On any board with a copper zone, update_pcb_from_schematic marked every board net as routed and refused every pad-net change as routed_pad_net_change, even when neither the old nor the new net had any track, arc or via. The zone's own net is readable in the protobuf, but the tool failed closed on all nets instead of just the zone's. Since nearly every real board has a ground pour, no connection on such a board could be changed by the agent.
From the Grok Haitch pain-radar compilation, finding 11, found 2026-10-03, score 9/10. Verbatim evidence: "Since nearly every real board has a ground pour, update_pcb_from_schematic cannot change any connection on such a board." Cost model assumes schematic-to-PCB sync is done manually outside the agent or the net changes are hand-edited.