diff --git a/components/AuthGate.tsx b/components/AuthGate.tsx
new file mode 100644
index 0000000..697ea46
--- /dev/null
+++ b/components/AuthGate.tsx
@@ -0,0 +1,193 @@
+import React, { useEffect, useState } from 'react';
+import type { Session } from '@supabase/supabase-js';
+import { supabaseAuth } from '../services/authClient';
+import CrazeLogo from './CrazeLogo';
+
+type AuthMode = 'login' | 'signup' | 'check_email' | 'loading';
+
+interface AuthGateProps {
+  children: React.ReactNode;
+}
+
+export const AuthGate: React.FC<AuthGateProps> = ({ children }) => {
+  const [session, setSession] = useState<Session | null>(null);
+  const [mode, setMode] = useState<AuthMode>('loading');
+  const [email, setEmail] = useState('');
+  const [password, setPassword] = useState('');
+  const [error, setError] = useState('');
+  const [submitting, setSubmitting] = useState(false);
+
+  useEffect(() => {
+    supabaseAuth.auth.getSession().then(({ data }) => {
+      setSession(data.session);
+      setMode(data.session ? 'loading' : 'login');
+    });
+
+    const { data: listener } = supabaseAuth.auth.onAuthStateChange((_event, sess) => {
+      setSession(sess);
+      if (sess) setMode('loading');
+    });
+
+    return () => listener.subscription.unsubscribe();
+  }, []);
+
+  const handleSignUp = async (e: React.FormEvent) => {
+    e.preventDefault();
+    setError('');
+    setSubmitting(true);
+    const { error: err } = await supabaseAuth.auth.signUp({
+      email,
+      password,
+      options: { emailRedirectTo: window.location.origin },
+    });
+    setSubmitting(false);
+    if (err) {
+      setError(err.message);
+    } else {
+      setMode('check_email');
+    }
+  };
+
+  const handleLogin = async (e: React.FormEvent) => {
+    e.preventDefault();
+    setError('');
+    setSubmitting(true);
+    const { error: err } = await supabaseAuth.auth.signInWithPassword({ email, password });
+    setSubmitting(false);
+    if (err) setError(err.message);
+  };
+
+  const handleSignOut = async () => {
+    await supabaseAuth.auth.signOut();
+    setSession(null);
+    setMode('login');
+    setEmail('');
+    setPassword('');
+  };
+
+  // Session active — render app
+  if (session) {
+    return (
+      <>
+        {children}
+        <button
+          onClick={handleSignOut}
+          className="fixed top-3 right-16 z-50 text-[10px] text-slate-600 hover:text-slate-400 font-bold uppercase tracking-wider transition-colors hidden md:block"
+          title="Sign out"
+        >
+          Sign out
+        </button>
+      </>
+    );
+  }
+
+  // Email sent confirmation
+  if (mode === 'check_email') {
+    return (
+      <div className="min-h-screen flex items-center justify-center bg-slate-950 p-4">
+        <div className="w-full max-w-sm text-center">
+          <div className="text-5xl mb-6">📬</div>
+          <h2 className="text-xl font-black text-white mb-2">Check your email</h2>
+          <p className="text-sm text-slate-400 mb-6">
+            Confirmation link sent to <span className="text-white font-bold">{email}</span>.<br />
+            Click it to activate your account.
+          </p>
+          <button
+            onClick={() => setMode('login')}
+            className="text-xs text-slate-500 hover:text-slate-300 underline transition-colors"
+          >
+            Back to login
+          </button>
+        </div>
+      </div>
+    );
+  }
+
+  // Initial loading
+  if (mode === 'loading') {
+    return (
+      <div className="min-h-screen flex items-center justify-center bg-slate-950">
+        <div className="w-10 h-10 border-4 border-indigo-500 border-t-transparent rounded-full animate-spin" />
+      </div>
+    );
+  }
+
+  const isSignUp = mode === 'signup';
+
+  return (
+    <div className="min-h-screen flex items-center justify-center bg-slate-950 p-4">
+      <div className="w-full max-w-sm">
+        {/* Logo */}
+        <div className="h-12 w-48 mx-auto mb-8">
+          <CrazeLogo />
+        </div>
+
+        <div className="bg-slate-900 border border-white/10 rounded-2xl shadow-2xl p-6">
+          <h2 className="text-lg font-black text-white mb-1">
+            {isSignUp ? 'Create account' : 'Welcome back'}
+          </h2>
+          <p className="text-xs text-slate-500 mb-6">
+            {isSignUp ? 'Sign up to access the dashboard' : 'Sign in to your account'}
+          </p>
+
+          <form onSubmit={isSignUp ? handleSignUp : handleLogin} className="space-y-4">
+            <div>
+              <label className="block text-xs font-bold text-slate-400 mb-1.5 uppercase tracking-wider">
+                Email
+              </label>
+              <input
+                type="email"
+                required
+                value={email}
+                onChange={e => setEmail(e.target.value)}
+                placeholder="you@example.com"
+                className="w-full bg-slate-800 border border-white/10 rounded-lg px-3 py-2.5 text-sm text-white placeholder-slate-600
+                  focus:outline-none focus:ring-2 focus:ring-indigo-500/50 focus:border-indigo-500/50 transition-all"
+              />
+            </div>
+
+            <div>
+              <label className="block text-xs font-bold text-slate-400 mb-1.5 uppercase tracking-wider">
+                Password
+              </label>
+              <input
+                type="password"
+                required
+                minLength={6}
+                value={password}
+                onChange={e => setPassword(e.target.value)}
+                placeholder="••••••••"
+                className="w-full bg-slate-800 border border-white/10 rounded-lg px-3 py-2.5 text-sm text-white placeholder-slate-600
+                  focus:outline-none focus:ring-2 focus:ring-indigo-500/50 focus:border-indigo-500/50 transition-all"
+              />
+            </div>
+
+            {error && (
+              <div className="bg-red-500/10 border border-red-500/20 rounded-lg px-3 py-2 text-xs text-red-400 font-medium">
+                {error}
+              </div>
+            )}
+
+            <button
+              type="submit"
+              disabled={submitting}
+              className="w-full py-2.5 bg-indigo-600 hover:bg-indigo-500 disabled:bg-indigo-800 disabled:cursor-not-allowed
+                text-white font-black text-sm rounded-lg transition-all active:scale-[0.98] shadow-lg shadow-indigo-500/20"
+            >
+              {submitting ? '...' : isSignUp ? 'Create account' : 'Sign in'}
+            </button>
+          </form>
+
+          <div className="mt-4 text-center">
+            <button
+              onClick={() => { setMode(isSignUp ? 'login' : 'signup'); setError(''); }}
+              className="text-xs text-slate-500 hover:text-slate-300 transition-colors"
+            >
+              {isSignUp ? 'Already have an account? Sign in' : "Don't have an account? Sign up"}
+            </button>
+          </div>
+        </div>
+      </div>
+    </div>
+  );
+};
diff --git a/index.tsx b/index.tsx
index a28080f..03c097b 100644
--- a/index.tsx
+++ b/index.tsx
@@ -2,6 +2,7 @@ import React from 'react';
 import ReactDOM from 'react-dom/client';
 import App from './App';
 import ErrorBoundary from './components/ErrorBoundary';
+import { AuthGate } from './components/AuthGate';
 
 const rootElement = document.getElementById('root');
 if (!rootElement) {
@@ -11,6 +12,8 @@ if (!rootElement) {
 const root = ReactDOM.createRoot(rootElement);
 root.render(
   <ErrorBoundary>
-    <App />
+    <AuthGate>
+      <App />
+    </AuthGate>
   </ErrorBoundary>
 );
\ No newline at end of file
diff --git a/services/authClient.ts b/services/authClient.ts
new file mode 100644
index 0000000..ad560b5
--- /dev/null
+++ b/services/authClient.ts
@@ -0,0 +1,14 @@
+/// <reference types="node" />
+import { createClient } from '@supabase/supabase-js';
+
+const url = process.env.SUPABASE_URL || '';
+const key = process.env.SUPABASE_ANON_KEY || '';
+
+export const supabaseAuth = createClient(url, key, {
+  auth: {
+    autoRefreshToken: true,
+    persistSession: true,
+    detectSessionInUrl: true,
+    storageKey: 'craze-auth-session',
+  },
+});