src/deriver/deriver.py is a helpers module with no __main__ guard —
running it directly loads it and exits cleanly in ~3s with no logs,
which is what we were seeing. The actual queue-processor entry point
is src/deriver/__main__.py (asyncio.run(run_deriver())), invoked via
"python -m src.deriver".
Discovered during honcho first-deploy on lincoln: deriver container
crash-looped (in the sense that systemd restarted it constantly) but
the underlying process was actually exiting 0 on completion of the
empty helpers module.