feat(feedback): 답변별 전달력 메트릭을 복기에 노출

backend/CLAUDE.md

@@ -362,8 +362,8 @@ docker compose up -d
 - **질문별 복기 본 구현**: V19 로 `interview_messages` 에 `model_answer`/`answer_rewrite`/`coaching_comment`
   추가. AI 가 `callback.feedback.answerCoaching[{messageId,…}]` 로 답변별 모범 답안·리라이트·코칭을 보내면
   `FeedbackCallbackService` 가 각 메시지에 `recordCoaching` 기록. `MessageResult`/`MessageResponse` 가 답변
-  평가 점수 + 복기를 노출하되 **종료 세션 조회에서만**(`expectedSignal` 과 동일 게이팅). 프론트는 답변 버블
-  아래 '복기' 아코디언으로 표시.
+  평가 점수 + 복기 + **답변 전달력 메트릭(WPM·무음·간투어, `MessageVoiceAnalysis` 에서 파싱)** 을 노출하되
+  **종료 세션 조회에서만**(`expectedSignal` 과 동일 게이팅). 프론트는 답변 버블 아래 '복기' 아코디언으로 표시.
 - **직무 맞춤 면접 모드(JOB_TAILORED) 본 구현**: `SessionMode.JOB_TAILORED` 추가(V18 — mode CHECK 갱신 +
   `target_company_name`/`target_job_description` 컬럼). 이 모드는 회사명+채용공고(JD)를 받아(JD 필수,
   `SessionService` 검증 `SESSION_JD_REQUIRED`) `InterviewSession.assignTargetRole` 로 보관. JD 는

backend/openapi.json

@@ -2828,6 +2828,21 @@
           },
           "coachingComment" : {
             "type" : "string"
+          },
+          "speakingRateWpm" : {
+            "type" : "number",
+            "format" : "double"
+          },
+          "silenceDurationSec" : {
+            "type" : "number",
+            "format" : "double"
+          },
+          "fillerWordCounts" : {
+            "type" : "object",
+            "additionalProperties" : {
+              "type" : "integer",
+              "format" : "int32"
+            }
           }
         }
       },

backend/src/main/java/com/stackup/stackup/session/application/InterviewMessageService.java

@@ -1,5 +1,7 @@
 package com.stackup.stackup.session.application;
 
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.json.JsonMapper;
 import com.stackup.stackup.common.exception.ApiErrorCode;
 import com.stackup.stackup.common.exception.DomainException;
 import com.stackup.stackup.common.storage.ObjectStorageClient;
@@ -11,11 +13,14 @@
 import com.stackup.stackup.session.domain.InterviewSessionRepository;
 import com.stackup.stackup.session.domain.MessageRole;
 import com.stackup.stackup.session.domain.MessageStatus;
+import com.stackup.stackup.session.domain.MessageVoiceAnalysis;
+import com.stackup.stackup.session.domain.MessageVoiceAnalysisRepository;
 import com.stackup.stackup.session.domain.SessionStatus;
 import com.stackup.stackup.session.domain.TtsStatus;
 import java.net.URI;
 import java.time.Duration;
 import java.util.List;
+import java.util.Map;
 import lombok.RequiredArgsConstructor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -33,29 +38,55 @@ public class InterviewMessageService {
     private static final Logger log = LoggerFactory.getLogger(InterviewMessageService.class);
     private static final Duration AUDIO_URL_TTL = Duration.ofMinutes(30);
 
+    private static final JsonMapper JSON = JsonMapper.builder().build();
+    private static final TypeReference<Map<String, Integer>> FILLER_TYPE = new TypeReference<>() {};
+
     private final InterviewSessionRepository sessionRepository;
     private final InterviewMessageRepository messageRepository;
+    private final MessageVoiceAnalysisRepository voiceAnalysisRepository;
     private final ObjectStorageClient storage;
     private final ApplicationEventPublisher events;
 
     public List<MessageResult> list(Long userId, Long sessionId) {
         InterviewSession session = ownedSession(userId, sessionId);
-        // 종료된 세션에서만 expected_signal 노출(라이브/대기 중엔 정답 유출 방지).
-        boolean revealExpectedSignal =
+        // 종료된 세션에서만 평가·복기·전달력 노출(라이브/대기 중엔 정답 유출 방지).
+        boolean revealInsights =
             session.getStatus() != SessionStatus.IN_PROGRESS
                 && session.getStatus() != SessionStatus.READY;
+        // 답변별 음성 분석(전달력 메트릭) — 메시지 id 로 매핑. 종료 세션에서만 조회.
+        Map<Long, MessageVoiceAnalysis> voiceByMessageId = revealInsights
+            ? voiceAnalysisRepository.findByMessage_Session_Id(sessionId).stream()
+                .collect(java.util.stream.Collectors.toMap(
+                    v -> v.getMessage().getId(), v -> v, (a, b) -> a))
+            : Map.of();
         return messageRepository.findBySession_IdOrderBySequenceNumberAsc(sessionId).stream()
-            .map(m -> toResultWithAudioUrls(m, revealExpectedSignal))
+            .map(m -> toResultWithAudioUrls(m, revealInsights, voiceByMessageId.get(m.getId())))
             .toList();
     }
 
     // 재생용 presigned URL 동봉: 질문 TTS(SUCCEEDED) + 음성 답변 원본.
     // presign 실패가 메시지 조회 전체를 깨뜨리지 않도록 개별 try/catch.
-    private MessageResult toResultWithAudioUrls(InterviewMessage m, boolean revealInsights) {
+    private MessageResult toResultWithAudioUrls(
+        InterviewMessage m, boolean revealInsights, MessageVoiceAnalysis voice) {
         String ttsUrl = m.getTtsStatus() == TtsStatus.SUCCEEDED
             ? presign(m.getTtsAudioPath()) : null;
         String audioUrl = presign(m.getAudioFilePath());
-        return MessageResult.of(m, ttsUrl, audioUrl, revealInsights);
+        Double wpm = voice == null ? null : voice.getSpeakingRateWpm();
+        Double silence = voice == null ? null : voice.getSilenceDurationSec();
+        Map<String, Integer> fillers = voice == null ? null : parseFillers(voice.getFillerWordCounts());
+        return MessageResult.of(m, ttsUrl, audioUrl, revealInsights, wpm, silence, fillers);
+    }
+
+    private Map<String, Integer> parseFillers(String json) {
+        if (json == null || json.isBlank()) {
+            return null;
+        }
+        try {
+            return JSON.readValue(json, FILLER_TYPE);
+        } catch (com.fasterxml.jackson.core.JsonProcessingException e) {
+            log.warn("filler_word_counts parse failed", e);
+            return null;
+        }
     }
 
     private String presign(String key) {

backend/src/main/java/com/stackup/stackup/session/application/dto/MessageResult.java

@@ -5,6 +5,7 @@
 import com.stackup.stackup.session.domain.MessageStatus;
 import com.stackup.stackup.session.domain.TtsStatus;
 import java.time.Instant;
+import java.util.Map;
 
 public record MessageResult(
     Long id,
@@ -34,7 +35,11 @@ public record MessageResult(
     Double answerCorrectness,
     String modelAnswer,
     String answerRewrite,
-    String coachingComment
+    String coachingComment,
+    // 답변 전달력 메트릭(음성 답변에만, 종료 세션 조회에서만). 별도 엔티티(MessageVoiceAnalysis)에서 온다.
+    Double speakingRateWpm,
+    Double silenceDurationSec,
+    Map<String, Integer> fillerWordCounts
 ) {
     public static MessageResult of(InterviewMessage m) {
         return of(m, null, null, false);
@@ -44,9 +49,15 @@ public static MessageResult of(InterviewMessage m, String ttsAudioUrl, String au
         return of(m, ttsAudioUrl, audioFileUrl, false);
     }
 
-    // revealInsights=true 면 답변 평가·복기·expectedSignal 노출(종료 세션). 라이브/대기 중엔 false.
     public static MessageResult of(
         InterviewMessage m, String ttsAudioUrl, String audioFileUrl, boolean revealInsights) {
+        return of(m, ttsAudioUrl, audioFileUrl, revealInsights, null, null, null);
+    }
+
+    // revealInsights=true 면 답변 평가·복기·전달력 메트릭·expectedSignal 노출(종료 세션). 라이브/대기 중엔 false.
+    public static MessageResult of(
+        InterviewMessage m, String ttsAudioUrl, String audioFileUrl, boolean revealInsights,
+        Double speakingRateWpm, Double silenceDurationSec, Map<String, Integer> fillerWordCounts) {
         return new MessageResult(
             m.getId(),
             m.getSession().getId(),
@@ -71,7 +82,10 @@ public static MessageResult of(
             revealInsights ? m.getAnswerCorrectness() : null,
             revealInsights ? m.getModelAnswer() : null,
             revealInsights ? m.getAnswerRewrite() : null,
-            revealInsights ? m.getCoachingComment() : null
+            revealInsights ? m.getCoachingComment() : null,
+            revealInsights ? speakingRateWpm : null,
+            revealInsights ? silenceDurationSec : null,
+            revealInsights ? fillerWordCounts : null
         );
     }
 }

backend/src/main/java/com/stackup/stackup/session/presentation/dto/MessageResponse.java

@@ -33,7 +33,11 @@ public record MessageResponse(
     Double answerCorrectness,
     String modelAnswer,
     String answerRewrite,
-    String coachingComment
+    String coachingComment,
+    // 답변 전달력 메트릭(음성 답변·종료 세션에서만).
+    Double speakingRateWpm,
+    Double silenceDurationSec,
+    java.util.Map<String, Integer> fillerWordCounts
 ) {
     public static MessageResponse from(MessageResult r) {
         return new MessageResponse(
@@ -60,7 +64,10 @@ public static MessageResponse from(MessageResult r) {
             r.answerCorrectness(),
             r.modelAnswer(),
             r.answerRewrite(),
-            r.coachingComment()
+            r.coachingComment(),
+            r.speakingRateWpm(),
+            r.silenceDurationSec(),
+            r.fillerWordCounts()
         );
     }
 }

backend/src/test/java/com/stackup/stackup/session/application/InterviewMessageServiceTest.java

@@ -18,8 +18,11 @@
 import com.stackup.stackup.session.domain.InterviewSession;
 import com.stackup.stackup.session.domain.InterviewSessionRepository;
 import com.stackup.stackup.session.domain.JobCategory;
+import com.stackup.stackup.session.domain.MessageVoiceAnalysis;
+import com.stackup.stackup.session.domain.MessageVoiceAnalysisRepository;
 import com.stackup.stackup.session.domain.SessionMode;
 import com.stackup.stackup.user.domain.User;
+import java.util.List;
 import java.util.Optional;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -39,10 +42,37 @@ class InterviewMessageServiceTest {
 
     @Mock InterviewSessionRepository sessionRepository;
     @Mock InterviewMessageRepository messageRepository;
+    @Mock MessageVoiceAnalysisRepository voiceAnalysisRepository;
     @Mock ObjectStorageClient storage;
     @Mock ApplicationEventPublisher events;
     @InjectMocks InterviewMessageService service;
 
+    @Test
+    void list_exposesPerAnswerVoiceMetricsForEndedSession() {
+        User user = User.createGithubUser(1L, "u", null, null, "t");
+        ReflectionTestUtils.setField(user, "id", USER_ID);
+        InterviewSession session = InterviewSession.create(
+            user, "t", null, SessionMode.TECHNICAL, JobCategory.BACKEND, 5, 30, null, null);
+        ReflectionTestUtils.setField(session, "id", SESSION_ID);
+        session.start();
+        session.end();  // COMPLETED → revealInsights=true
+        InterviewMessage answer = InterviewMessage.interviewee(session, 2, "내 답변", null, null);
+        ReflectionTestUtils.setField(answer, "id", 600L);
+        MessageVoiceAnalysis va = MessageVoiceAnalysis.of(answer, 145.0, 6.0, "{\"음\":4,\"어\":2}", -0.3);
+
+        when(sessionRepository.findByIdAndUser_IdAndDeletedFalse(SESSION_ID, USER_ID))
+            .thenReturn(Optional.of(session));
+        when(voiceAnalysisRepository.findByMessage_Session_Id(SESSION_ID)).thenReturn(List.of(va));
+        when(messageRepository.findBySession_IdOrderBySequenceNumberAsc(SESSION_ID))
+            .thenReturn(List.of(answer));
+
+        MessageResult r = service.list(USER_ID, SESSION_ID).get(0);
+
+        assertThat(r.speakingRateWpm()).isEqualTo(145.0);
+        assertThat(r.silenceDurationSec()).isEqualTo(6.0);
+        assertThat(r.fillerWordCounts()).containsEntry("음", 4).containsEntry("어", 2);
+    }
+
     @Test
     void submitAnswer_insertsIntervieweeAndPublishesEvent() {
         InterviewSession session = sessionInProgress(10L);

frontend/src/features/interview/ui/live/AnswerCoachingAccordion.tsx

@@ -12,14 +12,31 @@ function score5(v?: number | null): string | null {
   return typeof v === 'number' ? `${v}/5` : null
 }
 
-// 종료된 세션의 답변 아래 붙는 '복기' 아코디언: 평가 점수 → 한 줄 코칭 → 모범 답안 → 내 답변 리라이트.
-// 코칭 데이터가 없으면(라이브 중·자기소개 답변 등) 렌더하지 않는다.
+// 답변 음성 전달력 메트릭 → 표시용 칩 문자열들.
+function deliveryChips(message: Message): string[] {
+  const chips: string[] = []
+  if (typeof message.speakingRateWpm === 'number') {
+    chips.push(`${Math.round(message.speakingRateWpm)} WPM`)
+  }
+  if (typeof message.silenceDurationSec === 'number' && message.silenceDurationSec > 0) {
+    chips.push(`무음 ${Math.round(message.silenceDurationSec)}초`)
+  }
+  const fillers = Object.entries(message.fillerWordCounts ?? {}).filter(([, c]) => c > 0)
+  if (fillers.length > 0) {
+    chips.push('간투어 ' + fillers.map(([w, c]) => `${w} ${c}`).join(' · '))
+  }
+  return chips
+}
+
+// 종료된 세션의 답변 아래 붙는 '복기' 아코디언: 전달력 메트릭 → 평가 점수 → 한 줄 코칭 → 모범 답안 → 리라이트.
+// 코칭·전달력 데이터가 모두 없으면(라이브 중·자기소개 답변 등) 렌더하지 않는다.
 export function AnswerCoachingAccordion({ message }: { message: Message }) {
   const [open, setOpen] = useState(false)
-  const hasCoaching = Boolean(
-    message.modelAnswer || message.answerRewrite || message.coachingComment,
+  const delivery = deliveryChips(message)
+  const hasContent = Boolean(
+    message.modelAnswer || message.answerRewrite || message.coachingComment || delivery.length > 0,
   )
-  if (!hasCoaching) return null
+  if (!hasContent) return null
 
   const spec = score5(message.answerSpecificity)
   const logic = score5(message.answerLogic)
@@ -44,6 +61,21 @@ export function AnswerCoachingAccordion({ message }: { message: Message }) {
       </button>
       {open && (
         <div className="mt-1.5 flex flex-col gap-3 rounded-lg border border-border bg-surface px-4 py-3 text-left">
+          {delivery.length > 0 && (
+            <div className="flex flex-col gap-1">
+              <span className="text-caption text-fg-subtle">전달력</span>
+              <div className="flex flex-wrap gap-1.5">
+                {delivery.map((d) => (
+                  <span
+                    key={d}
+                    className="rounded-pill bg-info-50 px-2 py-0.5 text-caption text-info-700"
+                  >
+                    {d}
+                  </span>
+                ))}
+              </div>
+            </div>
+          )}
           {evals.length > 0 && (
             <div className="flex flex-wrap gap-1.5">
               {evals.map((e) => (

frontend/src/shared/api/generated.ts

@@ -910,6 +910,13 @@ export interface components {
             modelAnswer?: string;
             answerRewrite?: string;
             coachingComment?: string;
+            /** Format: double */
+            speakingRateWpm?: number;
+            /** Format: double */
+            silenceDurationSec?: number;
+            fillerWordCounts?: {
+                [key: string]: number;
+            };
         };
         VoiceStreamBeginResponse: {
             /** Format: int64 */