run_drc passed the report path and the board path straight to kicad-cli without checking they differ. On KiCad 10.0.5, the same path for both made KiCad load the board and then replace it with the text DRC report. The wrapper still returned "drc violations: 2, unconnected pads: 2" as if nothing happened, even with save_board=False. The ERC path has the same bug. A verification step that destroys its input and reports success is about the worst failure a check can have.