fix: prevent notebook writing redirect to agent chat

frontend-web/src/open-canvas/pages/AIWritingPage.tsx

@@ -414,6 +414,8 @@ function AIWritingBody({
   const routeBase = useAIWritingRouteBase();
   const agentRoute = useAIWritingAgentRouteState(routeBase);
   const isAdmin = getStoredAuth()?.system_role === 'admin';
+  const externalNotebookMode =
+    studioToken != null || initialNotebookId != null || initialDocumentIds != null;
 
   // 需求 0616 #5：左栏点「笔记本 / 所有空间」→ 在右侧内嵌打开对应页，替换右侧内容
   // （写作布局不卸载，仅 display:none 隐藏，避免 WritingSetupChat 重挂丢线程）。
@@ -432,12 +434,12 @@ function AIWritingBody({
     }
   }, [agentRoute.active]);
 
-  const agentsActive = sidebarTab === 'agents';
+  const agentsActive = !externalNotebookMode && sidebarTab === 'agents';
 
   // 研究模板侧栏在「写作配置(idle)」与「历史回看」两态都展示（点历史记录后保留侧栏、
   // 历史内容显示到右侧区域）；写作进行中收起；嵌入态(studioToken)始终不展示。
   const showSidebar =
-    !studioToken && (state.status === 'idle' || isHistoryMode || agentsActive);
+    !externalNotebookMode && (state.status === 'idle' || isHistoryMode || agentsActive);
   const compactAppearanceActions = compactChrome ? (
     <AIWritingCompactAppearanceActions />
   ) : null;