Function run_multi_statement_hooked 

pub async fn run_multi_statement_hooked<T: StatementTransport, A: AuthProvider>(
    cx: &Cx,
    client: &T,
    auth: &mut A,
    request: SubmitStatementRequest,
    params: SubmitQueryParams,
    poll_plan: PollPlan,
    observer: Option<&mut dyn DriverObserver>,
) -> (SnowflakeOutcome<MultiStatementResult>, DriverStats)

Run a request whose MULTI_STATEMENT_COUNT is above one (reality-check bead L1): the parent statement, then each statement fetched by the handle the parent lists (GET /api/v2/statements/{handle}), in statement order. Each statement assembles like a single one (polls, partitions, the plan’s row cap). A failing statement fails the request with 422 before any result is fetched. The observer sees every step.