nx_vessel_faults.nx

nx_vessel_faults.nx -- H2 of the HARDWARE-IN-THE-LOOP ladder: FAULT INJECTION (the "iron bird" / FMEA rig). Aerospace proves a system fails safe by deliberately breaking it in simulation -- stuck actuators, dead sensors, lost power -- before it ever flies. H2 does the same for the fermenter: inject each hardware failure and prove the design contains the hazard or flags the batch, never silently overheating or shipping unsafe food. THE LAST LINE OF DEFENSE is an INDEPENDENT THERMAL CUTOFF -- a bimetallic thermostat / thermal fuse that acts on the TRUE temperature, wired around the controller. It catches the two failures the controller cannot: a heater stuck on (the command is irrelevant) and a dead sensor (the controller is blind). This is exactly how real appliances are made safe. genealogy_id: fmea_fault_injection + independent_thermal_cutoff + nishi_ferment_safety_r0