A material path is also an interface agreement
Begin at the physical transfer: what arrives, in what condition, at what connection and on whose request? Follow product, rejects, returns and cleaning media separately. A machine may perform correctly in isolation while its receiver is unavailable or its feed arrives in unsuitable batches.
Three boundaries to review together
The mechanical boundary covers geometry, material passages and services. The operating boundary covers permitted material conditions, holding and useful output. The information boundary covers what each side actually knows about availability, state and exceptions. These boundaries should refer to the same labelled equipment and connections.
Coordinate without erasing local responsibility
The line-level request and the machine-level decision to run are distinct. Existing OEM protections, guards and validated process conditions remain part of the engineering review. Define ownership of each command, state and recovery decision before software changes are specified.
