diff --git a/static/src/app/methods/history.ts b/static/src/app/methods/history.ts
index e5c0d88..46fbf4c 100644
--- a/static/src/app/methods/history.ts
+++ b/static/src/app/methods/history.ts
@@ -26,6 +26,18 @@ function parseSystemNoticeLabel(rawContent: any): string | null {
   return parseSubAgentDoneLabel(rawContent) || parseBackgroundRunCommandDoneLabel(rawContent);
 }
 
+function isSystemAutoUserMessageMeta(meta: any): boolean {
+  if (!meta || typeof meta !== 'object') {
+    return false;
+  }
+  return !!(
+    meta.is_auto_generated ||
+    meta.auto_message_type ||
+    meta.sub_agent_notice ||
+    meta.background_command_notice
+  );
+}
+
 export const historyMethods = {
   // ==========================================
   // 关键功能：获取并显示历史对话内容
@@ -199,6 +211,14 @@ export const historyMethods = {
         debugLog('跳过系统代发的图片/视频消息（仅用于模型查看，不在前端展示）');
         return;
       }
+      if (message.role === 'user' && isSystemAutoUserMessageMeta(meta)) {
+        debugLog('跳过系统自动代发的 user 消息（前端不渲染）', {
+          auto_message_type: meta.auto_message_type || null,
+          sub_agent_notice: !!meta.sub_agent_notice,
+          background_command_notice: !!meta.background_command_notice
+        });
+        return;
+      }
 
       if (message.role === 'user') {
         // 用户消息 - 先结束之前的assistant消息
diff --git a/static/src/app/methods/taskPolling.ts b/static/src/app/methods/taskPolling.ts
index 78bbac1..5fc9fbe 100644
--- a/static/src/app/methods/taskPolling.ts
+++ b/static/src/app/methods/taskPolling.ts
@@ -10,12 +10,60 @@ const keyNotifyLog = (...args: any[]) => {
 const jsonDebug = (...args: any[]) => {
   console.log('[JSONDEBUG]', ...args);
 };
+const userMDebug = (...args: any[]) => {
+  console.log('[USERMDEBUG]', ...args);
+};
+
+function isSystemAutoUserMessagePayload(data: any): boolean {
+  if (!data || typeof data !== 'object') {
+    return false;
+  }
+  const meta = data.metadata || {};
+  return !!(
+    data.is_auto_generated ||
+    meta.is_auto_generated ||
+    data.auto_message_type ||
+    meta.auto_message_type ||
+    data.sub_agent_notice ||
+    meta.sub_agent_notice ||
+    data.background_command_notice ||
+    meta.background_command_notice
+  );
+}
+
+function isEmptyAssistantPlaceholderMessage(message: any): boolean {
+  if (!message || message.role !== 'assistant') {
+    return false;
+  }
+  const actions = Array.isArray(message.actions) ? message.actions : [];
+  return actions.length === 0 && !!message.awaitingFirstContent;
+}
 
 /**
  * 任务轮询事件处理器
  * 将从 REST API 轮询获取的事件转换为前端状态更新
  */
 export const taskPollingMethods = {
+  cleanupTrailingEmptyAssistantPlaceholder(reason = 'unspecified') {
+    if (!Array.isArray(this.messages) || !this.messages.length) {
+      return false;
+    }
+    const last = this.messages[this.messages.length - 1];
+    if (!isEmptyAssistantPlaceholderMessage(last)) {
+      return false;
+    }
+    this.messages.pop();
+    if (typeof this.currentMessageIndex === 'number') {
+      this.currentMessageIndex = this.messages.length - 1;
+    }
+    userMDebug('taskPolling.cleanupTrailingEmptyAssistantPlaceholder:removed', {
+      reason,
+      messagesLengthAfter: this.messages.length,
+      currentMessageIndex: this.currentMessageIndex
+    });
+    return true;
+  },
+
   stopWaitingTaskProbe() {
     if (this.waitingTaskProbeTimer) {
       debugNotifyLog('[DEBUG_NOTIFY][ui] stopWaitingTaskProbe');
@@ -369,12 +417,34 @@ export const taskPollingMethods = {
 
     // 判断是否是刷新恢复的情况：
     // 1. 有assistant消息
-    // 2. 且该消息正在streaming或者没有任何内容（说明是刚创建的）
-    // 3. 且不是历史加载完成的消息（历史消息的awaitingFirstContent应该是false）
+    // 2. 且最后一条 assistant 仍处于“未完成流式状态”（而不是普通已完成消息）
+    // 3. 且任务确实仍在进行中
+    const lastActions = Array.isArray(lastMessage?.actions) ? lastMessage.actions : [];
+    const hasUnfinishedAction = lastActions.some((action: any) => {
+      if (!action) return false;
+      if (action.streaming) return true;
+      if (action.type === 'tool' && action.tool) {
+        const status = String(action.tool.status || '').toLowerCase();
+        return ['preparing', 'running', 'pending', 'queued', 'awaiting_approval'].includes(status);
+      }
+      return false;
+    });
+    const hasNoActionsYet = !lastActions.length;
     const isRefreshRestore =
       hasAssistantMessage &&
-      (this.streamingMessage || !lastMessage.actions || lastMessage.actions.length === 0) &&
-      (lastMessage.awaitingFirstContent === true || this.taskInProgress);
+      (hasNoActionsYet || hasUnfinishedAction || lastMessage.awaitingFirstContent === true) &&
+      (this.taskInProgress || this.streamingMessage);
+
+    userMDebug('taskPolling.handleAiMessageStart:decision', {
+      eventIdx,
+      hasAssistantMessage,
+      hasNoActionsYet,
+      hasUnfinishedAction,
+      awaitingFirstContent: !!lastMessage?.awaitingFirstContent,
+      taskInProgress: this.taskInProgress,
+      streamingMessage: this.streamingMessage,
+      isRefreshRestore
+    });
 
     console.log('[AiMessageStart] 场景判断', {
       isRefreshRestore,
@@ -942,6 +1012,7 @@ export const taskPollingMethods = {
       this.clearProcessedEvents();
       this.startWaitingTaskProbe();
     } else {
+      this.cleanupTrailingEmptyAssistantPlaceholder('task_complete');
       // 主任务已结束：若有遗留工具块处于 running/preparing，会导致发送按钮继续显示“停止”。
       // 这里统一清理遗留中的工具状态，避免前端忙碌态卡死。
       if (typeof this.clearPendingTools === 'function') {
@@ -988,6 +1059,7 @@ export const taskPollingMethods = {
     debugLog('[TaskPolling] 任务已停止, idx:', eventIdx, data);
 
     this.markLatestUserWorkCompleted();
+    this.cleanupTrailingEmptyAssistantPlaceholder('task_stopped');
     this.streamingMessage = false;
     this.taskInProgress = false;
     this.stopRequested = false;
@@ -1043,10 +1115,18 @@ export const taskPollingMethods = {
       sub_agent_notice: !!data?.sub_agent_notice,
       background_command_notice: !!data?.background_command_notice
     });
-    this.chatAddUserMessage(message, data?.images || [], data?.videos || []);
-    this.taskInProgress = true;
-    this.streamingMessage = false;
-    this.stopRequested = false;
+    const isAutoUserMessage = isSystemAutoUserMessagePayload(data);
+    if (!isAutoUserMessage) {
+      this.chatAddUserMessage(message, data?.images || [], data?.videos || []);
+      this.taskInProgress = true;
+      this.streamingMessage = false;
+      this.stopRequested = false;
+    } else {
+      debugLog('[TaskPolling] 跳过自动代发 user_message 渲染', {
+        messagePreview: message.slice(0, 80),
+        data
+      });
+    }
     if (data?.sub_agent_notice) {
       if (typeof data?.has_running_sub_agents === 'boolean') {
         this.waitingForSubAgent = data.has_running_sub_agents;
@@ -1070,16 +1150,23 @@ export const taskPollingMethods = {
 
   handleSystemMessage(data: any) {
     const content = (data?.content || data?.message || '').trim();
-    console.log('[DEBUG_SYSTEM][polling] 收到 system_message 事件', {
+    userMDebug('taskPolling.handleSystemMessage:incoming', {
       raw: data,
       normalizedContent: content,
-      currentConversationId: this.currentConversationId
+      currentConversationId: this.currentConversationId,
+      currentMessagesLength: Array.isArray(this.messages) ? this.messages.length : -1
     });
     if (!content) {
-      console.log('[DEBUG_SYSTEM][polling] system_message 内容为空，跳过');
+      userMDebug('taskPolling.handleSystemMessage:empty-skip');
       return;
     }
+    this.cleanupTrailingEmptyAssistantPlaceholder('before_system_message_append');
     this.appendSystemAction(content);
+    userMDebug('taskPolling.handleSystemMessage:after-append', {
+      currentMessagesLength: Array.isArray(this.messages) ? this.messages.length : -1,
+      lastRole: this.messages?.[this.messages.length - 1]?.role || null,
+      lastActions: this.messages?.[this.messages.length - 1]?.actions?.map((a: any) => a?.type) || []
+    });
   },
 
   handleTaskError(data: any) {
diff --git a/static/src/app/methods/ui.ts b/static/src/app/methods/ui.ts
index bc525a0..0841658 100644
--- a/static/src/app/methods/ui.ts
+++ b/static/src/app/methods/ui.ts
@@ -19,6 +19,9 @@ import { debugLog } from './common';
 
 const SUB_AGENT_DONE_PREFIX_RE = /^(?:✅\s*)?子智能体\s*#?\s*(\d+)\s*任务摘要[:：]/;
 const BG_RUN_COMMAND_DONE_PREFIX_RE = /^\[后台\s*run_command\s*完成\]/;
+const userMDebug = (...args: any[]) => {
+  console.log('[USERMDEBUG]', ...args);
+};
 
 function parseSubAgentDoneLabel(rawContent: any): string | null {
   const content = (rawContent || '').toString().trim();
@@ -1114,14 +1117,14 @@ export const uiMethods = {
   },
 
   addSystemMessage(content) {
-    console.log('[DEBUG_SYSTEM][ui] addSystemMessage 入参', { content });
+    userMDebug('ui.addSystemMessage:incoming', { content });
     const systemNoticeLabel = parseSystemNoticeLabel(content);
     if (!systemNoticeLabel) {
       // 其他 system 消息全部隐藏，且不进入渲染链路，避免出现空白块
-      console.log('[DEBUG_SYSTEM][ui] addSystemMessage 被拦截（非完成通知）', { content });
+      userMDebug('ui.addSystemMessage:blocked', { content });
       return;
     }
-    console.log('[DEBUG_SYSTEM][ui] addSystemMessage 通过，写入 action', {
+    userMDebug('ui.addSystemMessage:accepted', {
       original: content,
       normalizedLabel: systemNoticeLabel
     });
diff --git a/static/src/components/chat/ChatArea.vue b/static/src/components/chat/ChatArea.vue
index 9b5e201..df65b1b 100644
--- a/static/src/components/chat/ChatArea.vue
+++ b/static/src/components/chat/ChatArea.vue
@@ -579,7 +579,7 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onBeforeUnmount, onMounted, ref } from 'vue';
+import { computed, nextTick, onBeforeUnmount, onMounted, ref, watch } from 'vue';
 import ToolAction from '@/components/chat/actions/ToolAction.vue';
 import StackedBlocks from './StackedBlocks.vue';
 import MinimalBlocks from './MinimalBlocks.vue';
@@ -622,6 +622,26 @@ const userName = computed(() => {
   }
   return personalization.form.user_name || '用户';
 });
+const isSystemAutoUserMessage = (message: any) => {
+  if (!message || message.role !== 'user') {
+    return false;
+  }
+  const meta = message.metadata || {};
+  return !!(
+    meta.is_auto_generated ||
+    meta.auto_message_type ||
+    meta.sub_agent_notice ||
+    meta.background_command_notice
+  );
+};
+const isEmptyAssistantMessage = (message: any) => {
+  if (!message || message.role !== 'assistant') {
+    return false;
+  }
+  const actions = Array.isArray(message.actions) ? message.actions : [];
+  const hasRenderable = actions.some((action) => isActionVisible(action));
+  return !hasRenderable && !message.awaitingFirstContent;
+};
 const filteredMessages = computed(() => {
   const source = props.messages || [];
   const droppedRoleSystem = source.filter((m) => m && m.role === 'system');
@@ -631,9 +651,33 @@ const filteredMessages = computed(() => {
       samples: droppedRoleSystem.slice(0, 3)
     });
   }
-  return source.filter(
-    (m) => !(m && m.metadata && m.metadata.system_injected_image) && m.role !== 'system'
-  );
+  const result = source.filter((m) => {
+    if (m && m.metadata && m.metadata.system_injected_image) {
+      return false;
+    }
+    if (m?.role === 'system') {
+      return false;
+    }
+    if (isSystemAutoUserMessage(m)) {
+      return false;
+    }
+    if (isEmptyAssistantMessage(m)) {
+      userMDebug('ChatArea.filteredMessages:drop-empty-assistant', {
+        actions: Array.isArray(m?.actions) ? m.actions.map((a: any) => a?.type) : [],
+        awaitingFirstContent: !!m?.awaitingFirstContent
+      });
+      return false;
+    }
+    return true;
+  });
+  if (source.length !== result.length) {
+    userMDebug('ChatArea.filteredMessages:dropped', {
+      sourceLength: source.length,
+      resultLength: result.length,
+      dropped: source.length - result.length
+    });
+  }
+  return result;
 });
 const latestMessageIndex = computed(() => filteredMessages.value.length - 1);
 const SUB_AGENT_DONE_LABEL_RE = /^子智能体\d+\s*任务完成$/;
@@ -651,6 +695,16 @@ const nowMs = ref(Date.now());
 let timerHandle: number | null = null;
 const debugLoggedSystemActionKeys = new Set<string>();
 const debugLoggedUnknownActionKeys = new Set<string>();
+const userMDebug = (...args: any[]) => {
+  console.log('[USERMDEBUG]', ...args);
+};
+const safeJson = (value: any) => {
+  try {
+    return JSON.stringify(value);
+  } catch {
+    return '[unserializable]';
+  }
+};
 
 const DEFAULT_GENERATING_TEXT = '生成中…';
 const rootEl = ref<HTMLElement | null>(null);
@@ -788,12 +842,27 @@ function isSubAgentNoticeOnlyMessage(msg: any): boolean {
     return false;
   }
   const onlyAction = visibleActions[0];
-  return onlyAction?.type === 'system' && !!getSubAgentSystemNoticeLabel(onlyAction);
+  const yes = onlyAction?.type === 'system' && !!getSubAgentSystemNoticeLabel(onlyAction);
+  if (yes) {
+    userMDebug('ChatArea.isSubAgentNoticeOnlyMessage:hit', {
+      actionId: onlyAction?.id,
+      content: onlyAction?.content
+    });
+  }
+  return yes;
 }
 
 function isFollowedBySubAgentNotice(index: number): boolean {
   const next = filteredMessages.value[index + 1];
-  return !!next && isSubAgentNoticeOnlyMessage(next);
+  const yes = !!next && isSubAgentNoticeOnlyMessage(next);
+  if (yes) {
+    userMDebug('ChatArea.isFollowedBySubAgentNotice:hit', {
+      index,
+      currentRole: filteredMessages.value[index]?.role,
+      nextRole: next?.role
+    });
+  }
+  return yes;
 }
 
 function assistantWorkLabel(index: number): string {
@@ -829,11 +898,72 @@ function assistantWorkLabel(index: number): string {
 }
 
 onMounted(() => {
+  userMDebug('ChatArea.mounted:tail-shape', {
+    filteredLength: filteredMessages.value.length,
+    tail: filteredMessages.value.slice(-8).map((m, i) => ({
+      idx: filteredMessages.value.length - 8 + i,
+      role: m?.role,
+      actionTypes: Array.isArray(m?.actions) ? m.actions.map((a: any) => a?.type) : []
+    }))
+  });
   timerHandle = window.setInterval(() => {
     nowMs.value = Date.now();
   }, 1000);
 });
 
+watch(
+  filteredMessages,
+  (next) => {
+    const tail = (next || []).slice(-6).map((m: any, i: number) => {
+      const actionTypes = Array.isArray(m?.actions)
+        ? m.actions.map((a: any) => `${a?.type}${a?.streaming ? ':streaming' : ''}`)
+        : [];
+      const idx = (next?.length || 0) - Math.min(6, next?.length || 0) + i;
+      return {
+        idx,
+        role: m?.role,
+        actionTypes,
+        isSubAgentNoticeOnlyMessage: isSubAgentNoticeOnlyMessage(m),
+        followedBySubAgentNotice: isFollowedBySubAgentNotice(idx)
+      };
+    });
+    userMDebug('ChatArea.watch:filteredMessages-changed', {
+      length: next?.length || 0,
+      tail
+    });
+    userMDebug('ChatArea.watch:filteredMessages-changed:json', safeJson({
+      length: next?.length || 0,
+      tail
+    }));
+
+    nextTick(() => {
+      requestAnimationFrame(() => {
+        const root = rootEl.value;
+        if (!root) return;
+        const blocks = Array.from(root.querySelectorAll('.message-block')) as HTMLElement[];
+        const last = blocks.slice(-4);
+        const geometry = last.map((el, i) => {
+          const r = el.getBoundingClientRect();
+          const prev = i > 0 ? last[i - 1].getBoundingClientRect() : null;
+          const gapFromPrev = prev ? Math.round((r.top - prev.bottom) * 100) / 100 : null;
+          return {
+            className: el.className,
+            top: Math.round(r.top * 100) / 100,
+            bottom: Math.round(r.bottom * 100) / 100,
+            height: Math.round(r.height * 100) / 100,
+            gapFromPrev
+          };
+        });
+        userMDebug('ChatArea.layout:last-blocks', {
+          totalBlocks: blocks.length,
+          geometry
+        });
+      });
+    });
+  },
+  { deep: true }
+);
+
 onBeforeUnmount(() => {
   if (timerHandle !== null) {
     clearInterval(timerHandle);
diff --git a/static/src/stores/chat.ts b/static/src/stores/chat.ts
index e0fb26e..e39c72b 100644
--- a/static/src/stores/chat.ts
+++ b/static/src/stores/chat.ts
@@ -70,6 +70,9 @@ function clearAwaitingFirstContent(message: any) {
     message.awaitingFirstContent = false;
   }
 }
+const userMDebug = (...args: any[]) => {
+  console.log('[USERMDEBUG]', ...args);
+};
 
 export const useChatStore = defineStore('chat', {
   state: (): ChatState => ({
@@ -290,22 +293,48 @@ export const useChatStore = defineStore('chat', {
       msg.currentStreamingType = null;
     },
     addSystemMessage(content: string, meta: any = null) {
-      const msg = this.ensureAssistantMessage();
+      // 与历史重建保持一致：子智能体/后台完成通知作为独立 assistant 消息渲染，
+      // 避免运行时与刷新后在垂直间距上不一致。
+      const useStandaloneMessage = meta?.variant === 'sub_agent_done';
+      if (useStandaloneMessage && Array.isArray(this.messages) && this.messages.length > 0) {
+        const last = this.messages[this.messages.length - 1];
+        const lastActions = Array.isArray(last?.actions) ? last.actions : [];
+        const isEmptyAssistantPlaceholder =
+          last?.role === 'assistant' && lastActions.length === 0 && !!last?.awaitingFirstContent;
+        if (isEmptyAssistantPlaceholder) {
+          userMDebug('chat.addSystemMessage:cleanup-empty-assistant-placeholder', {
+            currentMessageIndex: this.currentMessageIndex,
+            messagesLengthBeforeCleanup: this.messages.length
+          });
+          this.messages.pop();
+          this.currentMessageIndex = this.messages.length - 1;
+        }
+      }
+      const msg = useStandaloneMessage ? createAssistantMessage() : this.ensureAssistantMessage();
       clearAwaitingFirstContent(msg);
-      console.log('[DEBUG_SYSTEM][store] addSystemMessage 写入 actions', {
+      userMDebug('chat.addSystemMessage:before', {
         content,
         meta,
+        useStandaloneMessage,
+        messagesLengthBefore: this.messages.length,
         currentMessageIndex: this.currentMessageIndex,
         actionsBefore: Array.isArray(msg?.actions) ? msg.actions.length : -1
       });
-      msg.actions.push({
+      const action = {
         id: randomId('system'),
         type: 'system',
         content,
         variant: meta?.variant || null,
         timestamp: Date.now()
-      });
-      console.log('[DEBUG_SYSTEM][store] addSystemMessage 写入完成', {
+      };
+      msg.actions.push(action);
+      if (useStandaloneMessage) {
+        this.messages.push(msg);
+        this.currentMessageIndex = this.messages.length - 1;
+      }
+      userMDebug('chat.addSystemMessage:after', {
+        messagesLengthAfter: this.messages.length,
+        currentMessageIndex: this.currentMessageIndex,
         actionsAfter: Array.isArray(msg?.actions) ? msg.actions.length : -1
       });
     },