Fix: Relax Helmet CSP for SPA and improve static file serving

backend/src/app.js

@@ -12,8 +12,32 @@ const { apiLimiter } = require('./middlewares/rateLimiter');
 const app = express();
 const PORT = process.env.PORT || 3000;
 
-// Security middleware
-app.use(helmet());
+// Security middleware with relaxed CSP for SPA
+app.use(
+  helmet({
+    contentSecurityPolicy: {
+      directives: {
+        defaultSrc: ["'self'"],
+        scriptSrc: [
+          "'self'",
+          "'unsafe-inline'", // Required for Vite HMR and some inline scripts
+          "'unsafe-eval'", // Required for Vite dev mode
+        ],
+        styleSrc: [
+          "'self'",
+          "'unsafe-inline'", // Required for inline styles
+        ],
+        imgSrc: ["'self'", "data:", "https:"],
+        fontSrc: ["'self'", "data:", "https:"],
+        connectSrc: ["'self'", "https:", "http:", "ws:", "wss:"], // Allow API calls
+        frameSrc: ["'none'"],
+        objectSrc: ["'none'"],
+        upgradeInsecureRequests: [], // Upgrade HTTP to HTTPS if needed
+      },
+    },
+    crossOriginEmbedderPolicy: false, // Disable for better compatibility
+  })
+);
 
 // Dynamic CORS configuration
 // Development: Allow ALL origins (no restrictions)
@@ -105,7 +129,22 @@ const path = require('path');
 const frontendDistPath = path.join(__dirname, '../../frontend/dist');
 const fs = require('fs');
 if (fs.existsSync(frontendDistPath)) {
-  app.use(express.static(frontendDistPath));
+  // Serve static files with proper headers for SPA
+  app.use(express.static(frontendDistPath, {
+    maxAge: '1y', // Cache static assets
+    etag: true,
+    lastModified: true,
+    setHeaders: (res, path) => {
+      // Set proper content type for JS/CSS files
+      if (path.endsWith('.js')) {
+        res.setHeader('Content-Type', 'application/javascript');
+      } else if (path.endsWith('.css')) {
+        res.setHeader('Content-Type', 'text/css');
+      }
+      // Allow CORS for assets (if needed)
+      res.setHeader('Access-Control-Allow-Origin', '*');
+    },
+  }));
 }
 
 // Session middleware