diff --git a/vendor/README.md b/vendor/README.md
index 7e8cf09c..229a7e85 100644
--- a/vendor/README.md
+++ b/vendor/README.md
@@ -34,6 +34,9 @@ Changes:
 ## truck-meshalgo 0.4.0 (Apache-2.0, © RICOS Co. Ltd., https://github.com/ricosjp/truck)
 
 Changes:
+- `tessellation/triangulation.rs`: meshed faces and edges are built unchecked: faces whose loop
+  runs along a seam edge both ways and closed edges (a full circle on one vertex) are valid,
+  but the debug-build checks rejected them (debug builds could not mesh them).
 - `tessellation/triangulation.rs`: parameter searches that land outside a surface's bounded,
   non-periodic domain are rejected (a hinted B-spline search can run off and extrapolate to
   thousands of parameter units, and meshing that grid never finishes); the last-resort nearest
diff --git a/vendor/truck-meshalgo/src/tessellation/triangulation.rs b/vendor/truck-meshalgo/src/tessellation/triangulation.rs
index ff259840..13fe3a43 100644
--- a/vendor/truck-meshalgo/src/tessellation/triangulation.rs
+++ b/vendor/truck-meshalgo/src/tessellation/triangulation.rs
@@ -111,7 +111,7 @@ where
             let v1 = vmap.get(&edge.absolute_back().id()).unwrap();
             let curve = edge.curve();
             let poly = bounded_polyline(&curve, curve.range_tuple(), tol);
-            (id, Edge::debug_new(v0, v1, poly))
+            (id, Edge::new_unchecked(v0, v1, poly))
         })
         .collect();
     let create_edge = |edge: &Edge<Point3, C>| -> Edge<_, _> {
@@ -161,7 +161,7 @@ where
             let v1 = vmap.entry_or_insert(vb).clone();
             let curve = edge.curve();
             let poly = bounded_polyline(&curve, curve.range_tuple(), tol);
-            Edge::debug_new(&v0, &v1, poly)
+            Edge::new_unchecked(&v0, &v1, poly)
         },
     );
     let mut create_edge = move |edge: &'a Edge<Point3, C>| -> Edge<_, _> {
@@ -260,7 +260,9 @@ fn shell_create_polygon<S: PreMeshableSurface>(
         let boundary = PolyBoundary::new(preboundary?, &surface, tol);
         Some(trimming_tessellation(surface, &boundary, tol, cap))
     })();
-    let mut new_face = Face::debug_new(wires, polygon);
+    // SolveCraft: faces with seam edges (a loop running along an edge both ways, as STEP
+    // writes cylinders) are valid here; `debug_new` asserts simple loops in debug builds.
+    let mut new_face = Face::new_unchecked(wires, polygon);
     if !orientation {
         new_face.invert();
     }