An entry prepared for Sanity Challenge — Path Two . What I Built Prop Continuity Desk is a rehearsal planning board for a small theatre production. Its fictional play, A Place on the Last Boat , has six scenes and twelve physical props. A parcel enters with a passenger, a torch leaves with a crew member, and a key ring changes hands in the final scene. The app catches two mistakes: placing the same physical prop twice in one scene, and moving a prop between scenes without re...