Contradictor: Evidence Before Acceptance

AI-assisted development can produce convincing completion claims before a team has reproducible evidence. Contradictor addresses the testing and repair handoff: developers need to know what failed, which build was tested, what changed, and whether the same challenge passes after repair. Fulcrum Force built a local developer workflow around IBM Bob IDE. An operator freezes a requirement and admits an independently authored challenge. A FastAPI backend executes the challenge; Contradictor binds the results to candidate and challenge identities, preserves stdout/stderr and structured evidence, and exports a review package. A confirmed finding becomes a bounded Bob repair packet. The same frozen challenge then runs again, and an independent reviewer makes the technical determination. Our self-case study challenged Contradictor itself. A plan could inherit authorization from its prototype. The frozen F9 challenge exposed that behavior: 29 of 30 tests passed and F9 failed. Bob added an own-property guard without weakening the challenge or existing authorization checks. The unchanged challenge then passed 30/30, including the legitimate own-property positive control. One of those 30 cases is an explicitly deferred observational check, not a resolved defect. Independent BUILD reproduction exercised both candidates through the live backend and confirmed the failure-to-pass transition. The accepted integrated candidate also passed typecheck, 146 Node regression tests, and eight backend tests. Evidence stays attributable to its actual executor; Bob's shell was unavailable, so Bob did not execute these checks. The prototype demonstrates a repeatable way to inspect failure, route repair, compare reruns, and distinguish test success from acceptance. We do not claim a measured productivity percentage. It is a trusted-local prototype, not a hostile-code sandbox or production authorization system. Acceptance covers the frozen HC-B01/F9 scope only; HC-B02 through HC-B05 and the zero-width-space policy are deferred.