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crates/fj-kernel/src/validate/cycle.rs

@@ -15,6 +15,11 @@ impl Validate2 for Cycle {
         _: &ValidationConfig,
     ) -> Result<(), Self::Error> {
         CycleValidationError::check_half_edge_connections(self)?;
+
+        // We don't need to check that all half-edges are defined in the same
+        // surface. We already check that they are connected by identical
+        // surface vertices, so that would be redundant.
+
         Ok(())
     }
 }

crates/fj-kernel/src/validate/edge.rs

@@ -24,6 +24,11 @@ impl Validate2 for HalfEdge {
         HalfEdgeValidationError::check_global_curve_identity(self)?;
         HalfEdgeValidationError::check_global_vertex_identity(self)?;
         HalfEdgeValidationError::check_vertex_positions(self, config)?;
+
+        // We don't need to check anything about surfaces here. We already check
+        // curves, which makes sure the vertices are consistent with each other,
+        // and the validation of those vertices checks the surfaces.
+
         Ok(())
     }
 }