The platform's message topology, derived from the service source (never a live broker) and CI-gated so it can't drift — see docs/bus-topology.md. Fan-out events travel the RebusTopics topic exchange; command queues are point-to-point.

Fan-out events (pub/sub)

Command queues (point-to-point)

Drift vs the catalog

Signals, not errors: an orphan is a catalogued event nobody subscribes to; an unlisted key is bound by a consumer but missing from docs/events.md.

Topology diagram