Joint shared-error interface
18/18 controls pass; state: complete.
Twelve known-answer systems check one common error across training and future epochs. Six negative controls reject mismatched source, time, center, domain or binding. Every physical and auxiliary column remains. No native evaluations, archive reads or observed fits.
This qualifies the supplied affine interface, not native roundoff or actual observational coverage. A separate generated native usefulness comparison is next.