absent through a full confirmation window, outside the imminent window, before a job is cancelled.