fix: clarify signature reporting status

api/src/dictionaries/dictionaries.service.spec.ts

@@ -128,4 +128,20 @@ describe('DictionariesService', () => {
     );
     expect(prisma.drainageField.create).toHaveBeenCalledTimes(1);
   });
+
+  it('only accepts Arabic numerals and English letters in report field codes', async () => {
+    const prisma = createPrismaMock();
+    const service = new DictionariesService(prisma as never);
+
+    await expect(service.createDrainageField({ code: 'License2026', name: '营业执照', fieldType: 'image' })).resolves.toEqual(
+      expect.objectContaining({ code: 'License2026' }),
+    );
+    expect(() => service.createDrainageField({ code: 'license_code', name: '营业执照', fieldType: 'image' })).toThrow(
+      'code must contain only Arabic numerals and English letters',
+    );
+    expect(() => service.createDrainageField({ code: '营业执照', name: '营业执照', fieldType: 'image' })).toThrow(
+      'code must contain only Arabic numerals and English letters',
+    );
+    expect(prisma.drainageField.create).toHaveBeenCalledTimes(1);
+  });
 });