C.31:10 - Rationale

C.31 is a characterization pattern because modularity and reusable-structure talk changes engineering action through characteristics: coupling, cohesion, interface variation, substitutability, reuse, evidence reuse, hidden coupling, source-return cost, and residual growth. Those heads are useful only when their subject, scale, declared measurement or comparison basis, false use, and repair action are visible.

The pattern puts ModularityVectorLite first to preserve affordability. Many practitioners need to see one relation to repair, one interface grammar to tighten, or one residue to account for. Requiring the full measurement apparatus too early would turn C.31 into a control form and would violate the architecture source invariant: repair succeeds only when one useful admissible action remains.

The pattern rejects a single complexity or modularity score because selected heads are not automatically commensurable. When a local score is genuinely useful, it belongs under disclosed scoring, comparator, characteristic, declared-measurement-basis, and subject-pattern discipline.