Function build_pcurve_on_surface_range_dense 

pub fn build_pcurve_on_surface_range_dense(
    surface: &NurbsSurface,
    curve: &NurbsCurve,
    edge_start: f64,
    edge_end: f64,
    forward: bool,
    tolerance: f64,
    base_samples: usize,
    refinement_rounds: usize,
    parameter_cap: usize,
) -> Result<NurbsCurve, String>

Range fitter with explicit sampling knobs. The default entry above keeps the long-standing (base 64, 3 refinement rounds, 513 cap) budget; STEP import retries failed fits with a denser budget — a vendor spline whose parameter speed varies by orders of magnitude across a corner can hide a deviation spike the coarse refinement cannot chase down.