edge_value = reduce(face_field[A], face_field[B]); face_normals+angle = dihedral. Thresholded edges + surface written to an ASCII .vtp and shown in the shared VTK.js viewer (viewer_vtk.html) in-node. Face field is a string (face_normals or any face_attributes key; available ones logged). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>