obd-poller asks 0x7DF for the nine obd2 signals, only while the bus is alive,
and publishes envelopes stamped with the reply's kernel time. The recorder
subscribes to yukart/vehicle/* and writes vehicle.ndjson beside the frames.
Tested against a fake ECU on vcan0.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz
