Function execute_one_shot 

pub fn execute_one_shot(
    be: &mut impl SessionBackend,
    txn: &SqlTxn,
) -> Result<SqlTxnOutput, SessionError>

Execute one mutation transaction through the shared admission and commit-tail discipline. Hosts provide only their storage operations through SessionBackend; absorbed replay, gap rejection, rollback-on-statement-error, LMID advancement, and the foreign-write producer watermark stay identical to interactive sessions by construction.