The report from a real SunSDR: transmit power and SWR still empty after the
sensors fix. The subscription went out once, at connect — while ExpertSDR3 is
still streaming its initial state dump, exactly where a unidirectional control
command can be ignored. It is now renewed every time the server says 'ready'.
The sensor messages also join the logged-on-arrival set, capped like the rest:
the next log will say whether TX_SENSORS ever arrives, which is the question —
a radio that never sends it (AetherSDR may not) and a frame that arrived and
was dropped leave the same blank meters and need opposite fixes.