fix: 썸네일 READY 상태와 오브젝트 키 정합성 보장

src/main/java/org/zipzip/zipzipserver/domain/album/service/SharedAlbumService.java

@@ -26,7 +26,6 @@
 import org.zipzip.zipzipserver.domain.album.repository.SharedAlbumPhotoRepository;
 import org.zipzip.zipzipserver.domain.album.repository.SharedAlbumRepository;
 import org.zipzip.zipzipserver.domain.photo.entity.Photo;
-import org.zipzip.zipzipserver.domain.photo.entity.PhotoThumbnailStatus;
 import org.zipzip.zipzipserver.domain.photo.repository.PhotoRepository;
 import org.zipzip.zipzipserver.domain.sharedgroup.entity.SharedGroup;
 import org.zipzip.zipzipserver.domain.storage.ObjectStorageService;
@@ -290,10 +289,7 @@ private List<SharedAlbumListResponse.Thumbnail> toThumbnails(UUID albumId) {
                 sharedAlbumPhotoRepository.findOldestPhotosBySharedAlbumId(
                         albumId, PageRequest.of(0, THUMBNAIL_COUNT));
         return oldestPhotos.stream()
-                .filter(
-                        photo ->
-                                photo.getThumbnailStatus() == PhotoThumbnailStatus.READY
-                                        && photo.getThumbnailObjectKey() != null)
+                .filter(Photo::hasUsableThumbnail)
                 .map(
                         photo -> {
                             PresignedDownload thumbnail =

src/main/java/org/zipzip/zipzipserver/domain/photo/entity/Photo.java

@@ -99,10 +99,19 @@ public void applyLocation(
     }
 
     public void markThumbnailReady(String thumbnailObjectKey) {
+        if (thumbnailObjectKey == null || thumbnailObjectKey.isBlank()) {
+            throw new IllegalArgumentException("썸네일 객체 키는 비어 있을 수 없습니다.");
+        }
         this.thumbnailObjectKey = thumbnailObjectKey;
         this.thumbnailStatus = PhotoThumbnailStatus.READY;
     }
 
+    public boolean hasUsableThumbnail() {
+        return thumbnailStatus == PhotoThumbnailStatus.READY
+                && thumbnailObjectKey != null
+                && !thumbnailObjectKey.isBlank();
+    }
+
     public void markThumbnailFailed() {
         this.thumbnailStatus = PhotoThumbnailStatus.FAILED;
     }

src/main/java/org/zipzip/zipzipserver/domain/photo/service/PhotoService.java

@@ -25,7 +25,6 @@
 import org.zipzip.zipzipserver.domain.photo.dto.response.PhotoListResponse;
 import org.zipzip.zipzipserver.domain.photo.dto.response.PhotoMetadataUpdateResponse;
 import org.zipzip.zipzipserver.domain.photo.entity.Photo;
-import org.zipzip.zipzipserver.domain.photo.entity.PhotoThumbnailStatus;
 import org.zipzip.zipzipserver.domain.photo.repository.PhotoRepository;
 import org.zipzip.zipzipserver.domain.sharedgroup.entity.SharedGroupRole;
 import org.zipzip.zipzipserver.domain.sharedgroup.repository.SharedGroupMembershipRepository;
@@ -319,8 +318,7 @@ private PhotoListResponse.PhotoListItem toListItem(
             Photo photo, SharedAlbum sharedAlbum, UUID appUserId) {
         String thumbnailUrl = null;
         Instant thumbnailUrlExpiresAt = null;
-        if (photo.getThumbnailStatus() == PhotoThumbnailStatus.READY
-                && photo.getThumbnailObjectKey() != null) {
+        if (photo.hasUsableThumbnail()) {
             PresignedDownload thumbnail =
                     objectStorageService.issueDownloadUrl(
                             photo.getThumbnailObjectKey(), DOWNLOAD_URL_TTL);

src/main/java/org/zipzip/zipzipserver/domain/reaction/service/ReactionService.java

@@ -14,7 +14,6 @@
 import org.zipzip.zipzipserver.domain.album.repository.SharedAlbumPhotoRepository;
 import org.zipzip.zipzipserver.domain.photo.code.PhotoErrorCode;
 import org.zipzip.zipzipserver.domain.photo.entity.Photo;
-import org.zipzip.zipzipserver.domain.photo.entity.PhotoThumbnailStatus;
 import org.zipzip.zipzipserver.domain.photo.repository.PhotoRepository;
 import org.zipzip.zipzipserver.domain.photo.service.PhotoAccessGuard;
 import org.zipzip.zipzipserver.domain.reaction.code.ReactionErrorCode;
@@ -197,8 +196,7 @@ private Photo requireActivePhoto(UUID photoId) {
     }
 
     private PresignedDownload issueThumbnailDownload(Photo photo) {
-        if (photo.getThumbnailStatus() != PhotoThumbnailStatus.READY
-                || photo.getThumbnailObjectKey() == null) {
+        if (!photo.hasUsableThumbnail()) {
             return null;
         }
         return objectStorageService.issueDownloadUrl(

src/main/java/org/zipzip/zipzipserver/domain/sharedgroup/service/SharedGroupInviteService.java

@@ -11,7 +11,6 @@
 import org.springframework.transaction.annotation.Transactional;
 import org.zipzip.zipzipserver.domain.album.repository.SharedAlbumPhotoRepository;
 import org.zipzip.zipzipserver.domain.photo.entity.Photo;
-import org.zipzip.zipzipserver.domain.photo.entity.PhotoThumbnailStatus;
 import org.zipzip.zipzipserver.domain.sharedgroup.code.SharedGroupErrorCode;
 import org.zipzip.zipzipserver.domain.sharedgroup.dto.request.SharedGroupJoinRequest;
 import org.zipzip.zipzipserver.domain.sharedgroup.dto.response.InviteCodeResponse;
@@ -173,8 +172,7 @@ private PresignedDownload findRepresentativeImage(UUID sharedGroupId) {
 
     private PresignedDownload issueRepresentativeImageDownload(Photo photo) {
         String objectKey =
-                photo.getThumbnailStatus() == PhotoThumbnailStatus.READY
-                                && photo.getThumbnailObjectKey() != null
+                photo.hasUsableThumbnail()
                         ? photo.getThumbnailObjectKey()
                         : photo.getOriginalObjectKey();
         return objectStorageService.issueDownloadUrl(objectKey, REPRESENTATIVE_IMAGE_URL_TTL);

src/main/resources/db/migration/V20260716103000__enforce_thumbnail_ready_object_key_integrity.sql

@@ -0,0 +1,19 @@
+-- 기존의 잘못된 READY 행은 썸네일 재시도 대상인 FAILED로 정리한 뒤,
+-- READY 상태가 비어 있지 않은 객체 키를 반드시 갖도록 보장한다.
+update photo
+set thumbnail_status = 'FAILED'
+where thumbnail_status = 'READY'
+  and (
+      thumbnail_object_key is null
+      or thumbnail_object_key ~ '^[[:space:]]*$'
+  );
+
+alter table photo
+    add constraint chk_photo__thumbnail_ready_object_key
+    check (
+        thumbnail_status <> 'READY'
+        or (
+            thumbnail_object_key is not null
+            and thumbnail_object_key !~ '^[[:space:]]*$'
+        )
+    );

src/test/java/org/zipzip/zipzipserver/domain/DomainEntityMappingTests.java

@@ -1,6 +1,7 @@
 package org.zipzip.zipzipserver.domain;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import jakarta.persistence.Table;
 import java.lang.reflect.Field;
@@ -99,15 +100,32 @@ void photoThumbnailStatusTransitions() {
 
         assertThat(photo.getThumbnailStatus()).isEqualTo(PhotoThumbnailStatus.PENDING);
         assertThat(photo.getThumbnailObjectKey()).isNull();
+        assertThat(photo.hasUsableThumbnail()).isFalse();
 
         photo.markThumbnailReady("photos/385ff765/thumbnail.jpg");
 
         assertThat(photo.getThumbnailStatus()).isEqualTo(PhotoThumbnailStatus.READY);
         assertThat(photo.getThumbnailObjectKey()).isEqualTo("photos/385ff765/thumbnail.jpg");
+        assertThat(photo.hasUsableThumbnail()).isTrue();
 
         photo.markThumbnailFailed();
 
         assertThat(photo.getThumbnailStatus()).isEqualTo(PhotoThumbnailStatus.FAILED);
+        assertThat(photo.hasUsableThumbnail()).isFalse();
+    }
+
+    @Test
+    void photo는_비어있는_썸네일_객체_키로_READY_상태가_될_수_없다() {
+        AppUser user = AppUser.create("apple-subject", "사용자");
+        Photo photo = Photo.create(user, null, "photos/385ff765/original.jpg", null, null, null);
+
+        assertThatThrownBy(() -> photo.markThumbnailReady(null))
+                .isInstanceOf(IllegalArgumentException.class);
+        assertThatThrownBy(() -> photo.markThumbnailReady("  \t\n"))
+                .isInstanceOf(IllegalArgumentException.class);
+
+        assertThat(photo.getThumbnailStatus()).isEqualTo(PhotoThumbnailStatus.PENDING);
+        assertThat(photo.getThumbnailObjectKey()).isNull();
     }
 
     @Test

src/test/java/org/zipzip/zipzipserver/domain/album/service/SharedAlbumServiceTest.java

@@ -19,6 +19,7 @@
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.test.util.ReflectionTestUtils;
 import org.zipzip.zipzipserver.domain.album.code.SharedAlbumErrorCode;
 import org.zipzip.zipzipserver.domain.album.dto.request.SharedAlbumIdsRequest;
 import org.zipzip.zipzipserver.domain.album.dto.request.SharedAlbumNameRequest;
@@ -29,6 +30,7 @@
 import org.zipzip.zipzipserver.domain.album.repository.SharedAlbumPhotoRepository;
 import org.zipzip.zipzipserver.domain.album.repository.SharedAlbumRepository;
 import org.zipzip.zipzipserver.domain.photo.entity.Photo;
+import org.zipzip.zipzipserver.domain.photo.entity.PhotoThumbnailStatus;
 import org.zipzip.zipzipserver.domain.photo.repository.PhotoRepository;
 import org.zipzip.zipzipserver.domain.sharedgroup.entity.InviteCodeReservation;
 import org.zipzip.zipzipserver.domain.sharedgroup.entity.SharedGroup;
@@ -376,6 +378,32 @@ albumId, requesterId, new SharedAlbumNameRequest("   ")))
                 .containsExactly("https://cdn/ready");
     }
 
+    @Test
+    void 공백_키를_가진_기존_READY_썸네일은_목록에서_제외된다() {
+        AppUser creator = anAppUser();
+        SharedGroup group = aSharedGroup(creator);
+        SharedAlbum album = anAlbum(creator, group);
+        Photo malformed = aPhoto(creator);
+        ReflectionTestUtils.setField(malformed, "thumbnailStatus", PhotoThumbnailStatus.READY);
+        ReflectionTestUtils.setField(malformed, "thumbnailObjectKey", " \t");
+
+        when(sharedAlbumAccessGuard.requireActiveSharedGroup(group.getId(), creator.getId()))
+                .thenReturn(group);
+        when(sharedAlbumRepository.findPageByActiveSharedGroupId(
+                        eq(group.getId()), any(), any(), any()))
+                .thenReturn(List.of(album));
+        when(sharedAlbumPhotoRepository.countBySharedAlbumIdAndPhotoDeletedAtIsNull(album.getId()))
+                .thenReturn(1L);
+        when(sharedAlbumPhotoRepository.findOldestPhotosBySharedAlbumId(eq(album.getId()), any()))
+                .thenReturn(List.of(malformed));
+
+        SharedAlbumListResponse response =
+                sharedAlbumService.listAlbums(group.getId(), creator.getId(), null, null);
+
+        assertThat(response.items().getFirst().thumbnails()).isEmpty();
+        verify(objectStorageService, never()).issueDownloadUrl(eq(" \t"), any());
+    }
+
     @Test
     void 사진이_없는_공유집은_빈_썸네일_목록을_반환한다() {
         AppUser creator = anAppUser();

src/test/java/org/zipzip/zipzipserver/domain/photo/repository/PhotoThumbnailIntegrityMigrationTest.java

@@ -0,0 +1,116 @@
+package org.zipzip.zipzipserver.domain.photo.repository;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.UUID;
+import org.flywaydb.core.Flyway;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.PostgreSQLContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+@Testcontainers(disabledWithoutDocker = true)
+class PhotoThumbnailIntegrityMigrationTest {
+
+    private static final String PREVIOUS_MIGRATION_VERSION = "20260710140929";
+
+    @Container
+    private static final PostgreSQLContainer<?> POSTGRES = new PostgreSQLContainer<>("postgres:18");
+
+    @Test
+    void 썸네일_READY_상태는_비어있지_않은_객체_키를_가져야_한다() throws SQLException {
+        migrateUpToPreviousVersion();
+        UUID userId = insertUser();
+        UUID malformedPhotoId = insertPhoto(userId, "READY", " \t\n");
+
+        migrateLatest();
+
+        assertThat(findThumbnailStatus(malformedPhotoId)).isEqualTo("FAILED");
+        assertThatThrownBy(() -> insertPhoto(userId, "READY", null))
+                .isInstanceOf(SQLException.class);
+        assertThatThrownBy(() -> insertPhoto(userId, "READY", "  "))
+                .isInstanceOf(SQLException.class);
+        assertThat(insertPhoto(userId, "PENDING", null)).isNotNull();
+        assertThat(insertPhoto(userId, "READY", "photos/thumbnail.jpg")).isNotNull();
+    }
+
+    private void migrateUpToPreviousVersion() {
+        Flyway.configure()
+                .dataSource(POSTGRES.getJdbcUrl(), POSTGRES.getUsername(), POSTGRES.getPassword())
+                .locations("classpath:db/migration")
+                .target(PREVIOUS_MIGRATION_VERSION)
+                .load()
+                .migrate();
+    }
+
+    private void migrateLatest() {
+        Flyway.configure()
+                .dataSource(POSTGRES.getJdbcUrl(), POSTGRES.getUsername(), POSTGRES.getPassword())
+                .locations("classpath:db/migration")
+                .load()
+                .migrate();
+    }
+
+    private UUID insertUser() throws SQLException {
+        UUID userId = UUID.randomUUID();
+        try (Connection connection = connection();
+                PreparedStatement statement =
+                        connection.prepareStatement(
+                                """
+                                insert into app_user (id, apple_subject, display_name)
+                                values (?, ?, '사용자')
+                                """)) {
+            statement.setObject(1, userId);
+            statement.setString(2, "apple-subject-" + userId);
+            statement.executeUpdate();
+        }
+        return userId;
+    }
+
+    private UUID insertPhoto(UUID userId, String thumbnailStatus, String thumbnailObjectKey)
+            throws SQLException {
+        UUID photoId = UUID.randomUUID();
+        try (Connection connection = connection();
+                PreparedStatement statement =
+                        connection.prepareStatement(
+                                """
+                                insert into photo (
+                                    id, uploaded_by_app_user_id, original_object_key, thumbnail_object_key,
+                                    thumbnail_status, is_inferred
+                                )
+                                values (?, ?, ?, ?, ?, false)
+                                """)) {
+            statement.setObject(1, photoId);
+            statement.setObject(2, userId);
+            statement.setString(3, "photos/" + photoId + "/original.jpg");
+            statement.setString(4, thumbnailObjectKey);
+            statement.setString(5, thumbnailStatus);
+            statement.executeUpdate();
+        }
+        return photoId;
+    }
+
+    private String findThumbnailStatus(UUID photoId) throws SQLException {
+        try (Connection connection = connection();
+                PreparedStatement statement =
+                        connection.prepareStatement(
+                                "select thumbnail_status from photo where id = ?")) {
+            statement.setObject(1, photoId);
+            try (ResultSet resultSet = statement.executeQuery()) {
+                resultSet.next();
+                return resultSet.getString("thumbnail_status");
+            }
+        }
+    }
+
+    private Connection connection() throws SQLException {
+        return DriverManager.getConnection(
+                POSTGRES.getJdbcUrl(), POSTGRES.getUsername(), POSTGRES.getPassword());
+    }
+}

src/test/java/org/zipzip/zipzipserver/domain/photo/service/PhotoServiceTest.java

@@ -20,20 +20,24 @@
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.test.util.ReflectionTestUtils;
 import org.zipzip.zipzipserver.domain.album.entity.SharedAlbum;
 import org.zipzip.zipzipserver.domain.album.entity.SharedAlbumPhoto;
 import org.zipzip.zipzipserver.domain.album.repository.SharedAlbumPhotoRepository;
 import org.zipzip.zipzipserver.domain.photo.code.PhotoErrorCode;
 import org.zipzip.zipzipserver.domain.photo.dto.request.PhotoIdsRequest;
 import org.zipzip.zipzipserver.domain.photo.dto.response.PhotoAttachResponse;
 import org.zipzip.zipzipserver.domain.photo.dto.response.PhotoDetachResponse;
+import org.zipzip.zipzipserver.domain.photo.dto.response.PhotoListResponse;
 import org.zipzip.zipzipserver.domain.photo.dto.response.PhotoMetadataUpdateResponse;
 import org.zipzip.zipzipserver.domain.photo.entity.Photo;
+import org.zipzip.zipzipserver.domain.photo.entity.PhotoThumbnailStatus;
 import org.zipzip.zipzipserver.domain.photo.repository.PhotoRepository;
 import org.zipzip.zipzipserver.domain.sharedgroup.entity.InviteCodeReservation;
 import org.zipzip.zipzipserver.domain.sharedgroup.entity.SharedGroup;
 import org.zipzip.zipzipserver.domain.sharedgroup.repository.SharedGroupMembershipRepository;
 import org.zipzip.zipzipserver.domain.storage.ObjectStorageService;
+import org.zipzip.zipzipserver.domain.storage.PresignedDownload;
 import org.zipzip.zipzipserver.domain.user.entity.AppUser;
 import org.zipzip.zipzipserver.global.exception.BusinessException;
 import org.zipzip.zipzipserver.global.idempotency.ApiIdempotencyRecord;
@@ -85,6 +89,27 @@ void setUp() {
                                         .isEqualTo(PhotoErrorCode.NOT_PHOTO_UPLOADER));
     }
 
+    @Test
+    void 공백_키를_가진_기존_READY_썸네일에는_URL을_발급하지_않는다() {
+        Photo photo = aPhoto(uploader);
+        ReflectionTestUtils.setField(photo, "thumbnailStatus", PhotoThumbnailStatus.READY);
+        ReflectionTestUtils.setField(photo, "thumbnailObjectKey", " \t");
+        when(photoAccessGuard.requireActiveSharedAlbum(sharedAlbum.getId(), uploader.getId()))
+                .thenReturn(sharedAlbum);
+        when(sharedAlbumPhotoRepository.findPageByActiveSharedAlbumId(
+                        eq(sharedAlbum.getId()), any(), any(), any()))
+                .thenReturn(List.of(photo));
+        when(objectStorageService.issueDownloadUrl(eq(photo.getOriginalObjectKey()), any()))
+                .thenReturn(
+                        new PresignedDownload("https://storage.example/original", Instant.now()));
+
+        PhotoListResponse response =
+                photoService.listPhotos(sharedAlbum.getId(), uploader.getId(), null, null);
+
+        assertThat(response.items().getFirst().thumbnailUrl()).isNull();
+        verify(objectStorageService, never()).issueDownloadUrl(eq(" \t"), any());
+    }
+
     @Test
     void 메타데이터_수정_takenAt_형식이_잘못되면_예외() {
         Photo photo = aPhoto(uploader);