Heartbeat should produce response

[broglep]

The current heartbeat mechanism does not reliably allow to detect if the connection is still alive. It would good if the heartbeat would trigger a FromRadio response so that it can be checked if the heartbeat was received.

Would that be a sensible extension to the protobuf protocol?

As a workaround, currently an admin message to request e.g. lora config can be used, so there are definitely ways around that shortcoming

[ianmcorvidae]

I think I'd agree that adding a heartbeat option to FromRadio to match the ToRadio one and having firmware just echo back a heartbeat when it receives one would likely be useful if it's not a pain to do in firmware, especially for folks writing anything custom. Definitely had a few different times folks have asked for ways to do this cleanly with the Python API.