diff --git a/web/charts.js b/web/charts.js
index d7d2edd..df763d7 100644
--- a/web/charts.js
+++ b/web/charts.js
@@ -42,6 +42,10 @@ let lwcVolumeSeries = null;
 let lwcResizeObserver = null;
 let lwcPriceLines = [];
 const symbolPriceMeta = new Map();
+let lwcModalCandles = [];
+let lwcModalInterval = "1d";
+let lwcModalPriceMeta = { tick_size: "0.01", price_precision: 2 };
+let lwcOnVisibleRangeChange = null;
 
 function cacheKey(symbol, interval) {
   return `${symbol}:${interval}`;
@@ -144,6 +148,38 @@ function findCandleExtremes(candles, interval) {
   return { maxHigh, minLow, highTime, lowTime };
 }
 
+function candlesInLogicalRange(candles, range) {
+  if (!range || !candles.length) return candles;
+  const from = Math.max(0, Math.floor(range.from));
+  const to = Math.min(candles.length - 1, Math.ceil(range.to));
+  if (from > to) return [];
+  return candles.slice(from, to + 1);
+}
+
+function updateHighLowForVisibleWindow() {
+  if (!lwcChart || !lwcCandleSeries || !lwcModalCandles.length) return;
+  const range = lwcChart.timeScale().getVisibleLogicalRange();
+  const visible = candlesInLogicalRange(lwcModalCandles, range);
+  const subset = visible.length ? visible : lwcModalCandles;
+  applyHighLowAnnotations(subset, lwcModalInterval, lwcModalPriceMeta);
+}
+
+function bindVisibleRangeHighLow() {
+  if (!lwcChart) return;
+  unbindVisibleRangeHighLow();
+  lwcOnVisibleRangeChange = () => {
+    updateHighLowForVisibleWindow();
+  };
+  lwcChart.timeScale().subscribeVisibleLogicalRangeChange(lwcOnVisibleRangeChange);
+}
+
+function unbindVisibleRangeHighLow() {
+  if (lwcChart && lwcOnVisibleRangeChange) {
+    lwcChart.timeScale().unsubscribeVisibleLogicalRangeChange(lwcOnVisibleRangeChange);
+  }
+  lwcOnVisibleRangeChange = null;
+}
+
 function toLwcTime(ms, interval) {
   if (interval === "1d" || interval === "1w") {
     const d = new Date(ms);
@@ -374,7 +410,9 @@ async function loadMiniChart(box) {
 }
 
 function destroyLwcChart() {
+  unbindVisibleRangeHighLow();
   clearHighLowAnnotations();
+  lwcModalCandles = [];
   if (lwcResizeObserver) {
     lwcResizeObserver.disconnect();
     lwcResizeObserver = null;
@@ -523,6 +561,8 @@ function ensureLwcChart(container) {
   });
   lwcResizeObserver.observe(container);
 
+  bindVisibleRangeHighLow();
+
   return lwcChart;
 }
 
@@ -536,11 +576,15 @@ function renderLwcChart(candles, interval, priceMeta) {
   const meta = getPriceMeta(chartModalSymbol, priceMeta);
   applySeriesPriceFormat(meta);
 
+  lwcModalCandles = candles;
+  lwcModalInterval = interval;
+  lwcModalPriceMeta = meta;
+
   const { ohlc, vol } = candlesToLwc(candles, interval);
   lwcCandleSeries.setData(ohlc);
   lwcVolumeSeries.setData(vol);
-  applyHighLowAnnotations(candles, interval, meta);
   lwcChart.timeScale().fitContent();
+  requestAnimationFrame(() => updateHighLowForVisibleWindow());
 }
 
 function updateIntervalTabs() {
@@ -556,7 +600,7 @@ function updateModalMeta(candles, source, interval) {
     title.textContent = `${chartModalSymbol} · ${interval.toUpperCase()} K线`;
   }
   if (hint) {
-    hint.textContent = `${candles.length} 根 · ${sourceLabel(source)} · 滚轮缩放 · 拖拽平移 · 十字线 · Esc 或点击遮罩关闭`;
+    hint.textContent = `${candles.length} 根 · ${sourceLabel(source)} · 最高/最低随可见窗口 · 滚轮缩放 · Esc 关闭`;
   }
 }