diff --git a/package-lock.json b/package-lock.json
index bdc6ddec..a537e3bc 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -35,6 +35,7 @@
         "sherpa-onnx": "^1.13.2",
         "socket.io-client": "^4.7.5",
         "unified": "^11.0.5",
+        "virtua": "^0.49.3",
         "vue": "^3.4.15",
         "vue-stick-to-bottom": "^1.0.0",
         "xterm": "^5.3.0"
@@ -7463,6 +7464,36 @@
         "url": "https://opencollective.com/unified"
       }
     },
+    "node_modules/virtua": {
+      "version": "0.49.3",
+      "resolved": "https://registry.npmjs.org/virtua/-/virtua-0.49.3.tgz",
+      "integrity": "sha512-k1Yn988Vz/L40uDtEWPjfdVo15Suumh4tU4/z5Srs0elNcU9DgBskqdh3llpHyAlXrCeHWTfcclYvY1uU4MmIg==",
+      "license": "MIT",
+      "peerDependencies": {
+        "react": ">=16.14.0",
+        "react-dom": ">=16.14.0",
+        "solid-js": ">=1.0",
+        "svelte": ">=5.0",
+        "vue": ">=3.2"
+      },
+      "peerDependenciesMeta": {
+        "react": {
+          "optional": true
+        },
+        "react-dom": {
+          "optional": true
+        },
+        "solid-js": {
+          "optional": true
+        },
+        "svelte": {
+          "optional": true
+        },
+        "vue": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/vite": {
       "version": "5.4.21",
       "resolved": "https://registry.npmjs.org/vite/-/vite-5.4.21.tgz",
diff --git a/package.json b/package.json
index 1361df58..89101463 100644
--- a/package.json
+++ b/package.json
@@ -42,6 +42,7 @@
     "sherpa-onnx": "^1.13.2",
     "socket.io-client": "^4.7.5",
     "unified": "^11.0.5",
+    "virtua": "^0.49.3",
     "vue": "^3.4.15",
     "vue-stick-to-bottom": "^1.0.0",
     "xterm": "^5.3.0"
diff --git a/static/src/components/chat/ChatArea.vue b/static/src/components/chat/ChatArea.vue
index 1edb7e89..2cd68160 100644
--- a/static/src/components/chat/ChatArea.vue
+++ b/static/src/components/chat/ChatArea.vue
@@ -5,15 +5,24 @@
     ref="scrollRef"
   >
     <div class="messages-flow" ref="contentRef">
+      <!-- 窗口化渲染：virtua 只挂载可视区+buffer 的消息块，未挂载项按实测高度缓存占位 -->
+      <Virtualizer
+        v-if="stickScrollElement"
+        :data="filteredMessages || []"
+        :scroll-ref="stickScrollElement"
+        :buffer-size="400"
+        :keep-mounted="keepMountedIndexes"
+      >
+        <template #default="{ item: msg, index }">
       <div
-        v-for="(msg, index) in filteredMessages || []"
-        :key="index"
+        :key="getMessageKey(msg, index)"
         class="message-block"
         :class="{
           'message-block--compact-user': getMessageVisibility(msg) === 'compact',
           'message-block--sub-agent-notice': isSubAgentNoticeOnlyMessage(msg),
           'message-block--before-sub-agent-notice': isFollowedBySubAgentNotice(index),
           'message-block--multi-agent': isMultiAgentMessage(msg),
+          'message-block--first': index === 0,
           'message-block--last': index === (filteredMessages || []).length - 1
         }"
       >
@@ -635,18 +644,7 @@
             </template>
           </template>
         </div>
-        <div
-          v-else
-          class="system-message"
-          @vue:mounted="
-            () =>
-              console.log('[ChatArea] 渲染系统消息:', {
-                index,
-                role: msg.role,
-                content: msg.content
-              })
-          "
-        >
+        <div v-else class="system-message">
           <div
             class="collapsible-block system-block"
             :class="{ expanded: expandedBlocks?.has(`system-${index}`) }"
@@ -674,6 +672,8 @@
           </div>
         </div>
       </div>
+        </template>
+      </Virtualizer>
     </div>
     <div class="messages-bottom-spacer" aria-hidden="true"></div>
   </div>
@@ -682,6 +682,7 @@
 <script setup lang="ts">
 import { computed, nextTick, onBeforeUnmount, onMounted, provide, ref, watch } from 'vue';
 import { useStickToBottom } from 'vue-stick-to-bottom';
+import { Virtualizer } from 'virtua/vue';
 import { useBlockExpansionAnchor } from '@/composables/useBlockExpansionAnchor';
 import ToolAction from '@/components/chat/actions/ToolAction.vue';
 import StackedBlocks from './StackedBlocks.vue';
@@ -773,6 +774,16 @@ const registerUserBubbleRef = (msg: any, index: number, el: Element | null) => {
   const key = getUserBubbleKey(msg, index);
   if (el instanceof HTMLElement) {
     userBubbleRefs.set(key, el);
+    // 虚拟列表下气泡随滚动挂载/卸载：挂载时补做观察与高度测量，保证折叠状态正确恢复
+    if (userBubbleResizeObserver) {
+      userBubbleResizeObserver.observe(el);
+    }
+    const state = userBubbleFoldStates.value[key];
+    if (state && state.foldHeight === 0) {
+      requestAnimationFrame(() => {
+        if (el.isConnected) measureUserBubbles();
+      });
+    }
   } else {
     userBubbleRefs.delete(key);
   }
@@ -1128,14 +1139,39 @@ const {
   scrollToBottom,
   stopScroll
 } = useStickToBottom({
-  resize: {
-    damping: 0.5,
-    stiffness: 0.28,
-    mass: 0.75
-  },
+  // 宽度拖拽挤压时不再弹簧追底：逐帧瞬时吸附底部，
+  // 视觉上内容向上生长（底部锚定），消除“变高→追底”的反复计算循环
+  resize: 'instant',
   initial: 'instant'
 });
 
+// —— 虚拟列表支撑 ——
+// 消息对象没有后端 id，这里按对象身份（WeakMap）分配稳定 key，
+// 供 virtua 的逐项高度缓存与列表项复用，避免改动 store / 后端消息结构
+const messageKeyCache = new WeakMap<object, string>();
+let messageKeySeq = 0;
+const getMessageKey = (msg: any, index: number): string => {
+  if (msg && typeof msg === 'object') {
+    let key = messageKeyCache.get(msg as object);
+    if (!key) {
+      const rawId = (msg as any).id;
+      key = rawId != null ? `msg-${String(rawId)}` : `mk-${++messageKeySeq}`;
+      messageKeyCache.set(msg as object, key);
+    }
+    return key;
+  }
+  return `idx-${index}`;
+};
+// Virtualizer 需要显式拿到滚动容器（其直接父元素 .messages-flow 并非滚动容器），
+// 等模板 ref 就绪后再挂载 Virtualizer，确保其内部滚动监听一次到位
+const stickScrollElement = computed<HTMLElement | undefined>(() => scrollRef.value ?? undefined);
+// 流式期间保持最后一条消息常驻，避免用户上翻时流式块反复卸载/重挂载
+const keepMountedIndexes = computed<number[]>(() => {
+  if (!props.streamingMessage) return [];
+  const last = latestMessageIndex.value;
+  return last >= 0 ? [last] : [];
+});
+
 // 公式渲染后如果已经在底部附近，主动追底，避免 KaTeX 渲染导致的高度跳变让 stick-to-bottom 锁不住
 provide('mathRenderedCallback', () => {
   if (isNearBottom.value && stickScrollToBottom) {
@@ -1168,7 +1204,9 @@ let wheelListener: ((event: WheelEvent) => void) | null = null;
 let traceAttachLogged = false;
 
 function isScrollBounceTraceEnabled() {
-  if (typeof window === 'undefined') return true;
+  // 默认关闭滚动追踪日志（逐 scroll 事件的高频日志本身就是性能开销），
+  // 排障时通过 window.__SCROLL_BOUNCE_TRACE__ = true 或 localStorage.scrollBounceTrace = '1' 显式打开
+  if (typeof window === 'undefined') return false;
   try {
     const explicit = (window as any).__SCROLL_BOUNCE_TRACE__;
     if (explicit === false || explicit === '0') return false;
@@ -1176,9 +1214,9 @@ function isScrollBounceTraceEnabled() {
     const localFlag = window.localStorage?.getItem('scrollBounceTrace');
     if (localFlag === '0' || localFlag === 'false') return false;
     if (localFlag === '1' || localFlag === 'true') return true;
-    return true;
+    return false;
   } catch {
-    return true;
+    return false;
   }
 }
 
@@ -1282,15 +1320,20 @@ function attachBounceListener() {
     lastObservedHeight = height;
 
     if (heightDelta !== 0) {
-      console.log('[ChatAreaScrollDebug] height-change', {
-        heightDelta,
-        scrollHeight: height,
-        top,
-        delta,
-        escapedFromLock: escapedFromLock.value,
-        isAtBottom: isAtBottom.value,
-        isNearBottom: isNearBottom.value,
-      });
+      bounceTraceLog(
+        'height-change',
+        {
+          heightDelta,
+          scrollHeight: height,
+          top,
+          delta,
+          escapedFromLock: escapedFromLock.value,
+          isAtBottom: isAtBottom.value,
+          isNearBottom: isNearBottom.value
+        },
+        'height-change',
+        120
+      );
     }
 
     // 大幅高度增长检测：当 scrollHeight 突增（内容大幅展开/渲染），
@@ -1303,15 +1346,20 @@ function attachBounceListener() {
       heightDelta > largeGrowthThreshold &&
       !escapedFromLock.value
     ) {
-      console.log('[ChatAreaScrollDebug] TRIGGER:large-growth-scroll', {
-        heightDelta,
-        threshold: largeGrowthThreshold,
-        top,
-        delta,
-        escapedFromLock: escapedFromLock.value,
-        isAtBottom: isAtBottom.value,
-        isNearBottom: isNearBottom.value,
-      });
+      bounceTraceLog(
+        'large-growth:trigger',
+        {
+          heightDelta,
+          threshold: largeGrowthThreshold,
+          top,
+          delta,
+          escapedFromLock: escapedFromLock.value,
+          isAtBottom: isAtBottom.value,
+          isNearBottom: isNearBottom.value
+        },
+        'large-growth:trigger',
+        0
+      );
       isHandlingLargeGrowth = true;
       markProgrammaticHint('ChatArea.largeGrowth');
       suppressUserIntentUntil = Date.now() + 900;
@@ -1408,7 +1456,7 @@ function attachBounceListener() {
     }
   };
   el.addEventListener('scroll', scrollListener, { passive: true });
-  if (!traceAttachLogged) {
+  if (!traceAttachLogged && isScrollBounceTraceEnabled()) {
     traceAttachLogged = true;
     console.warn('[SCROLL_BOUNCE_TRACE]', 'listener-attached', {
       hasElement: !!el,
@@ -1550,15 +1598,6 @@ async function stickScrollToBottom(
 ) {
   const el = scrollRef.value;
   if (el) {
-    console.log('[ChatAreaScrollDebug] CALL:stickScrollToBottom', {
-      behavior: options.behavior || 'auto',
-      force: !!options.force,
-      preserveScrollPosition: !!options.preserveScrollPosition,
-      isAtBottom: isAtBottom.value,
-      isNearBottom: isNearBottom.value,
-      escapedFromLock: escapedFromLock.value,
-      ...getScrollMetrics(el),
-    });
     bounceTraceLog(
       'programmatic:scrollToBottom:before',
       {
@@ -1999,9 +2038,11 @@ onMounted(() => {
     });
     nextTick(() => observeUserBubbles());
   }
-  console.warn('[SCROLL_BOUNCE_TRACE]', 'mounted', {
-    hasScrollRef: !!scrollRef.value
-  });
+  if (isScrollBounceTraceEnabled()) {
+    console.warn('[SCROLL_BOUNCE_TRACE]', 'mounted', {
+      hasScrollRef: !!scrollRef.value
+    });
+  }
   timerHandle = window.setInterval(() => {
     nowMs.value = Date.now();
   }, 1000);
diff --git a/static/src/styles/components/chat/_chat-area.scss b/static/src/styles/components/chat/_chat-area.scss
index f6de49d1..90300228 100644
--- a/static/src/styles/components/chat/_chat-area.scss
+++ b/static/src/styles/components/chat/_chat-area.scss
@@ -122,7 +122,8 @@
   contain: layout style;
 }
 
-.messages-flow > .message-block.message-block--last {
+/* 窗口化后 message-block 外层有 virtua 列表项包装，不再是 messages-flow 直接子元素，改用后代选择器 */
+.messages-flow .message-block--last {
   margin-bottom: 0;
 }
 
@@ -214,7 +215,8 @@
     padding-right: 12px !important;
   }
 
-  .message-block:first-child {
+  /* 窗口化后每个 message-block 都是包装项的首子，:first-child 会匹配所有块，改用显式 class */
+  .message-block--first {
     margin-top: 0;
   }