Function sample_edge_polyline_checked 

pub fn sample_edge_polyline_checked(
    edge: &EdgeRecord,
    start: Vec3,
    end: Vec3,
    chord_tolerance: f64,
) -> Result<Vec<(f64, Vec3)>, EdgeChordError>

Certify the full rational curve, rather than a finite set of sag probes. Positive homogeneous weights place each Bezier arc inside its control hull; distance to a segment is convex, so the largest control-point distance bounds the entire arc. Subdivision tightens that bound without omitting knot spans. Endpoints are the shared topology vertices, including their displacement from the curve. Unsupported representations fail closed.