Function run_download 

pub fn run_download<M, S>(
    http: &Downloader,
    url: Url,
    item: M,
    sink: S,
) -> impl Stream<Item = Result<Outcome<M, S::Location>, Error>> + Send + '_
where
    M: Source,
    S: Sink + Send + 'static,

Streams one item’s download. Only emits the happy-path Outcome variants (Progress, Skipped, Downloaded); per-item faults bubble out as Err and drive turns them into Failed. StreamFailed is never produced here — it’s reserved for pre-item errors at the drive layer.