\caption{Diagram engine review with original illustrative workflows. (a) An asynchronous service architecture. Module labels wrap within 34 mm; connectors attach to measured ports. A request enters validation, is queued, processed and stored; monitoring and audit services receive separate events. (b) Three labelled channels between two services. Label positions are selected automatically against all shafts, node artwork and other label plates. These diagrams describe an illustrative system, not a deployed service. Recipe and artwork: MIT, Mark Marosi.}