16.3 Transport defects and partial reuse

Four defects organize the fallback behavior:

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coverage defect

the new presentation contains objects or arrows not reached by the transported diagram;

semantic defect

a formerly invertible universal comparison ceases to be invertible;

observer defect

the target observer distinguishes behaviors that the source quotient identified;

admission defect

a transported action, repair, or witness violates the target safety subobject.

These defects need not force total rejection. The maximal subdiagram on which all four vanish is the candidate persistence core. The remaining region is a localized accommodation problem for the next chapter.

Guiding question.

Which Beck–Chevalley, homotopy-coherence, and tangent-stability conditions are jointly sufficient for a learned decision construction to transport across an environment morphism?