PeriodAround's ring term is one rule: self feels the mean, over the members whose pull it takes (itself if bodied, else every
bodied ring member), of half the rest of the ring. A station on a binary's ring no longer stands still. The 0.1 u window is a
named constant, pinned just inside and just outside it; a bodyless node's children are pinned never to read the node's parent's well.
Both commits build.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
