The cutoff is not an endpoint certificate

A positive $M_{\mathrm{cut}}$ specifies the boundary of the supplied clock's validity. It does not establish complement constancy at that boundary, or determine later mass loss, a burst, a remnant, or outgoing quantum access.

Conversely, zero leakage does not force zero energy. The isometry

has zero leakage and positive residual energy. Likewise, a zero-energy residual sector may have a degeneracy that retains the entire code. Energy labels do not count all inaccessible logical degrees of freedom CheungHawk01B,CheungEn07B.

For a pure, unreferenced complete state, radiation purity is equivalent to purity of its residual marginal. It is not equivalent to channel constancy of that residual on every logical input. The latter is the recovery criterion.