Tablekeeper Factory — 3-Seat Band

Tablekeeper Factory is our Dark Factory entry on the Tablekeeper track: a restaurant reservation service with one hard guarantee — it never double-books. The system handles single tables and declared combinable pairs, policy-driven pricing, capacity, and opening hours, plus recurring reservation series with clock-time amendments. Its centerpiece is a manager replan solver: when a table closes, it computes the provably optimal reseating by minimizing moved bookings first, then wasted seats, then the table-rank order. Every operation is timezone-correct (local wall-clock, never UTC-shifted), idempotent with exact-replay semantics, and atomic — failed operations change nothing. It was built the way the event intends: by a band of three coding-agent seats (Architect, Builder, Checker) with generic mandates, working in a BAND Desktop room, with every commit gated against the official track harness before the next task. Final scores: stage 1 at 116/120, stages 2, 3, and 4 fully green. Each stage is a complete service that builds clean and serves from a container with no outbound network. The public repo holds all four stages, the seat mandates, the factory description, the full room export, and the walkthrough video.