Reshapes are the heart of the danger in Booking.com feeds. A reshaped block can arrive in three places: as a brand-new UID (looks like a new booking), as a cancelled UID reappearing widened (looks like a rebooking), or as a tracked booking's own UID widening to swallow a neighbour (looks like a date change). Each path has a guard in Lemon's sync: the block is recognised as a reshape of stays already tracked, those stays are protected, and any nights no tracked booking explains are surfaced to the host as uncovered nights rather than acted on.
The reshape family is why Lemon does not apply a date change that would make a booking overlap another tracked booking on the same feed.