\section{Exact checks and audit scope}\label{app:checks} \subsection{The kernel, Gram and arithmetic identities} The proof of rank in Section~\ref{sec:gram} applies to every $m$ and $B$. The accompanying computations check its formulas and normalization, together with the denominator and dilation identities. They use exact integer and rational arithmetic. For the Gram entries, the residue formula and the moment integral provide two calculations. With every fraction reduced, put \[ \Delta=\prod_{\alpha=v/d\in\Lambda}d^2,\qquad P_*(x)=\prod_{v/d\in\Lambda\setminus\mathcal A}(d^2x+v^2). \] Since $\mathcal A\subseteq\Lambda$, \[ \frac{\prod_{\alpha\in\Lambda}(x+\alpha^2)}{Q(x)} =\frac{P_*(x)}{\Delta}. \] For $0\le j