fix: Buy default pack when signing up

src/main/java/com/renzzle/backend/domain/auth/service/AccountService.java

@@ -4,6 +4,7 @@
 import com.renzzle.backend.domain.auth.api.request.SignupRequest;
 import com.renzzle.backend.domain.auth.api.response.LoginResponse;
 import com.renzzle.backend.domain.user.dao.UserRepository;
+import com.renzzle.backend.domain.puzzle.training.service.TrainingService;
 import com.renzzle.backend.domain.user.domain.UserEntity;
 import com.renzzle.backend.global.exception.CustomException;
 import com.renzzle.backend.global.exception.ErrorCode;
@@ -23,6 +24,7 @@ public class AccountService {
     private final UserRepository userRepository;
     private final PasswordEncoder passwordEncoder = new BCryptPasswordEncoder();
     private final AuthService authService;
+    private final TrainingService trainingService;
 
     @Transactional(readOnly = true)
     public boolean isDuplicatedEmail(String email) {
@@ -46,7 +48,8 @@ public LoginResponse signUp(SignupRequest request) {
         }
 
         UserEntity user = createNewUser(request.email(), request.password(), request.nickname(), request.deviceId());
-
+        // 회원가입 시 packId = 1 자동 지급
+        trainingService.grantPackToUser(user, 1L);
         return authService.createAuthTokens(user.getId());
     }
 

src/main/java/com/renzzle/backend/domain/puzzle/training/service/TrainingService.java

@@ -308,4 +308,28 @@ public GetTrainingPuzzleAnswerResponse purchaseTrainingPuzzleAnswer(UserEntity u
                 .price(ItemPrice.HINT.getPrice())
                 .build();
     }
+
+    // 회원가입 시 무료로 특정 Pack을 지급 (잔액 차감 없음)
+    @Transactional
+    public void grantPackToUser(UserEntity user, Long packId) {
+        if (user == null || packId == null) {
+            throw new CustomException(ErrorCode.VALIDATION_ERROR);
+        }
+
+        Pack pack = packRepository.findById(packId)
+                .orElseThrow(() -> new CustomException(ErrorCode.NO_SUCH_TRAINING_PACK));
+
+        // 이미 보유한 경우 무시
+        if (userPackRepository.findByUserIdAndPackId(user.getId(), packId).isPresent()) {
+            return;
+        }
+
+        UserPack userPack = UserPack.builder()
+                .user(user)
+                .pack(pack)
+                .solvedCount(0)
+                .build();
+
+        userPackRepository.save(userPack);
+    }
 }

src/test/java/com/renzzle/backend/domain/auth/service/AccountServiceTest.java

@@ -4,6 +4,7 @@
 import com.renzzle.backend.domain.auth.api.request.SignupRequest;
 import com.renzzle.backend.domain.auth.api.response.LoginResponse;
 import com.renzzle.backend.domain.user.dao.UserRepository;
+import com.renzzle.backend.domain.puzzle.training.service.TrainingService;
 import com.renzzle.backend.domain.user.domain.UserEntity;
 import com.renzzle.backend.global.exception.CustomException;
 import com.renzzle.backend.global.exception.ErrorCode;
@@ -34,6 +35,8 @@ public class AccountServiceTest {
     private UserRepository userRepository;
     @Mock
     private AuthService authService;
+    @Mock
+    private TrainingService trainingService;
 
     @InjectMocks
     private AccountService accountService;
@@ -62,6 +65,7 @@ public void signUp_ShouldCreateUserAndReturnTokens_WhenValid() {
         when(userRepository.existsByDeviceId(deviceId)).thenReturn(false);
         when(userRepository.save(any(UserEntity.class))).thenAnswer(i -> UserEntity.builder().id(1L).build());
         when(authService.createAuthTokens(anyLong())).thenReturn(mock(LoginResponse.class));
+        doNothing().when(trainingService).grantPackToUser(any(UserEntity.class), eq(1L));
 
         // when
         LoginResponse response = accountService.signUp(validSignupRequest);