}, delay);
      }
      //console.log("isOkay =",isOkay,"currentDelay =",Chat.timer.currentDelay);
    }
  };
  afterPollFetch.isFirstCall = true;

  /**
     FIXME: when polling fails because the remote server is
     reachable but it's not accepting HTTP requests, we should back
     off on polling for a while. e.g. if the remote web server process
     is killed, the poll fails quickly and immediately retries,
     hammering the remote server until the httpd is back up. That
     happens often during development of this application.

     XHR does not offer a direct way of distinguishing between
     HTTP/connection errors, but we can hypothetically use the
     xhrRequest.status value to do so, with status==0 being a
     connection error. We do not currently have a clean way of passing
     that info back to the fossil.fetch() client, so we'll need to
     hammer on that API a bit to get this working.
  */
  const poll = Chat.poll = async function f(){
    if(f.running) return;
    f.running = true;
    Chat._isBatchLoading = f.isFirstCall;
    if(true===f.isFirstCall){
      f.isFirstCall = false;
      Chat.aPollErr = [];