fix: multiple backup import issues found in code review

- Single atomic write instead of two-phase (prevents split state on crash)
- Timestamped pre-import backup (multiple imports don't overwrite safety net)
- Fix UI refresh: correct function names + refresh globalSettings/alwaysOnTop
- Zero sensitive buffers (key, plaintext, decrypted) after use

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/backup-crypto.js

@@ -27,6 +27,8 @@ function encrypt(config, password) {
   const encrypted = Buffer.concat([cipher.update(plaintext), cipher.final()]);
   const tag = cipher.getAuthTag();
 
+  plaintext.fill(0);
+  key.fill(0);
   return Buffer.concat([MAGIC, salt, iv, tag, encrypted]);
 }
 
@@ -65,6 +67,9 @@ function decrypt(buffer, password) {
     return JSON.parse(decrypted.toString('utf-8'));
   } catch {
     throw new Error('Entschlüsselte Daten sind kein gültiges JSON');
+  } finally {
+    decrypted.fill(0);
+    key.fill(0);
   }
 }
 

main.js

@@ -649,17 +649,19 @@ ipcMain.handle('import-backup', async (_event, password) => {
   });
   if (canceled || !filePaths.length) return { ok: false, canceled: true };
   const buffer = fs.readFileSync(filePaths[0]);
-  const config = backupCrypto.decrypt(buffer, password);
-  // Safety net: save current config before overwriting
-  const preImportPath = configStore.filePath + '.pre-import.json';
+  const imported = backupCrypto.decrypt(buffer, password);
+  // Safety net: timestamped backup so multiple imports don't overwrite each other
+  const ts = new Date().toISOString().replace(/[:.]/g, '-');
+  const preImportPath = configStore.filePath.replace('.json', `.pre-import-${ts}.json`);
   try { fs.copyFileSync(configStore.filePath, preImportPath); } catch {}
-  await configStore.save(config);
-  if (config.history) {
-    // Overwrite history too (save() doesn't touch history)
-    const full = configStore.load();
-    full.history = config.history;
-    await configStore._atomicWrite(JSON.stringify(full, null, 2));
-  }
+  // Single atomic write — no split state, no TOCTOU race
+  const merged = {
+    hosters: imported.hosters,
+    hosterSettings: imported.hosterSettings,
+    globalSettings: imported.globalSettings,
+    history: imported.history || []
+  };
+  await configStore._atomicWrite(JSON.stringify(merged, null, 2));
   return { ok: true, config: configStore.load() };
 });
 

renderer/app.js

@@ -857,9 +857,14 @@ async function confirmBackupAction() {
       if (result.ok) {
         config = result.config;
         hosterSettings = config.hosterSettings || {};
+        // Refresh global settings state (always-on-top, etc.)
+        alwaysOnTopState = !!(config.globalSettings && config.globalSettings.alwaysOnTop);
+        window.api.setAlwaysOnTop(alwaysOnTopState);
         closeBackupModal();
-        renderSettingsPanel();
-        renderAccountsList();
+        renderSettings();
+        renderAccounts();
+        renderHosterSummary();
+        renderHosterModal();
         loadHistory();
         showCopyToast('Backup importiert');
       }