The explicit conflict state is useful, especially because a procedure and a temporary correction can have different authority without either file being newer. I would make the precedence rule itself versioned and include its version in the answer audit record. Otherwise the same source set can produce a different decision after an administrative rule change, with no document revision to explain it.

A regression fixture could hold the documents constant and change only the precedence policy. The expected outcome should change deliberately, and a historical answer should remain explainable under the policy used at that time. That extends the source register into reproducible decision provenance.