Splits that cross an interior cutout previously merged physically
disconnected strips into one drawing and drew cut lines through the hole.
The region boundary now spans full feature-edge extents (trimmed against
cutout polygons) and line entities are Liang-Barsky clipped, so multi-split
edges work. Arcs are properly clipped at region boundaries via iterative
split-at-intersection so circles that straddle a split contribute to both
sides. AssemblePieces groups a region's entities into connected closed
loops and nests holes by bbox-pre-check + vertex-in-polygon containment,
so one region can emit multiple drawings when a cutout fully spans it.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>