fix: improve 답변 Null로 반환하는 이슈 해결

src/main/java/com/example/trouble_log/domain/interview/controller/InterviewSubmissionController.java

@@ -21,19 +21,19 @@
 @RestController
 @RequiredArgsConstructor
 @RequestMapping("/api/projects")
-@Tag(name = "Interview Submission", description = "면접 답변 최종 제출 및 개인정보 감지 API")
+@Tag(name = "Interview Submission", description = "면접 답변 최종 제출 API")
 public class InterviewSubmissionController {
 
     private final InterviewSubmissionService interviewSubmissionService;
 
     @Operation(
             summary = "면접 답변 최종 제출",
-            description = "프로젝트 세션에 생성된 면접 질문 3개에 대한 최종 답변을 저장합니다. 답변 내 개인정보가 감지되면 제출을 차단하고 감지 유형과 경고 메시지를 반환합니다."
+            description = "프로젝트 세션에 생성된 면접 질문 3개에 대한 최종 답변을 저장합니다. 개인정보와 민감정보 감지는 최초 소스코드 입력 단계에서 수행합니다."
     )
     @ApiResponses({
             @ApiResponse(responseCode = "200", description = "최종 제출 성공",
                     content = @Content(schema = @Schema(implementation = InterviewSubmitResponse.class))),
-            @ApiResponse(responseCode = "400", description = "필수 값 누락, 질문 3개 미준비, 답변 개수 불일치, 개인정보 감지"),
+            @ApiResponse(responseCode = "400", description = "필수 값 누락, 질문 3개 미준비, 답변 개수 불일치"),
             @ApiResponse(responseCode = "403", description = "해당 프로젝트 세션에 접근할 수 없음"),
             @ApiResponse(responseCode = "404", description = "프로젝트 세션을 찾을 수 없음")
     })

src/main/java/com/example/trouble_log/domain/interview/dto/PersonalInfoDetectionResponse.java

@@ -0,0 +1,18 @@
+package com.example.trouble_log.domain.interview.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import java.util.List;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+@Getter
+@AllArgsConstructor
+@Schema(description = "개인정보 감지 차단 응답")
+public class PersonalInfoDetectionResponse {
+
+    @Schema(description = "차단 사유", example = "PERSONAL_INFO_DETECTED")
+    private String blockedReason;
+
+    @Schema(description = "개인정보 감지 경고 목록")
+    private List<PersonalInfoWarning> warnings;
+}

src/main/java/com/example/trouble_log/domain/interview/service/InterviewService.java

@@ -34,6 +34,9 @@
 @Transactional(readOnly = true)
 public class InterviewService {
 
+    private static final String DEFAULT_IMPROVEMENT_MESSAGE =
+            "현재 답변은 질문의 핵심을 잘 짚고 있어요. 이 흐름을 유지하면서 본인이 직접 고민하고 해결한 과정까지 차분히 이어가면 더 설득력 있는 답변이 될 수 있습니다.";
+
     private final InterviewQuestionRepository questionRepository;
     private final InterviewAnswerRepository answerRepository;
     private final ProjectSessionRepository sessionRepository;
@@ -93,7 +96,7 @@ public AnswerResponse saveAnswer(Long sessionId, Long questionId, AnswerRequest
                 feedbackJson = "{}";
             }
 
-            improvement = feedbackResult.getImprovement();
+            improvement = normalizeImprovement(feedbackResult.getImprovement());
             warning = feedbackResult.getWarning();
         }
 
@@ -109,6 +112,12 @@ public AnswerResponse saveAnswer(Long sessionId, Long questionId, AnswerRequest
         return new AnswerResponse(saved.getId(), improvement, warning);
     }
 
+    private String normalizeImprovement(String improvement) {
+        return improvement == null || improvement.isBlank()
+                ? DEFAULT_IMPROVEMENT_MESSAGE
+                : improvement;
+    }
+
     // ── 트러블슈팅 리포트 생성 ────────────────────────────────
     @Transactional
     public ReportResponse generateReport(Long sessionId) {

src/main/java/com/example/trouble_log/domain/interview/service/InterviewSubmissionService.java

@@ -4,10 +4,8 @@
 import com.example.trouble_log.domain.interview.dto.InterviewSubmitAnswerRequest;
 import com.example.trouble_log.domain.interview.dto.InterviewSubmitRequest;
 import com.example.trouble_log.domain.interview.dto.InterviewSubmitResponse;
-import com.example.trouble_log.domain.interview.dto.PersonalInfoWarning;
 import com.example.trouble_log.domain.interview.entity.InterviewAnswer;
 import com.example.trouble_log.domain.interview.entity.InterviewQuestion;
-import com.example.trouble_log.domain.interview.exception.PersonalInfoDetectedException;
 import com.example.trouble_log.domain.interview.repository.InterviewAnswerRepository;
 import com.example.trouble_log.domain.interview.repository.InterviewQuestionRepository;
 import com.example.trouble_log.domain.projectSession.entity.ProjectSession;
@@ -17,7 +15,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.function.Function;
 import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.HttpStatus;
@@ -31,15 +28,13 @@
 public class InterviewSubmissionService {
 
     private static final int REQUIRED_QUESTION_COUNT = 3;
-    private static final String UNANSWERED_MESSAGE = "사용자 답변 안 함";
 
     private final ProjectSessionRepository projectSessionRepository;
     private final InterviewQuestionRepository interviewQuestionRepository;
     private final InterviewAnswerRepository interviewAnswerRepository;
-    private final PersonalInfoDetectionService personalInfoDetectionService;
     private final AuditLogService auditLogService;
 
-    // 최종 답변 3개를 저장한 뒤 개인정보 감지 결과에 따라 리포트 생성 가능 상태를 반환한다.
+    // 최종 답변 3개를 저장한 뒤 리포트 생성 가능 상태를 반환한다.
     @Transactional
     public InterviewSubmitResponse submit(Long sessionId, InterviewSubmitRequest request) {
         validateRequest(sessionId, request);
@@ -55,19 +50,6 @@ public InterviewSubmitResponse submit(Long sessionId, InterviewSubmitRequest req
         Map<Long, String> finalAnswers = validateAndNormalizeFinalAnswers(questions, request.getAnswers());
         List<InterviewAnswer> savedAnswers = saveFinalAnswers(questions, finalAnswers);
 
-        String answersText = buildAnswersText(questions, savedAnswers);
-        List<PersonalInfoWarning> warnings = personalInfoDetectionService.detect(answersText);
-        if (!warnings.isEmpty()) {
-            auditLogService.recordFailure(
-                    request.getMemberId(),
-                    sessionId,
-                    "INTERVIEW_ANSWER_SUBMIT",
-                    buildSubmitRequestSummary(questions, savedAnswers),
-                    "개인정보 감지: " + warnings.stream().map(PersonalInfoWarning::getType).toList()
-            );
-            throw new PersonalInfoDetectedException(warnings);
-        }
-
         auditLogService.recordSuccess(
                 request.getMemberId(),
                 sessionId,
@@ -176,21 +158,6 @@ private InterviewAnswer saveFinalAnswer(InterviewQuestion question, String final
         return interviewAnswerRepository.save(interviewAnswer);
     }
 
-    // 개인정보 감지와 리포트 생성 요청에 사용할 질문/답변 텍스트를 만든다.
-    private String buildAnswersText(List<InterviewQuestion> questions, List<InterviewAnswer> answers) {
-        Map<Long, InterviewAnswer> answerByQuestionId = answers.stream()
-                .collect(Collectors.toMap(answer -> answer.getInterviewQuestion().getId(), Function.identity()));
-
-        return questions.stream()
-                .map(question -> question.getQuestion() + "\n" + toReportAnswer(answerByQuestionId.get(question.getId()).getAnswer()))
-                .reduce("", (left, right) -> left + "\n" + right);
-    }
-
-    // 답변이 비어 있으면 AI 리포트가 미답변 상태를 이해할 수 있는 명시 문구로 변환한다.
-    private String toReportAnswer(String answer) {
-        return answer == null || answer.isBlank() ? UNANSWERED_MESSAGE : answer;
-    }
-
     // 최종 제출 요청 내용을 감사 로그용 요약 문자열로 변환한다.
     private String buildSubmitRequestSummary(List<InterviewQuestion> questions, List<InterviewAnswer> answers) {
         int answerLength = answers.stream()

src/main/java/com/example/trouble_log/domain/projectSession/controller/ProjectSessionController.java

@@ -1,5 +1,6 @@
 package com.example.trouble_log.domain.projectSession.controller;
 
+import com.example.trouble_log.domain.interview.dto.PersonalInfoDetectionResponse;
 import com.example.trouble_log.domain.projectSession.dto.PreContextRequest;
 import com.example.trouble_log.domain.projectSession.dto.PreContextResponse;
 import com.example.trouble_log.domain.projectSession.dto.ProjectSessionRequest;
@@ -31,12 +32,13 @@ public class ProjectSessionController {
 
     @Operation(
             summary = "프로젝트 세션 생성",
-            description = "회원이 입력한 소스코드와 선택적인 GitHub URL을 저장하고, 이후 사전 컨텍스트와 면접 질문 생성에 사용할 세션 ID를 반환합니다."
+            description = "회원이 입력한 소스코드에서 개인정보와 민감정보를 먼저 감지합니다. 문제가 없으면 소스코드와 선택적인 GitHub URL을 저장하고, 이후 사전 컨텍스트와 면접 질문 생성에 사용할 세션 ID를 반환합니다."
     )
     @ApiResponses({
             @ApiResponse(responseCode = "201", description = "프로젝트 세션 생성 성공",
                     content = @Content(schema = @Schema(implementation = ProjectSessionResponse.class))),
-            @ApiResponse(responseCode = "400", description = "회원 ID 또는 소스코드 누락"),
+            @ApiResponse(responseCode = "400", description = "회원 ID 또는 소스코드 누락, 개인정보 또는 민감정보 감지",
+                    content = @Content(schema = @Schema(implementation = PersonalInfoDetectionResponse.class))),
             @ApiResponse(responseCode = "404", description = "회원을 찾을 수 없음")
     })
     @PostMapping()

src/main/java/com/example/trouble_log/domain/projectSession/service/ProjectSessionService.java

@@ -3,8 +3,11 @@
 import com.example.trouble_log.domain.ai.service.AzureOpenAiPromptService;
 import com.example.trouble_log.domain.audit.service.AuditLogService;
 import com.example.trouble_log.domain.interview.dto.InterviewQuestionResponse;
+import com.example.trouble_log.domain.interview.dto.PersonalInfoWarning;
 import com.example.trouble_log.domain.interview.entity.InterviewQuestion;
+import com.example.trouble_log.domain.interview.exception.PersonalInfoDetectedException;
 import com.example.trouble_log.domain.interview.repository.InterviewQuestionRepository;
+import com.example.trouble_log.domain.interview.service.PersonalInfoDetectionService;
 import com.example.trouble_log.domain.projectSession.dto.PreContextRequest;
 import com.example.trouble_log.domain.projectSession.dto.PreContextResponse;
 import com.example.trouble_log.domain.projectSession.dto.ProjectSessionRequest;
@@ -37,12 +40,14 @@ public class ProjectSessionService {
     private final InterviewQuestionRepository interviewQuestionRepository;
     private final AzureOpenAiPromptService azureOpenAiPromptService;
     private final AuditLogService auditLogService;
+    private final PersonalInfoDetectionService personalInfoDetectionService;
 
     @Transactional
     // 회원의 코드와 GitHub URL을 기반으로 새 프로젝트 세션을 생성한다.
     public ProjectSessionResponse create(ProjectSessionRequest request) {
         validateRequestBody(request);
         validateRequiredFields("회원 ID와 소스코드는 필수입니다.", request.getMemberId(), request.getCodeContent());
+        validateCodeContentDoesNotContainPersonalInfo(request);
 
         Member member = memberRepository.findById(request.getMemberId())
                 .orElseThrow(() -> {
@@ -75,6 +80,22 @@ public ProjectSessionResponse create(ProjectSessionRequest request) {
         return new ProjectSessionResponse(savedProjectSession.getId());
     }
 
+    private void validateCodeContentDoesNotContainPersonalInfo(ProjectSessionRequest request) {
+        List<PersonalInfoWarning> warnings = personalInfoDetectionService.detect(request.getCodeContent());
+        if (warnings.isEmpty()) {
+            return;
+        }
+
+        auditLogService.recordFailure(
+                request.getMemberId(),
+                null,
+                "PROJECT_SESSION_CREATE",
+                buildProjectSessionRequestSummary(request),
+                "개인정보 감지: " + warnings.stream().map(PersonalInfoWarning::getType).toList()
+        );
+        throw new PersonalInfoDetectedException(warnings);
+    }
+
     @Transactional
     // 사전 컨텍스트를 저장하고 AI 면접 질문을 생성해 함께 반환한다.
     public PreContextResponse createPreContext(Long sessionId, PreContextRequest request) {

src/main/java/com/example/trouble_log/global/exception/GlobalExceptionHandler.java

@@ -1,8 +1,7 @@
 package com.example.trouble_log.global.exception;
 
-import com.example.trouble_log.domain.interview.dto.InterviewSubmitResponse;
+import com.example.trouble_log.domain.interview.dto.PersonalInfoDetectionResponse;
 import com.example.trouble_log.domain.interview.exception.PersonalInfoDetectedException;
-import java.util.List;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.ExceptionHandler;
@@ -12,10 +11,8 @@
 public class GlobalExceptionHandler {
 
     @ExceptionHandler(PersonalInfoDetectedException.class)
-    public ResponseEntity<InterviewSubmitResponse> handlePersonalInfoDetected(PersonalInfoDetectedException e) {
-        InterviewSubmitResponse response = new InterviewSubmitResponse(
-                false,
-                false,
+    public ResponseEntity<PersonalInfoDetectionResponse> handlePersonalInfoDetected(PersonalInfoDetectedException e) {
+        PersonalInfoDetectionResponse response = new PersonalInfoDetectionResponse(
                 "PERSONAL_INFO_DETECTED",
                 e.getWarnings()
         );

src/test/java/com/example/trouble_log/domain/interview/service/InterviewServiceTest.java

@@ -30,6 +30,7 @@
 class InterviewServiceTest {
 
     private InterviewAnswerRepository answerRepository;
+    private AzureOpenAiPromptService promptService;
     private InterviewService interviewService;
 
     @BeforeEach
@@ -38,7 +39,7 @@ void setUp() {
         answerRepository = mock(InterviewAnswerRepository.class);
         ProjectSessionRepository sessionRepository = mock(ProjectSessionRepository.class);
         PreContextRepository preContextRepository = mock(PreContextRepository.class);
-        AzureOpenAiPromptService promptService = mock(AzureOpenAiPromptService.class);
+        promptService = mock(AzureOpenAiPromptService.class);
 
         interviewService = new InterviewService(
                 questionRepository,
@@ -85,6 +86,48 @@ void saveAnswerUpdatesExistingAnswerInsteadOfCreatingDuplicate() {
         assertThat(existingAnswer.getFeedback()).isNotBlank();
     }
 
+    @Test
+    void saveAnswerReturnsDefaultImprovementWhenAiImprovementIsNull() {
+        AnswerFeedbackResult feedbackResult = new AnswerFeedbackResult();
+        feedbackResult.setImprovement(null);
+        when(promptService.evaluateAnswer(any(ProjectSession.class), any(PreContext.class), any(), any()))
+                .thenReturn(feedbackResult);
+
+        InterviewAnswer existingAnswer = new InterviewAnswer(question(), null, true, null);
+        ReflectionTestUtils.setField(existingAnswer, "id", 10L);
+        when(answerRepository.findByInterviewQuestionId(1L)).thenReturn(Optional.of(existingAnswer));
+
+        AnswerRequest request = new AnswerRequest();
+        request.setAnswer("좋은 답변입니다.");
+
+        AnswerResponse response = interviewService.saveAnswer(1L, 1L, request);
+
+        assertThat(response.getImprovement()).isEqualTo(
+                "현재 답변은 질문의 핵심을 잘 짚고 있어요. 이 흐름을 유지하면서 본인이 직접 고민하고 해결한 과정까지 차분히 이어가면 더 설득력 있는 답변이 될 수 있습니다."
+        );
+    }
+
+    @Test
+    void saveAnswerReturnsDefaultImprovementWhenAiImprovementIsBlank() {
+        AnswerFeedbackResult feedbackResult = new AnswerFeedbackResult();
+        feedbackResult.setImprovement("   ");
+        when(promptService.evaluateAnswer(any(ProjectSession.class), any(PreContext.class), any(), any()))
+                .thenReturn(feedbackResult);
+
+        InterviewAnswer existingAnswer = new InterviewAnswer(question(), null, true, null);
+        ReflectionTestUtils.setField(existingAnswer, "id", 10L);
+        when(answerRepository.findByInterviewQuestionId(1L)).thenReturn(Optional.of(existingAnswer));
+
+        AnswerRequest request = new AnswerRequest();
+        request.setAnswer("좋은 답변입니다.");
+
+        AnswerResponse response = interviewService.saveAnswer(1L, 1L, request);
+
+        assertThat(response.getImprovement()).isEqualTo(
+                "현재 답변은 질문의 핵심을 잘 짚고 있어요. 이 흐름을 유지하면서 본인이 직접 고민하고 해결한 과정까지 차분히 이어가면 더 설득력 있는 답변이 될 수 있습니다."
+        );
+    }
+
     private ProjectSession projectSession() {
         Member member = new Member("user@example.com", "password", "user");
         ReflectionTestUtils.setField(member, "id", 1L);

src/test/java/com/example/trouble_log/domain/interview/service/InterviewSubmissionServiceTest.java

@@ -1,7 +1,6 @@
 package com.example.trouble_log.domain.interview.service;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.Mockito.mock;
@@ -13,7 +12,6 @@
 import com.example.trouble_log.domain.interview.dto.InterviewSubmitResponse;
 import com.example.trouble_log.domain.interview.entity.InterviewAnswer;
 import com.example.trouble_log.domain.interview.entity.InterviewQuestion;
-import com.example.trouble_log.domain.interview.exception.PersonalInfoDetectedException;
 import com.example.trouble_log.domain.interview.repository.InterviewAnswerRepository;
 import com.example.trouble_log.domain.interview.repository.InterviewQuestionRepository;
 import com.example.trouble_log.domain.projectSession.entity.ProjectSession;
@@ -41,7 +39,6 @@ void setUp() {
                 projectSessionRepository,
                 interviewQuestionRepository,
                 interviewAnswerRepository,
-                new PersonalInfoDetectionService(),
                 mock(AuditLogService.class)
         );
 
@@ -50,7 +47,7 @@ void setUp() {
     }
 
     @Test
-    void submitBlocksWhenAnswerContainsPersonalInfo() {
+    void submitDoesNotBlockWhenAnswerContainsPersonalInfo() {
         ProjectSession projectSession = projectSession();
         InterviewSubmitRequest request = request(List.of(
                 answerRequest(1L, "제 이메일은 test@example.com 입니다."),
@@ -67,11 +64,10 @@ void submitBlocksWhenAnswerContainsPersonalInfo() {
         when(interviewQuestionRepository.findByProjectSessionIdOrderByQuestionSequenceAsc(anyLong()))
                 .thenReturn(questions);
 
-        assertThatThrownBy(() -> interviewSubmissionService.submit(1L, request))
-                .isInstanceOf(PersonalInfoDetectedException.class)
-                .satisfies(e -> assertThat(((PersonalInfoDetectedException) e).getWarnings())
-                        .extracting("type")
-                        .containsExactly(com.example.trouble_log.domain.interview.type.PersonalInfoType.EMAIL));
+        InterviewSubmitResponse response = interviewSubmissionService.submit(1L, request);
+
+        assertThat(response.getSubmitted()).isTrue();
+        assertThat(response.getReportGenerationReady()).isTrue();
     }
 
     @Test