step 1, 2 and 3 of the implementation plan

app/Http/Controllers/Auth/SocialiteController.php

@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers\Auth;
+
+use App\Http\Controllers\Controller;
+use App\Models\User;
+use Illuminate\Http\RedirectResponse;
+use Illuminate\Http\Request;
+use Laravel\Socialite\Facades\Socialite;
+
+final class SocialiteController extends Controller
+{
+    /**
+     * Redirect the user to the Azure AD authentication page.
+     */
+    public function redirect(): RedirectResponse
+    {
+        return Socialite::driver('azure')->redirect();
+    }
+
+    /**
+     * Handle the callback from Azure AD after authentication.
+     */
+    public function callback(): RedirectResponse
+    {
+        $azureUser = Socialite::driver('azure')->user();
+
+        $user = User::query()->firstOrCreate(
+            ['email' => $azureUser->getEmail()],
+            [
+                'name' => $azureUser->getName(),
+                'password' => null,
+            ]
+        );
+
+        auth()->login($user);
+
+        return redirect('/');
+    }
+
+    /**
+     * Log the user out and redirect to landing page.
+     */
+    public function logout(Request $request): RedirectResponse
+    {
+        auth()->logout();
+
+        $request->session()->invalidate();
+        $request->session()->regenerateToken();
+
+        return redirect('/');
+    }
+}

app/Http/Middleware/HandleInertiaRequests.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Middleware;
+
+use Illuminate\Http\Request;
+use Illuminate\Support\Arr;
+use Inertia\Middleware;
+
+final class HandleInertiaRequests extends Middleware
+{
+    /**
+     * The root template that is loaded on the first page visit.
+     */
+    protected $rootView = 'app';
+
+    /**
+     * Determine the current asset version.
+     */
+    public function version(Request $request): ?string
+    {
+        return parent::version($request);
+    }
+
+    /**
+     * Define the props that are shared by default.
+     */
+    public function share(Request $request): array
+    {
+        return [
+            ...parent::share($request),
+            'auth' => [
+                'user' => $this->getAuthenticatedUser(),
+            ],
+            'flash' => [
+                'success' => fn () => Arr::get($request->session()->all(), 'success'),
+                'error' => fn () => Arr::get($request->session()->all(), 'error'),
+            ],
+        ];
+    }
+
+    /**
+     * Get authenticated user data for frontend.
+     */
+    private function getAuthenticatedUser(): ?array
+    {
+        $user = auth()->user();
+
+        if ($user === null) {
+            return null;
+        }
+
+        return [
+            'id' => $user->id,
+            'name' => $user->name,
+            'email' => $user->email,
+        ];
+    }
+}