pool-blackhole-stalls: each due endpoint's identity is read on its own thread
under a 5 s bound, and a batch waits for reads only while no healthy primary
exists to start on, so a dark endpoint never delays work a healthy one can do.
pool-pins-first-identity: the pool is told the model the collection was built
with (Embedder::built_under, called by reconcile and refresh before the
identity read) and never writes with an endpoint serving another; it adopts a
model only when there is no collection, in list order.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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