PFP VI: Retained Failure Evidence and Controlled Reuse

PFP VI: Retained Failure Evidence and Controlled Reuse This paper examines what it takes to keep rejected proposals as evidence in the Proposal Fidelity Protocol (PFP), a proposal-and-check protocol developed under the legacy name Symbol Game. A rejected proposal can explain a defect or supply a negative test, but the record must stay interpretable, its integrity must be checkable, and later reuse must not turn a rejection into authority. The paper audits the repository's refusal store at a fixed commit. The store writes JSON Lines records chained by SHA-256 predecessor digests under a header that holds the entry count and head digest, and it emits a count-and-head receipt of cached state, requiring successful disk verification before persisted-snapshot comparison. The paper states which modifications the reload checks detect, shows that a rewritten but internally consistent shorter file still passes local verification, and explains why an independently retained anchor is needed. A worked two-record example, replayed by a package test, separates local replay from snapshot comparison. The store is logically append-only through its interface but rewrites the whole file on each append. It offers no immutable media, concurrent-writer safety, authenticated provenance, or power-loss durability, and its sorted-key JSON encoding is not a full RFC 8785 implementation. The paper then specifies a bounded procedure for turning a retained failure into a proposed detector, using existing checks for benign examples, an inclusive trigger-based downgrade threshold, invalid patterns, and batch-invariant decay under fixed-parameter assumptions. A retained catalog of 61 harvested detector candidates is described as a data file only: 56 entries are marked candidate, 49 carry placeholder fixtures, and no audited code applies the fixtures. No improvement in model accuracy, cost, or discovery yield is claimed. The first-publication review distinguishes the historical audit from later source changes, adds replay checks for cached receipts and failed writes, and includes a digest-bound catalog snapshot for offline census. The teaching companion contains 24 graded problems, a worked study guide, a separate instructor key, and an exact standard-library worksheet. Returned maintenance records do not by themselves establish host enforcement.