Function create_event_forwarder 

pub fn create_event_forwarder(
    session_id: String,
    broadcast_tx: Sender<AgentEvent>,
    runners: Arc<RwLock<HashMap<String, AgentRunner>>>,
    account_feed_inbox: Option<AccountFeedInbox>,
) -> (Sender<AgentEvent>, JoinHandle<()>)

Create an MPSC channel for agent events and spawn a forwarding task that relays events to the broadcast sender while tracking runner diagnostic fields for live visibility.

account_feed_inbox, when present, also mirrors durable change events onto the account-wide feed for resumable multi-client sync.

Returns (mpsc_tx, forwarder_handle).