diff --git a/Inventory_frontend b/Inventory_frontend
index 165e0a6..98f5d98 160000
--- a/Inventory_frontend
+++ b/Inventory_frontend
@@ -1 +1 @@
-Subproject commit 165e0a634120bcc0254a3c3b7187dcd8032f764d
+Subproject commit 98f5d983b38945babfc24be8ac11c8ef3d1a9872
diff --git a/src/Controller/MachineStructureController.php b/src/Controller/MachineStructureController.php
index 50361d4..00d39ba 100644
--- a/src/Controller/MachineStructureController.php
+++ b/src/Controller/MachineStructureController.php
@@ -573,7 +573,7 @@ class MachineStructureController extends AbstractController
             'constructeurs'     => $this->normalizeConstructeurs($machine->getConstructeurs()),
             'customFields'      => $this->normalizeCustomFields($machine->getCustomFields()),
             'documents'         => null,
-            'customFieldValues' => null,
+            'customFieldValues' => $this->normalizeCustomFieldValues($machine->getCustomFieldValues()),
         ];
     }
 
diff --git a/tests/Api/Controller/MachineCustomFieldDefinitionTest.php b/tests/Api/Controller/MachineCustomFieldDefinitionTest.php
new file mode 100644
index 0000000..bc5f1c7
--- /dev/null
+++ b/tests/Api/Controller/MachineCustomFieldDefinitionTest.php
@@ -0,0 +1,122 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Api\Controller;
+
+use App\Tests\AbstractApiTestCase;
+
+/**
+ * @internal
+ */
+class MachineCustomFieldDefinitionTest extends AbstractApiTestCase
+{
+    public function testCreateCustomFieldForMachine(): void
+    {
+        $machine = $this->createMachine('Machine CF Create');
+
+        $client = $this->createGestionnaireClient();
+        $client->request('POST', '/api/custom_fields', [
+            'headers' => ['Content-Type' => 'application/ld+json'],
+            'json'    => [
+                'name'    => 'Tension',
+                'type'    => 'number',
+                'machine' => self::iri('machines', $machine->getId()),
+            ],
+        ]);
+
+        $this->assertResponseStatusCodeSame(201);
+        $this->assertJsonContains(['name' => 'Tension', 'type' => 'number']);
+
+        // Verify via structure endpoint
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+        $this->assertResponseIsSuccessful();
+
+        $data = $client->getResponse()->toArray();
+        $this->assertArrayHasKey('customFields', $data['machine']);
+        $this->assertNotEmpty($data['machine']['customFields'], 'customFields should contain the new field');
+
+        $found = false;
+        foreach ($data['machine']['customFields'] as $cf) {
+            if ('Tension' === $cf['name'] && 'number' === $cf['type']) {
+                $found = true;
+
+                break;
+            }
+        }
+        $this->assertTrue($found, 'Structure should contain the created custom field "Tension"');
+    }
+
+    public function testUpdateCustomFieldForMachine(): void
+    {
+        $machine = $this->createMachine('Machine CF Update');
+        $cf      = $this->createCustomField('OldName', 'text', $machine);
+
+        $client = $this->createGestionnaireClient();
+        $client->request('PATCH', self::iri('custom_fields', $cf->getId()), [
+            'headers' => ['Content-Type' => 'application/merge-patch+json'],
+            'json'    => ['name' => 'NewName'],
+        ]);
+
+        $this->assertResponseIsSuccessful();
+        $this->assertJsonContains(['name' => 'NewName']);
+
+        // Verify via structure endpoint
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+        $this->assertResponseIsSuccessful();
+
+        $data = $client->getResponse()->toArray();
+        $this->assertNotEmpty($data['machine']['customFields']);
+
+        $names = array_column($data['machine']['customFields'], 'name');
+        $this->assertContains('NewName', $names, 'Structure should reflect the updated custom field name');
+        $this->assertNotContains('OldName', $names, 'Old name should no longer appear');
+    }
+
+    public function testDeleteCustomFieldForMachine(): void
+    {
+        $machine = $this->createMachine('Machine CF Delete');
+        $cf      = $this->createCustomField('ToDelete', 'text', $machine);
+
+        $client = $this->createGestionnaireClient();
+        $client->request('DELETE', self::iri('custom_fields', $cf->getId()));
+
+        $this->assertResponseStatusCodeSame(204);
+
+        // Verify via structure endpoint
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+        $this->assertResponseIsSuccessful();
+
+        $data = $client->getResponse()->toArray();
+        $this->assertSame([], $data['machine']['customFields'], 'customFields should be empty after deletion');
+    }
+
+    public function testAddCustomFieldsEndpointInitializesValues(): void
+    {
+        $machine = $this->createMachine('Machine CF Values');
+        $cf      = $this->createCustomField('Voltage', 'number', $machine);
+        $cf->setDefaultValue('220');
+        $em = $this->getEntityManager();
+        $em->persist($cf);
+        $em->flush();
+
+        $client = $this->createGestionnaireClient();
+        $client->request('POST', sprintf('/api/machines/%s/add-custom-fields', $machine->getId()));
+
+        $this->assertResponseIsSuccessful();
+        $response = $client->getResponse()->toArray();
+        $this->assertTrue($response['success']);
+        $this->assertNotEmpty($response['customFieldValues'], 'customFieldValues should not be empty after add-custom-fields');
+
+        // Verify via structure endpoint
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+        $this->assertResponseIsSuccessful();
+
+        $data = $client->getResponse()->toArray();
+        $this->assertNotEmpty($data['machine']['customFieldValues'], 'Structure should contain initialized custom field values');
+
+        $cfv = $data['machine']['customFieldValues'][0];
+        $this->assertSame('220', $cfv['value'], 'Value should match the default value');
+        $this->assertSame('Voltage', $cfv['customField']['name']);
+    }
+}
diff --git a/tests/Api/Controller/MachineStructureCustomFieldValuesTest.php b/tests/Api/Controller/MachineStructureCustomFieldValuesTest.php
new file mode 100644
index 0000000..b5a898e
--- /dev/null
+++ b/tests/Api/Controller/MachineStructureCustomFieldValuesTest.php
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Api\Controller;
+
+use App\Tests\AbstractApiTestCase;
+
+/**
+ * @internal
+ */
+class MachineStructureCustomFieldValuesTest extends AbstractApiTestCase
+{
+    public function testStructureIncludesCustomFieldValues(): void
+    {
+        $machine = $this->createMachine('Machine CFV');
+        $cf      = $this->createCustomField('Tension', 'number', $machine);
+        $this->createCustomFieldValue($cf, '220', $machine);
+
+        $client = $this->createViewerClient();
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+
+        $this->assertResponseIsSuccessful();
+        $data = $client->getResponse()->toArray();
+
+        $this->assertArrayHasKey('machine', $data);
+        $this->assertArrayHasKey('customFieldValues', $data['machine']);
+        $this->assertIsArray($data['machine']['customFieldValues']);
+        $this->assertNotEmpty($data['machine']['customFieldValues'], 'customFieldValues should not be empty');
+
+        $cfv = $data['machine']['customFieldValues'][0];
+        $this->assertSame('220', $cfv['value']);
+        $this->assertArrayHasKey('customField', $cfv);
+        $this->assertSame('Tension', $cfv['customField']['name']);
+        $this->assertSame('number', $cfv['customField']['type']);
+    }
+
+    public function testStructureReturnsEmptyArrayWhenNoCustomFieldValues(): void
+    {
+        $machine = $this->createMachine('Machine sans CFV');
+
+        $client = $this->createViewerClient();
+        $client->request('GET', sprintf('/api/machines/%s/structure', $machine->getId()));
+
+        $this->assertResponseIsSuccessful();
+        $data = $client->getResponse()->toArray();
+
+        $this->assertArrayHasKey('customFieldValues', $data['machine']);
+        $this->assertSame([], $data['machine']['customFieldValues']);
+    }
+}