R1's rules win where both sides decided the same question: a zero-byte file is
not a store (refused as unreadable in every runtime), only nothing at the path is
empty, a dangling link is an I/O error, refusals never echo stored values and echo
a header only as cultcache.store.v<digits>, writes report Rejected, NotReplaced
and ReplacedNotDurable. C2a's rules win on what it added: the v3 element-id
header, variants, whole-file proof, typed unreadable errors in C#, TypeScript and
Python. Rust keeps R1's CultCacheStoreUnreadable{path, kind}; C2a's
StoreUnreadableError is deleted. The readability manifest's zero-byte row is
refuses x4.
Not yet built or tested: verification follows in the next commits.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>