Abstract

We formulate a finite, linearly typed interface for destructive computational-basis measurement, external classical geometry, and declared matter–geometry coupling. The observation boundary includes not only coupling observables but also control, guards, capacity tests, locations, and retained storage. Under explicit noninterference hypotheses, arbitrary spectator extensions with the same accessible reduction preserve geometric traces. Immediate destructive readout and a restricted coherent-then-readout implementation agree on their common record–matter output.

For a channel $T$, coarse effects $E_w$, and aggregated fine effects ${\Pi }_w$, record compatibility for every input is equivalent to $T^{\ast }(E_w)={\Pi }_w$. Its exact unassisted worst-case total-variation error is an event operator norm. Residual compatibility requires a separate instrument certificate. Complete-record equality does not identify a hidden mechanism; a persistent classical register can produce carrier-only history dependence.

Prescribed finite channel networks admit a causal-cut factorization through their scheduled ancestors, including in the presence of an untouched reference. This channel statement is not transferred to nonlinear geometric coupling. Conditional stability, integrated residual, and independent-run sampling certificates are stated with their additional hypotheses.

An external conical witness, a static gauge flip, and one complete four-face adjacency exchange illustrate the interface. The exchange has explicit charts, edge laws, event germs, an exact guard, a compact collar, location transport, and a finite reversible event implementation. The ambient spacetime is fixed. No gravitational field equation, continuum limit, or quantum-memory-resource theorem is asserted.