forked from 1b-agent/opencadstudio-upstream
A 35-unit arc sweeping 6.5e-7 rad has arc length 2.3e-5 — past the arc-length floor — yet start/mid/end bow off the chord by only ~2e-12. truck's 3-point circle_arc fit then returns a near-infinite radius and parameter_division subdivides without bound, hanging the load. Gate on the sagitta (r·(1−cos(sweep/2))), the true measure of the fit's conditioning, so long thin arcs survive and sub-precision ones drop. Co-Authored-By: Claude Opus 4.8 <[email protected]>