it('attaches activity_metrics entity to page ping payload when using callback with extendedActivityTracking', async () => {
  const ACTIVITY_METRICS_SCHEMA = 'iglu:com.snowplowanalytics.snowplow/activity_metrics/jsonschema/1-0-0';
  const state = new SharedState();
  const t =
    addTracker('sp8', 'sp8', '', '', state, {
      stateStorageStrategy: 'cookie',
      encodeBase64: false,
      customFetch,
      eventStore,
    }) ?? fail('Failed to create tracker');

  t.enableActivityTrackingCallback({
    minimumVisitLength: 0,
    heartbeatDelay: 10,
    extendedActivityTracking: true,
    callback: () => {},  // no-op — we're testing the payload, not the callback data
  });
  t.trackPageView();

  // advance 1s, fire two clicks, then complete the heartbeat window
  jest.advanceTimersByTime(1000);
  document.dispatchEvent(new MouseEvent('click'));
  document.dispatchEvent(new MouseEvent('click'));
  jest.advanceTimersByTime(9000);

  const events = await eventStore.getAllPayloads();
  const pings = getPPEvents(events);
  expect(F.size(pings)).toBe(1);

  const entities = JSON.parse(pings[0].co as string).data as Array<{ schema: string; data: any }>;
  const metricsEntity = entities.find((e) => e.schema === ACTIVITY_METRICS_SCHEMA);
  expect(metricsEntity).toBeDefined();
  expect(metricsEntity!.data.clicks).toBe(2);
});