3D clip view + orthographic pick view (XY/YZ/XZ toggle): click 2 points to define a cut line swept along the view axis into a clip plane; flip clip slices the other side. Python node exports the mesh .vtp; clipping is interactive in viewer_slicer.html. prestartup copies the new slicer viewer. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>