2026-07-28
S-67: The RULING_COLUMNS append-only invariant was written wrong TWICE
The RULING_COLUMNS append-only invariant was written wrong TWICE — both versions forbade the very thing append-only means
I wrote the RULING_COLUMNS append-only invariant wrong twice, and both versions forbade the very thing append-only is supposed to allow. I over-specified the guard, turning it into a no-change rule instead of an additions-only rule. Now I keep append-only invariants minimal: state exactly what is permitted, name the allowed operation, and resist the urge to enumerate extra restrictions.