refactor: clarify nullable card metadata

src/modules/banking/bank-cards/application/bank-cards.service.ts

@@ -103,13 +103,9 @@ export class BankCardsService {
         id,
         name: dto.name ?? previous.name,
         bankName:
-          dto.bankName === undefined
+          dto.bankName === undefined ? previous.bankName : dto.bankName,
-            ? (previous.bankName ?? undefined)
-            : (dto.bankName ?? undefined),
         lastFour:
-          dto.lastFour === undefined
+          dto.lastFour === undefined ? previous.lastFour : dto.lastFour,
-            ? (previous.lastFour ?? undefined)
-            : (dto.lastFour ?? undefined),
         paymentSystem:
           dto.paymentSystem === undefined
             ? previous.paymentSystem

test/bank-cards.e2e-spec.ts

@@ -188,6 +188,17 @@ describe('Manual bank cards configured HTTP and real SQLite', () => {
     ).toBe(0);
     expect((await summary('2026-08', card.id)).net.value).toBe('0');
   });
+  it('retains omitted metadata on a name-only patch and clears explicit nulls', async () => {
+    const card = await createCard('0', owner, { bankName: 'Bank', lastFour: '1234' });
+    const renamed = (await auth('patch', '/' + card.id)
+      .send({ version: card.version, name: 'Renamed' }).expect(200)).body as BankCardDto;
+    expect(renamed).toMatchObject({ name: 'Renamed', bankName: 'Bank', lastFour: '1234' });
+    const cleared = (await auth('patch', '/' + card.id)
+      .send({ version: renamed.version, bankName: null, lastFour: null }).expect(200)).body as BankCardDto;
+    expect(cleared).toMatchObject({ name: 'Renamed', bankName: null, lastFour: null });
+    expect(cleared.version).toBe(renamed.version + 1);
+  });
+
   it('rejects explicit null on nonnullable write fields without changing values or versions', async () => {
     const card = await createCard();
     const expense = await createOp(op(card.id));