Revocable merges (a contradiction-driven undo of identity.merged) ship
in the clusterer work; this reserves the topic up-front so identity.>
subscribers receive it day one without a re-subscribe.
The clusterer worker's ClusterResult fan-out now publishes on
identity.unmerged when populated. The skeleton clusterer never
populates it; the revocable-merge commit will.
Wiki update lives in wiki-checkout/Service-Bus.md (separate repo).