The coherent apparatus ledger

The physical carrier $K$ in the coherent dilation is a quantum system. It becomes the observable $\mathsf{Bit}$ interface only after the inaccessible factor $E$ is omitted. A coherent superposition across outcome labels is not a state of the classical algebra.

For a fully measured qubit,

Neither marginal retains the unknown phase; joint $KE$ access does. There is no conflict with no-hiding, because neither marginal channel is constant on the entire qubit code.

Classical discard may be dilated by moving the record carrier into another inaccessible register. Under complete unitary implementation, that register and the other apparatus factors remain in the ledger. The observable trace does not prove physical disappearance.

This accounting is compatible with the joint-apparatus and coherent comparison discipline in CheungEm03C,CheungEn02C. No apparatus model from those manuscripts is silently substituted for the dilation specified here.