Root cause (from the brewpi Pi's log): HendiCtrl.disconnect() only
caught HendiException (a protocol-level NAK), but a genuine unplug
fails deep inside pyserial itself - flushInput()/readline() raise
termios.error/OSError on the now-dead fd. That escaped disconnect()
uncaught (skipping self.ser.close() too), then kept propagating up
through every caller that invoked disconnect() from its own except
handler (HeaterHendi.process()/activate(), AHeater.open()'s
context-manager exit), all the way out of HeaterTask.on_process()'s
coroutine entirely. Nothing restarts a dead ATask, so the heater's
process()/duty-cycle loop was gone for the rest of the process's
life - reconnecting afterward changed `connected` back to True but
nothing was left running to ever call process() again.
Fixes:
- HendiCtrl.disconnect() now catches broadly and always closes the
port, matching Pololu1376.disconnect()'s already-correct pattern.
- HeaterTask/StirrerTask.on_process() gain an outer retry loop as a
safety net: even an unanticipated exception now logs, marks
disconnected, and re-enters rather than permanently killing the
task.
Verified by reproducing the exact failure (comm error raising a raw
OSError, not HendiException) against a fake device - the task now
survives and resumes process()ing once reconnected.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YaPLuRPpyjWcwhMvCvpHCL
jensandClaude Sonnet 5
671e0c2474