diff --git a/backend/src/__tests__/auth.test.ts b/backend/src/__tests__/auth.test.ts
index 8e1cf66..4afd6a2 100644
--- a/backend/src/__tests__/auth.test.ts
+++ b/backend/src/__tests__/auth.test.ts
@@ -52,7 +52,7 @@ describe('Auth Routes', () => {
 
       expect(res.status).toBe(200);
       expect(res.body.user.tenant).toBeTruthy();
-      expect(res.body.user.tenant.id).toBe('tenant-a-id');
+      expect(res.body.user.tenant.id).toBe(TEST_CUSTOMER_USER_A.tenantId);
       expect(res.body.user.tenant.name).toBe('Tenant A');
       expect(res.body.user.tenant.slug).toBe('tenant-a');
     });
@@ -162,7 +162,7 @@ describe('Auth Routes', () => {
 
       expect(res.status).toBe(200);
       expect(res.body.tenant).toBeTruthy();
-      expect(res.body.tenant.id).toBe('tenant-a-id');
+      expect(res.body.tenant.id).toBe(TEST_CUSTOMER_USER_A.tenantId);
       expect(res.body.tenant.name).toBe('Tenant A');
     });
 
@@ -193,7 +193,7 @@ describe('Auth Routes', () => {
           lastName: TEST_CUSTOMER_USER_A.lastName,
         },
         process.env.JWT_SECRET!,
-        { expiresIn: '0s' }
+        { algorithm: 'HS256', expiresIn: '0s' }
       );
 
       // Small delay to ensure token is expired
diff --git a/backend/src/__tests__/setup.ts b/backend/src/__tests__/setup.ts
index 3c35ea2..4918664 100644
--- a/backend/src/__tests__/setup.ts
+++ b/backend/src/__tests__/setup.ts
@@ -300,7 +300,7 @@ jest.mock('../lib/prisma', () => ({
 // ============================================================
 
 export const TEST_TENANT_A = {
-  id: 'tenant-a-id',
+  id: 'a0000000-0000-0000-0000-000000000001',
   name: 'Tenant A',
   slug: 'tenant-a',
   logo: null,
@@ -310,7 +310,7 @@ export const TEST_TENANT_A = {
 };
 
 export const TEST_TENANT_B = {
-  id: 'tenant-b-id',
+  id: 'b0000000-0000-0000-0000-000000000002',
   name: 'Tenant B',
   slug: 'tenant-b',
   logo: null,
@@ -354,7 +354,7 @@ export const TEST_CUSTOMER_ADMIN_A = {
   firstName: 'Customer',
   lastName: 'AdminA',
   role: 'CUSTOMER_ADMIN' as const,
-  tenantId: 'tenant-a-id',
+  tenantId: 'a0000000-0000-0000-0000-000000000001',
   active: true,
   createdAt: new Date('2025-01-01'),
   updatedAt: new Date('2025-01-01'),
@@ -367,7 +367,7 @@ export const TEST_CUSTOMER_USER_A = {
   firstName: 'Customer',
   lastName: 'UserA',
   role: 'CUSTOMER_USER' as const,
-  tenantId: 'tenant-a-id',
+  tenantId: 'a0000000-0000-0000-0000-000000000001',
   active: true,
   createdAt: new Date('2025-01-01'),
   updatedAt: new Date('2025-01-01'),
@@ -380,7 +380,7 @@ export const TEST_CUSTOMER_USER_B = {
   firstName: 'Customer',
   lastName: 'UserB',
   role: 'CUSTOMER_USER' as const,
-  tenantId: 'tenant-b-id',
+  tenantId: 'b0000000-0000-0000-0000-000000000002',
   active: true,
   createdAt: new Date('2025-01-01'),
   updatedAt: new Date('2025-01-01'),
@@ -393,7 +393,7 @@ export const TEST_INACTIVE_USER = {
   firstName: 'Inactive',
   lastName: 'User',
   role: 'CUSTOMER_USER' as const,
-  tenantId: 'tenant-a-id',
+  tenantId: 'a0000000-0000-0000-0000-000000000001',
   active: false,
   createdAt: new Date('2025-01-01'),
   updatedAt: new Date('2025-01-01'),
@@ -420,18 +420,21 @@ export function generateTestToken(user: {
       lastName: user.lastName,
     },
     process.env.JWT_SECRET!,
-    { expiresIn: '15m' }
+    { algorithm: 'HS256', expiresIn: '15m' }
   );
 }
 
+// Counter to ensure each refresh token is unique even within the same second
+let refreshTokenCounter = 0;
+
 /**
  * Generate a JWT refresh token for testing.
  */
 export function generateTestRefreshToken(userId: string): string {
   return jwt.sign(
-    { id: userId, type: 'refresh' },
+    { id: userId, type: 'refresh', jti: `test-${Date.now()}-${++refreshTokenCounter}` },
     process.env.JWT_REFRESH_SECRET!,
-    { expiresIn: '7d' }
+    { algorithm: 'HS256', expiresIn: '7d' }
   );
 }
 
@@ -465,7 +468,7 @@ export function seedTestData(): void {
     id: 'workflow-a1-id',
     title: 'Workflow A1',
     description: 'Test workflow for tenant A',
-    tenantId: 'tenant-a-id',
+    tenantId: 'a0000000-0000-0000-0000-000000000001',
     categoryId: null,
     status: 'DRAFT',
     version: 1,
@@ -482,7 +485,7 @@ export function seedTestData(): void {
     id: 'workflow-b1-id',
     title: 'Workflow B1',
     description: 'Test workflow for tenant B',
-    tenantId: 'tenant-b-id',
+    tenantId: 'b0000000-0000-0000-0000-000000000002',
     categoryId: null,
     status: 'PUBLISHED',
     version: 1,
diff --git a/backend/src/__tests__/workflows.test.ts b/backend/src/__tests__/workflows.test.ts
index f7a05d9..6ad8695 100644
--- a/backend/src/__tests__/workflows.test.ts
+++ b/backend/src/__tests__/workflows.test.ts
@@ -110,7 +110,7 @@ describe('Workflow Routes', () => {
     const validWorkflow = {
       title: 'New Test Workflow',
       description: 'A test workflow description',
-      tenantId: 'tenant-a-id',
+      tenantId: TEST_TENANT_A.id,
       tags: ['new', 'test'],
     };
 
@@ -145,14 +145,14 @@ describe('Workflow Routes', () => {
         .send(validWorkflow);
 
       expect(res.status).toBe(201);
-      expect(res.body.data.tenantId).toBe('tenant-a-id');
+      expect(res.body.data.tenantId).toBe(TEST_TENANT_A.id);
     });
 
     it('should reject CUSTOMER_ADMIN creating workflow in another tenant', async () => {
       const res = await request(app)
         .post('/api/workflows')
         .set('Authorization', `Bearer ${customerAdminAToken}`)
-        .send({ ...validWorkflow, tenantId: 'tenant-b-id' });
+        .send({ ...validWorkflow, tenantId: TEST_TENANT_B.id });
 
       expect(res.status).toBe(403);
     });
@@ -178,7 +178,7 @@ describe('Workflow Routes', () => {
       const res = await request(app)
         .post('/api/workflows')
         .set('Authorization', `Bearer ${systemAdminToken}`)
-        .send({ tenantId: 'tenant-a-id' });
+        .send({ tenantId: TEST_TENANT_A.id });
 
       expect(res.status).toBe(400);
       expect(res.body).toHaveProperty('error');