When a merged block is recognised and the stays underneath it are protected, there may be nights left over — a second guest the feed only ever showed inside the merge. Those nights are real but unproven. Lemon mints a placeholder booking for them with a synthetic UID keyed on the checkout (rule 2), so it stays stable while Booking.com trims the check-in, and puts it on the host dashboard as a question with two answers: confirm (create the job) or dismiss (which also cancels any job and tells the cleaner).
If the OTA later splits the block and exports the real reservation separately, the placeholder is promoted onto the real event instead of blocking it (synthetic_promoted). In the 30 days to 2026-09-10, 8 uncovered ranges were surfaced and 2 promoted.