refactor: HikingRecord 확장 마이그레이션 V9 + 리뷰 반영

- 002_hiking_record_extension.sql 삭제, V9__extend_hiking_record.sql 신규 작성
  - 기존 002 내용 + tracking_session_id UNIQUE 제약 (세션당 기록 1건 강제)
- HikingRecord.altitude 필드명을 컬럼명과 정합되게 maxAltitude 로 변경
  (DTO 응답 키 호환 위해 HikingRecordSummaryResponse 필드명은 유지)
- TrackingSessionService.complete: stats.pointCount == 0 일 때 경고 로그 추가

Author: JangInho

src/main/java/com/semosan/api/domain/hiking/dto/HikingRecordSummaryResponse.java

@@ -18,7 +18,7 @@ public static HikingRecordSummaryResponse from(HikingRecord record) {
                 record.getMountain().getName(),
                 record.getCourse().getName(),
                 record.getDuration(),
-                record.getAltitude(),
+                record.getMaxAltitude(),
                 record.getCalories(),
                 record.getCliveImageUrl(),
                 record.getPhotoReportImageUrl()

src/main/java/com/semosan/api/domain/hiking/entity/HikingRecord.java

@@ -45,7 +45,7 @@ public class HikingRecord extends BaseEntity {
 
     /** 등산 중 도달한 최고 고도 (m). */
     @Column(name = "max_altitude", nullable = false)
-    private Double altitude;
+    private Double maxAltitude;
 
     /**
      * 소모 칼로리 (kcal).
@@ -99,7 +99,7 @@ public static HikingRecord fromTrackingSession(
                 .course(session.getCourse())
                 .trackingSession(session)
                 .duration(duration)
-                .altitude(maxAltitude == null ? 0.0 : maxAltitude)
+                .maxAltitude(maxAltitude == null ? 0.0 : maxAltitude)
                 .calories(0)  // TODO: 칼로리 산정 공식 도입 시 교체
                 .distance(distance)
                 .ascent(ascent)

src/main/java/com/semosan/api/domain/tracking/service/TrackingSessionService.java

@@ -19,12 +19,14 @@
 import com.semosan.api.domain.user.entity.User;
 import com.semosan.api.domain.user.service.UserReader;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.util.Optional;
 
+@Slf4j
 @Service
 @RequiredArgsConstructor
 @Transactional(readOnly = true)
@@ -92,6 +94,10 @@ public TrackingSessionResponse complete(Long userId, Long sessionId) {
         session.complete();
 
         TrackingSessionStatsService.Stats stats = statsService.getStats(sessionId);
+        if (stats.pointCount() == 0) {
+            // GPS 점이 한 건도 들어오지 않은 채 종료 — 사용자의 명시적 종료는 존중하되 통계가 비어있음을 알림.
+            log.warn("Completing tracking session {} with no GPS points; stats will be zero/null", sessionId);
+        }
         HikingRecord record = HikingRecord.fromTrackingSession(
                 session,
                 stats.distanceMeters(),

src/main/resources/db/migration/002_hiking_record_extension.sql

@@ -0,0 +1,41 @@
+-- =====================================================================
+-- V9__extend_hiking_record.sql
+-- 목적: 트래킹 흐름에서 생성될 HikingRecord 확장.
+--        - 트래킹 세션 참조 (tracking_session_id, UNIQUE — 세션당 기록 1건 강제)
+--        - 시간 정보 (started_at, ended_at, paused_seconds_total)
+--        - GPS 통계 (distance, ascent, descent)
+--        - 자유 기록 대응 (course_id NOT NULL → NULLABLE)
+-- =====================================================================
+
+-- 1) course_id 를 nullable 로 (자유 기록 대응)
+ALTER TABLE hiking_records
+    ALTER COLUMN course_id DROP NOT NULL;
+
+-- 2) 트래킹 세션 참조
+ALTER TABLE hiking_records
+    ADD COLUMN IF NOT EXISTS tracking_session_id bigint;
+
+-- 3) 시간 정보
+ALTER TABLE hiking_records
+    ADD COLUMN IF NOT EXISTS started_at timestamp(6);
+ALTER TABLE hiking_records
+    ADD COLUMN IF NOT EXISTS ended_at timestamp(6);
+ALTER TABLE hiking_records
+    ADD COLUMN IF NOT EXISTS paused_seconds_total integer not null default 0;
+
+-- 4) GPS 통계
+ALTER TABLE hiking_records
+    ADD COLUMN IF NOT EXISTS distance double precision;
+ALTER TABLE hiking_records
+    ADD COLUMN IF NOT EXISTS ascent double precision;
+ALTER TABLE hiking_records
+    ADD COLUMN IF NOT EXISTS descent double precision;
+
+-- 5) FK + UNIQUE 제약 (NULL 은 표준 UNIQUE 검사에서 제외돼 수동 기록은 영향 없음)
+ALTER TABLE hiking_records
+    ADD CONSTRAINT fk_hiking_records_tracking_session
+        FOREIGN KEY (tracking_session_id) REFERENCES tracking_sessions(id);
+
+ALTER TABLE hiking_records
+    ADD CONSTRAINT uk_hiking_records_tracking_session
+        UNIQUE (tracking_session_id);