Function stack_failed_push 

pub fn stack_failed_push(
    request: &StackRequest<'_>,
    failed_code: i64,
    err: &mut dyn Write,
) -> Option<i32>

What: Integrate the remote’s new commits after an explicit push failed, or say nothing when the failure was no divergence. Option<i32> is “the new exit status, or nothing to change”. Why: The status is 0 when the merge was published, and the failing status when the run says why it was not (a conflict, a gate that refused the merge, a remote that kept moving); every other failure returns nothing and prints nothing, so the person sees only Git’s own report.

In TS you’d write (pseudocode):

async function stackFailedPush(request, failedCode, err): Promise<number | undefined>;