Function validate_fast 

pub fn validate_fast(
    params: &ValidationParameters,
    model: &Model,
) -> Result<(), Vec<GeopError>>

A cheap subset of validate: only the checks that are purely structural/combinatorial (pointer validity, two-way next/prev/backref consistency, pcurve loop continuity) or a single pass over already-stored geometry (vertices vs. their edges’/faces’ curves/surfaces) — none of the O(n^2) pairwise numerical-intersection searches (disjointness_check, face_face_numerical_intersection) or the sampling-based curve_and_surface_sampling_check. Meant for call sites that want a quick “is this model still well-formed” check after every mutating step (e.g. a test sweeping many scenes) without paying for the searches that dominate validate’s cost.