diff --git a/backend/src/modules/cards/cards.service.ts b/backend/src/modules/cards/cards.service.ts
index de315df..29a8ba2 100644
--- a/backend/src/modules/cards/cards.service.ts
+++ b/backend/src/modules/cards/cards.service.ts
@@ -252,7 +252,12 @@ export class CardsService {
     }
 
     card.purge_at = this.purgeAt(card.type.retention_days, card.statut);
-    await this.cardsRepo.save(card);
+    // update() et non save() : save() avec relations responses/audience
+    // resynchronise les FK et tente UPDATE card_responses SET id_card=null.
+    await this.cardsRepo.update(
+      { id: card.id },
+      { statut: card.statut, purge_at: card.purge_at },
+    );
     const full = await this.loadCard(cardId);
     const dtoOut = this.toDto(full, userId);
     this.emitAudience(full, 'response.added', {
@@ -304,7 +309,12 @@ export class CardsService {
     };
     card.statut = CardInstanceStatutType.OUVERTE;
     card.purge_at = this.purgeAt(card.type.retention_days, card.statut);
-    await this.cardsRepo.save(card);
+    await this.cardsRepo.manager.query(
+      `UPDATE card_instances
+       SET statut = $1, purge_at = $2, payload = $3::jsonb, modifie_le = now()
+       WHERE id = $4`,
+      [card.statut, card.purge_at, JSON.stringify(card.payload), card.id],
+    );
     const full = await this.loadCard(cardId);
     const dtoOut = this.toDto(full, userId);
     this.emitAudience(full, 'card.updated', dtoOut);