diff --git a/frontend/app/pages/catalogues/pieces.vue b/frontend/app/pages/catalogues/pieces.vue
index 71d81c6..fb3c711 100644
--- a/frontend/app/pages/catalogues/pieces.vue
+++ b/frontend/app/pages/catalogues/pieces.vue
@@ -167,7 +167,7 @@ import { usePieces } from '~/composables/usePieces'
 import { usePieceTypes } from '~/composables/usePieceTypes'
 import { useDataTable } from '~/composables/useDataTable'
 import DocumentThumbnail from '~/components/DocumentThumbnail.vue'
-import { resolveDeleteImpact, buildDeleteMessage } from '~/shared/utils/deleteImpactUtils'
+import { buildDeleteMessageWithUsage, type UsageInfo } from '~/shared/utils/deleteImpactUtils'
 import { resolvePrimaryDocument, resolvePreviewAlt, resolveSupplierNames, buildSuppliersDisplay } from '~/shared/utils/catalogDisplayUtils'
 import { formatFrenchDate } from '~/utils/date'
 
@@ -249,10 +249,25 @@ const buildPieceSuppliersDisplay = (piece: Record<string, any>) =>
   buildSuppliersDisplay(resolveSupplierNames(piece, 'product'))
 
 const { confirm } = useConfirm()
+const api = useApi()
 
 const handleDeletePiece = async (piece: Record<string, any>) => {
   const pieceName = piece?.name || 'cette pièce'
-  const message = buildDeleteMessage(pieceName, resolveDeleteImpact(piece))
+
+  let usage: UsageInfo = {}
+  try {
+    const result = await api.get(`/pieces/${piece.id}/used-in`)
+    if (result.success && result.data) {
+      usage = {
+        machines: result.data.machines ?? [],
+        composants: result.data.composants ?? [],
+      }
+    }
+  } catch (error) {
+    console.warn('Impossible de récupérer les usages de la pièce avant suppression :', error)
+  }
+
+  const message = buildDeleteMessageWithUsage(pieceName, 'Cette pièce', usage)
   const confirmed = await confirm({ title: 'Supprimer la pièce', message, dangerous: true })
   if (!confirmed) return
   await deletePiece(piece.id)
diff --git a/frontend/app/shared/utils/deleteImpactUtils.ts b/frontend/app/shared/utils/deleteImpactUtils.ts
index 7f1289f..6a15f87 100644
--- a/frontend/app/shared/utils/deleteImpactUtils.ts
+++ b/frontend/app/shared/utils/deleteImpactUtils.ts
@@ -14,6 +14,77 @@ export const buildDeleteMessage = (entityName: string, impacts: string[]): strin
   if (impacts.length) {
     lines.push(`Cela supprimera également :\n• ${impacts.join('\n• ')}`)
   }
+  lines.push('Cette action est irréversible.')
+  return lines.join('\n\n')
+}
+
+interface UsedInMachine {
+  id: string
+  name: string | null
+  site?: { id: string; name: string | null } | null
+}
+
+interface UsedInEntity {
+  id: string
+  name: string | null
+}
+
+export interface UsageInfo {
+  machines?: UsedInMachine[]
+  composants?: UsedInEntity[]
+  pieces?: UsedInEntity[]
+}
+
+const formatMachineLine = (m: UsedInMachine): string => {
+  const name = m.name?.trim() || '(sans nom)'
+  const siteName = m.site?.name?.trim()
+  return siteName ? `${name} (${siteName})` : name
+}
+
+/**
+ * Builds a delete-confirmation message that lists the machines (and other
+ * entities) currently using the item. The user sees exactly what will be
+ * detached before they confirm the deletion.
+ */
+export const buildDeleteMessageWithUsage = (
+  entityName: string,
+  entityLabel: string,
+  usage: UsageInfo,
+): string => {
+  const machines = usage.machines ?? []
+  const composants = usage.composants ?? []
+  const pieces = usage.pieces ?? []
+
+  const lines = [`Voulez-vous vraiment supprimer « ${entityName} » ?`]
+
+  if (machines.length > 0) {
+    const header = machines.length === 1
+      ? `${entityLabel} est actuellement utilisée par 1 machine :`
+      : `${entityLabel} est actuellement utilisée par ${machines.length} machines :`
+    const bullets = machines.map((m) => `• ${formatMachineLine(m)}`).join('\n')
+    lines.push(`${header}\n${bullets}\n\nLa supprimer la retirera de ${machines.length === 1 ? 'cette machine' : 'ces machines'}.`)
+  }
+
+  if (composants.length > 0) {
+    const header = composants.length === 1
+      ? 'Elle est également référencée par 1 composant :'
+      : `Elle est également référencée par ${composants.length} composants :`
+    const bullets = composants
+      .map((c) => `• ${c.name?.trim() || '(sans nom)'}`)
+      .join('\n')
+    lines.push(`${header}\n${bullets}`)
+  }
+
+  if (pieces.length > 0) {
+    const header = pieces.length === 1
+      ? 'Elle est également utilisée par 1 pièce :'
+      : `Elle est également utilisée par ${pieces.length} pièces :`
+    const bullets = pieces
+      .map((p) => `• ${p.name?.trim() || '(sans nom)'}`)
+      .join('\n')
+    lines.push(`${header}\n${bullets}`)
+  }
+
   lines.push('Cette action est irréversible.')
   return lines.join('\n\n')
 }
\ No newline at end of file
diff --git a/migrations/Version20260528090000_FixPieceCascadeFKs.php b/migrations/Version20260528090000_FixPieceCascadeFKs.php
new file mode 100644
index 0000000..cbb4fc5
--- /dev/null
+++ b/migrations/Version20260528090000_FixPieceCascadeFKs.php
@@ -0,0 +1,250 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Align all FKs pointing to `pieces.id` with what entities declare
+ * (ON DELETE CASCADE / SET NULL). Cleans up pre-existing orphan rows
+ * inserted before the constraints existed, so the new FKs can be added.
+ *
+ * Mirror of Version20260506140000_FixComposantCascadeFKs for the Piece side.
+ */
+final class Version20260528090000_FixPieceCascadeFKs extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Align CASCADE/SET NULL FKs on pieces references (machine_piece_links, composant_piece_slots, piece_product_slots, documents, custom_field_values, piece_constructeur_links); cleanup pre-existing orphans';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // =========================================================================
+        // 1. Audit log : snapshot des rows orphelines avant suppression.
+        // =========================================================================
+        $this->addSql(<<<'SQL'
+            INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+            SELECT
+              'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+              'machine_piece_link',
+              l.id,
+              'delete',
+              json_build_object(
+                'id', l.id,
+                'machineId', l.machineid,
+                'pieceId', l.pieceid,
+                'note', 'Cleaned by FK cascade fix migration (Version20260528090000) - referenced piece no longer existed'
+              ),
+              NULL,
+              NOW()
+            FROM machine_piece_links l
+            WHERE l.pieceid IS NOT NULL
+              AND l.pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+            SELECT
+              'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+              'piece_product_slot',
+              s.id,
+              'delete',
+              json_build_object(
+                'id', s.id,
+                'pieceId', s.pieceid,
+                'note', 'Cleaned by FK cascade fix migration (Version20260528090000) - referenced piece no longer existed'
+              ),
+              NULL,
+              NOW()
+            FROM piece_product_slots s
+            WHERE s.pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+            SELECT
+              'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+              'document',
+              d.id,
+              'delete',
+              json_build_object(
+                'id', d.id,
+                'name', d.name,
+                'filename', d.filename,
+                'pieceId', d.pieceid,
+                'note', 'Cleaned by FK cascade fix migration (Version20260528090000) - referenced piece no longer existed'
+              ),
+              NULL,
+              NOW()
+            FROM documents d
+            WHERE d.pieceid IS NOT NULL
+              AND d.pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+            SELECT
+              'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+              'custom_field_value',
+              v.id,
+              'delete',
+              json_build_object(
+                'id', v.id,
+                'pieceId', v.pieceid,
+                'note', 'Cleaned by FK cascade fix migration (Version20260528090000) - referenced piece no longer existed'
+              ),
+              NULL,
+              NOW()
+            FROM custom_field_values v
+            WHERE v.pieceid IS NOT NULL
+              AND v.pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+            SELECT
+              'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+              'piece_constructeur_link',
+              l.id,
+              'delete',
+              json_build_object(
+                'id', l.id,
+                'pieceId', l.pieceid,
+                'constructeurId', l.constructeurid,
+                'note', 'Cleaned by FK cascade fix migration (Version20260528090000) - referenced piece no longer existed'
+              ),
+              NULL,
+              NOW()
+            FROM piece_constructeur_links l
+            WHERE l.pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        // =========================================================================
+        // 2. Nettoyage des orphelins (avant ADD CONSTRAINT, sinon PG rejette).
+        // =========================================================================
+        $this->addSql(<<<'SQL'
+            DELETE FROM machine_piece_links
+            WHERE pieceid IS NOT NULL
+              AND pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            UPDATE composant_piece_slots SET selectedpieceid = NULL
+            WHERE selectedpieceid IS NOT NULL
+              AND selectedpieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            DELETE FROM piece_product_slots
+            WHERE pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            DELETE FROM documents
+            WHERE pieceid IS NOT NULL
+              AND pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            DELETE FROM custom_field_values
+            WHERE pieceid IS NOT NULL
+              AND pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            DELETE FROM piece_constructeur_links
+            WHERE pieceid NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        $this->addSql(<<<'SQL'
+            DELETE FROM piece_products
+            WHERE piece_id NOT IN (SELECT id FROM pieces)
+            SQL);
+
+        // =========================================================================
+        // 3. Drop des éventuelles FK existantes vers `pieces` (quel que soit leur
+        //    nom historique), puis ADD CONSTRAINT avec le bon ON DELETE.
+        // =========================================================================
+        $this->dropFksReferencingPieces('machine_piece_links', 'pieceid');
+        $this->addSql(<<<'SQL'
+            ALTER TABLE machine_piece_links ADD CONSTRAINT fk_mpl_piece
+              FOREIGN KEY (pieceid) REFERENCES pieces(id) ON DELETE CASCADE
+            SQL);
+
+        $this->dropFksReferencingPieces('composant_piece_slots', 'selectedpieceid');
+        $this->addSql(<<<'SQL'
+            ALTER TABLE composant_piece_slots ADD CONSTRAINT fk_cps_selected_piece
+              FOREIGN KEY (selectedpieceid) REFERENCES pieces(id) ON DELETE SET NULL
+            SQL);
+
+        $this->dropFksReferencingPieces('piece_product_slots', 'pieceid');
+        $this->addSql(<<<'SQL'
+            ALTER TABLE piece_product_slots ADD CONSTRAINT fk_pps_piece
+              FOREIGN KEY (pieceid) REFERENCES pieces(id) ON DELETE CASCADE
+            SQL);
+
+        $this->dropFksReferencingPieces('documents', 'pieceid');
+        $this->addSql(<<<'SQL'
+            ALTER TABLE documents ADD CONSTRAINT fk_documents_piece
+              FOREIGN KEY (pieceid) REFERENCES pieces(id) ON DELETE CASCADE
+            SQL);
+
+        $this->dropFksReferencingPieces('custom_field_values', 'pieceid');
+        $this->addSql(<<<'SQL'
+            ALTER TABLE custom_field_values ADD CONSTRAINT fk_cfv_piece
+              FOREIGN KEY (pieceid) REFERENCES pieces(id) ON DELETE CASCADE
+            SQL);
+
+        $this->dropFksReferencingPieces('piece_constructeur_links', 'pieceid');
+        $this->addSql(<<<'SQL'
+            ALTER TABLE piece_constructeur_links ADD CONSTRAINT fk_pcl_piece
+              FOREIGN KEY (pieceid) REFERENCES pieces(id) ON DELETE CASCADE
+            SQL);
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE machine_piece_links      DROP CONSTRAINT IF EXISTS fk_mpl_piece');
+        $this->addSql('ALTER TABLE composant_piece_slots    DROP CONSTRAINT IF EXISTS fk_cps_selected_piece');
+        $this->addSql('ALTER TABLE piece_product_slots      DROP CONSTRAINT IF EXISTS fk_pps_piece');
+        $this->addSql('ALTER TABLE documents                DROP CONSTRAINT IF EXISTS fk_documents_piece');
+        $this->addSql('ALTER TABLE custom_field_values      DROP CONSTRAINT IF EXISTS fk_cfv_piece');
+        $this->addSql('ALTER TABLE piece_constructeur_links DROP CONSTRAINT IF EXISTS fk_pcl_piece');
+    }
+
+    /**
+     * Drop every FK on $table.$column that references the `pieces` table,
+     * regardless of its historic name. Idempotent.
+     */
+    private function dropFksReferencingPieces(string $table, string $column): void
+    {
+        $sql = <<<SQL
+            DO \$\$
+            DECLARE
+              fk_name TEXT;
+            BEGIN
+              FOR fk_name IN
+                SELECT tc.constraint_name
+                FROM information_schema.table_constraints tc
+                JOIN information_schema.key_column_usage kcu
+                  ON kcu.constraint_name = tc.constraint_name
+                 AND kcu.table_schema    = tc.table_schema
+                JOIN information_schema.constraint_column_usage ccu
+                  ON ccu.constraint_name = tc.constraint_name
+                 AND ccu.table_schema    = tc.table_schema
+                WHERE tc.table_name      = '{$table}'
+                  AND tc.constraint_type = 'FOREIGN KEY'
+                  AND kcu.column_name    = '{$column}'
+                  AND ccu.table_name     = 'pieces'
+              LOOP
+                EXECUTE format('ALTER TABLE {$table} DROP CONSTRAINT %I', fk_name);
+              END LOOP;
+            END \$\$;
+            SQL;
+        $this->addSql($sql);
+    }
+}
diff --git a/scripts/cleanup_orphan_piece_refs.sql b/scripts/cleanup_orphan_piece_refs.sql
new file mode 100644
index 0000000..c445875
--- /dev/null
+++ b/scripts/cleanup_orphan_piece_refs.sql
@@ -0,0 +1,223 @@
+-- =============================================================================
+-- cleanup_orphan_piece_refs.sql
+-- =============================================================================
+-- Contexte : la suppression directe de rows dans `pieces` (bypass Doctrine /
+-- FK DB sans ON DELETE CASCADE) laisse des références orphelines dans plusieurs
+-- tables, ce qui fait planter l'API au chargement d'une Machine :
+--   Doctrine\ORM\EntityNotFoundException: Entity of type 'App\Entity\Piece' ...
+--
+-- Ce script fait deux choses :
+--   1. ÉTAPE 1 (toujours exécutée) : compte les références orphelines par table
+--      pour visualiser l'ampleur du problème.
+--   2. ÉTAPE 2 (commentée par défaut) : insère un audit_log par row, puis
+--      DELETE / UPDATE SET NULL selon la sémantique attendue côté entité.
+--      Décommenter le bloc `BEGIN; ... COMMIT;` pour appliquer.
+--
+-- Usage :
+--   # Dry-run (compte seulement)
+--   psql -h <host> -U <user> -d inventory -f scripts/cleanup_orphan_piece_refs.sql
+--
+--   # Application : décommenter le bloc transactionnel en bas du fichier,
+--   # puis relancer la même commande. La transaction garantit l'atomicité.
+-- =============================================================================
+
+
+-- ============================== ÉTAPE 1 : DRY-RUN ============================
+\echo ''
+\echo '=== Orphelins par table (Pieces) ==='
+
+SELECT 'machine_piece_links'      AS table_name, count(*) AS orphans
+  FROM machine_piece_links
+  WHERE pieceid IS NOT NULL
+    AND pieceid NOT IN (SELECT id FROM pieces)
+UNION ALL
+SELECT 'composant_piece_slots',     count(*)
+  FROM composant_piece_slots
+  WHERE selectedpieceid IS NOT NULL
+    AND selectedpieceid NOT IN (SELECT id FROM pieces)
+UNION ALL
+SELECT 'piece_product_slots',       count(*)
+  FROM piece_product_slots
+  WHERE pieceid NOT IN (SELECT id FROM pieces)
+UNION ALL
+SELECT 'documents',                 count(*)
+  FROM documents
+  WHERE pieceid IS NOT NULL
+    AND pieceid NOT IN (SELECT id FROM pieces)
+UNION ALL
+SELECT 'custom_field_values',       count(*)
+  FROM custom_field_values
+  WHERE pieceid IS NOT NULL
+    AND pieceid NOT IN (SELECT id FROM pieces)
+UNION ALL
+SELECT 'piece_constructeur_links',  count(*)
+  FROM piece_constructeur_links
+  WHERE pieceid NOT IN (SELECT id FROM pieces)
+UNION ALL
+SELECT 'piece_products',            count(*)
+  FROM piece_products
+  WHERE piece_id NOT IN (SELECT id FROM pieces)
+ORDER BY table_name;
+
+\echo ''
+\echo '=> Pour appliquer le cleanup, décommenter le bloc BEGIN/COMMIT ci-dessous.'
+\echo ''
+
+
+-- ============================== ÉTAPE 2 : APPLY =============================
+-- Décommenter ce bloc pour exécuter le cleanup. La transaction garantit
+-- l'atomicité : tout passe, ou rien (en cas d'erreur, ROLLBACK auto).
+--
+-- BEGIN;
+--
+-- -- 1. Audit log : snapshot des rows qui vont être supprimées (traçabilité prod).
+--
+-- INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+-- SELECT
+--   'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+--   'machine_piece_link',
+--   l.id,
+--   'delete',
+--   json_build_object(
+--     'id', l.id,
+--     'machineId', l.machineid,
+--     'pieceId', l.pieceid,
+--     'note', 'Cleaned by cleanup_orphan_piece_refs.sql - referenced piece no longer existed'
+--   ),
+--   NULL,
+--   NOW()
+-- FROM machine_piece_links l
+-- WHERE l.pieceid IS NOT NULL
+--   AND l.pieceid NOT IN (SELECT id FROM pieces);
+--
+-- INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+-- SELECT
+--   'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+--   'piece_product_slot',
+--   s.id,
+--   'delete',
+--   json_build_object(
+--     'id', s.id,
+--     'pieceId', s.pieceid,
+--     'note', 'Cleaned by cleanup_orphan_piece_refs.sql - referenced piece no longer existed'
+--   ),
+--   NULL,
+--   NOW()
+-- FROM piece_product_slots s
+-- WHERE s.pieceid NOT IN (SELECT id FROM pieces);
+--
+-- INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+-- SELECT
+--   'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+--   'document',
+--   d.id,
+--   'delete',
+--   json_build_object(
+--     'id', d.id,
+--     'name', d.name,
+--     'filename', d.filename,
+--     'pieceId', d.pieceid,
+--     'note', 'Cleaned by cleanup_orphan_piece_refs.sql - referenced piece no longer existed'
+--   ),
+--   NULL,
+--   NOW()
+-- FROM documents d
+-- WHERE d.pieceid IS NOT NULL
+--   AND d.pieceid NOT IN (SELECT id FROM pieces);
+--
+-- INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+-- SELECT
+--   'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+--   'custom_field_value',
+--   v.id,
+--   'delete',
+--   json_build_object(
+--     'id', v.id,
+--     'pieceId', v.pieceid,
+--     'note', 'Cleaned by cleanup_orphan_piece_refs.sql - referenced piece no longer existed'
+--   ),
+--   NULL,
+--   NOW()
+-- FROM custom_field_values v
+-- WHERE v.pieceid IS NOT NULL
+--   AND v.pieceid NOT IN (SELECT id FROM pieces);
+--
+-- INSERT INTO audit_logs (id, entitytype, entityid, action, snapshot, actorprofileid, createdat)
+-- SELECT
+--   'cl' || substring(md5(random()::text || clock_timestamp()::text), 1, 24),
+--   'piece_constructeur_link',
+--   l.id,
+--   'delete',
+--   json_build_object(
+--     'id', l.id,
+--     'pieceId', l.pieceid,
+--     'constructeurId', l.constructeurid,
+--     'note', 'Cleaned by cleanup_orphan_piece_refs.sql - referenced piece no longer existed'
+--   ),
+--   NULL,
+--   NOW()
+-- FROM piece_constructeur_links l
+-- WHERE l.pieceid NOT IN (SELECT id FROM pieces);
+--
+-- -- 2. Nettoyage des orphelins.
+--
+-- DELETE FROM machine_piece_links
+--   WHERE pieceid IS NOT NULL
+--     AND pieceid NOT IN (SELECT id FROM pieces);
+--
+-- UPDATE composant_piece_slots SET selectedpieceid = NULL
+--   WHERE selectedpieceid IS NOT NULL
+--     AND selectedpieceid NOT IN (SELECT id FROM pieces);
+--
+-- DELETE FROM piece_product_slots
+--   WHERE pieceid NOT IN (SELECT id FROM pieces);
+--
+-- DELETE FROM documents
+--   WHERE pieceid IS NOT NULL
+--     AND pieceid NOT IN (SELECT id FROM pieces);
+--
+-- DELETE FROM custom_field_values
+--   WHERE pieceid IS NOT NULL
+--     AND pieceid NOT IN (SELECT id FROM pieces);
+--
+-- DELETE FROM piece_constructeur_links
+--   WHERE pieceid NOT IN (SELECT id FROM pieces);
+--
+-- DELETE FROM piece_products
+--   WHERE piece_id NOT IN (SELECT id FROM pieces);
+--
+-- -- 3. Vérification post-cleanup : tout doit être à 0.
+-- SELECT 'machine_piece_links'      AS table_name, count(*) AS remaining_orphans
+--   FROM machine_piece_links
+--   WHERE pieceid IS NOT NULL
+--     AND pieceid NOT IN (SELECT id FROM pieces)
+-- UNION ALL
+-- SELECT 'composant_piece_slots',     count(*)
+--   FROM composant_piece_slots
+--   WHERE selectedpieceid IS NOT NULL
+--     AND selectedpieceid NOT IN (SELECT id FROM pieces)
+-- UNION ALL
+-- SELECT 'piece_product_slots',       count(*)
+--   FROM piece_product_slots
+--   WHERE pieceid NOT IN (SELECT id FROM pieces)
+-- UNION ALL
+-- SELECT 'documents',                 count(*)
+--   FROM documents
+--   WHERE pieceid IS NOT NULL
+--     AND pieceid NOT IN (SELECT id FROM pieces)
+-- UNION ALL
+-- SELECT 'custom_field_values',       count(*)
+--   FROM custom_field_values
+--   WHERE pieceid IS NOT NULL
+--     AND pieceid NOT IN (SELECT id FROM pieces)
+-- UNION ALL
+-- SELECT 'piece_constructeur_links',  count(*)
+--   FROM piece_constructeur_links
+--   WHERE pieceid NOT IN (SELECT id FROM pieces)
+-- UNION ALL
+-- SELECT 'piece_products',            count(*)
+--   FROM piece_products
+--   WHERE piece_id NOT IN (SELECT id FROM pieces)
+-- ORDER BY table_name;
+--
+-- COMMIT;
diff --git a/src/Controller/CustomFieldValueController.php b/src/Controller/CustomFieldValueController.php
index d614db2..34ea823 100644
--- a/src/Controller/CustomFieldValueController.php
+++ b/src/Controller/CustomFieldValueController.php
@@ -6,6 +6,7 @@ namespace App\Controller;
 
 use App\Entity\CustomField;
 use App\Entity\CustomFieldValue;
+use App\Entity\Piece;
 use App\Repository\ComposantRepository;
 use App\Repository\CustomFieldRepository;
 use App\Repository\CustomFieldValueRepository;
@@ -15,6 +16,7 @@ use App\Repository\MachineRepository;
 use App\Repository\PieceRepository;
 use App\Repository\ProductRepository;
 use Doctrine\ORM\EntityManagerInterface;
+use Doctrine\ORM\EntityNotFoundException;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Request;
@@ -288,12 +290,31 @@ class CustomFieldValueController extends AbstractController
 
             case 'machinePieceLink':
                 $value->setMachinePieceLink($entity);
-                $value->setPiece($entity->getPiece());
+                $value->setPiece($this->ensurePieceExists($entity->getPiece()));
 
                 break;
         }
     }
 
+    /**
+     * Returns the Piece if its underlying row still exists in DB, otherwise null.
+     * Forces a lazy proxy to initialize via getId() and swallows EntityNotFoundException
+     * so an orphan link to a deleted piece doesn't crash custom-field value writes.
+     */
+    private function ensurePieceExists(?Piece $piece): ?Piece
+    {
+        if (null === $piece) {
+            return null;
+        }
+        try {
+            $piece->getId();
+
+            return $piece;
+        } catch (EntityNotFoundException) {
+            return null;
+        }
+    }
+
     private function normalizeCustomFieldValue(CustomFieldValue $value): array
     {
         $customField = $value->getCustomField();
diff --git a/src/Controller/MachineStructureController.php b/src/Controller/MachineStructureController.php
index 4859235..602ac9d 100644
--- a/src/Controller/MachineStructureController.php
+++ b/src/Controller/MachineStructureController.php
@@ -26,6 +26,7 @@ use App\Repository\PieceRepository;
 use App\Repository\ProductRepository;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\EntityManagerInterface;
+use Doctrine\ORM\EntityNotFoundException;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Request;
@@ -676,7 +677,7 @@ class MachineStructureController extends AbstractController
     private function normalizePieceLinks(array $links): array
     {
         return array_map(function (MachinePieceLink $link): array {
-            $piece      = $link->getPiece();
+            $piece      = $this->ensurePieceExists($link->getPiece());
             $modelType  = $link->getModelType();
             $parentLink = $link->getParentLink();
             $type       = $piece?->getTypePiece();
@@ -704,7 +705,7 @@ class MachineStructureController extends AbstractController
     private function resolvePieceQuantity(MachinePieceLink $link): int
     {
         $parentLink = $link->getParentLink();
-        $piece      = $link->getPiece();
+        $piece      = $this->ensurePieceExists($link->getPiece());
 
         if (!$parentLink || !$piece) {
             return $link->getQuantity();
@@ -716,7 +717,8 @@ class MachineStructureController extends AbstractController
         }
 
         foreach ($composant->getPieceSlots() as $slot) {
-            if ($slot->getSelectedPiece()?->getId() === $piece->getId()) {
+            $selected = $this->ensurePieceExists($slot->getSelectedPiece());
+            if ($selected?->getId() === $piece->getId()) {
                 return $slot->getQuantity();
             }
         }
@@ -771,15 +773,16 @@ class MachineStructureController extends AbstractController
     {
         $pieces = [];
         foreach ($composant->getPieceSlots() as $slot) {
+            $selectedPiece = $this->ensurePieceExists($slot->getSelectedPiece());
             $pieceData = [
                 'slotId'          => $slot->getId(),
                 'typePieceId'     => $slot->getTypePiece()?->getId(),
                 'typePiece'       => $this->normalizeModelType($slot->getTypePiece()),
                 'quantity'        => $slot->getQuantity(),
-                'selectedPieceId' => $slot->getSelectedPiece()?->getId(),
+                'selectedPieceId' => $selectedPiece?->getId(),
             ];
-            if ($slot->getSelectedPiece()) {
-                $pieceData['resolvedPiece'] = $this->normalizePiece($slot->getSelectedPiece());
+            if ($selectedPiece) {
+                $pieceData['resolvedPiece'] = $this->normalizePiece($selectedPiece);
             }
             $pieces[] = $pieceData;
         }
@@ -810,6 +813,25 @@ class MachineStructureController extends AbstractController
         ];
     }
 
+    /**
+     * Returns the Piece if its underlying row still exists in DB, otherwise null.
+     * Forces a lazy proxy to initialize via getId() and swallows EntityNotFoundException
+     * so a stale FK (orphan link to a deleted piece) doesn't crash the whole machine view.
+     */
+    private function ensurePieceExists(?Piece $piece): ?Piece
+    {
+        if (null === $piece) {
+            return null;
+        }
+        try {
+            $piece->getId();
+
+            return $piece;
+        } catch (EntityNotFoundException) {
+            return null;
+        }
+    }
+
     private function normalizePiece(Piece $piece): array
     {
         $type = $piece->getTypePiece();