Remark: The order of limits is essential

At fixed $q$, the displayed comparison does not vanish as $t$ and volume grow. This paper therefore proves no finite-$q$ strict-convexity or differentiability theorem for this circuit.

Moreover, the comparison is a support-history or observable comparison. It is not a diamond comparison between the full Clifford payload channel and the CNOT channel of Section sec:bridge1. Their quantum residuals differ. A complete-channel ledger must record that distinction.