diff --git a/ui/src/conversation-panel/components/content/items/group-tool/index.vue b/ui/src/conversation-panel/components/content/items/group-tool/index.vue
index e5832420d06..c0963e7b9f5 100644
--- a/ui/src/conversation-panel/components/content/items/group-tool/index.vue
+++ b/ui/src/conversation-panel/components/content/items/group-tool/index.vue
@@ -39,7 +39,7 @@ function resolveToolRenderer(toolName: unknown): Component | undefined {
   return toolRenderers[String(toolName || '').toLowerCase()]
 }
 
-// 组内专用渲染器的展开状态：执行中默认展开，结束后默认收起，手动切换后以手动为准
+// 组内专用渲染器的展开状态：默认收起（执行中也是），手动切换后以手动为准
 const manualToolExpanded = ref<Dict<boolean>>({})
 
 function toolKey(toolItem: ChatContent, index: number) {
@@ -47,14 +47,14 @@ function toolKey(toolItem: ChatContent, index: number) {
 }
 
 function isToolExpanded(toolItem: ChatContent, index: number) {
-  return manualToolExpanded.value[toolKey(toolItem, index)] ?? toolItem.status === 'RUNNING'
+  return manualToolExpanded.value[toolKey(toolItem, index)] ?? false
 }
 
 function toggleTool(toolItem: ChatContent, index: number) {
   manualToolExpanded.value[toolKey(toolItem, index)] = !isToolExpanded(toolItem, index)
 }
 
-// 汇总执行状态；分组和工具的手动展开状态优先于默认状态。
+// 汇总执行状态；分组默认收起，手动切换后以手动为准。
 const groupStatus = computed(() => {
   const childStatuses = toolItems.value.map((toolItem) => toolItem.status)
   if (childStatuses.includes('RUNNING')) return 'running'
@@ -62,11 +62,7 @@ const groupStatus = computed(() => {
   return childStatuses.length ? 'success' : ''
 })
 
-const manualExpanded = ref<boolean>()
-const isExpanded = computed({
-  get: () => manualExpanded.value ?? groupStatus.value === 'running',
-  set: (value: boolean) => (manualExpanded.value = value),
-})
+const isExpanded = ref(false)
 </script>
 
 <template>
diff --git a/ui/src/conversation-panel/components/content/items/group/index.vue b/ui/src/conversation-panel/components/content/items/group/index.vue
index 913f06f5fdc..dca16b4fb53 100644
--- a/ui/src/conversation-panel/components/content/items/group/index.vue
+++ b/ui/src/conversation-panel/components/content/items/group/index.vue
@@ -1,12 +1,13 @@
 <script setup lang="ts">
-import { computed, ref } from 'vue'
+import { computed, ref, useTemplateRef } from 'vue'
 import type { ChatContent } from '@/api/types'
 import ContentList from '@/conversation-panel/components/content-list/index.vue'
+import { useBottomFollow } from '@/conversation-panel/core/bottom-follow'
 
 /**
  * 通用分组：content.name 为标题，content.status 可选（不传不显示状态），
  * content.children 为任意内容项（可再嵌套 GROUP），交由 ContentList 渲染。
- * 执行中或无状态时默认展开，结束后默认收起，手动切换后以手动为准；收起时展示最新一条子项在做什么。
+ * 默认收起（执行中也是），手动切换后以手动为准。
  */
 defineOptions({ name: 'ConversationGroupContent' })
 
@@ -31,11 +32,10 @@ const statusType = computed(() => {
 
 const isFailed = computed(() => props.content.status === 'FAIL' || props.content.status === 'FAILURE')
 
-const manualExpanded = ref<boolean>()
-const isExpanded = computed({
-  get: () => manualExpanded.value ?? (!props.content.status || props.content.status === 'RUNNING'),
-  set: (value: boolean) => (manualExpanded.value = value),
-})
+const isExpanded = ref(false)
+
+// 分组内容限高滚动，高度与新建文件的差异区一致；子项流式更新时跟随到底部
+useBottomFollow(useTemplateRef<HTMLElement>('groupScrollRef'))
 
 function tail(text: string) {
   const trimmed = text.trim()
@@ -82,7 +82,7 @@ const currentActivity = computed(() => {
       <el-tag v-if="isFailed" size="small" :type="statusType">{{ statusText }}</el-tag>
     </template>
 
-    <div v-if="isExpanded && childContents.length" class="mt-1 border-l-2 border-N900/15 pl-3">
+    <div v-if="isExpanded && childContents.length" ref="groupScrollRef" class="mt-1 max-h-[400px] overflow-y-auto border-l-2 border-N900/15 pl-3">
       <ContentList :content-list="childContents" />
     </div>
   </MkCollapse>
diff --git a/ui/src/conversation-panel/components/content/items/reasoning.vue b/ui/src/conversation-panel/components/content/items/reasoning.vue
index 7a38d15a605..650f262c768 100644
--- a/ui/src/conversation-panel/components/content/items/reasoning.vue
+++ b/ui/src/conversation-panel/components/content/items/reasoning.vue
@@ -1,21 +1,15 @@
 <script setup lang="ts">
-import { ref, watch } from 'vue'
+import { ref, useTemplateRef } from 'vue'
+import { useBottomFollow } from '@/conversation-panel/core/bottom-follow'
 
 defineOptions({ name: 'ConversationReasoningContent' })
 
-const props = defineProps<{ content: { content?: string | null; status?: string } }>()
-const isExpanded = ref(true)
-let prevStatus = props.content.status
+defineProps<{ content: { content?: string | null; status?: string } }>()
+// 默认收起，思考中也只显示状态文案，手动展开后查看内容
+const isExpanded = ref(false)
 
-watch(
-  () => props.content.status,
-  (status) => {
-    if (prevStatus === 'RUNNING' && status !== 'RUNNING') {
-      isExpanded.value = false
-    }
-    prevStatus = status
-  },
-)
+// 思考内容限高滚动，高度与新建文件的差异区一致；流式输出时跟随到底部
+useBottomFollow(useTemplateRef<HTMLElement>('reasoningScrollRef'))
 </script>
 
 <template>
@@ -35,7 +29,7 @@ watch(
         {{ content.status === 'RUNNING' ? '思考中' : '思考完成' }}
       </span>
     </template>
-    <div class="text-N500! whitespace-pre-wrap break-words">
+    <div ref="reasoningScrollRef" class="max-h-[400px] overflow-y-auto text-N500! whitespace-pre-wrap break-words">
       {{ content.content }}
     </div>
   </MkCollapse>
diff --git a/ui/src/conversation-panel/components/content/items/tool/index.vue b/ui/src/conversation-panel/components/content/items/tool/index.vue
index aaaed43ae09..4bb90bb1a44 100644
--- a/ui/src/conversation-panel/components/content/items/tool/index.vue
+++ b/ui/src/conversation-panel/components/content/items/tool/index.vue
@@ -19,7 +19,7 @@ const props = defineProps<{ content: ChatContent }>()
 
 // 工具执行状态与展开状态。
 const loading = computed(() => props.content.status === 'RUNNING')
-const isExpanded = ref(props.content.status === 'RUNNING')
+const isExpanded = ref(false)
 
 // 工具执行完成自动收起
 watch(loading, (current, previous) => {
diff --git a/ui/src/conversation-panel/core/bottom-follow.ts b/ui/src/conversation-panel/core/bottom-follow.ts
new file mode 100644
index 00000000000..699b1977d34
--- /dev/null
+++ b/ui/src/conversation-panel/core/bottom-follow.ts
@@ -0,0 +1,34 @@
+import { onBeforeUnmount, watch, type Ref } from 'vue'
+import { Scroll } from './scroll'
+
+/**
+ * 限高滚动容器的底部跟随：容器挂载后定位到底部，内容变化时仅在用户仍位于底部附近才跟随。
+ * 容器随展开 / 收起挂载和卸载，跟随实例与内容监听随之创建和释放。
+ */
+export function useBottomFollow(containerRef: Ref<HTMLElement | null | undefined>) {
+  let scroll: Scroll | undefined
+  let observer: MutationObserver | undefined
+
+  function release() {
+    observer?.disconnect()
+    observer = undefined
+    scroll?.destroy()
+    scroll = undefined
+  }
+
+  watch(
+    containerRef,
+    (container) => {
+      release()
+      if (!container) return
+      const follow = new Scroll(container)
+      scroll = follow
+      follow.forceBottom()
+      observer = new MutationObserver(() => follow.scrollBottom())
+      observer.observe(container, { childList: true, subtree: true, characterData: true })
+    },
+    { flush: 'post', immediate: true },
+  )
+
+  onBeforeUnmount(release)
+}