The tolerance that drops the sweep's slivers came from the whole path's bounding box, so a
contour a million units wide welded away the real half-unit edges of a separate small contour.
Each closed subpath now sets its own.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Model-Effort: Opus 5.5 drove and wrote
Add figcraft_pathops::round_corners(path, radius, smoothing): every vertex of a closed subpath that is still sharp rounds with a circular arc, convex and concave alike. The sweep's noise is cleaned first (short pieces welded, straight runs merged), smooth joins are not corners, and a corner shrinks to what the edges beside it can hold (half an edge when both ends round, the whole piece beside a smooth join). Corners between straight edges use smoothed_corner; corners beside a curve cut both sides and join them with one cubic. A subpath with nothing to round comes back unchanged.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Model-Effort: Opus 5.5 drove; Fable 5.1 designed; Sonnet 5.5 wrote at medium
Trevor BrownandClaude Opus 5.5