The Split feature takes an optional face tool (FaceAt, the face through a point on a named body) and splits with kernel split_body, the tool's surface extended; otherwise the plane as before. Engine test: a box split by a cylinder's side into the core and the rest. Co-Authored-By: Claude Opus 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL