Function adopt_migration_checksums 

pub fn adopt_migration_checksums(
    tx: &Connection,
    tag: &str,
    checksum: Option<&str>,
    content_checksum: &str,
) -> Result<(), BookkeepingError>

Backfill a migration row’s optional identities without overwriting values already made durable. Hosts own the surrounding transaction because producer metadata commits differently on HCTree and WAL2; the column contract is shared.