feat: improve error logging and enhance settings sync functionality

app/api/settings/route.ts

@@ -47,7 +47,9 @@ export async function GET(request: NextRequest) {
     }
     return NextResponse.json({ settings });
   } catch (error) {
-    logger.error('Settings load error', { error: error instanceof Error ? error.message : 'Unknown error' });
+    const message = error instanceof Error ? error.message : 'Unknown error';
+    const code = (error as NodeJS.ErrnoException).code;
+    logger.error('Settings load error', { error: message, code });
     return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
   }
 }
@@ -74,7 +76,9 @@ export async function POST(request: NextRequest) {
     await saveUserSettings(username, serverUrl, settings);
     return NextResponse.json({ ok: true });
   } catch (error) {
-    logger.error('Settings save error', { error: error instanceof Error ? error.message : 'Unknown error' });
+    const message = error instanceof Error ? error.message : 'Unknown error';
+    const code = (error as NodeJS.ErrnoException).code;
+    logger.error('Settings save error', { error: message, code });
     return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
   }
 }

lib/settings-sync.ts

@@ -1,5 +1,5 @@
 import { createHash, createCipheriv, createDecipheriv, randomBytes } from 'node:crypto';
-import { readFile, writeFile, unlink, mkdir } from 'node:fs/promises';
+import { readFile, writeFile, unlink, mkdir, rename } from 'node:fs/promises';
 import { existsSync } from 'node:fs';
 import path from 'node:path';
 import { logger } from '@/lib/logger';
@@ -45,7 +45,10 @@ export async function saveUserSettings(username: string, serverUrl: string, sett
   const tag = cipher.getAuthTag();
 
   const data = Buffer.concat([iv, tag, encrypted]);
-  await writeFile(getSettingsPath(username, serverUrl), data);
+  const targetPath = getSettingsPath(username, serverUrl);
+  const tmpPath = targetPath + '.tmp';
+  await writeFile(tmpPath, data);
+  await rename(tmpPath, targetPath);
 }
 
 export async function loadUserSettings(username: string, serverUrl: string): Promise<Record<string, unknown> | null> {

stores/settings-store.ts

@@ -562,26 +562,34 @@ if (typeof window !== 'undefined') {
   applyAnimations(store.animationsEnabled);
 
   // Shared sync function used by all store subscribers
+  const syncToServer = async (retries = 1): Promise<void> => {
+    const settings = JSON.parse(useSettingsStore.getState().exportSettings());
+    syncLog('Syncing settings to server...');
+    const res = await fetch('/api/settings', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ username: syncUsername, serverUrl: syncServerUrl, settings }),
+    });
+    if (res.status === 404) {
+      syncWarn('Settings sync endpoint returned 404, disabling sync');
+      syncEnabled = false;
+    } else if (res.status >= 500 && retries > 0) {
+      syncWarn('Settings sync got server error, retrying...');
+      await new Promise((r) => setTimeout(r, 2000));
+      return syncToServer(retries - 1);
+    } else if (!res.ok) {
+      syncError('Settings sync failed with status', res.status);
+    } else {
+      syncLog('Settings synced to server successfully');
+    }
+  };
+
   const triggerSync = () => {
     if (!syncEnabled || !syncUsername || !syncServerUrl || isLoadingFromServer) return;
     if (syncTimeout) clearTimeout(syncTimeout);
     syncTimeout = setTimeout(async () => {
       try {
-        const settings = JSON.parse(useSettingsStore.getState().exportSettings());
+        await syncToServer();
-        syncLog('Syncing settings to server...');
-        const res = await fetch('/api/settings', {
-          method: 'POST',
-          headers: { 'Content-Type': 'application/json' },
-          body: JSON.stringify({ username: syncUsername, serverUrl: syncServerUrl, settings }),
-        });
-        if (res.status === 404) {
-          syncWarn('Settings sync endpoint returned 404, disabling sync');
-          syncEnabled = false;
-        } else if (!res.ok) {
-          syncError('Settings sync failed with status', res.status);
-        } else {
-          syncLog('Settings synced to server successfully');
-        }
       } catch (error) {
         syncError('Settings sync error:', error);
       }