Function run 

pub async fn run<B, R, W, G, F, A>(
    session: Session<B>,
    reader: R,
    writer: W,
    side: Side,
    feed: &Feed,
    authorize: G,
) -> Result<(), B::Error>
where
    B: ReplicaStore,
    R: MessageReader<Error = Error>,
    W: MessageWriter<Error = Error> + 'static,
    G: Fn(Activity) -> F + Clone + Send + Sync + 'static,
    F: Future<Output = Result<A, Error>> + Send,
    A: ActivityGuard,

Call after validating the opening, endpoint bindings, Thread, and facets. authorize rechecks the live host permission, including expiry/revocation. It runs before every admission and output, including queued output. Readers must enforce the negotiated frame bound before allocating message bodies.