修复：close超时保护、移除冗余变量、优化文件大小计算、去重formatBytes

main.js

@@ -6,7 +6,6 @@ let mainWindow = null;
 let currentFilePath = null;
 let pendingFilePath = null;
 let fileWatcher = null;
-let isModifiedExternally = false;
 
 function createWindow() {
   mainWindow = new BrowserWindow({
@@ -39,11 +38,24 @@ function createWindow() {
 
   mainWindow.setMenu(null);
 
-  // Unsaved changes warning on close
+  // Unsaved changes warning on close (with timeout fallback)
   mainWindow.on('close', (e) => {
-    mainWindow.webContents.send('window:closing');
     e.preventDefault();
-    mainWindow.webContents.send('window:confirmClose');
+    try {
+      mainWindow.webContents.send('window:confirmClose');
+    } catch (err) {
+      // Renderer is gone, force close
+      mainWindow.removeAllListeners('close');
+      mainWindow.close();
+      return;
+    }
+    // Safety: if renderer doesn't respond within 5s, force close
+    setTimeout(() => {
+      if (mainWindow && !mainWindow.isDestroyed()) {
+        mainWindow.removeAllListeners('close');
+        mainWindow.close();
+      }
+    }, 5000);
   });
 
   mainWindow.on('closed', () => {
@@ -56,7 +68,6 @@ function createWindow() {
 function startWatching(filePath) {
   stopWatching();
   try {
-    isModifiedExternally = false;
     fileWatcher = fs.watch(filePath, (eventType) => {
       if (eventType === 'change' && mainWindow && !mainWindow.isDestroyed()) {
         isModifiedExternally = true;
@@ -201,7 +212,6 @@ ipcMain.handle('file:reload', async () => {
   if (!currentFilePath) return { success: false, error: '没有打开的文件' };
   try {
     const content = fs.readFileSync(currentFilePath, 'utf-8');
-    isModifiedExternally = false;
     return { success: true, content, filePath: currentFilePath };
   } catch (err) {
     return { success: false, error: err.message };