Team-StackUp · i3months · Aug 18, 2026 · Aug 18, 2026
diff --git a/backend/src/main/java/com/stackup/stackup/session/application/InterviewMessageService.java b/backend/src/main/java/com/stackup/stackup/session/application/InterviewMessageService.java
@@ -25,6 +25,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -167,10 +168,22 @@ public MessageResult submitAnswer(Long userId, Long sessionId, String content, S
             .orElseThrow(() -> new DomainException(ApiErrorCode.SESSION_INVALID_STATE));
         InterviewMessage parentQuestion = resolveAnswerParent(latest);
         int nextSeq = latest.getSequenceNumber() + 1;
-        InterviewMessage answer = messageRepository.save(
-            InterviewMessage.interviewee(session, nextSeq, content, parentQuestion,
-                idempotencyKey != null && !idempotencyKey.isBlank() ? idempotencyKey : null)
-        );
+        InterviewMessage answer;
+        try {
+            // saveAndFlush — INSERT 를 여기서 터뜨려야 아래에서 잡을 수 있다. 커밋 시점까지
+            // 미루면 트랜잭션 밖에서 500 으로 새어 나간다.
+            answer = messageRepository.saveAndFlush(
+                InterviewMessage.interviewee(session, nextSeq, content, parentQuestion,
+                    idempotencyKey != null && !idempotencyKey.isBlank() ? idempotencyKey : null)
+            );
+        } catch (DataIntegrityViolationException e) {
+            // 같은 질문에 두 요청이 동시에 들어오면 둘 다 같은 nextSeq 를 계산한다.
+            // (session_id, sequence_number) UNIQUE 가 한쪽을 막는데, 그대로 두면 사용자에겐
+            // 정체불명의 500 이 된다. 실제 의미는 '이 턴은 이미 답변됐다' 이므로 그렇게 알린다.
+            log.info("answer sequence conflict — turn already answered. sessionId={}, seq={}",
+                sessionId, nextSeq);
+            throw new DomainException(ApiErrorCode.SESSION_INVALID_STATE);
+        }
 
         events.publishEvent(new AnswerSubmittedEvent(
             userId, sessionId, parentQuestion.getId(), answer.getId()

diff --git a/backend/src/main/java/com/stackup/stackup/session/application/VoiceAnswerUploadService.java b/backend/src/main/java/com/stackup/stackup/session/application/VoiceAnswerUploadService.java
@@ -16,6 +16,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -61,10 +62,19 @@ public VoicePlaceholder createVoicePlaceholder(Long userId, Long sessionId, Stri
             throw new DomainException(ApiErrorCode.SESSION_INVALID_STATE);
         }
         int nextSeq = latest.getSequenceNumber() + 1;
-        InterviewMessage placeholder = messageRepository.save(
-            InterviewMessage.voiceInterviewee(session, nextSeq, latest,
-                idempotencyKey != null && !idempotencyKey.isBlank() ? idempotencyKey : null)
-        );
+        InterviewMessage placeholder;
+        try {
+            // 텍스트 답변(InterviewMessageService.submitAnswer)과 같은 이유로 saveAndFlush +
+            // 제약 위반 변환 — 같은 턴에 동시 제출이 들어오면 둘 다 같은 seq 를 계산한다.
+            placeholder = messageRepository.saveAndFlush(
+                InterviewMessage.voiceInterviewee(session, nextSeq, latest,
+                    idempotencyKey != null && !idempotencyKey.isBlank() ? idempotencyKey : null)
+            );
+        } catch (DataIntegrityViolationException e) {
+            log.info("voice answer sequence conflict — turn already answered. sessionId={}, seq={}",
+                sessionId, nextSeq);
+            throw new DomainException(ApiErrorCode.SESSION_INVALID_STATE);
+        }
         return new VoicePlaceholder(session, placeholder, latest);
     }
 

diff --git a/...nd/src/test/java/com/stackup/stackup/session/application/InterviewMessageServiceTest.java b/...nd/src/test/java/com/stackup/stackup/session/application/InterviewMessageServiceTest.java
@@ -9,6 +9,7 @@
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import com.stackup.stackup.common.exception.ApiErrorCode;
 import com.stackup.stackup.common.exception.DomainException;
 import com.stackup.stackup.common.storage.ObjectStorageClient;
 import com.stackup.stackup.session.application.dto.MessageResult;
@@ -81,7 +82,7 @@ void submitAnswer_insertsIntervieweeAndPublishesEvent() {
 
         when(sessionRepository.findByIdAndUser_IdAndDeletedFalse(10L, 1L)).thenReturn(Optional.of(session));
         when(messageRepository.findFirstBySession_IdOrderBySequenceNumberDesc(10L)).thenReturn(Optional.of(question));
-        when(messageRepository.save(any(InterviewMessage.class))).thenAnswer(inv -> {
+        when(messageRepository.saveAndFlush(any(InterviewMessage.class))).thenAnswer(inv -> {
             InterviewMessage m = inv.getArgument(0);
             ReflectionTestUtils.setField(m, "id", 200L);
             return m;
@@ -111,6 +112,27 @@ void submitAnswer_returnsExistingWhenIdempotencyKeyHit() {
         verify(events, never()).publishEvent(any(AnswerSubmittedEvent.class));
     }
 
+    // 같은 턴에 두 요청이 동시에 들어오면 둘 다 같은 seq 를 계산한다.
+    // (session_id, sequence_number) UNIQUE 가 한쪽을 막는데, 500 이 아니라 '이미 답변된 턴'이어야 한다.
+    @Test
+    void submitAnswer_translatesSequenceConflictToInvalidState() {
+        InterviewSession session = sessionInProgress(10L);
+        InterviewMessage question = InterviewMessage.interviewer(session, 1, "Q1?");
+        ReflectionTestUtils.setField(question, "id", 100L);
+
+        when(sessionRepository.findByIdAndUser_IdAndDeletedFalse(10L, 1L)).thenReturn(Optional.of(session));
+        when(messageRepository.findFirstBySession_IdOrderBySequenceNumberDesc(10L)).thenReturn(Optional.of(question));
+        when(messageRepository.saveAndFlush(any(InterviewMessage.class)))
+            .thenThrow(new org.springframework.dao.DataIntegrityViolationException(
+                "duplicate key value violates unique constraint"));
+
+        assertThatThrownBy(() -> service.submitAnswer(1L, 10L, "answer", null))
+            .isInstanceOfSatisfying(DomainException.class, e ->
+                assertThat(e.getErrorCode()).isEqualTo(ApiErrorCode.SESSION_INVALID_STATE));
+
+        verify(events, never()).publishEvent(any(AnswerSubmittedEvent.class));
+    }
+
     @Test
     void submitAnswer_rejectsWhenPreviousMessageNotInterviewer() {
         InterviewSession session = sessionInProgress(10L);
@@ -135,7 +157,7 @@ void submitAnswer_allowsTextRetryAfterFailedVoiceAnswer() {
 
         when(sessionRepository.findByIdAndUser_IdAndDeletedFalse(10L, 1L)).thenReturn(Optional.of(session));
         when(messageRepository.findFirstBySession_IdOrderBySequenceNumberDesc(10L)).thenReturn(Optional.of(failedVoice));
-        when(messageRepository.save(any(InterviewMessage.class))).thenAnswer(inv -> {
+        when(messageRepository.saveAndFlush(any(InterviewMessage.class))).thenAnswer(inv -> {
             InterviewMessage m = inv.getArgument(0);
             ReflectionTestUtils.setField(m, "id", 201L);
             return m;

diff --git a/...d/src/test/java/com/stackup/stackup/session/application/VoiceAnswerUploadServiceTest.java b/...d/src/test/java/com/stackup/stackup/session/application/VoiceAnswerUploadServiceTest.java
@@ -52,7 +52,7 @@ void createVoicePlaceholder_insertsAfterLatestQuestion() {
         when(sessionRepository.findByIdAndUser_IdAndDeletedFalse(10L, 1L)).thenReturn(Optional.of(session));
         when(messageRepository.findFirstBySession_IdOrderBySequenceNumberDesc(10L))
             .thenReturn(Optional.of(question));
-        when(messageRepository.save(any(InterviewMessage.class))).thenAnswer(inv -> {
+        when(messageRepository.saveAndFlush(any(InterviewMessage.class))).thenAnswer(inv -> {
             InterviewMessage m = inv.getArgument(0);
             ReflectionTestUtils.setField(m, "id", 200L);
             return m;
@@ -135,6 +135,24 @@ void createVoicePlaceholder_rejectsWhenLastMessageIsNotQuestion() {
         verify(messageRepository, never()).save(any());
     }
 
+    // 텍스트 답변과 동일 — 동시 제출로 seq 가 충돌하면 500 이 아니라 '이미 답변된 턴'.
+    @Test
+    void createVoicePlaceholder_translatesSequenceConflictToInvalidState() {
+        InterviewSession session = sessionInProgress(10L);
+        InterviewMessage question = InterviewMessage.interviewer(session, 1, "Q1?");
+        ReflectionTestUtils.setField(question, "id", 100L);
+
+        when(sessionRepository.findByIdAndUser_IdAndDeletedFalse(10L, 1L)).thenReturn(Optional.of(session));
+        when(messageRepository.findFirstBySession_IdOrderBySequenceNumberDesc(10L))
+            .thenReturn(Optional.of(question));
+        when(messageRepository.saveAndFlush(any(InterviewMessage.class)))
+            .thenThrow(new org.springframework.dao.DataIntegrityViolationException("duplicate key"));
+
+        assertThatThrownBy(() -> service.createVoicePlaceholder(1L, 10L, null))
+            .isInstanceOfSatisfying(DomainException.class, e ->
+                assertThat(e.getErrorCode()).isEqualTo(ApiErrorCode.SESSION_INVALID_STATE));
+    }
+
     // ── attachAudioAndRequestAnalysis ─────────────────────────────────────────
 
     // analyze.voice 는 여기서 직접 발행하지 않는다 — 이벤트만 내고 AFTER_COMMIT 리스너가 발행한다.

diff --git a/frontend/src/features/history/ui/SessionCard.test.tsx b/frontend/src/features/history/ui/SessionCard.test.tsx
@@ -0,0 +1,62 @@
+import { describe, it, expect } from 'vitest'
+import { render, screen } from '@testing-library/react'
+import { MemoryRouter } from 'react-router-dom'
+import { SessionCard } from './SessionCard'
+import type { Session } from '../api/historyApi'
+
+const base: Session = {
+  id: 7,
+  title: '백엔드 모의면접',
+  status: 'COMPLETED',
+  mode: 'TECHNICAL',
+  jobCategory: 'BACKEND',
+  totalQuestionCount: 5,
+  createdAt: '2026-08-18T00:00:00Z',
+}
+
+function renderCard(session: Partial<Session>) {
+  return render(
+    <MemoryRouter>
+      <SessionCard session={{ ...base, ...session }} />
+    </MemoryRouter>,
+  )
+}
+
+describe('SessionCard', () => {
+  it('완료 세션은 피드백 리포트로 간다', () => {
+    renderCard({ status: 'COMPLETED' })
+
+    expect(screen.getByRole('link')).toHaveAttribute('href', '/sessions/7/feedback')
+    expect(screen.getByText('리포트 →')).toBeInTheDocument()
+  })
+
+  // 중단된 면접은 피드백이 없다. 문답 기록으로 갈 경로가 없으면 한 말이 통째로 사라진다.
+  it('중단 세션은 세션 화면(기록)으로 간다', () => {
+    renderCard({ status: 'INTERRUPTED' })
+
+    expect(screen.getByRole('link')).toHaveAttribute('href', '/sessions/7')
+    expect(screen.getByText('기록 보기 →')).toBeInTheDocument()
+  })
+
+  // 진행 중 면접에서 이탈했을 때 돌아갈 경로.
+  it('진행 중 세션은 이어서 진행할 수 있다', () => {
+    renderCard({ status: 'IN_PROGRESS' })
+
+    expect(screen.getByRole('link')).toHaveAttribute('href', '/sessions/7')
+    expect(screen.getByText('이어서 →')).toBeInTheDocument()
+  })
+
+  it('준비 상태 세션은 로비로 간다', () => {
+    renderCard({ status: 'READY' })
+
+    expect(screen.getByRole('link')).toHaveAttribute('href', '/sessions/7')
+  })
+
+  // 시작 전 취소라 보여줄 문답이 없다 — 링크를 만들지 않는다.
+  it('취소 세션은 눌리지 않는다', () => {
+    renderCard({ status: 'CANCELLED' })
+
+    expect(screen.queryByRole('link')).not.toBeInTheDocument()
+    expect(screen.getByText('취소됨')).toBeInTheDocument()
+  })
+})
diff --git a/frontend/src/features/history/ui/SessionCard.tsx b/frontend/src/features/history/ui/SessionCard.tsx
@@ -25,9 +25,21 @@ const JOB: Record<string, string> = {
   DBA: 'DBA',
 }
 
+/**
+ * 상태별로 눌렀을 때 갈 곳. 예전에는 COMPLETED 만 링크였고 나머지는 아예 눌리지 않아,
+ * 중단된 면접의 문답을 다시 볼 방법도 · 진행 중이던 면접으로 돌아갈 방법도 없었다.
+ * (CANCELLED 는 시작 전 취소라 볼 것이 없어 그대로 둔다.)
+ */
+const LINK: Record<string, { to: (id: number) => string; cta: string }> = {
+  COMPLETED: { to: (id) => `/sessions/${id}/feedback`, cta: '리포트 →' },
+  INTERRUPTED: { to: (id) => `/sessions/${id}`, cta: '기록 보기 →' },
+  IN_PROGRESS: { to: (id) => `/sessions/${id}`, cta: '이어서 →' },
+  READY: { to: (id) => `/sessions/${id}`, cta: '시작하기 →' },
+}
+
 export function SessionCard({ session }: { session: Session }) {
   const status = session.status ? STATUS[session.status] : undefined
-  const completed = session.status === 'COMPLETED'
+  const link = session.status ? LINK[session.status] : undefined
   const jobs = session.jobCategories?.length
     ? session.jobCategories
     : session.jobCategory
@@ -48,15 +60,17 @@ export function SessionCard({ session }: { session: Session }) {
       </div>
       <div className="flex items-center gap-3">
         {status && <StatusBadge tone={status.tone}>{status.label}</StatusBadge>}
-        {completed && (
-          <span className="shrink-0 text-caption font-medium text-primary-fg">리포트 →</span>
+        {link && (
+          <span className="shrink-0 text-caption font-medium text-primary-fg">
+            {link.cta}
+          </span>
         )}
       </div>
     </div>
   )
 
-  return completed ? (
-    <Link to={`/sessions/${session.id}/feedback`}>{body}</Link>
+  return link && session.id != null ? (
+    <Link to={link.to(session.id)}>{body}</Link>
   ) : (
     body
   )

diff --git a/frontend/src/features/interview/ui/live/SessionEndedPanel.tsx b/frontend/src/features/interview/ui/live/SessionEndedPanel.tsx
@@ -2,13 +2,20 @@ import { Link } from 'react-router-dom'
 import { Button } from '@/shared/ui/Button'
 import { Eyebrow } from '@/shared/ui'
 import type { SessionStatus } from '@/domain/session'
+import { InterviewTranscript } from '../InterviewTranscript'
 
 const messageByStatus: Partial<Record<SessionStatus, string>> = {
   COMPLETED: '면접이 종료되었습니다. 피드백을 준비 중입니다.',
   INTERRUPTED: '면접이 중단되었습니다.',
   CANCELLED: '면접이 취소되었습니다.',
 }
 
+// 중단된 면접은 피드백이 만들어지지 않는다. 그렇다고 주고받은 문답까지 못 보게 하면
+// 사용자가 한 말이 통째로 사라진 것처럼 보이므로, 여기서 기록을 그대로 노출한다.
+// (취소된 세션은 시작 전이라 자기소개 질문 하나뿐 — 보여줄 게 없다.)
+const showsTranscript = (status: SessionStatus) =>
+  status === 'COMPLETED' || status === 'INTERRUPTED'
+
 export function SessionEndedPanel({
   status,
   sessionId,
@@ -17,24 +24,32 @@ export function SessionEndedPanel({
   sessionId: number
 }) {
   return (
-    <div className="flex h-full flex-col items-center justify-center gap-4 px-6 text-center">
-      <Eyebrow>면접 종료</Eyebrow>
-      <p
-        className="font-sans text-[22px] font-bold tracking-[-0.03em] text-fg"
-        style={{ wordBreak: 'keep-all' }}
-      >
-        {messageByStatus[status] ?? '면접이 종료되었습니다.'}
-      </p>
-      <div className="mt-2 flex flex-wrap items-center justify-center gap-3">
-        {status === 'COMPLETED' && (
-          <Link to={`/sessions/${sessionId}/feedback`}>
-            <Button>피드백 보기</Button>
+    <div className="flex h-full flex-col overflow-y-auto">
+      <div className="flex flex-col items-center justify-center gap-4 px-6 py-16 text-center">
+        <Eyebrow>면접 종료</Eyebrow>
+        <p
+          className="font-sans text-[22px] font-bold tracking-[-0.03em] text-fg"
+          style={{ wordBreak: 'keep-all' }}
+        >
+          {messageByStatus[status] ?? '면접이 종료되었습니다.'}
+        </p>
+        <div className="mt-2 flex flex-wrap items-center justify-center gap-3">
+          {status === 'COMPLETED' && (
+            <Link to={`/sessions/${sessionId}/feedback`}>
+              <Button>피드백 보기</Button>
+            </Link>
+          )}
+          <Link to="/workspace">
+            <Button variant="secondary">워크스페이스로</Button>
           </Link>
-        )}
-        <Link to="/workspace">
-          <Button variant="secondary">워크스페이스로</Button>
-        </Link>
+        </div>
       </div>
+
+      {showsTranscript(status) && (
+        <div className="mx-auto w-full max-w-3xl px-6 pb-16">
+          <InterviewTranscript sessionId={sessionId} />
+        </div>
+      )}
     </div>
   )
 }