Merging regions united the faces' outlines with a boolean union. Each
face had been refit on its own, so two faces' shared edge could come out
a hair apart: the union then kept the edge between them, or a spur of
it, and a stroked merged shape (unfilled art) showed a stray line inside.
Subtracting the merged shape from the others left slivers along it too.
pathops::FaceMerger merges faces from the planar arrangement itself,
made once per merge: their contours share their edges exactly, so the
edges between merged faces vanish. The Shape Builder builds the merged
shape that way, and what is left of each shape from its faces not merged
(rather than subtracting the merged shape from it). Selections with open
paths keep the old union.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2023a47188