Expectation selection and spectator invariance

Equality of the one scalar $I_f$ suffices for this geometric constructor. Equality of an arbitrary controller's output requires its declared input agreement; it cannot be inferred merely from one current unless that controller is declared to factor through that current.

A consumed name is absent from the codomain of (eq:readout). Pulling an observable back through a readout channel does not make the consumed input name a surviving output name. If a produced record is explicitly included in the source algebra, invariance refers to that record-containing interface; it does not assert a record-blind deferred-readout comparison.