What it does: when a patient cancels, Backfill offers the slot to everyone on the waitlist whose service, day and time match, all at once. The first to tap Claim gets it. The slot is re-checked first, so nobody is ever double-booked. Everyone else is told it's taken and keeps their place. The front desk sees every step on a live dashboard, along with the revenue recovered. If nobody claims within 30 minutes, staff get a "Needs you" alert.