The conveyor state machine and why “flow” beat “single-shot”

The line became a machine when failure states became explicit.

The old single mode waited until a named part was already present before starting the belt. Flow mode starts from motion: object enters delivery → stop/inspect → verdict or 4 s unknown → run → pickup → stop/arm.

Unknown at pickup never calls the arm; without recognition the belt does not run. tools/test_linie_fluss.py is the bench test. 0.25 s / 4 s values are not final conveyor tuning.