fix: pass tab content via URL params instead of IPC

- Pass content, unsavedContent, isEditing via URL query params
- PopoutPage reads directly from URL params on mount
- Eliminates IPC race condition entirely
- Direct store update with loaded:true to prevent auto-reload

src/pages/NoteBrowser.tsx

@@ -122,21 +122,12 @@ export const NoteBrowser = () => {
     const tabState = tabs.get(file.path)
     if (!tabState) return
 
-    const tabData = {
-      file: file,
-      content: tabState.content,
-      unsavedContent: tabState.unsavedContent,
-      isEditing: tabState.isEditing,
-      loading: tabState.loading,
-      loaded: tabState.loaded,
-    }
+    const content = tabState.content || ''
+    const unsavedContent = tabState.unsavedContent || content
+    const isEditing = tabState.isEditing
 
-    const route = `/popout?path=${encodeURIComponent(file.path)}&name=${encodeURIComponent(file.name)}`
-    const result = await window.electronAPI?.createWindow({ route, title: file.name })
-
-    if (result?.success && result.windowId) {
-      await window.electronAPI?.transferTabData(result.windowId!, tabData)
-    }
+    const route = `/popout?path=${encodeURIComponent(file.path)}&name=${encodeURIComponent(file.name)}&content=${encodeURIComponent(content)}&unsaved=${encodeURIComponent(unsavedContent)}&editing=${isEditing}`
+    await window.electronAPI?.createWindow({ route, title: file.name })
 
     closeFile(file)
   }, [tabs, closeFile])

src/pages/PopoutPage.tsx

@@ -6,39 +6,85 @@ import { MarkdownTabPage } from '@/components/tabs/MarkdownTabPage'
 import { RemoteTabPage } from '@/modules/remote/RemoteTabPage'
 import { FileTransferPage } from '@/modules/remote/components/file-transfer/FileTransferPage'
 import { Minus, Square, X, Maximize2 } from 'lucide-react'
-import { usePopOutTab } from '@/hooks/domain/usePopOutTab'
+import { useTabStore } from '@/stores'
 
 export const PopoutPage = () => {
   const [searchParams] = useSearchParams()
   const [file, setFile] = useState<FileItemDTO | null>(null)
-  const [error, setError] = useState<string | null>(null)
+  const [content, setContent] = useState<string>('')
+  const [unsavedContent, setUnsavedContent] = useState<string>('')
+  const [isEditing, setIsEditing] = useState(false)
   const [isMaximized, setIsMaximized] = useState(false)
+  const [ready, setReady] = useState(false)
 
-  usePopOutTab()
+  const { selectFile } = useTabStore()
 
   useEffect(() => {
     const path = searchParams.get('path')
     const name = searchParams.get('name')
+    const contentParam = searchParams.get('content')
+    const unsavedParam = searchParams.get('unsaved')
+    const editingParam = searchParams.get('editing')
 
     if (!path || !name) {
-      setError('Missing path or name parameter')
       return
     }
 
+    const decodedPath = decodeURIComponent(path)
+    const decodedName = decodeURIComponent(name)
+    const decodedContent = contentParam ? decodeURIComponent(contentParam) : ''
+    const decodedUnsaved = unsavedParam ? decodeURIComponent(unsavedParam) : decodedContent
+    const decodedEditing = editingParam === 'true'
+
     setFile({
-      name: decodeURIComponent(name),
-      path: decodeURIComponent(path),
+      name: decodedName,
+      path: decodedPath,
       type: 'file',
       size: 0,
       modified: new Date().toISOString(),
     })
+    setContent(decodedContent)
+    setUnsavedContent(decodedUnsaved)
+    setIsEditing(decodedEditing)
+
+    useTabStore.setState((state) => {
+      const newTabs = new Map(state.tabs)
+      newTabs.set(decodedPath, {
+        file: {
+          name: decodedName,
+          path: decodedPath,
+          type: 'file' as const,
+          size: 0,
+          modified: new Date().toISOString(),
+        },
+        content: decodedContent,
+        unsavedContent: decodedUnsaved,
+        isEditing: decodedEditing,
+        loading: false,
+        loaded: true,
+      })
+      return {
+        tabs: newTabs,
+        activeTabId: decodedPath,
+      }
+    })
+
+    selectFile({
+      name: decodedName,
+      path: decodedPath,
+      type: 'file',
+      size: 0,
+      modified: new Date().toISOString(),
+    })
+
+    setReady(true)
 
     window.electronAPI?.windowIsMaximized().then((result) => {
       if (result.success) {
         setIsMaximized(result.isMaximized)
       }
     })
-  }, [searchParams])
+  }, [searchParams, selectFile])
 
   const handleMinimize = () => {
     window.electronAPI?.windowMinimize()
@@ -55,15 +101,7 @@ export const PopoutPage = () => {
     window.electronAPI?.windowClose()
   }
 
-  if (error) {
-    return (
-      <div className="flex items-center justify-center h-screen bg-white dark:bg-gray-900">
-        <div className="text-red-500">{error}</div>
-      </div>
-    )
-  }
-
-  if (!file) {
+  if (!file || !ready) {
     return (
       <div className="flex items-center justify-center h-screen bg-white dark:bg-gray-900">
         <div className="text-gray-500">Loading...</div>