Rust module: older ck-mc on a v53+ store fails note inserts/deletes — is binary rollback supported?

[iceteaSA]

Problem. Store migration v53 moved note-ownership checks into triggers that read a singleton, mc_privilege_state.note_caller_project. A ck-mc binary older than v53 opens a v53+ store as store-ahead and continues, by design. It never fills that row, so ctx_note inserts and deletes on module-owned notes abort with note ownership insert is outside the caller project. Content and status updates still pass. The only signal is a startup warn line. We found this when the rollback binaries we had kept all turned out to predate v53.

Evidence (master 564687284):

• crates/mc-store/src/lib.rs:2575-2600: the v53 singleton and ownership triggers. The comment says McStore::open "intentionally logs and accepts a store-ahead outcome for rollback binaries".
• crates/mc-store/src/lib.rs:7798-7808: a store-ahead open logs "older binary on a newer store; continuing without migrating" and proceeds. The comment says older ck-mc binaries stay placeable on purpose.
• crates/mc-store/src/lib.rs:24454-24457 (test): "ownership-sensitive note writes fail closed. This known rollback limitation is why v53 requires a coordinated module bounce."

Question. Is running an older ck-mc on a newer store a supported rollback?

• If yes, the pre-v53 write path or the v53 triggers need a fix, so that note writes keep working.
• If no, or not across v53, McStore::open could refuse, or fail loudly, when the migrations it is missing carry invariants the old binary can't keep. Today it warns and continues, and the first sign is a note write failing later. A stated minimum rollback version would also do.