diff --git a/static/src/components/chat/ChatArea.vue b/static/src/components/chat/ChatArea.vue
index 895d187..f0281ad 100644
--- a/static/src/components/chat/ChatArea.vue
+++ b/static/src/components/chat/ChatArea.vue
@@ -117,6 +117,8 @@
                 class="stacked-blocks-wrapper"
                 :actions="group.actions"
                 :expanded-blocks="expandedBlocks"
+                :conversation-running="streamingMessage"
+                :is-latest-message="index === latestMessageIndex"
                 :icon-style="iconStyleSafe"
                 :toggle-block="toggleBlock"
                 :register-thinking-ref="registerThinkingRef"
@@ -1535,20 +1537,15 @@ const splitActionGroups = (actions: any[] = [], messageIndex = 0) => {
   }
 
   const flushBuffer = () => {
-    if (buffer.length >= 2) {
+    // 单个可堆叠块(thinking/tool)也走 stack 路径，避免 1↔2 块时在 single/stack
+    // 两套渲染路径之间整体切换导致 StackedBlocks 重新挂载(表现为外框瞬间塌成最扁再展开)。
+    // 单块时 StackedBlocks 内部 moreVisible=false，不显示「更多」头，外观由 CSS 对齐 single。
+    if (buffer.length >= 1) {
       result.push({
         kind: 'stack',
         actions: buffer.slice(),
         key: `stack-${messageIndex}-${result.length}`
       });
-    } else if (buffer.length === 1) {
-      const single = buffer[0];
-      result.push({
-        kind: 'single',
-        action: single,
-        actionIndex: actions.indexOf(single),
-        key: single.id || `single-${messageIndex}-${result.length}`
-      });
     }
     buffer = [];
   };
diff --git a/static/src/components/chat/StackedBlocks.vue b/static/src/components/chat/StackedBlocks.vue
index 8912eb7..8d04f29 100644
--- a/static/src/components/chat/StackedBlocks.vue
+++ b/static/src/components/chat/StackedBlocks.vue
@@ -1,6 +1,7 @@
 <template>
   <div
     class="stacked-shell"
+    :class="{ 'stacked-shell--single': isSingle, 'stacked-shell--not-ready': !ready }"
     ref="shell"
     :style="{
       height: `${shellHeight}px`,
@@ -28,7 +29,8 @@
         class="stacked-inner"
         ref="inner"
         :style="{ transform: `translateY(${innerOffset}px)` }"
-        appear
+        :appear="animated"
+        :css="animated"
       >
         <div
           v-for="(action, idx) in stackableActions"
@@ -158,6 +160,8 @@ defineOptions({ name: 'StackedBlocks' });
 const props = defineProps<{
   actions: any[];
   expandedBlocks: Set<string>;
+  conversationRunning?: boolean;
+  isLatestMessage?: boolean;
   iconStyle: (key: string, size?: string) => Record<string, string>;
   toggleBlock: (blockId: string) => void;
   registerThinkingRef?: (key: string, el: Element | null) => void;
@@ -198,13 +202,13 @@ const shellHeight = ref(0);
 const moreHeight = ref(0);
 const innerOffset = ref(0);
 const viewportHeight = ref(0);
+// 首帧就绪标志：false 时禁用高度过渡（初始挂载/批量加载直接到位），首次 measure 后置 true。
+const ready = ref(false);
 const contentHeights = ref<Record<string, number>>({});
-const ANIMATION_SYNC_MS = 360;
-const MORE_ANIMATION_MS = 300;
 const COLLAPSE_MAX_HEIGHT = 600;
-let syncRaf: number | null = null;
-let syncUntil = 0;
-const isMoreAnimating = ref(false);
+const HEADER_FALLBACK = 36; // 仅在 DOM 未挂载、读不到 header 时兜底
+// content-inner 真实 DOM 引用，用于读取稳定的内容高度（不受 max-height 过渡影响）
+const contentInnerEls = new Map<string, HTMLElement>();
 
 const stackableActions = computed(() =>
   (props.actions || []).filter((item) => item && (item.type === 'thinking' || item.type === 'tool'))
@@ -212,6 +216,14 @@ const stackableActions = computed(() =>
 
 const hiddenCount = computed(() => Math.max(0, stackableActions.value.length - VISIBLE_LIMIT));
 const moreVisible = computed(() => hiddenCount.value > 0 || showAll.value);
+// 单块场景：外观需与原 single 路径(.collapsible-block 12px 圆角/透明底)一致，
+// 由 .stacked-shell--single 还原，避免「单块也走堆叠组件」后单块外观变样。
+const isSingle = computed(() => stackableActions.value.length === 1);
+
+// 是否播放进场动画：仅「对话运行中 + 当前是最新消息」时播（新块逐个平滑进场）。
+// 历史加载 / 对话重建 / 非最新消息：禁用 appear + enter 动画，块瞬间出现，
+// 避免一次性挂载多个块时整个对话区剧烈高度跳动。
+const animated = computed(() => !!props.conversationRunning && !!props.isLatestMessage);
 const totalSteps = computed(() => stackableActions.value.length);
 const moreTitle = computed(() => (showAll.value ? '已展开全部' : '更多'));
 const moreDesc = computed(() =>
@@ -235,17 +247,24 @@ const isToolProcessing = (action: any) => {
 const isToolCompleted = (action: any) => action?.tool?.status === 'completed';
 
 const toggleMore = () => {
-  animateMoreToggle(!showAll.value);
+  showAll.value = !showAll.value;
+  scheduleMeasure();
 };
 
 const toggleBlock = (blockId: string) => {
   if (typeof props.toggleBlock === 'function') {
     props.toggleBlock(blockId);
-    nextTick(() => runSync());
+    scheduleMeasure();
   }
 };
 
 const registerThinking = (key: string, el: Element | null) => {
+  // 记录 content-inner 真实引用用于高度测量，同时透传给上层（思考块自动滚动）
+  if (el instanceof HTMLElement) {
+    contentInnerEls.set(key, el);
+  } else {
+    contentInnerEls.delete(key);
+  }
   if (typeof props.registerThinkingRef === 'function') {
     props.registerThinkingRef(key, el);
   }
@@ -271,27 +290,38 @@ const moreBaseHeight = () => {
   return Math.max(48, Math.ceil(label?.getBoundingClientRect().height || 56));
 };
 
-const setShellMetrics = () => {
+// 核心：测真实 DOM 的稳定值算每块高度，再算 shell/offset/viewport。
+// 关键稳定性保证：
+//  - header.offsetHeight：表头固定高(min/max-height:36)，展开/折叠都不变；
+//  - content-inner.offsetHeight：内容自然高度，即使父级 collapsible-content 的 max-height
+//    正在 0↔目标 过渡（被 overflow:hidden 裁切），content-inner 自身 offsetHeight 仍是
+//    稳定的完整值（裁切不影响子级布局高度）。
+// 因此任何时刻读到的都是「目标态」高度，不是动画中间帧 → 写入 shellHeight/innerOffset 后由
+// CSS transition 平滑（外框增高 / 传送带上移 / 展开收起），绝不抖动。
+const measureAndCompute = () => {
   const innerEl = resolveEl(inner.value);
   const shellEl = resolveEl(shell.value);
   if (!shellEl || !innerEl) return;
 
   const children = Array.from(innerEl.children) as HTMLElement[];
+  const acts = stackableActions.value;
   const heights: number[] = [];
   const nextContentHeights: Record<string, number> = {};
 
   children.forEach((el, idx) => {
-    const action = stackableActions.value[idx];
+    const action = acts[idx];
     const key = blockKey(action, idx);
-    const content = el.querySelector('.collapsible-content') as HTMLElement | null;
-    const contentHeight = content
-      ? Math.min(Math.ceil(content.scrollHeight), COLLAPSE_MAX_HEIGHT)
-      : 0;
-    nextContentHeights[key] = contentHeight;
-
-    // 使用当前真实高度而非「展开/折叠」状态推导值，避免在折叠动画过程中出现高度骤减导致的闪烁
-    const liveHeight = Math.ceil(el.getBoundingClientRect().height || el.offsetHeight || 0);
-    heights.push(liveHeight);
+    const header = el.querySelector('.collapsible-header') as HTMLElement | null;
+    const innerC = el.querySelector('.content-inner') as HTMLElement | null;
+    const headerH = header ? Math.ceil(header.offsetHeight) : HEADER_FALLBACK;
+    // 展开后内容可见高度（封顶 600）；content-inner 自身高度稳定（思考块被自己的
+    // max-height:240 限制，工具块为内容自然高），不受 collapsible-content 过渡影响。
+    const fullContent = innerC ? Math.min(Math.ceil(innerC.offsetHeight), COLLAPSE_MAX_HEIGHT) : 0;
+    nextContentHeights[key] = fullContent;
+    const expanded = isExpandedById(key);
+    // .stacked-item 之间 1px 分隔（最后一个无 border-bottom）
+    const borderH = idx === children.length - 1 ? 0 : 1;
+    heights.push(headerH + (expanded ? fullContent : 0) + borderH);
   });
 
   contentHeights.value = nextContentHeights;
@@ -302,123 +332,48 @@ const setShellMetrics = () => {
   const windowHeight = sum(heights.slice(-VISIBLE_LIMIT));
 
   moreHeight.value = moreVisible.value ? moreBaseHeight() : 0;
-
   const targetShell =
     moreHeight.value + (showAll.value || !moreVisible.value ? totalHeight : windowHeight);
-  const targetOffset = showAll.value || !moreVisible.value ? 0 : -hiddenHeight;
-
   shellHeight.value = targetShell;
-  innerOffset.value = targetOffset;
+  innerOffset.value = showAll.value || !moreVisible.value ? 0 : -hiddenHeight;
   viewportHeight.value = Math.max(0, targetShell - moreHeight.value);
 };
 
-const lerp = (a: number, b: number, t: number) => a + (b - a) * t;
-const easeOutCubic = (t: number) => 1 - Math.pow(1 - t, 3);
-
-const animateMoreToggle = (nextShowAll: boolean) => {
-  if (isMoreAnimating.value) return;
-
-  // 停掉其他同步，避免冲突
-  if (syncRaf) {
-    cancelAnimationFrame(syncRaf);
-    syncRaf = null;
-  }
-
-  const innerEl = resolveEl(inner.value);
-  const shellEl = resolveEl(shell.value);
-  if (!innerEl || !shellEl) {
-    showAll.value = nextShowAll;
-    nextTick(() => runSync());
-    return;
-  }
-
-  // 先计算当前状态
-  setShellMetrics();
-  const start = {
-    shell: shellHeight.value,
-    offset: innerOffset.value,
-    viewport: viewportHeight.value,
-    more: moreHeight.value
-  };
-
-  // 切换到目标状态并计算目标值
-  showAll.value = nextShowAll;
-  setShellMetrics();
-  const target = {
-    shell: shellHeight.value,
-    offset: innerOffset.value,
-    viewport: viewportHeight.value,
-    more: moreHeight.value
-  };
-
-  // 回到起点数值，准备动画
-  shellHeight.value = start.shell;
-  innerOffset.value = start.offset;
-  viewportHeight.value = start.viewport;
-  moreHeight.value = start.more;
-
-  isMoreAnimating.value = true;
-  const startedAt = performance.now();
-
-  const step = () => {
-    const now = performance.now();
-    const t = Math.min(1, (now - startedAt) / MORE_ANIMATION_MS);
-    const eased = easeOutCubic(t);
-
-    shellHeight.value = lerp(start.shell, target.shell, eased);
-    innerOffset.value = lerp(start.offset, target.offset, eased);
-    viewportHeight.value = lerp(start.viewport, target.viewport, eased);
-    moreHeight.value = lerp(start.more, target.more, eased);
-
-    if (t < 1) {
-      requestAnimationFrame(step);
-    } else {
-      isMoreAnimating.value = false;
-      shellHeight.value = target.shell;
-      innerOffset.value = target.offset;
-      viewportHeight.value = target.viewport;
-      moreHeight.value = target.more;
-      setShellMetrics();
-    }
-  };
-
-  requestAnimationFrame(step);
-};
-
-const runSync = () => {
-  if (isMoreAnimating.value) return;
-  if (syncRaf) {
-    cancelAnimationFrame(syncRaf);
-    syncRaf = null;
-  }
-  syncUntil = performance.now() + ANIMATION_SYNC_MS;
-  const step = () => {
-    setShellMetrics();
-    if (performance.now() < syncUntil) {
-      syncRaf = requestAnimationFrame(step);
-    } else {
-      syncRaf = null;
-    }
-  };
-  syncRaf = requestAnimationFrame(step);
+// 等 DOM 渲染稳定后测量一次（双帧：Vue patch + 浏览器布局完成后再读 offsetHeight）。
+const scheduleMeasure = () => {
+  nextTick(() => {
+    requestAnimationFrame(() => {
+      measureAndCompute();
+      // 首次测量、高度直接到位后，再下一帧启用过渡；此后展开/收起/增长等变化才平滑，
+      // 而初始挂载/批量加载不会从 0 高度过渡跳动。
+      if (!ready.value) {
+        requestAnimationFrame(() => {
+          ready.value = true;
+        });
+      }
+    });
+  });
 };
 
 let resizeObserver: ResizeObserver | null = null;
-let heightRaf: number | null = null;
+let roRaf: number | null = null;
+
+const observeAll = () => {
+  if (!resizeObserver) return;
+  resizeObserver.disconnect();
+  // 只观察 content-inner（内容自然高度，流式增长会变）。不观察 collapsible-content /
+  // stacked-inner 等被 transition 的元素，避免「写 → 触发 RO → 再写」的回环抖动。
+  contentInnerEls.forEach((el) => resizeObserver!.observe(el));
+};
 
 onMounted(() => {
-  const innerEl = resolveEl(inner.value);
-  setShellMetrics();
-  resizeObserver = new ResizeObserver(() => {
-    if (heightRaf) {
-      cancelAnimationFrame(heightRaf);
-    }
-    heightRaf = requestAnimationFrame(() => {
-      setShellMetrics();
+  scheduleMeasure();
+  if (typeof ResizeObserver !== 'undefined') {
+    resizeObserver = new ResizeObserver(() => {
+      if (roRaf) cancelAnimationFrame(roRaf);
+      roRaf = requestAnimationFrame(() => measureAndCompute());
     });
-  });
-  if (innerEl) {
-    resizeObserver.observe(innerEl);
+    nextTick(() => observeAll());
   }
 });
 
@@ -427,24 +382,82 @@ onBeforeUnmount(() => {
     resizeObserver.disconnect();
     resizeObserver = null;
   }
-  if (heightRaf) {
-    cancelAnimationFrame(heightRaf);
-    heightRaf = null;
+  if (roRaf) {
+    cancelAnimationFrame(roRaf);
+    roRaf = null;
   }
-  if (syncRaf) {
-    cancelAnimationFrame(syncRaf);
-    syncRaf = null;
-  }
-});
-
-watch([stackableActions, moreVisible], () => {
-  nextTick(() => runSync());
 });
 
 watch(
-  () => (props.expandedBlocks ? props.expandedBlocks.size : 0),
   () => {
-    nextTick(() => runSync());
+    const acts = stackableActions.value;
+    const firstId = acts[0]?.blockId || acts[0]?.id || '';
+    const lastId = acts[acts.length - 1]?.blockId || acts[acts.length - 1]?.id || '';
+    // 指纹：块数 + 首尾 + moreVisible + 每块内部状态/内容长度桶（追踪流式增长），
+    // 比直接 watch 数组引用更精准，避免父组件重渲染传新引用导致的过度触发。
+    const snap = acts
+      .map((a: any) => {
+        if (a?.type === 'tool') return `T:${a?.tool?.status || '?'}${a?.tool?.result ? 'R' : '-'}`;
+        if (a?.type === 'thinking')
+          return `H:${a?.streaming ? 'S' : '-'}${Math.floor((a?.content?.length || 0) / 48)}`;
+        return '?';
+      })
+      .join(',');
+    return `${acts.length}|${firstId}|${lastId}|${moreVisible.value}|${snap}`;
+  },
+  () => {
+    nextTick(() => {
+      observeAll();
+      scheduleMeasure();
+    });
   }
 );
+
+watch(
+  () => (props.expandedBlocks ? props.expandedBlocks.size : 0),
+  () => scheduleMeasure()
+);
 </script>
+
+<style scoped>
+/* 重构核心：shell 高度、viewport 高度、inner 位移三者用同一条 transition，使「外框增高」
+   「内部显示区裁切边界」「传送带上移/展开收起」完全同步过渡，时长/缓动与单块
+   collapsible-content(max-height 260ms) 对齐，互不打架。
+   替换了原先 JS 逐帧 lerp(animateMoreToggle) + 360ms runSync 轮询的方案，从根上去抖。
+   注意：viewport(显示区) 必须与 shell 同步过渡，否则收起瞬间 viewport 高度先跳到折叠后
+   终值，把还在收缩的下方块瞬间裁掉再重现，造成割裂。 */
+.stacked-shell {
+  transition:
+    height 260ms cubic-bezier(0.4, 0, 0.2, 1),
+    padding-top 260ms cubic-bezier(0.4, 0, 0.2, 1);
+  will-change: height;
+}
+.stacked-viewport {
+  transition: height 260ms cubic-bezier(0.4, 0, 0.2, 1);
+  will-change: height;
+}
+.stacked-inner {
+  transition: transform 260ms cubic-bezier(0.4, 0, 0.2, 1);
+  will-change: transform;
+}
+/* 首帧未就绪（ready=false）：禁用 shell/viewport/inner 的高度/位移过渡，让初始挂载 /
+   批量历史加载时高度直接到位，避免从 0 高度过渡造成整个对话区剧烈跳动。
+   首次 measure 完成后置 ready=true，此后展开/收起、流式增长、传送带等高度变化均平滑——
+   注意：展开/收起是用户主动交互，历史对话里也必须平滑，故用 ready(一次性) 而非 animated 控制。
+   块的 enter/appear 进场动画另由模板 :css/:appear="animated" 控制（仅运行中+最新才播）。
+   同时禁用内部 collapsible-content 的 max-height/opacity 过渡，否则历史加载时已展开块的
+   内容会从 opacity:0 淡入(表现为内部文字仍有动画)。 */
+.stacked-shell--not-ready,
+.stacked-shell--not-ready .stacked-viewport,
+.stacked-shell--not-ready .stacked-inner,
+.stacked-shell--not-ready .collapsible-content {
+  transition: none !important;
+}
+/* 单块场景：还原原 single 路径(.collapsible-block)的外观——12px 圆角 + 透明底，
+   而非多块外壳的 16px 圆角 + card 底。其余(1px 边框)两者本就一致。
+   这样「单块也走堆叠组件」后，单块视觉与改造前完全相同。 */
+.stacked-shell--single {
+  border-radius: 12px;
+  background: transparent;
+}
+</style>