fix: save写入失败时恢复文件监听、窗口销毁安全检查、暗色主题跟随系统偏好

main.js

@@ -159,15 +159,34 @@ function openFileInTab(filePath) {
 function switchActiveFile(filePath) {
   activeFilePath = filePath || null;
   startWatching(filePath);
-  if (filePath) {
-    mainWindow.setTitle(`MarkLite - ${path.basename(filePath)}`);
-  } else {
-    mainWindow.setTitle('MarkLite');
+  if (mainWindow && !mainWindow.isDestroyed()) {
+    if (filePath) {
+      mainWindow.setTitle(`MarkLite - ${path.basename(filePath)}`);
+    } else {
+      mainWindow.setTitle('MarkLite');
+    }
   }
 }
 
 // IPC Handlers
 
+// Save file to a specific path with watcher management
+function saveToPath(filePath, content) {
+  stopWatching();
+  try {
+    fs.writeFileSync(filePath, content, 'utf-8');
+  } catch (err) {
+    startWatching(activeFilePath); // Restore watcher on failure
+    return { success: false, error: err.message };
+  }
+  activeFilePath = filePath;
+  startWatching(filePath);
+  if (mainWindow && !mainWindow.isDestroyed()) {
+    mainWindow.setTitle(`MarkLite - ${path.basename(filePath)}`);
+  }
+  return { success: true, filePath };
+}
+
 // Open single file via dialog
 ipcMain.handle('dialog:openFile', async () => {
   try {
@@ -198,12 +217,7 @@ ipcMain.handle('file:read', async (event, filePath) => {
 ipcMain.handle('file:save', async (event, { filePath, content }) => {
   try {
     if (filePath) {
-      stopWatching();
-      fs.writeFileSync(filePath, content, 'utf-8');
-      activeFilePath = filePath;
-      startWatching(filePath);
-      mainWindow.setTitle(`MarkLite - ${path.basename(filePath)}`);
-      return { success: true, filePath };
+      return saveToPath(filePath, content);
     } else {
       const result = await dialog.showSaveDialog(mainWindow, {
         filters: [
@@ -211,12 +225,7 @@ ipcMain.handle('file:save', async (event, { filePath, content }) => {
         ]
       });
       if (!result.canceled) {
-        stopWatching();
-        fs.writeFileSync(result.filePath, content, 'utf-8');
-        activeFilePath = result.filePath;
-        startWatching(result.filePath);
-        mainWindow.setTitle(`MarkLite - ${path.basename(result.filePath)}`);
-        return { success: true, filePath: result.filePath };
+        return saveToPath(result.filePath, content);
       }
       return { success: false, canceled: true };
     }
@@ -233,12 +242,7 @@ ipcMain.handle('file:saveAs', async (event, { content }) => {
       ]
     });
     if (!result.canceled) {
-      stopWatching();
-      fs.writeFileSync(result.filePath, content, 'utf-8');
-      activeFilePath = result.filePath;
-      startWatching(result.filePath);
-      mainWindow.setTitle(`MarkLite - ${path.basename(result.filePath)}`);
-      return { success: true, filePath: result.filePath };
+      return saveToPath(result.filePath, content);
     }
     return { success: false, canceled: true };
   } catch (err) {

renderer/renderer.js

@@ -85,7 +85,9 @@
       iconLight.style.display = isDark ? '' : 'none';
     }
 
-    apply(!!settings.darkMode);
+    // Respect system preference if no saved setting
+    const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
+    apply(settings.darkMode !== undefined ? !!settings.darkMode : prefersDark);
 
     btnDark.addEventListener('click', () => {
       const isDark = !document.documentElement.classList.contains('dark');