owner

Returns the peer that owns taskId under the current roster, or null if the roster is empty.

The owner is the first peer clockwise of hash(taskId) on the ring. Deterministic: same roster + same seed → same result for every peer in the session.

Returns the owner of taskId restricted to the eligible subset of the roster, or null if no ring peer is eligible.

This is the H8 location-eligibility hook (design §14.6): consistent-hashing over only the eligible peers is identical to walking the full ring and returning the first clockwise peer that is in eligible — removing a peer from a consistent-hash ring is exactly "skip its virtual nodes." Passing an eligible set that contains the whole roster therefore reproduces owner bit-for-bit, so the no-affinity path is unchanged.

Deterministic: the same ring + same eligible set → same result on every peer. Callers derive eligible by filtering the roster with a task's Affinity against each peer's advertised CapSet; every peer computes the same eligible set from the same convergent capability view.