diff --git a/backend/src/modules/credit/driver-credit.service.spec.ts b/backend/src/modules/credit/driver-credit.service.spec.ts
index 16fce28..3ddc9a1 100644
--- a/backend/src/modules/credit/driver-credit.service.spec.ts
+++ b/backend/src/modules/credit/driver-credit.service.spec.ts
@@ -8,6 +8,8 @@ import { DEFAULT_SIGNUP_BONUS, DEFAULT_DEBT_ALLOWANCE } from './credit-policy';
 
 const TENANT = '11111111-1111-1111-1111-111111111111';
 const DRIVER = '22222222-2222-2222-2222-222222222222';
+// trip_id عمود uuid — نصّ عادي مثل 'trip-1' يرفضه Postgres الحقيقي (كما رفضه pg-mem هنا).
+const TRIP = '55555555-5555-5555-5555-555555555555';
 
 /** مستأجر مزيّف — `settings` هي ما يضبطه المشغّل لسياسته. */
 function fakeTenants(settings: Record<string, any> = {}) {
@@ -74,36 +76,36 @@ describe('DriverCreditService (docs/18)', () => {
 
   it('مثال المالك المرجعي: شحن 4 ثم عمولة 0.4 → 3.6', async () => {
     await credit.topup(TENANT, DRIVER, 4);
-    const c = await credit.chargeCommission(TENANT, DRIVER, 0.4, 'trip-1');
+    const c = await credit.chargeCommission(TENANT, DRIVER, 0.4, TRIP);
     expect(Number(c.balance)).toBeCloseTo(3.6);
   });
 
   describe('الرصيد السالب مسموح — الرحلة لا تُقطع', () => {
     it('العمولة تُخصم ولو تجاوزت الرصيد', async () => {
       await credit.topup(TENANT, DRIVER, 1);
-      const c = await credit.chargeCommission(TENANT, DRIVER, 3, 'trip-1');
+      const c = await credit.chargeCommission(TENANT, DRIVER, 3, TRIP);
       expect(Number(c.balance)).toBeCloseTo(-2); // دين، لا رفض
     });
 
     it('الخصم من رصيد صفر ينجح ويصير ديناً', async () => {
-      const c = await credit.chargeCommission(TENANT, DRIVER, 0.5, 'trip-1');
+      const c = await credit.chargeCommission(TENANT, DRIVER, 0.5, TRIP);
       expect(Number(c.balance)).toBeCloseTo(-0.5);
     });
   });
 
   describe('الحجب عند تجاوز الدين المسموح فقط', () => {
     it('دين ضمن المسموح لا يحجب', async () => {
-      await credit.chargeCommission(TENANT, DRIVER, 1, 'trip-1'); // −1، والمسموح 2
+      await credit.chargeCommission(TENANT, DRIVER, 1, TRIP); // −1، والمسموح 2
       expect(await credit.isBlocked(TENANT, DRIVER)).toBe(false);
     });
 
     it('تجاوز المسموح يحجب', async () => {
-      await credit.chargeCommission(TENANT, DRIVER, 3, 'trip-1'); // −3 < −2
+      await credit.chargeCommission(TENANT, DRIVER, 3, TRIP); // −3 < −2
       expect(await credit.isBlocked(TENANT, DRIVER)).toBe(true);
     });
 
     it('الشحن يفكّ الحجب', async () => {
-      await credit.chargeCommission(TENANT, DRIVER, 3, 'trip-1');
+      await credit.chargeCommission(TENANT, DRIVER, 3, TRIP);
       await credit.topup(TENANT, DRIVER, 10);
       expect(await credit.isBlocked(TENANT, DRIVER)).toBe(false);
     });
@@ -112,13 +114,13 @@ describe('DriverCreditService (docs/18)', () => {
   describe('سياسة المستأجر تتجاوز الافتراض (docs/18 §5.2)', () => {
     it('مشغّل يسمح بدين أوسع', async () => {
       const c = withPolicy({ credit: { debt_allowance: { JOD: 20 } } });
-      await c.chargeCommission(TENANT, DRIVER, 15, 'trip-1'); // −15، والمسموح 20
+      await c.chargeCommission(TENANT, DRIVER, 15, TRIP); // −15، والمسموح 20
       expect(await c.isBlocked(TENANT, DRIVER)).toBe(false);
     });
 
     it('مشغّل يمنع الدين تماماً (0) — أي رصيد سالب يحجب فوراً', async () => {
       const c = withPolicy({ credit: { debt_allowance: { JOD: 0 } } });
-      await c.chargeCommission(TENANT, DRIVER, 0.4, 'trip-1'); // −0.4
+      await c.chargeCommission(TENANT, DRIVER, 0.4, TRIP); // −0.4
       expect(await c.isBlocked(TENANT, DRIVER)).toBe(true);
     });
 
@@ -129,7 +131,7 @@ describe('DriverCreditService (docs/18)', () => {
 
     it('حتى مع منع الدين، الرحلة الجارية لا تُقطع — الخصم ينجح', async () => {
       const c = withPolicy({ credit: { debt_allowance: { JOD: 0 } } });
-      const res = await c.chargeCommission(TENANT, DRIVER, 0.4, 'trip-1');
+      const res = await c.chargeCommission(TENANT, DRIVER, 0.4, TRIP);
       expect(Number(res.balance)).toBeCloseTo(-0.4); // خُصم ثم يُحجب لاحقاً
     });
 
@@ -178,7 +180,7 @@ describe('DriverCreditService (docs/18)', () => {
 
   it('الدفتر يطابق الرصيد ويسجّل سبب كل خصم', async () => {
     await credit.topup(TENANT, DRIVER, 10, 'pay-1');
-    await credit.chargeCommission(TENANT, DRIVER, 0.4, 'trip-1');
+    await credit.chargeCommission(TENANT, DRIVER, 0.4, TRIP);
     await credit.promoBonus(TENANT, DRIVER, 5, 'promo-1');
 
     const txns = await credit.history(TENANT, DRIVER);
@@ -189,7 +191,7 @@ describe('DriverCreditService (docs/18)', () => {
 
     // كل خصم عمولة يشير لرحلته — وإلا لم يعرف السائق لماذا نقص رصيده
     const commissionTxn = txns.find((t) => t.type === 'commission')!;
-    expect(commissionTxn.trip_id).toBe('trip-1');
+    expect(commissionTxn.trip_id).toBe(TRIP);
     expect(Number(commissionTxn.amount)).toBeCloseTo(-0.4);
   });