* refactor(routing): replace hash-ring rebalancer with rendezvous (HRW) hashing
Routing was a stored bucket table maintained by a central rebalancer
daemon, which shared its liveness primitive (services.last_heartbeat)
with the collector — when a heartbeat-fresh node went into a zombie
HTTP-handler-broken state, neither the collector nor the rebalancer
could self-correct, and the router kept directing traffic at it.
Rendezvous hashing makes the route a pure function of (ws_id,
live_services) so the heartbeat is the single source of truth and any
liveness-eviction propagates to the next route call without a separate
state-publication step.
The rebalancer's central state has no analogue: the new router computes
the per-key node winner on every call, the collector pushes membership
updates into the router cache from its discovery thread, and per-route
overrides survive on workstream_overrides. Eager workstream migration
goes away; in-flight workstreams lazily rehydrate from storage on the
new owner — already the dead-node behaviour.
* fix(tools): describe rendezvous re-routing on spawn/inspect node_id
The first pass overclaimed `node_id` "stays canonical for this
workstream's lifetime" — under rendezvous routing the active owner
re-derives per-call from live membership, so a node join/drop after
spawn can shift it. Tool descriptions now say `node_id` is the
spawn-time binding; subsequent ops re-route via rendezvous over the
current live-node set; the new owner lazily rehydrates from shared
storage; coordinators should re-read with inspect_workstream rather
than caching the value.
Patrick Buckley