fix: missing session item for mercure alert topic

src/User/Framework/EventListener/LoginSuccessListener.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\User\Framework\EventListener;
+
+use Symfony\Component\EventDispatcher\Attribute\AsEventListener;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\Security\Core\Event\AuthenticationSuccessEvent;
+
+final class LoginSuccessListener
+{
+    public function __construct(
+        private readonly RequestStack $requestStack,
+    ) {}
+
+    #[AsEventListener(event: 'security.authentication.success')]
+    public function setMercureTopics(AuthenticationSuccessEvent $event): void
+    {
+        // Set the unique Mercure topic name for the User's alerts
+        $this->requestStack->getSession()->set('mercure_alert_topic', 'alerts_' . uniqid());
+    }
+}