Function supervise_event_subscription 

pub async fn supervise_event_subscription<S>(
    source: Arc<S>,
    reconnect_policy: EventReconnectPolicy,
    shutdown: CancellationToken,
    updates: Sender<EventSubscriptionUpdate<S::Item>>,
)
where
    S: EventSubscriptionSource + ?Sized,

Supervises one transient subscription until shutdown or receiver closure.

Consumers handle updates sequentially. Connected/Recovered is therefore observed before the first item from that subscription, so products can reconcile authoritative state first.