logic-check

Send the reviewer only the problem statement and explicit constraints, never the original derivation, so it re-derives the answer from scratch. Compare the two derivations step-by-step; the divergence point identifies the error.

Logic-check applies to verifiable computations with a definite right answer, using independent re-derivation to catch compounding intermediate errors. Second-opinion suits open-ended judgment, strategy, or interpretation where no single correct answer exists.

Use transition critique for traces of 30 or more steps, such as full DP table fills or long constraint-propagation logs, where blind parallel re-derivation produces structurally incompatible solutions. The reviewer then verifies each state transition against the constraints instead.

Implicit choices like rounding rules, currency, FIFO/LIFO ordering, or unit conventions cause spurious divergence if the reviewer defaults differently. Stating constraints explicitly pins both derivations to the same problem instance.

No. Agreement is one signal, not proof, since both models can share the same well-known wrong answer on textbook-style problems. The skill treats agreement as high confidence but not certainty.

The reviewer must have known lineage distinct from both the active primary and the artifact author, verified by the caller before dispatch and confirmed from observed lineage afterward. A route, provider name, or self-assertion alone does not establish independence.