A record whose schema id the catalog lists only as a compatible id now opens (the cache resolved a persisted schema by entry id
alone). CultMesh's fallback to the older catalog-entry reader fires only for a store in that layout, decided by the entry's slot 5,
not for any decode failure, so a current-layout store with a malformed slot is refused as CultCache refuses it.
CultStoreUnreadableException.Path names the refused file. New vectors: compatible-id-only-v3 (accepted by all four) and three
current-layout catalogs with one malformed slot. The contract states the writer's invariant.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>