A .kicad_dru rule says HV nets need 0.6 mm, but route.py prints it as handled, lists no unsupported rules, and ships HV copper 0.2 to 0.58 mm apart. With --clearance-ceiling 0.1 it also rewrites the .kicad_pro HV class to 0.1 mm, so kicad-cli DRC and check_drc both report a clean board.