fix: prevent race condition on newsletter consent confirmation

src/Repository/NewsletterConsentRepository.php

@@ -38,4 +38,31 @@ class NewsletterConsentRepository extends ServiceEntityRepository
             'mailjetListId' => $mailjetListId,
         ]);
     }
+
+    /**
+     * @param list<int> $mailjetListIds
+     *
+     * @return array<int, NewsletterConsent> existing consents indexed by mailjetListId
+     */
+    public function findByEmailAndListIds(string $email, array $mailjetListIds): array
+    {
+        if ([] === $mailjetListIds) {
+            return [];
+        }
+
+        $consents = $this->createQueryBuilder('c')
+            ->where('c.email = :email')
+            ->andWhere('c.mailjetListId IN (:listIds)')
+            ->setParameter('email', mb_strtolower(trim($email)))
+            ->setParameter('listIds', $mailjetListIds)
+            ->getQuery()
+            ->getResult();
+
+        $byListId = [];
+        foreach ($consents as $consent) {
+            $byListId[$consent->getMailjetListId()] = $consent;
+        }
+
+        return $byListId;
+    }
 }