old-reader-refusal.sh stages the C0 merge (e382bb4, or OLD_READER_REV) plus the v3 vector
and one probe per runtime onto a commit; the probe run from that tree is the old reader.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
A store that can hold element ids declares cultcache.store.v3. These runtimes pass payload
bytes through, so they read it and write back the header they found; they do not decide
when a document carries ids. Vector: tests/vectors/document-variants-c2a/v3-base.msgpack.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>