Update src/config/passport.js

src/config/passport.js

@@ -2,6 +2,24 @@ import passport from 'passport';
 import { Strategy as GoogleStrategy } from 'passport-google-oauth20';
 import User from '../models/User.js';
 
+async function generateUniqueUsername(email) {
+  const base = email
+    .split('@')[0]
+    .toLowerCase()
+    .replace(/[^a-z0-9]/g, '_')
+    .slice(0, 15); // leave room for suffix
+
+  let username = base;
+  let suffix = 0;
+
+  while (await User.exists({ username })) {
+    suffix += 1;
+    username = `${base}_${suffix}`;
+  }
+
+  return username;
+}
+
 passport.serializeUser((user, done) => {
   done(null, user.id); // Save only ID to session
 });
@@ -32,10 +50,16 @@ passport.use(
           return done(null, existingUser);
         }
 
+        const email = profile.emails[0].value;
+
+        // 👇 AUTO-GENERATE USERNAME
+        const username = await generateUniqueUsername(email);
+
         // Create new user
         const newUser = await new User({
           googleId: profile.id,
           email: profile.emails[0].value,
+          username,
           displayName: profile.displayName,
           firstName: profile.name.givenName,
           lastName: profile.name.familyName