Function useProgressiveEntryLimit

packages/app-core/src/components/Sidebar.tsx:3726–3770

(
  total: number,
  enabled: boolean,
)

}

function useProgressiveEntryLimit(
  total: number,
  enabled: boolean,
): [number, (node: HTMLDivElement | null) => void] {
  const initial = getInitialSidebarEntryLimit(total, enabled);
  const [limit, setLimit] = useState(initial);
  const observerRef = useRef<IntersectionObserver | null>(null);

  useEffect(() => {
    setLimit(getInitialSidebarEntryLimit(total, enabled));
  }, [enabled, total]);

  useEffect(() => {
    return () => {
      observerRef.current?.disconnect();
      observerRef.current = null;
    };
  }, []);

  const setSentinelRef = useCallback(
    (node: HTMLDivElement | null): void => {
      observerRef.current?.disconnect();
      observerRef.current = null;

      if (!enabled || !node || limit >= total) return;
      if (typeof IntersectionObserver === "undefined") return;

      const observer = new IntersectionObserver(
        (entries) => {
          if (!entries.some((entry) => entry.isIntersecting)) return;
          setLimit((current) => getNextSidebarEntryLimit(current, total));
        },
        {
          root: null,
          rootMargin: `${SIDEBAR_PROGRESSIVE_SENTINEL_MARGIN_PX}px 0px`,
        },
      );
      observer.observe(node);
      observerRef.current = observer;
    },
    [enabled, limit, total],
  );

  return [enabled ? Math.min(limit, total) : total, setSentinelRef];
}

function buildTree(
  notes: NoteMeta[],