* fix: retire stale review lookups after cache invalidation
* test: pin the fence a retired review lookup answer has to clear
The extraction widened canAdoptDetachedAnswer: a retired owner is no longer in
the in-flight index, so with no replacement reader the scope generation is the
only thing stopping its pre-invalidation "no review" from being adopted as
current — which would short-circuit the lookup for the review Orca just opened.
Cover that interleaving, and restore the invariant comments the extraction
dropped (token identity, expire idempotency, and that a size-cap eviction
forfeits the wall-clock sweep).
Neil
dc8f623a3a