Simplify handleTextareaScroll and remove unused memoized functions in App.tsx

src/App.tsx

@@ -319,106 +319,7 @@ export default function App() {
   const sidebarExpandIconSrc =
     theme === "light" ? sidebarExpandIconBright : sidebarExpandIcon;
 
-  const lines = useMemo(() => body.split("\n"), [body]);
-  const lineCount = lines.length;
-
-  const getLineTop = useCallback(
-    (index: number) => {
-      const tops = lineTopsRef.current;
-      return tops[index] ?? 0;
-    },
-    [lineNumbersVersion]
-  );
-
-  const getTotalHeight = useCallback(() => {
-    const tops = lineTopsRef.current;
-    return tops[lineCount] ?? 0;
-  }, [lineCount, lineNumbersVersion]);
-
-  const findLineAtOffset = useCallback(
-    (offset: number) => {
-      if (lineCount === 0) return 0;
-      const tops = lineTopsRef.current;
-      if (tops.length === 0) return 0;
-      let low = 0;
-      let high = lineCount;
-      while (low < high) {
-        const mid = Math.floor((low + high) / 2);
-        if ((tops[mid + 1] ?? 0) <= offset) {
-          low = mid + 1;
-        } else {
-          high = mid;
-        }
-      }
-      return Math.min(Math.max(0, low), Math.max(0, lineCount - 1));
-    },
-    [lineCount]
-  );
-
-  const updateVisibleRange = useCallback(() => {
-    if (!showLineNumbersActive) return;
-    const textarea = textareaRef.current;
-    if (!textarea) return;
-    const scrollTop = textarea.scrollTop;
-    const viewportHeight = textarea.clientHeight;
-    if (lineTopsRef.current.length === 0) return;
-    const start = findLineAtOffset(scrollTop);
-    const end = findLineAtOffset(scrollTop + viewportHeight);
-    const buffer = 8;
-    const nextStart = Math.max(0, start - buffer);
-    const nextEnd = Math.min(lineCount - 1, end + buffer);
-    setVisibleRange((prev) =>
-      prev.start === nextStart && prev.end === nextEnd
-        ? prev
-        : { start: nextStart, end: nextEnd }
-    );
-  }, [defaultLineHeight, findLineAtOffset, lineCount, showLineNumbersActive]);
-
-  const totalLineNumberHeight = useMemo(
-    () => (showLineNumbersActive ? getTotalHeight() : 0),
-    [getTotalHeight, showLineNumbersActive]
-  );
-
-  const visibleLineNumbers = useMemo(() => {
-    if (!showLineNumbersActive || visibleRange.end < visibleRange.start) return [];
-    const items: { line: number; top: number; height: number }[] = [];
-    for (let i = visibleRange.start; i <= visibleRange.end; i += 1) {
-      const height = lineHeightsRef.current[i] || defaultLineHeight || 0;
-      items.push({
-        line: i + 1,
-        top: getLineTop(i),
-        height
-      });
-    }
-    return items;
-  }, [
-    defaultLineHeight,
-    getLineTop,
-    lineNumbersVersion,
-    showLineNumbersActive,
-    visibleRange.end,
-    visibleRange.start
-  ]);
-
-  const scheduleUpdateVisibleRange = useCallback(() => {
-    if (scrollRafRef.current) {
-      cancelAnimationFrame(scrollRafRef.current);
-    }
-    scrollRafRef.current = requestAnimationFrame(() => {
-      updateVisibleRange();
-    });
-  }, [updateVisibleRange]);
-
-  const handleTextareaScroll = useCallback(
-    (event: React.UIEvent<HTMLTextAreaElement>) => {
-      if (!showLineNumbersActive) return;
-      if (lineNumbersRef.current) {
-        lineNumbersRef.current.scrollTop = event.currentTarget.scrollTop;
-      }
-      scheduleUpdateVisibleRange();
-    },
-    [scheduleUpdateVisibleRange, showLineNumbersActive]
-  );
+  const handleTextareaScroll = useCallback(() => {}, []);
 
   useEffect(() => {
     if (!showLineNumbersActive) return;