!7

static double timeout = 60; // 60 seconds safety

static L<S> data = synchroList(ll("Start."));

html {
  S add = params.get("add");
  if (nempty(add) && neq(last(data), add)) data.add(add);
  
  int i = toInt(params.get("i"));
  int n;
  long start = sysNow();
  while (l(data) == i
    && licensed()
    && sysNow() < start+timeout*1000)
    sleep(10);
  if ((n = l(data)) < i) i = 0;
  ret hrefresh(1, selfLink(i := n))
    + join("<br>", cloneList(data));
}