Pocketful: a dark factory that proves its own work

In this hackathon most graded tests are hidden: for stage 3 you see about 9% of them, so passing the visible checks proves little. Our factory is built around that. It is four Claude Code seats in Band Desktop, each with a generic mandate. The lead turns the whole specification into a numbered requirements ledger: every "must", limit, error, ordering rule and example, plus a recorded ruling for every sentence that could be read two ways. The builder writes the code in small commits tied to ledger entries and never reads the shipped tests. The verifier builds its own evidence from the spec alone: a tiny reference model, one check per requirement, and thousands of random operations replayed against both the product and the model, with invariants (money conserved, no negative balances, history unchanged) checked after every step, plus the official checks in host and isolated mode. The customer uses the app in a real browser at desktop and phone widths and screenshots every state the spec names. Every verdict names an exact commit, and a check that errored counts as a failure. In the submitted run the factory built all four stages from one dispatch in 4 h 36 min with no human input: 328 of 328 requirements with passing evidence, and every stage folder claims its stage on the official checks in isolated mode. The review changed the work three times. For example, the verifier found that an amount of 1000.00000000000000001 was rounded by the JSON parser and accepted as a whole number; the lead rejected the build, the builder moved integrality checks onto the exact number as typed, and the verifier re-proved everything. FACTORY.md reports measured time per stage and token usage per seat. The verifier is the most expensive seat: the factory spends more proving the product than writing it. Every seat runs in a Docker Sandbox: full permissions inside, no access to the host.