MAC3-R1 from the fix verification: refreshCachesForEffectiveContext purged
on every effective-context move, so the cache the Subscriptions fix meant
to keep was already empty when its keep-path ran. A move under an unchanged
selection now fences the feed cache non-destructively; only a genuine
selection move still purges. Also settles the destination loader's
observer callback onto the main actor without a capture-of-var warning.
40d6f4e71f