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;
+    }
 }

src/Service/NewsletterManager.php

@@ -327,8 +327,7 @@ class NewsletterManager
             $this->newsletterService->ensureSubscribed($confirmation->getEmail(), $mailjetListId);
         }
 
-        $confirmation->markConfirmed();
-        $this->upsertConfirmedConsents($confirmation->getEmail(), $mailjetListIds, $confirmation->getFirstName(), $confirmation->getLastName(), false, false);
+        $this->upsertConfirmedConsents($confirmation->getEmail(), $mailjetListIds, $confirmation->getFirstName(), $confirmation->getLastName(), flush: false, deletePending: false);
         $this->entityManager->remove($confirmation);
         $this->entityManager->flush();
 
@@ -468,8 +467,10 @@ class NewsletterManager
      */
     private function upsertConfirmedConsents(string $email, array $mailjetListIds, ?string $firstName, ?string $lastName, bool $flush = true, bool $deletePending = true): void
     {
+        $existingByListId = $this->consentRepository->findByEmailAndListIds($email, $mailjetListIds);
+
         foreach ($mailjetListIds as $mailjetListId) {
-            $consent = $this->consentRepository->findOneByEmailAndListId($email, $mailjetListId);
+            $consent = $existingByListId[$mailjetListId] ?? null;
             if (null === $consent) {
                 $consent = new NewsletterConsent($email, $mailjetListId, $firstName, $lastName);
                 $this->entityManager->persist($consent);