fix: reject degenerate boolean intersection polylines

vendor/README.md

@@ -7,6 +7,9 @@ are marked `SolveCraft:` in the source.
 ## truck-shapeops 0.4.0 (Apache-2.0, © RICOS Co. Ltd., https://github.com/ricosjp/truck)
 
 Changes:
+- `transversal/intersection_curve/mod.rs`: reject empty/single-point polylines and
+  collapsed or non-finite segments before endpoint indexing and normalization. A hidden
+  constructor re-export lets the kernel workspace tests exercise the actual vendored code.
 - `transversal/integrate/mod.rs`: mesh both shells with `robust_triangulation` (faces made by
   earlier booleans have boundaries that lie on their surface only within tolerance).
 - `transversal/divide_face/mod.rs`: when projecting a loop onto a face's surface, fall back to

vendor/truck-shapeops/src/lib.rs

@@ -34,4 +34,7 @@ mod healing;
 pub use healing::{RobustSplitClosedEdgesAndFaces, SplitClosedEdgesAndFaces};
 mod transversal;
 pub use transversal::{and, or, ShapeOpsCurve, ShapeOpsSurface};
+// SolveCraft: exercised by kernel regressions in the workspace CI.
+#[doc(hidden)]
+pub use transversal::IntersectionCurveWithParameters;
 mod alternative;

vendor/truck-shapeops/src/transversal/intersection_curve/mod.rs

@@ -19,12 +19,21 @@ impl<S> From<IntersectionCurveWithParameters<S>> for IntersectionCurve<PolylineC
 impl<S> IntersectionCurveWithParameters<S>
 where S: ParametricSurface3D + SearchNearestParameter<D2, Point = Point3>
 {
+    /// SolveCraft: construct a projected curve, returning `None` for degenerate input.
     pub fn try_new(
         surface0: S,
         surface1: S,
         poly: PolylineCurve<Point3>,
         tol: f64,
     ) -> Option<Self> {
+        // SolveCraft: a point contact is not a curve. Reject it before indexing the
+        // endpoints, and reject collapsed/non-finite segments before normalizing.
+        if poly.len() < 2 || poly.windows(2).any(|p| {
+            let length2 = (p[1] - p[0]).magnitude2();
+            !length2.is_finite() || length2 <= 0.0
+        }) {
+            return None;
+        }
         let mut polyline = PolylineCurve(Vec::new());
         let mut params0 = PolylineCurve(Vec::new());
         let mut params1 = PolylineCurve(Vec::new());

vendor/truck-shapeops/src/transversal/mod.rs

@@ -2,6 +2,9 @@ mod divide_face;
 mod faces_classification;
 mod integrate;
 mod intersection_curve;
+// SolveCraft: expose the constructor for workspace regression coverage of the vendored fix.
+#[doc(hidden)]
+pub use intersection_curve::IntersectionCurveWithParameters;
 mod loops_store;
 mod polyline_construction;
 pub use integrate::{and, or, ShapeOpsCurve, ShapeOpsSurface};