diff --git a/src/Module/Commercial/Domain/Entity/ClientAddress.php b/src/Module/Commercial/Domain/Entity/ClientAddress.php
index 29ca240..99a998f 100644
--- a/src/Module/Commercial/Domain/Entity/ClientAddress.php
+++ b/src/Module/Commercial/Domain/Entity/ClientAddress.php
@@ -63,6 +63,11 @@ use Symfony\Component\Validator\Context\ExecutionContextInterface;
             uriVariables: [
                 'clientId' => new Link(fromClass: Client::class, toProperty: 'client'),
             ],
+            // read:false : pas de stade lecture du parent. Le Link toProperty
+            // resoudrait l'enfant (SELECT ClientAddress ... WHERE client = :id) et
+            // casse en NonUniqueResult des >= 2 enfants. Le parent est rattache
+            // manuellement par ClientAddressProcessor::linkParent (404 si absent).
+            read: false,
             security: "is_granted('commercial.clients.manage')",
             normalizationContext: ['groups' => ['client_address:read']],
             denormalizationContext: ['groups' => ['client_address:write']],
diff --git a/src/Module/Commercial/Domain/Entity/ClientContact.php b/src/Module/Commercial/Domain/Entity/ClientContact.php
index b28aaa2..80247c8 100644
--- a/src/Module/Commercial/Domain/Entity/ClientContact.php
+++ b/src/Module/Commercial/Domain/Entity/ClientContact.php
@@ -50,6 +50,11 @@ use Symfony\Component\Validator\Constraints as Assert;
             uriVariables: [
                 'clientId' => new Link(fromClass: Client::class, toProperty: 'client'),
             ],
+            // read:false : pas de stade lecture du parent. Le Link toProperty
+            // resoudrait l'enfant (SELECT ClientContact ... WHERE client = :id) et
+            // casse en NonUniqueResult des >= 2 enfants. Le parent est rattache
+            // manuellement par ClientContactProcessor::linkParent (404 si absent).
+            read: false,
             security: "is_granted('commercial.clients.manage')",
             normalizationContext: ['groups' => ['client_contact:read']],
             denormalizationContext: ['groups' => ['client_contact:write']],
diff --git a/src/Module/Commercial/Domain/Entity/ClientRib.php b/src/Module/Commercial/Domain/Entity/ClientRib.php
index 956ee80..c2fb408 100644
--- a/src/Module/Commercial/Domain/Entity/ClientRib.php
+++ b/src/Module/Commercial/Domain/Entity/ClientRib.php
@@ -54,6 +54,11 @@ use Symfony\Component\Validator\Constraints as Assert;
             uriVariables: [
                 'clientId' => new Link(fromClass: Client::class, toProperty: 'client'),
             ],
+            // read:false : pas de stade lecture du parent. Le Link toProperty
+            // resoudrait l'enfant (SELECT ClientRib ... WHERE client = :id) et
+            // casse en NonUniqueResult des >= 2 enfants. Le parent est rattache
+            // manuellement par ClientRibProcessor::linkParent (404 si absent).
+            read: false,
             security: "is_granted('commercial.clients.accounting.manage')",
             normalizationContext: ['groups' => ['client_rib:read']],
             denormalizationContext: ['groups' => ['client_rib:write']],
diff --git a/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientAddressProcessor.php b/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientAddressProcessor.php
index 1720432..01249e9 100644
--- a/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientAddressProcessor.php
+++ b/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientAddressProcessor.php
@@ -12,6 +12,7 @@ use App\Module\Commercial\Domain\Entity\Client;
 use App\Module\Commercial\Domain\Entity\ClientAddress;
 use Doctrine\ORM\EntityManagerInterface;
 use Symfony\Component\DependencyInjection\Attribute\Autowire;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 /**
  * Processor d'ecriture de la sous-ressource Adresse d'un client (M1, § 4.5).
@@ -75,9 +76,14 @@ final class ClientAddressProcessor implements ProcessorInterface
             ? $clientId
             : $this->em->getRepository(Client::class)->find($clientId);
 
-        if ($client instanceof Client) {
-            $address->setClient($client);
+        // read:false sur le POST : sans stade lecture, un parent introuvable n'est
+        // plus intercepte en amont -> 404 explicite (sinon 500 au persist sur la
+        // contrainte client_id NOT NULL).
+        if (!$client instanceof Client) {
+            throw new NotFoundHttpException('Client introuvable.');
         }
+
+        $address->setClient($client);
     }
 
     /**
diff --git a/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientContactProcessor.php b/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientContactProcessor.php
index 3ddffc0..4806336 100644
--- a/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientContactProcessor.php
+++ b/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientContactProcessor.php
@@ -14,6 +14,7 @@ use App\Module\Commercial\Domain\Entity\ClientContact;
 use Doctrine\ORM\EntityManagerInterface;
 use Symfony\Component\DependencyInjection\Attribute\Autowire;
 use Symfony\Component\HttpKernel\Exception\ConflictHttpException;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 use Symfony\Component\Validator\ConstraintViolation;
 use Symfony\Component\Validator\ConstraintViolationList;
 
@@ -88,9 +89,14 @@ final class ClientContactProcessor implements ProcessorInterface
             ? $clientId
             : $this->em->getRepository(Client::class)->find($clientId);
 
-        if ($client instanceof Client) {
-            $contact->setClient($client);
+        // read:false sur le POST : sans stade lecture, un parent introuvable n'est
+        // plus intercepte en amont -> 404 explicite (sinon 500 au persist sur la
+        // contrainte client_id NOT NULL).
+        if (!$client instanceof Client) {
+            throw new NotFoundHttpException('Client introuvable.');
         }
+
+        $contact->setClient($client);
     }
 
     /**
diff --git a/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientRibProcessor.php b/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientRibProcessor.php
index baf55ec..39e280c 100644
--- a/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientRibProcessor.php
+++ b/src/Module/Commercial/Infrastructure/ApiPlatform/State/Processor/ClientRibProcessor.php
@@ -12,6 +12,7 @@ use App\Module\Commercial\Domain\Entity\ClientRib;
 use Doctrine\ORM\EntityManagerInterface;
 use Symfony\Component\DependencyInjection\Attribute\Autowire;
 use Symfony\Component\HttpKernel\Exception\ConflictHttpException;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 /**
  * Processor d'ecriture de la sous-ressource RIB d'un client (M1, § 4.5).
@@ -77,9 +78,14 @@ final class ClientRibProcessor implements ProcessorInterface
             ? $clientId
             : $this->em->getRepository(Client::class)->find($clientId);
 
-        if ($client instanceof Client) {
-            $rib->setClient($client);
+        // read:false sur le POST : sans stade lecture, un parent introuvable n'est
+        // plus intercepte en amont -> 404 explicite (sinon 500 au persist sur la
+        // contrainte client_id NOT NULL).
+        if (!$client instanceof Client) {
+            throw new NotFoundHttpException('Client introuvable.');
         }
+
+        $rib->setClient($client);
     }
 
     /**