The geometry stays on the CPU as per-frame plans shared with the CPU effects (bolts, mask
strokes, scribbles, contour segments, audio marks, glyph strokes, waves, flood-fill region,
eyedropper sample); segments and convex polygons are tile-binned and rasterised on the GPU
with the CPU's coverage functions. CPU output unchanged (gen_golden). CC Threads' exact ties
at round parameter values are a documented exception; Fractal stays on the CPU (needs f64).
Regenerated docs/effects.md, docs/parity.md EFF-5.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>