forked from 1b-agent/fieldcraft-upstream
A cross-section region with three corners (a fillet's quarter disk, a pocket corner cut off by a partition) was left to the free all-quad mesher. It now gets midpoint subdivision's triangle primitive (Tam and Armstrong 1991; Li, Armstrong, McKeag 1997): lines from a centre to a node on each side split it into three mapped blocks, the interior then smoothed and every quadrilateral checked (a fold falls back to free). Interval assignment gains dominance constraints (a side shorter than the other two together) so the split always exists. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo