Of C2PA, Open Policy Agent, and study preregistration, only C2PA's mechanism matches the narrow append-only-log-as-truth criterion; the other two match only the broader 'gate at admission, verdict elsewhere' pattern

CANONIC's related-work table groups C2PA, Open Policy Agent, and study preregistration together as precedents under one broad label — "gate at admission, verdict held elsewhere" (claim-canonic-situates-its-ledger-in-a-named-immutability-lineage) — without distinguishing that shape from the narrower append-only-log-as-truth mechanism the vault has been tracking through CANONIC, ActiveGraph, and R-LAM. Checked individually against primary sources, the three precedents split. C2PA is structurally an append-only, additive manifest chain functioning as the asset's record of truth, but it has no admission gate — nothing requires an asset to carry a manifest before it can exist or publish. OPA is an admission gate whose verdict is a stateless live computation, with logging an optional add-on rather than the truth-bearing substrate. Preregistration is an admission gate (a study must be registered before it counts as confirmatory) whose artifact is a single frozen document, not a log.

None of the three reproduces the full shape shared by CANONIC, ActiveGraph, and R-LAM — log-as-ground-truth and judgment pushed outside it. The broad "gate at admission, verdict elsewhere" description covers OPA and preregistration; the narrow append-only-log-as-truth description covers only C2PA's record-keeping half, and even there without the admission-gate component. This resolves question-c2pa-opa-preregistration-append-only-log-criterion and refines claim-append-only-log-recurrence-is-event-sourcing-diffusion-not-blind-convergence: the diffusion argument's precedent list should not treat these three as equivalent instances of the log mechanism.