The per-machine form gains the keys below the machine's own, <node>.>, for every
per-machine state and a membership's too (PerMachineKeys), every module's key keeping
its form; buscompose exports WirePattern, which a reader uses to turn a stream's events
into the bus's subjects (the tool runner's marks).
Builds: design 46 7-approval-mark §13, §5
Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h