Does every computable magnitude come through a convex dual?

Speculative — an open question, recorded because it is a retrodiction that has never been checked forward.

The claim. Every magnitude actually computed in the work came through a convex dual — a pressure or rate function, a Legendre/Varadhan transform turning an integral into a supremum; every magnitude that resisted has no convex dual. Proposed as a criterion that predicts the record retrospectively.

Why it stays a probe. A criterion that fits the record after the fact is a retrodiction; it earns nothing until it predicts forward. Discriminator (the gate): name, in advance, a magnitude neither computed nor filed; predict computable-or-not from whether it has a convex dual; attempt it; score. Until that runs, this is a pattern in a small self-selected sample, not a law.