refactor: 删除分屏功能 + 代码审计修复 + 安全加固

## 删除分屏功能
- 删除 ViewMode 'split' 类型，仅保留 editor/preview
- 删除 splitRatio 状态和 Resizer 组件
- 删除滚动同步模块 (scrollSync.ts, rehypeSourceLine.ts)
- 更新快捷键: Ctrl+1 编辑, Ctrl+2 预览

## Bug 修复
- 修复 Toast setTimeout 内存泄漏 (App.tsx)
- 修复 ModifiedBanner reload 更新错误标签 (改用 modifiedFilePath 匹配)
- 修复 FileWatcher error 未重置 isSelfWriting (file-watcher.ts)
- 修复另存为时未 stop watcher (ipc-handlers.ts)

## 死代码清理 (10 项)
- 删除 main/ipc-channels.ts (与 shared/ 重复)
- 删除 main/file-system.ts 未使用的 formatBytes
- 删除 constants.ts 6 个未使用常量
- 删除 fileUtils.ts 未使用的 formatBytes
- 删除 Icons.tsx 5 个未使用图标 (SplitView/ChevronUp/ChevronDown/X/ArrowUp/ArrowDown)
- 删除 useCodeMirror 未使用的 getContent/scrollTo
- 删除 TabBar 未使用的 menuRef
- 删除 Tab.scrollLeft/previewScrollTop 字段
- 删除 tabStore 未使用的 getTabIndex
- 删除 Toast/ModifiedBanner 多余 React import

## 安全加固
- ipc-handlers: 添加路径遍历防护 (validatePath 函数)
- preload: openExternal 仅允许 http/https 协议
- window-manager: 启用 sandbox: true
- preload: removeAllListeners 改为精确取消订阅 (返回 Unsubscribe 函数)

## 状态持久化
- activeTabId 持久化到 IndexedDB (刷新后恢复正确标签)
- sidebar 状态持久化到 IndexedDB (isVisible/sidebarWidth)

## 代码优化
- preload 使用 IPC_CHANNELS 常量替代硬编码字符串
- ipc-handlers _event 类型改为 IpcMainInvokeEvent
- settingsRepository 删除 splitRatio 字段

DESIGN.md

@@ -112,7 +112,7 @@ MarkLite 是一款轻量级的 Windows 本地 Markdown 编辑器桌面应用程
 │  │ tabStore │ │editorStore│ │sidebarStore│ │searchStore│  │
 │  │ - tabs   │ │- viewMode│ │- tree     │ │- matches  │  │
 │  │- activeId│ │- darkMode│ │- expanded │ │- index    │  │
-│  │ - mru    │ │- splitPct│ │- rootPath │ │- options  │  │
+│  │ - mru    │ │- viewMode│ │- rootPath │ │- options  │  │
 │  └────┬─────┘ └────┬─────┘ └────┬─────┘ └──────────┘   │
 │       │            │            │                        │
 │  ┌────▼────────────▼────────────▼────────────────────┐  │
@@ -144,9 +144,7 @@ interface TabState {
 
 ```typescript
 interface EditorState {
-  viewMode: 'split' | 'editor' | 'preview'  // 视图模式
+  viewMode: 'editor' | 'preview'  // 视图模式
-  darkMode: boolean                          // 暗色主题
-  splitRatio: number                         // 分屏比例 (20~80)
 }
 ```
 
@@ -198,7 +196,7 @@ db.version(1).stores({
 | Store | 字段 | 说明 |
 |-------|------|------|
 | `tabSnapshots` | id, filePath, content, scrollTop, scrollLeft, selectionStart, selectionEnd, previewScrollTop, isModified, updatedAt | 标签页状态快照，关闭时保存，启动时恢复 |
-| `settings` | id(固定'default'), darkMode, viewMode, splitRatio, sidebarCollapsed, sidebarWidth | 用户偏好设置 |
+| `settings` | id(固定'default'), darkMode, viewMode, sidebarCollapsed, sidebarWidth | 用户偏好设置 |
 | `recentFiles` | ++id, filePath, lastOpened | 最近打开文件列表 |
 
 ### 4.3 IndexedDB 优势（vs localStorage）
@@ -418,7 +416,7 @@ dangerouslySetInnerHTML  渲染到 React DOM
 ┌──────────────────────────────────────────────────────────────────────────┐
 │  MarkLite - filename.md                                         ─ □ ✕  │
 ├──────────────────────────────────────────────────────────────────────────┤
-│  📁 打开 │ 💾 保存 │ ⬜ 分屏 │ ✏️ 编辑 │ 👁 预览 │              🌙    │
+│  📁 打开 │ 💾 保存 │ ✏️ 编辑 │ 👁 预览 │                    🌙    │
 ├──────────────────────────────────────────────────────────────────────────┤
 │  [file1.md] [file2.md] [未命名]  [+]                                    │
 ├──────────────────────────────────────────────────────────────────────────┤
@@ -448,9 +446,8 @@ dangerouslySetInnerHTML  渲染到 React DOM
 | `Ctrl + O` | 打开文件 |
 | `Ctrl + S` | 保存文件 |
 | `Ctrl + Shift + S` | 另存为 |
-| `Ctrl + 1` | 编辑 + 预览（分屏） |
+| `Ctrl + 1` | 编辑模式 |
-| `Ctrl + 2` | 纯编辑模式 |
+| `Ctrl + 2` | 预览模式 |
-| `Ctrl + 3` | 纯预览模式 |
 | `Ctrl + F` | 搜索 |
 | `Ctrl + H` | 搜索并替换 |
 | `Enter` / `Shift+Enter` | 下一个 / 上一个匹配 |

README.md

@@ -33,8 +33,7 @@
 | ✏️ **实时编辑** | 左侧编辑器，支持 Tab 缩进、行号显示、光标位置、大文件虚拟化行号 |
 | 👁 **实时预览** | 右侧预览面板，基于 unified/rehype 管线渲染，编辑即更新 |
 | 🔤 **代码高亮** | 基于 rehype-highlight，支持 180+ 种编程语言语法高亮 |
-| 🎨 **三种视图** | 分屏模式 / 纯编辑 / 纯预览，自由切换 |
+| 🎨 **两种视图** | 编辑模式 / 预览模式，自由切换 |
-| 📐 **分屏调节** | 拖拽中间分隔条，自由调整编辑区与预览区比例 |
 | 🌙 **暗色主题** | 一键切换亮色/暗色主题，偏好自动记忆（IndexedDB） |
 | 🔔 **文件监听** | 外部修改文件时自动提示，支持重新加载或忽略 |
 | 💾 **文件保存** | 保存 / 另存为，支持 .md / .markdown / .txt 格式 |
@@ -50,7 +49,7 @@
 ┌──────────────────────────────────────────────────────────────────────────┐
 │  MarkLite - README.md                                           ─ □ ✕  │
 ├──────────────────────────────────────────────────────────────────────────┤
-│  📁 打开 │ 💾 保存 │ ⬜ 分屏 │ ✏️ 编辑 │ 👁 预览 │              🌙    │
+│  📁 打开 │ 💾 保存 │ ✏️ 编辑 │ 👁 预览 │                    🌙    │
 ├──────────────────────────────────────────────────────────────────────────┤
 │  [README.md] [DESIGN.md] [main.ts]  [+]                                 │
 ├──────────┬─────────────────────────┬─────────────────────────────────────┤
@@ -125,9 +124,8 @@ npm run lint
 | `Ctrl + O` | 打开文件 |
 | `Ctrl + S` | 保存文件 |
 | `Ctrl + Shift + S` | 另存为 |
-| `Ctrl + 1` | 编辑 + 预览（分屏） |
+| `Ctrl + 1` | 编辑模式 |
-| `Ctrl + 2` | 纯编辑模式 |
+| `Ctrl + 2` | 预览模式 |
-| `Ctrl + 3` | 纯预览模式 |
 | `Ctrl + F` | 搜索 |
 | `Ctrl + H` | 搜索并替换 |
 | `Enter` / `Shift+Enter` | 下一个 / 上一个匹配 |
@@ -194,7 +192,7 @@ MarkLite/
 │   │   │
 │   │   ├── stores/                 # ----- Zustand 状态管理 -----
 │   │   │   ├── tabStore.ts         # 标签页状态（tabs、activeTabId、mruStack）
-│   │   │   ├── editorStore.ts      # 编辑器状态（viewMode、darkMode、splitRatio）
+│   │   │   ├── editorStore.ts      # 编辑器状态（viewMode、darkMode）
 │   │   │   ├── sidebarStore.ts     # 侧边栏状态（tree、expandedDirs、rootPath）
 │   │   │   └── searchStore.ts      # 搜索替换状态（matches、currentIndex、options）
 │   │   │

src/main/file-system.ts

@@ -74,9 +74,3 @@ export async function buildDirTree(dirPath: string, depth = 0, maxDepth = 10): P
   }
   return children
 }
-
-export function formatBytes(bytes: number): string {
-  if (bytes < 1024) return bytes + ' B'
-  if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + ' KB'
-  return (bytes / (1024 * 1024)).toFixed(1) + ' MB'
-}

src/main/file-watcher.ts

@@ -29,6 +29,7 @@ export class FileWatcher {
           this.watcher = null
         }
         this.currentPath = null
+        this.isSelfWriting = false
       })
     } catch {
       // silently ignore

src/main/ipc-channels.ts

@@ -1,23 +0,0 @@
-export const IPC_CHANNELS = {
-  DIALOG_OPEN_FILE: 'dialog:openFile',
-  FILE_READ: 'file:read',
-  FILE_SAVE: 'file:save',
-  FILE_SAVE_AS: 'file:saveAs',
-  FILE_GET_CURRENT_PATH: 'file:getCurrentPath',
-  FILE_STATS: 'file:stats',
-  FILE_RELOAD: 'file:reload',
-  TAB_SWITCHED: 'tab:switched',
-  WINDOW_FORCE_CLOSE: 'window:forceClose',
-  WINDOW_CANCEL_CLOSE: 'window:cancelClose',
-  DIR_READ_TREE: 'dir:readTree',
-  DIR_OPEN_DIALOG: 'dir:openDialog',
-  DIR_WATCH: 'dir:watch',
-  DIR_UNWATCH: 'dir:unwatch',
-  FILE_OPEN_IN_TAB: 'file:openInTab',
-  FILE_EXTERNALLY_MODIFIED: 'file:externallyModified',
-  MENU_SAVE: 'menu:save',
-  MENU_SAVE_AS: 'menu:saveAs',
-  MENU_VIEW_MODE: 'menu:viewMode',
-  WINDOW_CONFIRM_CLOSE: 'window:confirmClose',
-  SIDEBAR_DIR_CHANGED: 'sidebar:dirChanged'
-} as const

src/main/ipc-handlers.ts

@@ -1,9 +1,22 @@
-import { ipcMain, dialog, BrowserWindow } from 'electron'
+import { ipcMain, dialog, BrowserWindow, type IpcMainInvokeEvent } from 'electron'
 import { readFileContent, saveFileContent, buildDirTree } from './file-system'
 import { FileWatcher, SidebarWatcher } from './file-watcher'
-import { IPC_CHANNELS } from './ipc-channels'
+import { IPC_CHANNELS } from '../shared/ipc-channels'
 import { stat } from 'fs/promises'
-import { join, basename } from 'path'
+import { join, basename, resolve, normalize, isAbsolute } from 'path'
+
+// 安全校验：拒绝路径遍历攻击
+function validatePath(filePath: string): boolean {
+  if (!filePath || typeof filePath !== 'string') return false
+  // 拒绝空字节
+  if (filePath.includes('\0')) return false
+  // 规范化路径后检查是否包含 ..
+  const normalized = normalize(filePath)
+  if (normalized.includes('..')) return false
+  // 必须是绝对路径
+  if (!isAbsolute(normalized)) return false
+  return true
+}
 
 export function registerIpcHandlers(
   getMainWindow: () => BrowserWindow | null,
@@ -38,12 +51,18 @@ export function registerIpcHandlers(
   })
 
   // 读取文件
-  ipcMain.handle(IPC_CHANNELS.FILE_READ, async (_event: unknown, filePath: string) => {
+  ipcMain.handle(IPC_CHANNELS.FILE_READ, async (_event: IpcMainInvokeEvent, filePath: string) => {
+    if (!validatePath(filePath)) {
+      return { success: false, error: '无效的文件路径' }
+    }
     return readFileContent(filePath)
   })
 
   // 保存文件
-  ipcMain.handle(IPC_CHANNELS.FILE_SAVE, async (_event: unknown, data: { filePath: string | null; content: string }) => {
+  ipcMain.handle(IPC_CHANNELS.FILE_SAVE, async (_event: IpcMainInvokeEvent, data: { filePath: string | null; content: string }) => {
+    if (data.filePath && !validatePath(data.filePath)) {
+      return { success: false, error: '无效的文件路径' }
+    }
     const win = getMainWindow()
     try {
       if (data.filePath) {
@@ -87,7 +106,7 @@ export function registerIpcHandlers(
   })
 
   // 另存为
-  ipcMain.handle(IPC_CHANNELS.FILE_SAVE_AS, async (_event: unknown, data: { content: string }) => {
+  ipcMain.handle(IPC_CHANNELS.FILE_SAVE_AS, async (_event: IpcMainInvokeEvent, data: { content: string }) => {
     const win = getMainWindow()
     if (!win) return { success: false, error: '窗口不可用' }
     try {
@@ -95,16 +114,24 @@ export function registerIpcHandlers(
         filters: [{ name: 'Markdown 文件', extensions: ['md'] }]
       })
       if (!result.canceled) {
+        fileWatcher.stop()
+        fileWatcher.setSelfWriting(true)
         const saveResult = await saveFileContent(result.filePath, data.content)
+        fileWatcher.setSelfWriting(false)
         if (saveResult.success) {
           state.activeFilePath = result.filePath
+          setTimeout(() => {
+            if (state.activeFilePath === result.filePath) {
               fileWatcher.start(result.filePath)
+            }
+          }, 300)
           win.setTitle(`MarkLite - ${basename(result.filePath)}`)
         }
         return saveResult
       }
       return { success: false, canceled: true }
     } catch (err) {
+      fileWatcher.setSelfWriting(false)
       return { success: false, error: (err as Error).message }
     }
   })
@@ -113,7 +140,10 @@ export function registerIpcHandlers(
   ipcMain.handle(IPC_CHANNELS.FILE_GET_CURRENT_PATH, () => state.activeFilePath)
 
   // 文件统计
-  ipcMain.handle(IPC_CHANNELS.FILE_STATS, async (_event: unknown, filePath: string) => {
+  ipcMain.handle(IPC_CHANNELS.FILE_STATS, async (_event: IpcMainInvokeEvent, filePath: string) => {
+    if (!validatePath(filePath)) {
+      return { success: false, error: '无效的文件路径' }
+    }
     try {
       const fileStat = await stat(filePath)
       return { success: true, size: fileStat.size, mtime: fileStat.mtime.toISOString() }
@@ -130,7 +160,10 @@ export function registerIpcHandlers(
   })
 
   // 目录树
-  ipcMain.handle(IPC_CHANNELS.DIR_READ_TREE, async (_event: unknown, dirPath: string) => {
+  ipcMain.handle(IPC_CHANNELS.DIR_READ_TREE, async (_event: IpcMainInvokeEvent, dirPath: string) => {
+    if (!validatePath(dirPath)) {
+      return { success: false, error: '无效的目录路径' }
+    }
     try {
       const tree = await buildDirTree(dirPath)
       return { success: true, tree, rootPath: dirPath }
@@ -151,7 +184,7 @@ export function registerIpcHandlers(
   })
 
   // 目录监听
-  ipcMain.handle(IPC_CHANNELS.DIR_WATCH, (_event: unknown, dirPath: string) => {
+  ipcMain.handle(IPC_CHANNELS.DIR_WATCH, (_event: IpcMainInvokeEvent, dirPath: string) => {
     sidebarWatcher.start(dirPath)
   })
 
@@ -160,7 +193,7 @@ export function registerIpcHandlers(
   })
 
   // 标签切换
-  ipcMain.handle(IPC_CHANNELS.TAB_SWITCHED, (_event: unknown, filePath: string | null) => {
+  ipcMain.handle(IPC_CHANNELS.TAB_SWITCHED, (_event: IpcMainInvokeEvent, filePath: string | null) => {
     state.activeFilePath = filePath || null
     fileWatcher.start(filePath || '')
     const win = getMainWindow()

src/main/window-manager.ts

@@ -12,7 +12,8 @@ export function createWindow(): BrowserWindow {
     webPreferences: {
       preload: join(__dirname, '../preload/index.js'),
       contextIsolation: true,
-      nodeIntegration: false
+      nodeIntegration: false,
+      sandbox: true
     },
     titleBarStyle: 'default',
     show: false

src/preload/index.ts

@@ -1,62 +1,75 @@
 import { contextBridge, ipcRenderer, shell } from 'electron'
-
+import { IPC_CHANNELS } from '../shared/ipc-channels'
-// M-01: 限制 removeAllListeners 只能操作白名单通道
-const ALLOWED_REMOVE_CHANNELS = new Set([
-  'file:openInTab',
-  'menu:save',
-  'menu:saveAs',
-  'menu:viewMode',
-  'file:externallyModified',
-  'sidebar:dirChanged',
-  'window:confirmClose'
-])
 
 contextBridge.exposeInMainWorld('electronAPI', {
   // File operations
-  openFile: () => ipcRenderer.invoke('dialog:openFile'),
+  openFile: () => ipcRenderer.invoke(IPC_CHANNELS.DIALOG_OPEN_FILE),
-  readFile: (filePath: string) => ipcRenderer.invoke('file:read', filePath),
+  readFile: (filePath: string) => ipcRenderer.invoke(IPC_CHANNELS.FILE_READ, filePath),
-  saveFile: (data: { filePath: string | null; content: string }) => ipcRenderer.invoke('file:save', data),
+  saveFile: (data: { filePath: string | null; content: string }) => ipcRenderer.invoke(IPC_CHANNELS.FILE_SAVE, data),
-  saveFileAs: (data: { content: string }) => ipcRenderer.invoke('file:saveAs', data),
+  saveFileAs: (data: { content: string }) => ipcRenderer.invoke(IPC_CHANNELS.FILE_SAVE_AS, data),
-  getCurrentPath: () => ipcRenderer.invoke('file:getCurrentPath'),
+  getCurrentPath: () => ipcRenderer.invoke(IPC_CHANNELS.FILE_GET_CURRENT_PATH),
-  getFileStats: (filePath: string) => ipcRenderer.invoke('file:stats', filePath),
+  getFileStats: (filePath: string) => ipcRenderer.invoke(IPC_CHANNELS.FILE_STATS, filePath),
-  reloadFile: () => ipcRenderer.invoke('file:reload'),
+  reloadFile: () => ipcRenderer.invoke(IPC_CHANNELS.FILE_RELOAD),
 
   // Tab management
-  tabSwitched: (filePath: string | null) => ipcRenderer.invoke('tab:switched', filePath),
+  tabSwitched: (filePath: string | null) => ipcRenderer.invoke(IPC_CHANNELS.TAB_SWITCHED, filePath),
 
   // Window control
-  forceClose: () => ipcRenderer.invoke('window:forceClose'),
+  forceClose: () => ipcRenderer.invoke(IPC_CHANNELS.WINDOW_FORCE_CLOSE),
-  cancelClose: () => ipcRenderer.invoke('window:cancelClose'),
+  cancelClose: () => ipcRenderer.invoke(IPC_CHANNELS.WINDOW_CANCEL_CLOSE),
 
-  // Shell
+  // Shell — 仅允许 http/https 协议
-  openExternal: (url: string) => shell.openExternal(url),
+  openExternal: (url: string) => {
+    try {
+      const parsed = new URL(url)
+      if (parsed.protocol === 'http:' || parsed.protocol === 'https:') {
+        shell.openExternal(url)
+      }
+    } catch {
+      // 无效 URL，忽略
+    }
+  },
 
   // File Tree (Sidebar)
-  readDirTree: (dirPath: string) => ipcRenderer.invoke('dir:readTree', dirPath),
+  readDirTree: (dirPath: string) => ipcRenderer.invoke(IPC_CHANNELS.DIR_READ_TREE, dirPath),
-  openFolderDialog: () => ipcRenderer.invoke('dir:openDialog'),
+  openFolderDialog: () => ipcRenderer.invoke(IPC_CHANNELS.DIR_OPEN_DIALOG),
-  watchDir: (dirPath: string) => ipcRenderer.invoke('dir:watch', dirPath),
+  watchDir: (dirPath: string) => ipcRenderer.invoke(IPC_CHANNELS.DIR_WATCH, dirPath),
-  unwatchDir: () => ipcRenderer.invoke('dir:unwatch'),
+  unwatchDir: () => ipcRenderer.invoke(IPC_CHANNELS.DIR_UNWATCH),
 
-  // Events from main process
+  // Events from main process — 返回取消订阅函数
-  onFileOpenInTab: (callback: (data: { filePath: string; content: string }) => void) =>
+  onFileOpenInTab: (callback: (data: { filePath: string; content: string }) => void) => {
-    ipcRenderer.on('file:openInTab', (_event, data) => callback(data)),
+    const handler = (_event: Electron.IpcRendererEvent, data: { filePath: string; content: string }) => callback(data)
-  onMenuSave: (callback: () => void) =>
+    ipcRenderer.on(IPC_CHANNELS.FILE_OPEN_IN_TAB, handler)
-    ipcRenderer.on('menu:save', () => callback()),
+    return () => { ipcRenderer.removeListener(IPC_CHANNELS.FILE_OPEN_IN_TAB, handler) }
-  onMenuSaveAs: (callback: () => void) =>
+  },
-    ipcRenderer.on('menu:saveAs', () => callback()),
+  onMenuSave: (callback: () => void) => {
-  onViewModeChange: (callback: (mode: string) => void) =>
+    const handler = () => callback()
-    ipcRenderer.on('menu:viewMode', (_event, mode) => callback(mode)),
+    ipcRenderer.on(IPC_CHANNELS.MENU_SAVE, handler)
-  onExternalModification: (callback: (filePath: string) => void) =>
+    return () => { ipcRenderer.removeListener(IPC_CHANNELS.MENU_SAVE, handler) }
-    ipcRenderer.on('file:externallyModified', (_event, filePath) => callback(filePath)),
+  },
-  onDirChanged: (callback: () => void) =>
+  onMenuSaveAs: (callback: () => void) => {
-    ipcRenderer.on('sidebar:dirChanged', () => callback()),
+    const handler = () => callback()
-  onConfirmClose: (callback: () => void) =>
+    ipcRenderer.on(IPC_CHANNELS.MENU_SAVE_AS, handler)
-    ipcRenderer.on('window:confirmClose', () => callback()),
+    return () => { ipcRenderer.removeListener(IPC_CHANNELS.MENU_SAVE_AS, handler) }
-
+  },
-  // M-01: 只允许移除白名单通道的监听器
+  onViewModeChange: (callback: (mode: string) => void) => {
-  removeAllListeners: (channel: string) => {
+    const handler = (_event: Electron.IpcRendererEvent, mode: string) => callback(mode)
-    if (ALLOWED_REMOVE_CHANNELS.has(channel)) {
+    ipcRenderer.on(IPC_CHANNELS.MENU_VIEW_MODE, handler)
-      ipcRenderer.removeAllListeners(channel)
+    return () => { ipcRenderer.removeListener(IPC_CHANNELS.MENU_VIEW_MODE, handler) }
-    }
+  },
+  onExternalModification: (callback: (filePath: string) => void) => {
+    const handler = (_event: Electron.IpcRendererEvent, filePath: string) => callback(filePath)
+    ipcRenderer.on(IPC_CHANNELS.FILE_EXTERNALLY_MODIFIED, handler)
+    return () => { ipcRenderer.removeListener(IPC_CHANNELS.FILE_EXTERNALLY_MODIFIED, handler) }
+  },
+  onDirChanged: (callback: () => void) => {
+    const handler = () => callback()
+    ipcRenderer.on(IPC_CHANNELS.SIDEBAR_DIR_CHANGED, handler)
+    return () => { ipcRenderer.removeListener(IPC_CHANNELS.SIDEBAR_DIR_CHANGED, handler) }
+  },
+  onConfirmClose: (callback: () => void) => {
+    const handler = () => callback()
+    ipcRenderer.on(IPC_CHANNELS.WINDOW_CONFIRM_CLOSE, handler)
+    return () => { ipcRenderer.removeListener(IPC_CHANNELS.WINDOW_CONFIRM_CLOSE, handler) }
   }
 })

src/renderer/App.tsx

@@ -1,6 +1,7 @@
 import React, { useState, useCallback, useEffect, useRef } from 'react'
 import { useTabStore } from './stores/tabStore'
 import { useEditorStore } from './stores/editorStore'
+import { useSidebarStore } from './stores/sidebarStore'
 import { useTheme } from './hooks/useTheme'
 import { useSettings } from './hooks/useSettings'
 import { useKeyboard } from './hooks/useKeyboard'
@@ -27,25 +28,29 @@ export default function App() {
   const setModified = useTabStore(s => s.setModified)
   const updateTabContent = useTabStore(s => s.updateTabContent)
   const loadFromDB = useTabStore(s => s.loadFromDB)
+  const loadSidebarFromDB = useSidebarStore(s => s.loadFromDB)
 
   const viewMode = useEditorStore(s => s.viewMode)
-  const splitRatio = useEditorStore(s => s.splitRatio)
 
   const { darkMode, toggleDarkMode } = useTheme()
-  const { saveViewMode, saveSplitRatio } = useSettings()
+  const { saveViewMode } = useSettings()
 
   const [showModifiedBanner, setShowModifiedBanner] = useState(false)
   const [modifiedFilePath, setModifiedFilePath] = useState<string | null>(null)
   const [toastMessage, setToastMessage] = useState<string | null>(null)
+  const toastTimer = useRef<number>(0)
 
-  // 启动时从 IndexedDB 加载标签页
+  // 启动时从 IndexedDB 加载标签页和 sidebar 设置
   useEffect(() => {
     loadFromDB()
-  }, [loadFromDB])
+    loadSidebarFromDB()
+    return () => clearTimeout(toastTimer.current)
+  }, [loadFromDB, loadSidebarFromDB])
 
   const showToast = useCallback((msg: string) => {
+    clearTimeout(toastTimer.current)
     setToastMessage(msg)
-    setTimeout(() => setToastMessage(null), 3000)
+    toastTimer.current = window.setTimeout(() => setToastMessage(null), 3000)
   }, [])
 
   // 拖拽打开
@@ -128,7 +133,7 @@ export default function App() {
   }, [createTab])
 
   // 视图模式切换
-  const handleViewModeChange = useCallback((mode: 'split' | 'editor' | 'preview') => {
+  const handleViewModeChange = useCallback((mode: 'editor' | 'preview') => {
     saveViewMode(mode)
   }, [saveViewMode])
 
@@ -150,28 +155,19 @@ export default function App() {
     const onSave = () => handleSaveRef.current()
     const onSaveAs = () => handleSaveAsRef.current()
 
-    api.onFileOpenInTab(onOpen)
+    const unsub1 = api.onFileOpenInTab(onOpen)
-    api.onMenuSave(onSave)
+    const unsub2 = api.onMenuSave(onSave)
-    api.onMenuSaveAs(onSaveAs)
+    const unsub3 = api.onMenuSaveAs(onSaveAs)
 
     return () => {
-      api.removeAllListeners('file:openInTab')
+      unsub1()
-      api.removeAllListeners('menu:save')
+      unsub2()
-      api.removeAllListeners('menu:saveAs')
+      unsub3()
     }
   }, [createTab])
 
-  const activeTab = getActiveTab()
   const hasTabs = tabs.length > 0
 
-  // 分屏样式
-  const editorStyle: React.CSSProperties = viewMode === 'split'
-    ? { flex: `0 0 ${splitRatio}%` }
-    : {}
-  const previewStyle: React.CSSProperties = viewMode === 'split'
-    ? { flex: `0 0 ${100 - splitRatio}%` }
-    : {}
-
   return (
     <div id="app" className={`mode-${viewMode}`}>
       <Toolbar
@@ -193,9 +189,9 @@ export default function App() {
             <ModifiedBanner
               onReload={() => {
                 if (window.electronAPI && modifiedFilePath) {
-                  window.electronAPI.reloadFile().then(result => {
+                  window.electronAPI.readFile(modifiedFilePath).then(result => {
                     if (result.success && result.content) {
-                      const tab = getActiveTab()
+                      const tab = tabs.find(t => t.filePath === modifiedFilePath)
                       if (tab) {
                         updateTabContent(tab.id, result.content)
                         setModified(tab.id, false)
@@ -211,14 +207,13 @@ export default function App() {
 
           {hasTabs ? (
             <div id="content-wrapper">
-              {viewMode !== 'preview' && (
+              {viewMode === 'editor' && (
-                <div id="editor-panel" style={editorStyle}>
+                <div id="editor-panel">
                   <Editor darkMode={darkMode} />
                 </div>
               )}
-              {viewMode !== 'editor' && <Resizer onResize={saveSplitRatio} />}
+              {viewMode === 'preview' && (
-              {viewMode !== 'editor' && (
+                <div id="preview-panel">
-                <div id="preview-panel" style={previewStyle}>
                   <Preview />
                 </div>
               )}
@@ -240,41 +235,3 @@ export default function App() {
     </div>
   )
 }
-
-// B-08: 分屏调节器组件
-function Resizer({ onResize }: { onResize: (ratio: number) => void }) {
-  const handleMouseDown = useCallback((e: React.MouseEvent) => {
-    e.preventDefault()
-    document.body.style.cursor = 'col-resize'
-    document.body.style.userSelect = 'none'
-
-    const handleMouseMove = (ev: MouseEvent) => {
-      const wrapper = document.getElementById('content-wrapper')
-      if (!wrapper) return
-      const rect = wrapper.getBoundingClientRect()
-      const pct = Math.max(20, Math.min(80, ((ev.clientX - rect.left) / rect.width) * 100))
-      const editorPanel = document.getElementById('editor-panel')
-      const previewPanel = document.getElementById('preview-panel')
-      if (editorPanel) editorPanel.style.flex = `0 0 ${pct}%`
-      if (previewPanel) previewPanel.style.flex = `0 0 ${100 - pct}%`
-    }
-
-    const handleMouseUp = (ev: MouseEvent) => {
-      document.removeEventListener('mousemove', handleMouseMove)
-      document.removeEventListener('mouseup', handleMouseUp)
-      document.body.style.cursor = ''
-      document.body.style.userSelect = ''
-      const wrapper = document.getElementById('content-wrapper')
-      if (wrapper) {
-        const rect = wrapper.getBoundingClientRect()
-        const pct = Math.max(20, Math.min(80, ((ev.clientX - rect.left) / rect.width) * 100))
-        onResize(pct)
-      }
-    }
-
-    document.addEventListener('mousemove', handleMouseMove)
-    document.addEventListener('mouseup', handleMouseUp)
-  }, [onResize])
-
-  return <div id="resizer" onMouseDown={handleMouseDown} />
-}

src/renderer/components/Editor/Editor.tsx

@@ -22,8 +22,7 @@ export function Editor({ darkMode }: EditorProps) {
     getScrollTop,
     setScrollTop,
     getSelection,
-    setSelection,
+    setSelection
-    setLineAtTop
   } = useCodeMirror({
     content: activeTab?.content ?? '',
     onChange: useCallback((value: string) => {
@@ -31,25 +30,9 @@ export function Editor({ darkMode }: EditorProps) {
       updateTabContent(activeTabId, value)
       setModified(activeTabId, true)
     }, [activeTabId, updateTabContent, setModified]),
-    darkMode,
+    darkMode
-    onScroll: useCallback((line: number) => {
-      // 派发行号给预览侧做滚动同步
-      window.dispatchEvent(new CustomEvent('editor-scroll', { detail: { line } }))
-    }, [])
   })
 
-  // 反向同步：监听预览滚动事件
-  useEffect(() => {
-    const handlePreviewScroll = (e: Event) => {
-      const line = (e as CustomEvent).detail?.line
-      if (typeof line === 'number') {
-        setLineAtTop(Math.floor(line) + 1) // setLineAtTop 是 1-indexed
-      }
-    }
-    window.addEventListener('preview-scroll', handlePreviewScroll)
-    return () => window.removeEventListener('preview-scroll', handlePreviewScroll)
-  }, [setLineAtTop])
-
   // 切换标签时加载内容
   useEffect(() => {
     if (!activeTab) return

src/renderer/components/Editor/useCodeMirror.ts

@@ -11,10 +11,9 @@ interface UseCodeMirrorOptions {
   content: string
   onChange: (value: string) => void
   darkMode: boolean
-  onScroll?: (line: number) => void
 }
 
-export function useCodeMirror({ content, onChange, darkMode, onScroll }: UseCodeMirrorOptions) {
+export function useCodeMirror({ content, onChange, darkMode }: UseCodeMirrorOptions) {
   const containerRef = useRef<HTMLDivElement>(null)
   const viewRef = useRef<EditorView | null>(null)
   const isExternalUpdate = useRef(false)
@@ -81,23 +80,7 @@ export function useCodeMirror({ content, onChange, darkMode, onScroll }: UseCode
 
     viewRef.current = view
 
-    // 滚动事件监听：派发行号（支持小数表示行内偏移）
-    const handleScroll = () => {
-      if (onScroll) {
-        const dom = view.scrollDOM
-        const scrollTop = dom.scrollTop
-        const block = view.lineBlockAtHeight(scrollTop)
-        const line = view.state.doc.lineAt(block.from)
-        const fraction = block.height > 0
-          ? (scrollTop - block.top) / block.height
-          : 0
-        onScroll(line.number - 1 + Math.max(0, fraction))  // 0-indexed + 行内比例
-      }
-    }
-    view.scrollDOM.addEventListener('scroll', handleScroll)
-
     return () => {
-      view.scrollDOM.removeEventListener('scroll', handleScroll)
       view.destroy()
       viewRef.current = null
     }
@@ -116,12 +99,6 @@ export function useCodeMirror({ content, onChange, darkMode, onScroll }: UseCode
       isExternalUpdate.current = false
     }
   }, [])
-
-  // 获取当前内容
-  const getContent = useCallback(() => {
-    return viewRef.current?.state.doc.toString() ?? ''
-  }, [])
-
   // 获取/设置滚动位置
   const getScrollTop = useCallback(() => {
     return viewRef.current?.scrollDOM.scrollTop ?? 0
@@ -147,35 +124,13 @@ export function useCodeMirror({ content, onChange, darkMode, onScroll }: UseCode
     view.dispatch({ selection: { anchor: from, head: to } })
     view.focus()
   }, [])
-
-  // 滚动到指定行
-  const scrollTo = useCallback((pos: number) => {
-    const view = viewRef.current
-    if (!view) return
-    view.dispatch({ effects: EditorView.scrollIntoView(pos, { y: 'center' }) })
-  }, [])
-
-  // 滚动使指定行出现在编辑器顶部（反向同步用）
-  const setLineAtTop = useCallback((lineNumber: number) => {
-    const view = viewRef.current
-    if (!view) return
-    const line = Math.max(1, Math.min(lineNumber, view.state.doc.lines))
-    const lineInfo = view.state.doc.line(line)
-    const block = view.lineBlockAt(lineInfo.from)
-    const currentTop = view.lineBlockAtHeight(view.scrollDOM.scrollTop).top
-    view.scrollDOM.scrollTop += block.top - currentTop
-  }, [])
-
   return {
     containerRef,
     viewRef,
     setContent,
-    getContent,
     getScrollTop,
     setScrollTop,
     getSelection,
-    setSelection,
+    setSelection
-    scrollTo,
-    setLineAtTop
   }
 }

src/renderer/components/Icons.tsx

@@ -58,19 +58,6 @@ export function Save({ size = defaultProps.size }: IconProps) {
   )
 }
 
-export function SplitView({ size = defaultProps.size }: IconProps) {
-  return (
-    <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.75" strokeLinecap="round" strokeLinejoin="round">
-      <rect x="3" y="3" width="18" height="18" rx="3"/>
-      <line x1="12" y1="3" x2="12" y2="21"/>
-      <rect x="5" y="7" width="5" height="2" rx="1" fill="currentColor" opacity="0.4"/>
-      <rect x="5" y="11" width="3" height="2" rx="1" fill="currentColor" opacity="0.3"/>
-      <rect x="14" y="7" width="5" height="2" rx="1" fill="currentColor" opacity="0.4"/>
-      <rect x="14" y="11" width="3" height="2" rx="1" fill="currentColor" opacity="0.3"/>
-    </svg>
-  )
-}
-
 export function EditMode({ size = defaultProps.size }: IconProps) {
   return (
     <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.75" strokeLinecap="round" strokeLinejoin="round">
@@ -175,32 +162,6 @@ export function FolderPlus({ size = 14 }: IconProps) {
   )
 }
 
-// ===== 搜索栏图标 =====
-export function ChevronUp({ size = 12 }: IconProps) {
-  return (
-    <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2.5" strokeLinecap="round" strokeLinejoin="round">
-      <polyline points="18 15 12 9 6 15"/>
-    </svg>
-  )
-}
-
-export function ChevronDown({ size = 12 }: IconProps) {
-  return (
-    <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2.5" strokeLinecap="round" strokeLinejoin="round">
-      <polyline points="6 9 12 15 18 9"/>
-    </svg>
-  )
-}
-
-export function X({ size = 14 }: IconProps) {
-  return (
-    <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round">
-      <line x1="18" y1="6" x2="6" y2="18"/>
-      <line x1="6" y1="6" x2="18" y2="18"/>
-    </svg>
-  )
-}
-
 // ===== 拖拽覆盖层图标 =====
 export function UploadCloud({ size = 64 }: IconProps) {
   return (
@@ -213,25 +174,6 @@ export function UploadCloud({ size = 64 }: IconProps) {
   )
 }
 
-// ===== 箭头/导航图标 =====
-export function ArrowUp({ size = 12 }: IconProps) {
-  return (
-    <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2.5" strokeLinecap="round" strokeLinejoin="round">
-      <line x1="12" y1="19" x2="12" y2="5"/>
-      <polyline points="5 12 12 5 19 12"/>
-    </svg>
-  )
-}
-
-export function ArrowDown({ size = 12 }: IconProps) {
-  return (
-    <svg width={size} height={size} viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2.5" strokeLinecap="round" strokeLinejoin="round">
-      <line x1="12" y1="5" x2="12" y2="19"/>
-      <polyline points="19 12 12 19 5 12"/>
-    </svg>
-  )
-}
-
 // ===== 欢迎屏幕图标 =====
 export function WelcomeFile({ size = 20 }: IconProps) {
   return (

src/renderer/components/ModifiedBanner/ModifiedBanner.tsx

@@ -1,5 +1,3 @@
-import React from 'react'
-
 interface ModifiedBannerProps {
   onReload: () => void
   onDismiss: () => void

src/renderer/components/Preview/Preview.tsx

@@ -1,13 +1,11 @@
 import React, { useState, useEffect, useCallback, useRef } from 'react'
 import { useTabStore } from '../../stores/tabStore'
 import { renderMarkdown } from '../../lib/markdown'
-import { scrollPreviewToLine, getLineAtScrollOffset, invalidateScrollCache } from '../../lib/scrollSync'
 
 export function Preview() {
   const [html, setHtml] = useState('')
   const previewRef = useRef<HTMLDivElement>(null)
   const requestIdRef = useRef(0)
-  const isSyncingRef = useRef(false)
 
   const activeTabId = useTabStore(s => s.activeTabId)
   const tabs = useTabStore(s => s.tabs)
@@ -24,49 +22,10 @@ export function Preview() {
     renderMarkdown(activeTab.content, activeTab.filePath).then(result => {
       if (requestId === requestIdRef.current) {
         setHtml(result)
-        invalidateScrollCache()
       }
     })
   }, [activeTabId, activeTab?.content])
 
-  // 滚动同步：监听编辑器滚动事件（VS Code 方案：行号 → 二分查找）
-  useEffect(() => {
-    const handleEditorScroll = (e: Event) => {
-      const line = (e as CustomEvent).detail?.line
-      if (typeof line !== 'number') return
-
-      const container = previewRef.current?.parentElement
-      if (!container || isSyncingRef.current) return
-
-      scrollPreviewToLine(line, container, isSyncingRef)
-    }
-
-    window.addEventListener('editor-scroll', handleEditorScroll)
-    return () => window.removeEventListener('editor-scroll', handleEditorScroll)
-  }, [])
-
-  // 反向同步：预览滚动 → 通知编辑器
-  useEffect(() => {
-    const container = previewRef.current?.parentElement
-    if (!container) return
-
-    const handleScroll = () => {
-      if (isSyncingRef.current) return
-
-      const line = getLineAtScrollOffset(container.scrollTop, container)
-      if (line !== null) {
-        isSyncingRef.current = true
-        window.dispatchEvent(new CustomEvent('preview-scroll', { detail: { line } }))
-        requestAnimationFrame(() => {
-          isSyncingRef.current = false
-        })
-      }
-    }
-
-    container.addEventListener('scroll', handleScroll, { passive: true })
-    return () => container.removeEventListener('scroll', handleScroll)
-  }, [activeTabId])
-
   // 拦截链接点击
   const handleClick = useCallback((e: React.MouseEvent) => {
     const link = (e.target as HTMLElement).closest('a')

src/renderer/components/Sidebar/Sidebar.tsx

@@ -74,12 +74,10 @@ export function Sidebar() {
 
   useEffect(() => {
     if (!window.electronAPI) return
-    window.electronAPI.onDirChanged(() => {
+    const unsubscribe = window.electronAPI.onDirChanged(() => {
       refreshTree()
     })
-    return () => {
+    return unsubscribe
-      window.electronAPI?.removeAllListeners('sidebar:dirChanged')
-    }
   }, [refreshTree])
 
   useEffect(() => {

src/renderer/components/TabBar/TabBar.tsx

@@ -1,4 +1,4 @@
-import React, { useCallback, useState, useEffect, useRef } from 'react'
+import React, { useCallback, useState, useEffect } from 'react'
 import { useTabStore } from '../../stores/tabStore'
 import { getFileName } from '../../lib/fileUtils'
 import { Close, Plus } from '../Icons'
@@ -21,7 +21,6 @@ export function TabBar() {
   const closeTabsToRight = useTabStore(s => s.closeTabsToRight)
 
   const [menu, setMenu] = useState<ContextMenuState>({ visible: false, x: 0, y: 0, tabId: '' })
-  const menuRef = useRef<HTMLDivElement>(null)
 
   const handleClose = useCallback((e: React.MouseEvent, tabId: string) => {
     e.stopPropagation()
@@ -133,7 +132,6 @@ export function TabBar() {
       {/* 右键菜单 */}
       {menu.visible && (
         <div
-          ref={menuRef}
           className="tab-context-menu" 
           style={{ left: menu.x, top: menu.y }}
           onClick={(e) => e.stopPropagation()}

src/renderer/components/Toast/Toast.tsx

@@ -1,5 +1,3 @@
-import React from 'react'
-
 interface ToastProps {
   message: string
 }

src/renderer/components/Toolbar/Toolbar.tsx

@@ -1,11 +1,11 @@
 import React from 'react'
-import { FolderOpen, Save, SplitView, EditMode, PreviewMode, Moon, Sun } from '../Icons'
+import { FolderOpen, Save, EditMode, PreviewMode, Moon, Sun } from '../Icons'
 
 interface ToolbarProps {
   onOpen: () => void
   onSave: () => void
-  viewMode: 'split' | 'editor' | 'preview'
+  viewMode: 'editor' | 'preview'
-  onViewModeChange: (mode: 'split' | 'editor' | 'preview') => void
+  onViewModeChange: (mode: 'editor' | 'preview') => void
   darkMode: boolean
   onToggleDark: () => void
 }
@@ -23,15 +23,11 @@ export function Toolbar({ onOpen, onSave, viewMode, onViewModeChange, darkMode,
           <span>保存</span>
         </button>
         <div className="toolbar-divider" />
-        <button className={`toolbar-btn ${viewMode === 'split' ? 'active' : ''}`} onClick={() => onViewModeChange('split')} title="编辑+预览 (Ctrl+1)">
+        <button className={`toolbar-btn ${viewMode === 'editor' ? 'active' : ''}`} onClick={() => onViewModeChange('editor')} title="编辑 (Ctrl+1)">
-          <SplitView size={18} />
-          <span>分屏</span>
-        </button>
-        <button className={`toolbar-btn ${viewMode === 'editor' ? 'active' : ''}`} onClick={() => onViewModeChange('editor')} title="纯编辑 (Ctrl+2)">
           <EditMode size={18} />
           <span>编辑</span>
         </button>
-        <button className={`toolbar-btn ${viewMode === 'preview' ? 'active' : ''}`} onClick={() => onViewModeChange('preview')} title="纯预览 (Ctrl+3)">
+        <button className={`toolbar-btn ${viewMode === 'preview' ? 'active' : ''}`} onClick={() => onViewModeChange('preview')} title="预览 (Ctrl+2)">
           <PreviewMode size={18} />
           <span>预览</span>
         </button>

src/renderer/db/schema.ts

@@ -5,19 +5,21 @@ export interface TabSnapshot {
   filePath: string | null
   content: string
   scrollTop: number
-  scrollLeft: number
   selectionStart: number
   selectionEnd: number
-  previewScrollTop: number
   isModified: boolean
   updatedAt: number
 }
 
+export interface ActiveTabRecord {
+  id: string // 固定为 'current'
+  activeTabId: string | null
+}
+
 export interface SettingsRecord {
   id: string // 固定为 'default'
   darkMode: boolean
-  viewMode: 'split' | 'editor' | 'preview'
+  viewMode: 'editor' | 'preview'
-  splitRatio: number
   sidebarCollapsed: boolean
   sidebarWidth: number
 }
@@ -32,12 +34,14 @@ const db = new Dexie('MarkLite') as Dexie & {
   tabSnapshots: EntityTable<TabSnapshot, 'id'>
   settings: EntityTable<SettingsRecord, 'id'>
   recentFiles: EntityTable<RecentFile, 'id'>
+  activeTab: EntityTable<ActiveTabRecord, 'id'>
 }
 
 db.version(1).stores({
   tabSnapshots: 'id, filePath, updatedAt',
   settings: 'id',
-  recentFiles: '++id, filePath, lastOpened'
+  recentFiles: '++id, filePath, lastOpened',
+  activeTab: 'id'
 })
 
 export { db }

src/renderer/db/settingsRepository.ts

@@ -9,7 +9,6 @@ export const settingsRepository = {
         return {
           darkMode: record.darkMode ?? DEFAULT_SETTINGS.darkMode,
           viewMode: record.viewMode ?? DEFAULT_SETTINGS.viewMode,
-          splitRatio: record.splitRatio ?? DEFAULT_SETTINGS.splitRatio,
           sidebarCollapsed: record.sidebarCollapsed ?? DEFAULT_SETTINGS.sidebarCollapsed,
           sidebarWidth: record.sidebarWidth ?? DEFAULT_SETTINGS.sidebarWidth
         }

src/renderer/db/tabRepository.ts

@@ -14,5 +14,14 @@ export const tabRepository = {
 
   async clearAll(): Promise<void> {
     await db.tabSnapshots.clear()
+  },
+
+  async saveActiveTabId(tabId: string | null): Promise<void> {
+    await db.activeTab.put({ id: 'current', activeTabId: tabId })
+  },
+
+  async loadActiveTabId(): Promise<string | null> {
+    const record = await db.activeTab.get('current')
+    return record?.activeTabId ?? null
   }
 }

src/renderer/hooks/useFileWatch.ts

@@ -7,15 +7,13 @@ export function useFileWatch() {
   useEffect(() => {
     if (!window.electronAPI) return
 
-    window.electronAPI.onExternalModification((filePath: string) => {
+    const unsubscribe = window.electronAPI.onExternalModification((filePath: string) => {
       const tab = getActiveTab()
       if (tab && tab.filePath === filePath) {
         window.dispatchEvent(new CustomEvent('file-externally-modified', { detail: filePath }))
       }
     })
 
-    return () => {
+    return unsubscribe
-      window.electronAPI?.removeAllListeners('file:externallyModified')
-    }
   }, [getActiveTab])
 }

src/renderer/hooks/useKeyboard.ts

@@ -12,9 +12,8 @@ export function useKeyboard(handleOpenFile: () => void, handleSave: () => void,
     if (isCtrl && e.key === 'o') { e.preventDefault(); handleOpenFile(); return }
     if (isCtrl && e.key === 's' && !e.shiftKey) { e.preventDefault(); handleSave(); return }
     if (isCtrl && e.shiftKey && e.key === 'S') { e.preventDefault(); handleSaveAs(); return }
-    if (isCtrl && e.key === '1') { e.preventDefault(); setViewMode('split'); return }
+    if (isCtrl && e.key === '1') { e.preventDefault(); setViewMode('editor'); return }
-    if (isCtrl && e.key === '2') { e.preventDefault(); setViewMode('editor'); return }
+    if (isCtrl && e.key === '2') { e.preventDefault(); setViewMode('preview'); return }
-    if (isCtrl && e.key === '3') { e.preventDefault(); setViewMode('preview'); return }
 
     const tabState = useTabStore.getState()
     if (isCtrl && e.key === 't') { e.preventDefault(); tabState.createTab(null, ''); return }

src/renderer/hooks/useSettings.ts

@@ -5,17 +5,14 @@ import type { ViewMode } from '../types/settings'
 
 export function useSettings() {
   const viewMode = useEditorStore(s => s.viewMode)
-  const splitRatio = useEditorStore(s => s.splitRatio)
   const setViewMode = useEditorStore(s => s.setViewMode)
-  const setSplitRatio = useEditorStore(s => s.setSplitRatio)
 
   // 初始化
   useEffect(() => {
     settingsRepository.load().then(settings => {
-      setViewMode(settings.viewMode ?? 'split')
+      setViewMode(settings.viewMode ?? 'editor')
-      setSplitRatio(settings.splitRatio ?? 50)
     })
-  }, [setViewMode, setSplitRatio])
+  }, [setViewMode])
 
   // M-10: 使用 useCallback 稳定函数引用
   const saveViewMode = useCallback((mode: ViewMode) => {
@@ -23,10 +20,5 @@ export function useSettings() {
     settingsRepository.save({ viewMode: mode })
   }, [setViewMode])
 
-  const saveSplitRatio = useCallback((ratio: number) => {
+  return { viewMode, saveViewMode }
-    setSplitRatio(ratio)
-    settingsRepository.save({ splitRatio: ratio })
-  }, [setSplitRatio])
-
-  return { viewMode, splitRatio, saveViewMode, saveSplitRatio }
 }

src/renderer/hooks/useUnsavedWarning.ts

@@ -15,7 +15,7 @@ export function useUnsavedWarning(hasUnsaved: () => boolean) {
 
     const api = window.electronAPI
 
-    api.onConfirmClose(() => {
+    const unsubscribe = api.onConfirmClose(() => {
       if (!hasUnsaved()) {
         api.forceClose()
         return
@@ -28,8 +28,6 @@ export function useUnsavedWarning(hasUnsaved: () => boolean) {
       }
     })
 
-    return () => {
+    return unsubscribe
-      api.removeAllListeners('window:confirmClose')
-    }
   }, [hasUnsaved])
 }

src/renderer/lib/constants.ts

@@ -5,9 +5,4 @@ export const SKIP_DIRS = new Set([
   'node_modules', '.git', '.svn', '.hg', 'dist', 'out',
   '.next', '.nuxt', '__pycache__', '.DS_Store'
 ])
-export const MARKDOWN_EXTS = new Set(['.md', '.markdown', '.txt'])
+
-export const UPDATE_DEBOUNCE_MS = 150
-export const LARGE_FILE_LINE_THRESHOLD = 2000
-export const CLOSE_TIMEOUT_MS = 5000
-export const WATCH_RESTART_DELAY_MS = 300
-export const DIR_REFRESH_DEBOUNCE_MS = 300

src/renderer/lib/fileUtils.ts

@@ -1,11 +1,5 @@
 import { ALLOWED_EXTENSIONS } from './constants'
 
-export function formatBytes(bytes: number): string {
-  if (bytes < 1024) return bytes + ' B'
-  if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + ' KB'
-  return (bytes / (1024 * 1024)).toFixed(1) + ' MB'
-}
-
 export function getFileName(filePath: string): string {
   return filePath.split(/[/\\]/).pop() || filePath
 }

src/renderer/lib/markdown.ts

@@ -7,7 +7,6 @@ import rehypeSanitize, { defaultSchema } from 'rehype-sanitize'
 import rehypeStringify from 'rehype-stringify'
 import rehypeHighlight from 'rehype-highlight'
 import type { Element, Root } from 'hast'
-import { rehypeSourceLine } from './rehypeSourceLine'
 
 // 自定义 rehype 插件：将相对路径图片转为 file:// 绝对路径
 function rehypeFixImages(filePath: string | null): Plugin<[], Root> {
@@ -58,7 +57,6 @@ export async function renderMarkdown(content: string, filePath?: string | null):
         }
       })
       .use(rehypeFixImages(filePath ?? null))
-      .use(rehypeSourceLine)
       .use(rehypeHighlight)
       .use(rehypeStringify)
 

src/renderer/lib/rehypeSourceLine.ts

@@ -1,36 +0,0 @@
-import { visit } from 'unist-util-visit'
-import type { Root, Element } from 'hast'
-
-/**
- * Rehype 插件：给块级元素注入 data-line 属性
- *
- * 利用 unified/remark 管线自动维护的 position 信息，
- * 将源文件行号附加到渲染后的 HTML 元素上，
- * 用于编辑器↔预览的滚动同步（VS Code 方案）。
- */
-export function rehypeSourceLine() {
-  return (tree: Root) => {
-    visit(tree, 'element', (node: Element) => {
-      const pos = node.position
-      if (!pos?.start?.line) return
-
-      // position.start.line 是 1-indexed，转为 0-indexed
-      const line = pos.start.line - 1
-
-      node.properties = {
-        ...node.properties,
-        'data-line': String(line),
-      }
-
-      // 追加 code-line class（保留原有 class）
-      const existing = node.properties?.class
-      if (typeof existing === 'string') {
-        node.properties.class = `${existing} code-line`
-      } else if (Array.isArray(existing)) {
-        node.properties.class = [...existing, 'code-line']
-      } else {
-        node.properties.class = 'code-line'
-      }
-    })
-  }
-}

src/renderer/lib/scrollSync.ts

@@ -1,164 +0,0 @@
-/**
- * 滚动同步 — VS Code 方案
- *
- * 核心思路：
- * 1. 渲染时 rehypeSourceLine 插件给块级元素注入 data-line 属性
- * 2. 预览侧收集所有 [data-line] 元素，按行号排序
- * 3. 编辑器派发当前行号 → 二分查找对应元素 → 线性插值滚动
- * 4. 预览侧反向映射：像素偏移 → 行号 → 通知编辑器
- */
-
-interface CodeLineElement {
-  element: HTMLElement
-  line: number
-  top: number
-  height: number
-}
-
-let cachedElements: CodeLineElement[] | null = null
-let cachedHTML = ''
-
-/**
- * 收集并缓存所有带 data-line 的元素，按行号排序
- */
-function getCodeLineElements(container: HTMLElement): CodeLineElement[] {
-  const html = container.innerHTML
-  if (cachedElements && cachedHTML === html) return cachedElements
-
-  cachedHTML = html
-  const els = container.querySelectorAll<HTMLElement>('[data-line]')
-  const result: CodeLineElement[] = []
-
-  for (const el of els) {
-    const line = parseInt(el.getAttribute('data-line')!, 10)
-    if (isNaN(line)) continue
-    // 跳过不可见元素
-    if (el.offsetHeight === 0) continue
-    result.push({
-      element: el,
-      line,
-      top: el.offsetTop,
-      height: el.offsetHeight,
-    })
-  }
-
-  result.sort((a, b) => a.line - b.line)
-  cachedElements = result
-  return result
-}
-
-/**
- * 使缓存失效（内容变化后调用）
- */
-export function invalidateScrollCache(): void {
-  cachedElements = null
-  cachedHTML = ''
-}
-
-/**
- * 二分查找：找到目标行对应的元素（精确匹配或前后夹逼）
- */
-function findElementsForLine(
-  elements: CodeLineElement[],
-  targetLine: number,
-): { previous: CodeLineElement; next: CodeLineElement | null } {
-  let lo = 0
-  let hi = elements.length - 1
-
-  // 二分查找最后一个 line <= targetLine 的元素
-  while (lo < hi) {
-    const mid = Math.floor((lo + hi + 1) / 2)
-    if (elements[mid].line <= targetLine) {
-      lo = mid
-    } else {
-      hi = mid - 1
-    }
-  }
-
-  const previous = elements[lo]
-  const next = lo < elements.length - 1 ? elements[lo + 1] : null
-
-  return { previous, next }
-}
-
-/**
- * 编辑器滚动 → 预览滚动
- *
- * @param line 编辑器当前可见区域顶部对应的源文件行号（0-indexed，支持小数表示行内偏移）
- * @param previewContainer 预览面板的滚动容器（#preview-panel）
- * @param isSyncingRef 双向同步锁，防止循环触发
- */
-export function scrollPreviewToLine(
-  line: number,
-  previewContainer: HTMLElement,
-  isSyncingRef: { current: boolean },
-): void {
-  const elements = getCodeLineElements(previewContainer)
-  if (elements.length === 0) return
-
-  isSyncingRef.current = true
-
-  const lineNumber = Math.floor(line)
-  const fraction = line - lineNumber
-
-  const { previous, next } = findElementsForLine(elements, lineNumber)
-
-  let scrollTo: number
-
-  if (previous.line === lineNumber) {
-    // 精确匹配：滚动到该元素顶部
-    scrollTo = previous.top + fraction * previous.height
-  } else if (next && next.line !== previous.line) {
-    // 在两个元素之间：线性插值
-    const progress = (lineNumber - previous.line + fraction) / (next.line - previous.line)
-    const gapTop = previous.top + previous.height
-    const gapHeight = next.top - gapTop
-    scrollTo = gapTop + progress * (previous.height + gapHeight)
-  } else {
-    // 最后一个元素之后：按行内比例偏移
-    scrollTo = previous.top + fraction * previous.height
-  }
-
-  previewContainer.scrollTo(0, Math.max(0, scrollTo))
-
-  requestAnimationFrame(() => {
-    isSyncingRef.current = false
-  })
-}
-
-/**
- * 预览滚动 → 编辑器行号（用于反向同步）
- *
- * @param scrollTop 预览面板的 scrollTop
- * @param previewContainer 预览面板的滚动容器
- * @returns 对应的源文件行号（0-indexed），无元素时返回 null
- */
-export function getLineAtScrollOffset(
-  scrollTop: number,
-  previewContainer: HTMLElement,
-): number | null {
-  const elements = getCodeLineElements(previewContainer)
-  if (elements.length === 0) return null
-
-  const position = scrollTop
-
-  // 二分查找最后一个 top <= position 的元素
-  let lo = 0
-  let hi = elements.length - 1
-  while (lo < hi) {
-    const mid = Math.floor((lo + hi + 1) / 2)
-    if (elements[mid].top <= position) {
-      lo = mid
-    } else {
-      hi = mid - 1
-    }
-  }
-
-  const el = elements[lo]
-  if (el.height === 0) return el.line
-
-  const progress = Math.min(1, Math.max(0, (position - el.top) / el.height))
-  const nextLine = lo < elements.length - 1 ? elements[lo + 1].line : el.line + 1
-
-  return el.line + progress * (nextLine - el.line)
-}

src/renderer/stores/editorStore.ts

@@ -4,21 +4,17 @@ import type { ViewMode } from '../types/settings'
 interface EditorState {
   viewMode: ViewMode
   darkMode: boolean
-  splitRatio: number
 
   setViewMode: (mode: ViewMode) => void
   setDarkMode: (dark: boolean) => void
-  setSplitRatio: (ratio: number) => void
   toggleDarkMode: () => void
 }
 
 export const useEditorStore = create<EditorState>((set) => ({
-  viewMode: 'split',
+  viewMode: 'editor',
   darkMode: false,
-  splitRatio: 50,
 
   setViewMode: (mode) => set({ viewMode: mode }),
   setDarkMode: (dark) => set({ darkMode: dark }),
-  setSplitRatio: (ratio) => set({ splitRatio: ratio }),
   toggleDarkMode: () => set(state => ({ darkMode: !state.darkMode }))
 }))

src/renderer/stores/sidebarStore.ts

@@ -1,5 +1,6 @@
 import { create } from 'zustand'
 import type { FileNode } from '../types/file'
+import { settingsRepository } from '../db/settingsRepository'
 
 interface SidebarState {
   isVisible: boolean
@@ -7,6 +8,7 @@ interface SidebarState {
   tree: FileNode[]
   expandedDirs: Set<string>
   sidebarWidth: number
+  _loaded: boolean
 
   setVisible: (visible: boolean) => void
   setRootPath: (path: string | null) => void
@@ -14,16 +16,37 @@ interface SidebarState {
   toggleDir: (path: string) => void
   expandDirs: (paths: string[]) => void
   setSidebarWidth: (width: number) => void
+  loadFromDB: () => Promise<void>
 }
 
-export const useSidebarStore = create<SidebarState>((set) => ({
+export const useSidebarStore = create<SidebarState>((set, get) => ({
   isVisible: true,
   rootPath: null,
   tree: [],
   expandedDirs: new Set<string>(),
   sidebarWidth: 240,
+  _loaded: false,
 
-  setVisible: (visible) => set({ isVisible: visible }),
+  // 从 IndexedDB 加载 sidebar 设置
+  loadFromDB: async () => {
+    if (get()._loaded) return
+    try {
+      const settings = await settingsRepository.load()
+      set({
+        isVisible: !settings.sidebarCollapsed,
+        sidebarWidth: settings.sidebarWidth,
+        _loaded: true
+      })
+    } catch {
+      set({ _loaded: true })
+    }
+  },
+
+  setVisible: (visible) => {
+    set({ isVisible: visible })
+    // 异步保存到 DB
+    settingsRepository.save({ sidebarCollapsed: !visible })
+  },
   setRootPath: (path) => set({ rootPath: path }),
   setTree: (tree) => set({ tree }),
   toggleDir: (path) =>
@@ -48,5 +71,9 @@ export const useSidebarStore = create<SidebarState>((set) => ({
       }
       return changed ? { expandedDirs: newSet } : state
     }),
-  setSidebarWidth: (width) => set({ sidebarWidth: width })
+  setSidebarWidth: (width) => {
+    set({ sidebarWidth: width })
+    // 异步保存到 DB
+    settingsRepository.save({ sidebarWidth: width })
+  }
 }))

src/renderer/stores/tabStore.ts

@@ -18,8 +18,7 @@ interface TabState {
   updateTabContent: (tabId: string, content: string) => void
   setModified: (tabId: string, modified: boolean) => void
   getActiveTab: () => Tab | null
-  getTabIndex: (tabId: string) => number
+  updateTabScroll: (tabId: string, scroll: Partial<Pick<Tab, 'scrollTop' | 'selectionStart' | 'selectionEnd'>>) => void
-  updateTabScroll: (tabId: string, scroll: Partial<Pick<Tab, 'scrollTop' | 'scrollLeft' | 'selectionStart' | 'selectionEnd' | 'previewScrollTop'>>) => void
   loadFromDB: () => Promise<void>
   saveToDB: () => Promise<void>
 }
@@ -34,7 +33,10 @@ export const useTabStore = create<TabState>((set, get) => ({
   loadFromDB: async () => {
     if (get()._loaded) return
     try {
-      const snapshots = await tabRepository.loadAll()
+      const [snapshots, savedActiveTabId] = await Promise.all([
+        tabRepository.loadAll(),
+        tabRepository.loadActiveTabId()
+      ])
       if (snapshots.length > 0) {
         const tabs: Tab[] = snapshots.map(s => ({
           id: s.id,
@@ -42,14 +44,16 @@ export const useTabStore = create<TabState>((set, get) => ({
           content: s.content,
           isModified: s.isModified,
           scrollTop: s.scrollTop,
-          scrollLeft: s.scrollLeft,
           selectionStart: s.selectionStart,
-          selectionEnd: s.selectionEnd,
+          selectionEnd: s.selectionEnd
-          previewScrollTop: s.previewScrollTop
         }))
+        // 使用保存的 activeTabId，如果不存在则取最后一个
+        const activeTabId = (savedActiveTabId && tabs.find(t => t.id === savedActiveTabId))
+          ? savedActiveTabId
+          : tabs[tabs.length - 1].id
         set({
           tabs,
-          activeTabId: tabs[tabs.length - 1].id,
+          activeTabId,
           _loaded: true
         })
       } else {
@@ -73,13 +77,12 @@ export const useTabStore = create<TabState>((set, get) => ({
       content: t.content,
       isModified: t.isModified,
       scrollTop: t.scrollTop,
-      scrollLeft: t.scrollLeft,
       selectionStart: t.selectionStart,
       selectionEnd: t.selectionEnd,
-      previewScrollTop: t.previewScrollTop,
       updatedAt: Date.now()
     }))
     await tabRepository.saveAll(snapshots)
+    await tabRepository.saveActiveTabId(get().activeTabId)
   },
 
   createTab: (filePath = null, content = '') => {
@@ -97,10 +100,8 @@ export const useTabStore = create<TabState>((set, get) => ({
       content,
       isModified: false,
       scrollTop: 0,
-      scrollLeft: 0,
       selectionStart: 0,
-      selectionEnd: 0,
+      selectionEnd: 0
-      previewScrollTop: 0
     }
 
     set(state => ({
@@ -187,6 +188,8 @@ export const useTabStore = create<TabState>((set, get) => ({
         : state.mruStack
       return { activeTabId: tabId, mruStack: newMru }
     })
+    // 异步保存 activeTabId
+    setTimeout(() => tabRepository.saveActiveTabId(tabId), 0)
   },
 
   updateTabContent: (tabId, content) => {
@@ -210,10 +213,6 @@ export const useTabStore = create<TabState>((set, get) => ({
     return tabs.find(t => t.id === activeTabId) ?? null
   },
 
-  getTabIndex: (tabId) => {
-    return get().tabs.findIndex(t => t.id === tabId)
-  },
-
   updateTabScroll: (tabId, scroll) => {
     set(state => ({
       tabs: state.tabs.map(t =>

src/renderer/styles/global.css

@@ -447,19 +447,6 @@ html, body {
   border-left-color: var(--text);
 }
 
-/* Resizer */
-#resizer {
-  width: 4px;
-  background: var(--border);
-  cursor: col-resize;
-  transition: background 0.15s ease;
-  flex-shrink: 0;
-}
-
-#resizer:hover, #resizer.active {
-  background: var(--primary);
-}
-
 /* Preview Panel */
 #preview-panel {
   flex: 1;
@@ -1031,11 +1018,8 @@ html, body {
 }
 
 /* View Modes */
-#app.mode-preview #editor-panel,
+#app.mode-preview #editor-panel { display: none; }
-#app.mode-preview #resizer { display: none; }
+#app.mode-editor #preview-panel { display: none; }
-
-#app.mode-editor #preview-panel,
-#app.mode-editor #resizer { display: none; }
 
 /* Toast */
 #toast-notification {

src/renderer/types/ipc.ts

@@ -26,6 +26,8 @@ export interface IpcInvokeMap {
   'dir:unwatch': [void, void]
 }
 
+export type Unsubscribe = () => void
+
 export interface ElectronAPI {
   openFile: () => Promise<OpenFileResponse>
   readFile: (filePath: string) => Promise<ReadFileResult>
@@ -42,14 +44,13 @@ export interface ElectronAPI {
   openFolderDialog: () => Promise<string | null>
   watchDir: (dirPath: string) => Promise<void>
   unwatchDir: () => Promise<void>
-  onFileOpenInTab: (callback: (data: { filePath: string; content: string }) => void) => void
+  onFileOpenInTab: (callback: (data: { filePath: string; content: string }) => void) => Unsubscribe
-  onMenuSave: (callback: () => void) => void
+  onMenuSave: (callback: () => void) => Unsubscribe
-  onMenuSaveAs: (callback: () => void) => void
+  onMenuSaveAs: (callback: () => void) => Unsubscribe
-  onViewModeChange: (callback: (mode: string) => void) => void
+  onViewModeChange: (callback: (mode: string) => void) => Unsubscribe
-  onExternalModification: (callback: (filePath: string) => void) => void
+  onExternalModification: (callback: (filePath: string) => void) => Unsubscribe
-  onDirChanged: (callback: () => void) => void
+  onDirChanged: (callback: () => void) => Unsubscribe
-  onConfirmClose: (callback: () => void) => void
+  onConfirmClose: (callback: () => void) => Unsubscribe
-  removeAllListeners: (channel: string) => void
 }
 
 declare global {

src/renderer/types/settings.ts

@@ -1,17 +1,15 @@
-export type ViewMode = 'split' | 'editor' | 'preview'
+export type ViewMode = 'editor' | 'preview'
 
 export interface Settings {
   darkMode: boolean
   viewMode: ViewMode
-  splitRatio: number
   sidebarCollapsed: boolean
   sidebarWidth: number
 }
 
 export const DEFAULT_SETTINGS: Settings = {
   darkMode: false,
-  viewMode: 'split',
+  viewMode: 'editor',
-  splitRatio: 50,
   sidebarCollapsed: false,
   sidebarWidth: 240
 }

src/renderer/types/tab.ts

@@ -4,8 +4,6 @@ export interface Tab {
   content: string
   isModified: boolean
   scrollTop: number
-  scrollLeft: number
   selectionStart: number
   selectionEnd: number
-  previewScrollTop: number
 }