Operator chose option A on all three questions Soul raised: one lock order
(cache, then store) with store I/O blocking that cache's readers; an
unconditional Commit is last-writer-wins like a flush; a store that fails to
hydrate on open throws and is never overwritten. Also records one key per
store, load-only OnUpdate, missing-file dirtiness, the late-route fixture,
TryGet kept for AquaSynth, the scoped SemaphoreSlim check, and the corrected
size target for CultCache.cs.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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