The Adversary Line — who checks the checker

Problem. A dark factory is only as good as its checks, and in this challenge the shipped checks are a sample — as little as 11% of a stage. A factory that trusts them ships the rest broken, and one that asks a human for help is not dark. Solution. The Adversary Line is a band of five coding-agent seats in Band Desktop. The Foreman plans and routes; the Builder and Finisher build the service and its screens; the Adversary writes a requirements ledger from the specification and verifies every commit against it; the Saboteur plants known defects in scratch copies and measures how many the checks catch — on stage 1 the shipped checks caught 8 of 11, the Adversary's probes 11 of 11. Review changes outcomes: at stage 3 the Adversary blocked a commit that passed every shipped check, over a field the specification requires; at stage 4 it disclosed that its own rows were too thin, the Builder's new fixture then failed on the Builder's own planner — a party of two seated at a six-seat table while a two-seat table stood free — and the Foreman voided its own acceptance until the fix was in. Result. From one dispatch and no other human message, the band built all four of Tablekeeper's stages — a restaurant reservation service with idempotent bookings, time zones, combined tables, booking screens, recurring bookings and replanning around closed tables — each stage claimed by the event's own harness in isolated mode, all 158 shipped checks of the last stage passing. Every seat runs a free model: $0 for 5,250 model turns, with 97% of the input served from cache, measured per seat. What went wrong is in FACTORY.md, including defects the seats planted in stage 4 and never took out; our packaging commit puts stage 4 back to the accepted tree. Who it is for. Any team that wants an unattended coding factory it can inspect: five generic mandates, one jailed launcher, and a step-by-step setup in FACTORY.md. Pointing it at a different problem changes only the task.