diff --git a/src/main/java/com/swyp/app/domain/battle/service/BattleServiceImpl.java b/src/main/java/com/swyp/app/domain/battle/service/BattleServiceImpl.java
index 1bba412..ea0671a 100644
--- a/src/main/java/com/swyp/app/domain/battle/service/BattleServiceImpl.java
+++ b/src/main/java/com/swyp/app/domain/battle/service/BattleServiceImpl.java
@@ -137,7 +137,7 @@ public BattleUserDetailResponse getBattleDetail(Long battleId) {
         List<Tag> allTags = getTagsByBattle(battle);
         List<BattleOption> options = battleOptionRepository.findByBattle(battle);
 
-        String voteStatus = voteRepository.findByBattleAndUserId(battle, 1L)
+        String voteStatus = voteRepository.findByBattleIdAndUserId(battleId, 1L)
                 .map(v -> v.getPostVoteOption() != null ? v.getPostVoteOption().getLabel().name() : "NONE")
                 .orElse("NONE");
 
diff --git a/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveCommentController.java b/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveCommentController.java
index d869a23..f7c78c9 100644
--- a/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveCommentController.java
+++ b/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveCommentController.java
@@ -11,6 +11,7 @@
 import io.swagger.v3.oas.annotations.tags.Tag;
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PatchMapping;
@@ -33,10 +34,9 @@ public class PerspectiveCommentController {
     @PostMapping("/perspectives/{perspectiveId}/comments")
     public ApiResponse<CreateCommentResponse> createComment(
             @PathVariable Long perspectiveId,
+            @AuthenticationPrincipal Long userId,
             @RequestBody @Valid CreateCommentRequest request
     ) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(commentService.createComment(perspectiveId, userId, request));
     }
 
@@ -44,11 +44,10 @@ public ApiResponse<CreateCommentResponse> createComment(
     @GetMapping("/perspectives/{perspectiveId}/comments")
     public ApiResponse<CommentListResponse> getComments(
             @PathVariable Long perspectiveId,
+            @AuthenticationPrincipal Long userId,
             @RequestParam(required = false) String cursor,
             @RequestParam(required = false) Integer size
     ) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(commentService.getComments(perspectiveId, userId, cursor, size));
     }
 
@@ -56,10 +55,9 @@ public ApiResponse<CommentListResponse> getComments(
     @DeleteMapping("/perspectives/{perspectiveId}/comments/{commentId}")
     public ApiResponse<Void> deleteComment(
             @PathVariable Long perspectiveId,
-            @PathVariable Long commentId
+            @PathVariable Long commentId,
+            @AuthenticationPrincipal Long userId
     ) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         commentService.deleteComment(perspectiveId, commentId, userId);
         return ApiResponse.onSuccess(null);
     }
@@ -69,10 +67,9 @@ public ApiResponse<Void> deleteComment(
     public ApiResponse<UpdateCommentResponse> updateComment(
             @PathVariable Long perspectiveId,
             @PathVariable Long commentId,
+            @AuthenticationPrincipal Long userId,
             @RequestBody @Valid UpdateCommentRequest request
     ) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(commentService.updateComment(perspectiveId, commentId, userId, request));
     }
 }
diff --git a/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveController.java b/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveController.java
index 4ad3125..e1e4bc1 100644
--- a/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveController.java
+++ b/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveController.java
@@ -12,6 +12,7 @@
 import io.swagger.v3.oas.annotations.tags.Tag;
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PatchMapping;
@@ -30,15 +31,13 @@ public class PerspectiveController {
 
     private final PerspectiveService perspectiveService;
 
-    // TODO: Prevote 의 여부를  Vote 도메인 개발 이후 교체
     @Operation(summary = "관점 생성", description = "특정 배틀에 대한 관점을 생성합니다. 사전 투표가 완료된 경우에만 가능합니다.")
     @PostMapping("/battles/{battleId}/perspectives")
     public ApiResponse<CreatePerspectiveResponse> createPerspective(
             @PathVariable Long battleId,
+            @AuthenticationPrincipal Long userId,
             @RequestBody @Valid CreatePerspectiveRequest request
     ) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(perspectiveService.createPerspective(battleId, userId, request));
     }
 
@@ -46,37 +45,36 @@ public ApiResponse<CreatePerspectiveResponse> createPerspective(
     @GetMapping("/battles/{battleId}/perspectives")
     public ApiResponse<PerspectiveListResponse> getPerspectives(
             @PathVariable Long battleId,
+            @AuthenticationPrincipal Long userId,
             @RequestParam(required = false) String cursor,
             @RequestParam(required = false) Integer size,
             @RequestParam(required = false) String optionLabel
     ) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(perspectiveService.getPerspectives(battleId, userId, cursor, size, optionLabel));
     }
 
     @Operation(summary = "내 PENDING 관점 조회", description = "특정 배틀에서 내가 작성한 관점이 PENDING 상태인 경우 반환합니다. PENDING 관점이 없으면 404를 반환합니다.")
     @GetMapping("/battles/{battleId}/perspectives/me/pending")
-    public ApiResponse<MyPerspectiveResponse> getMyPendingPerspective(@PathVariable Long battleId) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
+    public ApiResponse<MyPerspectiveResponse> getMyPendingPerspective(
+            @PathVariable Long battleId,
+            @AuthenticationPrincipal Long userId) {
         return ApiResponse.onSuccess(perspectiveService.getMyPendingPerspective(battleId, userId));
     }
 
     @Operation(summary = "관점 삭제", description = "본인이 작성한 관점을 삭제합니다.")
     @DeleteMapping("/perspectives/{perspectiveId}")
-    public ApiResponse<Void> deletePerspective(@PathVariable Long perspectiveId) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
+    public ApiResponse<Void> deletePerspective(
+            @PathVariable Long perspectiveId,
+            @AuthenticationPrincipal Long userId) {
         perspectiveService.deletePerspective(perspectiveId, userId);
         return ApiResponse.onSuccess(null);
     }
 
     @Operation(summary = "관점 검수 재시도", description = "검수 실패(MODERATION_FAILED) 상태의 관점에 대해 GPT 검수를 다시 요청합니다.")
     @PostMapping("/perspectives/{perspectiveId}/moderation/retry")
-    public ApiResponse<Void> retryModeration(@PathVariable Long perspectiveId) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
+    public ApiResponse<Void> retryModeration(
+            @PathVariable Long perspectiveId,
+            @AuthenticationPrincipal Long userId) {
         perspectiveService.retryModeration(perspectiveId, userId);
         return ApiResponse.onSuccess(null);
     }
@@ -85,10 +83,9 @@ public ApiResponse<Void> retryModeration(@PathVariable Long perspectiveId) {
     @PatchMapping("/perspectives/{perspectiveId}")
     public ApiResponse<UpdatePerspectiveResponse> updatePerspective(
             @PathVariable Long perspectiveId,
+            @AuthenticationPrincipal Long userId,
             @RequestBody @Valid UpdatePerspectiveRequest request
     ) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(perspectiveService.updatePerspective(perspectiveId, userId, request));
     }
 }
diff --git a/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveLikeController.java b/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveLikeController.java
index c73d0f4..abe7cc7 100644
--- a/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveLikeController.java
+++ b/src/main/java/com/swyp/app/domain/perspective/controller/PerspectiveLikeController.java
@@ -7,6 +7,7 @@
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
@@ -30,17 +31,17 @@ public ApiResponse<LikeCountResponse> getLikeCount(@PathVariable Long perspectiv
 
     @Operation(summary = "좋아요 등록", description = "특정 관점에 좋아요를 등록합니다.")
     @PostMapping("/perspectives/{perspectiveId}/likes")
-    public ApiResponse<LikeResponse> addLike(@PathVariable Long perspectiveId) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
+    public ApiResponse<LikeResponse> addLike(
+            @PathVariable Long perspectiveId,
+            @AuthenticationPrincipal Long userId) {
         return ApiResponse.onSuccess(likeService.addLike(perspectiveId, userId));
     }
 
     @Operation(summary = "좋아요 취소", description = "특정 관점에 등록한 좋아요를 취소합니다.")
     @DeleteMapping("/perspectives/{perspectiveId}/likes")
-    public ApiResponse<LikeResponse> removeLike(@PathVariable Long perspectiveId) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
+    public ApiResponse<LikeResponse> removeLike(
+            @PathVariable Long perspectiveId,
+            @AuthenticationPrincipal Long userId) {
         return ApiResponse.onSuccess(likeService.removeLike(perspectiveId, userId));
     }
 }
diff --git a/src/main/java/com/swyp/app/domain/perspective/entity/Perspective.java b/src/main/java/com/swyp/app/domain/perspective/entity/Perspective.java
index 622633e..48ece7a 100644
--- a/src/main/java/com/swyp/app/domain/perspective/entity/Perspective.java
+++ b/src/main/java/com/swyp/app/domain/perspective/entity/Perspective.java
@@ -1,14 +1,17 @@
 package com.swyp.app.domain.perspective.entity;
 
+import com.swyp.app.domain.battle.entity.Battle;
+import com.swyp.app.domain.battle.entity.BattleOption;
 import com.swyp.app.domain.perspective.enums.PerspectiveStatus;
+import com.swyp.app.domain.user.entity.User;
 import com.swyp.app.global.common.BaseEntity;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.EnumType;
 import jakarta.persistence.Enumerated;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
 import jakarta.persistence.Table;
 import jakarta.persistence.UniqueConstraint;
 import lombok.AccessLevel;
@@ -25,17 +28,17 @@
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class Perspective extends BaseEntity {
 
-    // TODO: Battle 엔티티 병합 후 @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "battle_id") 로 교체
-    @Column(name = "battle_id", nullable = false)
-    private Long battleId;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "battle_id", nullable = false)
+    private Battle battle;
 
-    // TODO: User 엔티티 병합 후 @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "user_id") 로 교체
-    @Column(name = "user_id", nullable = false)
-    private Long userId;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = false)
+    private User user;
 
-    // TODO: BattleOption 엔티티 병합 후 @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "option_id") 로 교체
-    @Column(name = "option_id", nullable = false)
-    private Long optionId;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "option_id", nullable = false)
+    private BattleOption option;
 
     @Column(nullable = false, columnDefinition = "TEXT")
     private String content;
@@ -51,10 +54,10 @@ public class Perspective extends BaseEntity {
     private PerspectiveStatus status;
 
     @Builder
-    private Perspective(Long battleId, Long userId, Long optionId, String content) {
-        this.battleId = battleId;
-        this.userId = userId;
-        this.optionId = optionId;
+    private Perspective(Battle battle, User user, BattleOption option, String content) {
+        this.battle = battle;
+        this.user = user;
+        this.option = option;
         this.content = content;
         this.likeCount = 0;
         this.commentCount = 0;
diff --git a/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveComment.java b/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveComment.java
index 19a940a..bf41727 100644
--- a/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveComment.java
+++ b/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveComment.java
@@ -1,5 +1,6 @@
 package com.swyp.app.domain.perspective.entity;
 
+import com.swyp.app.domain.user.entity.User;
 import com.swyp.app.global.common.BaseEntity;
 import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
@@ -22,17 +23,17 @@ public class PerspectiveComment extends BaseEntity {
     @JoinColumn(name = "perspective_id", nullable = false)
     private Perspective perspective;
 
-    // TODO: User 엔티티 병합 후 @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "user_id") 로 교체
-    @Column(name = "user_id", nullable = false)
-    private Long userId;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = false)
+    private User user;
 
     @Column(nullable = false, columnDefinition = "TEXT")
     private String content;
 
     @Builder
-    private PerspectiveComment(Perspective perspective, Long userId, String content) {
+    private PerspectiveComment(Perspective perspective, User user, String content) {
         this.perspective = perspective;
-        this.userId = userId;
+        this.user = user;
         this.content = content;
     }
 
diff --git a/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveLike.java b/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveLike.java
index 3850c32..db399a6 100644
--- a/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveLike.java
+++ b/src/main/java/com/swyp/app/domain/perspective/entity/PerspectiveLike.java
@@ -1,7 +1,7 @@
 package com.swyp.app.domain.perspective.entity;
 
+import com.swyp.app.domain.user.entity.User;
 import com.swyp.app.global.common.BaseEntity;
-import jakarta.persistence.Column;
 import jakarta.persistence.Entity;
 import jakarta.persistence.FetchType;
 import jakarta.persistence.JoinColumn;
@@ -26,13 +26,13 @@ public class PerspectiveLike extends BaseEntity {
     @JoinColumn(name = "perspective_id", nullable = false)
     private Perspective perspective;
 
-    // TODO: User 엔티티 병합 후 @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "user_id") 로 교체
-    @Column(name = "user_id", nullable = false)
-    private Long userId;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = false)
+    private User user;
 
     @Builder
-    private PerspectiveLike(Perspective perspective, Long userId) {
+    private PerspectiveLike(Perspective perspective, User user) {
         this.perspective = perspective;
-        this.userId = userId;
+        this.user = user;
     }
 }
diff --git a/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveCommentRepository.java b/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveCommentRepository.java
index e28e877..ad44196 100644
--- a/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveCommentRepository.java
+++ b/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveCommentRepository.java
@@ -16,8 +16,7 @@ public interface PerspectiveCommentRepository extends JpaRepository<PerspectiveC
 
     List<PerspectiveComment> findByPerspectiveAndCreatedAtBeforeOrderByCreatedAtDesc(Perspective perspective, LocalDateTime cursor, Pageable pageable);
 
-    // MypageService: 사용자 댓글 활동 조회 (offset 페이지네이션)
-    @Query("SELECT c FROM PerspectiveComment c JOIN FETCH c.perspective WHERE c.userId = :userId ORDER BY c.createdAt DESC")
+    @Query("SELECT c FROM PerspectiveComment c JOIN FETCH c.perspective WHERE c.user.id = :userId ORDER BY c.createdAt DESC")
     List<PerspectiveComment> findByUserIdOrderByCreatedAtDesc(@Param("userId") Long userId, Pageable pageable);
 
     long countByUserId(Long userId);
diff --git a/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveLikeRepository.java b/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveLikeRepository.java
index 267a6ba..f71877c 100644
--- a/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveLikeRepository.java
+++ b/src/main/java/com/swyp/app/domain/perspective/repository/PerspectiveLikeRepository.java
@@ -18,8 +18,7 @@ public interface PerspectiveLikeRepository extends JpaRepository<PerspectiveLike
 
     long countByPerspective(Perspective perspective);
 
-    // MypageService: 사용자 좋아요 활동 조회 (offset 페이지네이션)
-    @Query("SELECT l FROM PerspectiveLike l JOIN FETCH l.perspective WHERE l.userId = :userId ORDER BY l.createdAt DESC")
+    @Query("SELECT l FROM PerspectiveLike l JOIN FETCH l.perspective WHERE l.user.id = :userId ORDER BY l.createdAt DESC")
     List<PerspectiveLike> findByUserIdOrderByCreatedAtDesc(@Param("userId") Long userId, Pageable pageable);
 
     long countByUserId(Long userId);
diff --git a/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveCommentService.java b/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveCommentService.java
index df7fc6e..88ded3c 100644
--- a/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveCommentService.java
+++ b/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveCommentService.java
@@ -10,6 +10,8 @@
 import com.swyp.app.domain.perspective.repository.PerspectiveCommentRepository;
 import com.swyp.app.domain.perspective.repository.PerspectiveRepository;
 import com.swyp.app.domain.user.dto.response.UserSummary;
+import com.swyp.app.domain.user.entity.User;
+import com.swyp.app.domain.user.repository.UserRepository;
 import com.swyp.app.domain.user.service.UserService;
 import com.swyp.app.global.common.exception.CustomException;
 import com.swyp.app.global.common.exception.ErrorCode;
@@ -30,25 +32,28 @@ public class PerspectiveCommentService {
 
     private final PerspectiveRepository perspectiveRepository;
     private final PerspectiveCommentRepository commentRepository;
+    private final UserRepository userRepository;
     private final UserService userQueryService;
 
     @Transactional
     public CreateCommentResponse createComment(Long perspectiveId, Long userId, CreateCommentRequest request) {
         Perspective perspective = findPerspectiveById(perspectiveId);
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
 
         PerspectiveComment comment = PerspectiveComment.builder()
                 .perspective(perspective)
-                .userId(userId)
+                .user(user)
                 .content(request.content())
                 .build();
 
         commentRepository.save(comment);
         perspective.incrementCommentCount();
 
-        UserSummary user = userQueryService.findSummaryById(userId);
+        UserSummary userSummary = userQueryService.findSummaryById(userId);
         return new CreateCommentResponse(
                 comment.getId(),
-                new CreateCommentResponse.UserSummary(user.userTag(), user.nickname(), user.characterType()),
+                new CreateCommentResponse.UserSummary(userSummary.userTag(), userSummary.nickname(), userSummary.characterType()),
                 comment.getContent(),
                 comment.getCreatedAt()
         );
@@ -67,12 +72,12 @@ public CommentListResponse getComments(Long perspectiveId, Long userId, String c
 
         List<CommentListResponse.Item> items = comments.stream()
                 .map(c -> {
-                    UserSummary user = userQueryService.findSummaryById(c.getUserId());
+                    UserSummary author = userQueryService.findSummaryById(c.getUser().getId());
                     return new CommentListResponse.Item(
                             c.getId(),
-                            new CommentListResponse.UserSummary(user.userTag(), user.nickname(), user.characterType()),
+                            new CommentListResponse.UserSummary(author.userTag(), author.nickname(), author.characterType()),
                             c.getContent(),
-                            c.getUserId().equals(userId),
+                            c.getUser().getId().equals(userId),
                             c.getCreatedAt()
                     );
                 })
@@ -116,7 +121,7 @@ private PerspectiveComment findCommentById(Long commentId) {
     }
 
     private void validateOwnership(PerspectiveComment comment, Long userId) {
-        if (!comment.getUserId().equals(userId)) {
+        if (!comment.getUser().getId().equals(userId)) {
             throw new CustomException(ErrorCode.COMMENT_FORBIDDEN);
         }
     }
diff --git a/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveLikeService.java b/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveLikeService.java
index 3b77392..24b3e95 100644
--- a/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveLikeService.java
+++ b/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveLikeService.java
@@ -6,6 +6,8 @@
 import com.swyp.app.domain.perspective.entity.PerspectiveLike;
 import com.swyp.app.domain.perspective.repository.PerspectiveLikeRepository;
 import com.swyp.app.domain.perspective.repository.PerspectiveRepository;
+import com.swyp.app.domain.user.entity.User;
+import com.swyp.app.domain.user.repository.UserRepository;
 import com.swyp.app.global.common.exception.CustomException;
 import com.swyp.app.global.common.exception.ErrorCode;
 import lombok.RequiredArgsConstructor;
@@ -19,6 +21,7 @@ public class PerspectiveLikeService {
 
     private final PerspectiveRepository perspectiveRepository;
     private final PerspectiveLikeRepository likeRepository;
+    private final UserRepository userRepository;
 
     public LikeCountResponse getLikeCount(Long perspectiveId) {
         Perspective perspective = findPerspectiveById(perspectiveId);
@@ -29,8 +32,10 @@ public LikeCountResponse getLikeCount(Long perspectiveId) {
     @Transactional
     public LikeResponse addLike(Long perspectiveId, Long userId) {
         Perspective perspective = findPerspectiveById(perspectiveId);
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
 
-        if (perspective.getUserId().equals(userId)) {
+        if (perspective.getUser().getId().equals(userId)) {
             throw new CustomException(ErrorCode.LIKE_SELF_FORBIDDEN);
         }
 
@@ -40,7 +45,7 @@ public LikeResponse addLike(Long perspectiveId, Long userId) {
 
         likeRepository.save(PerspectiveLike.builder()
                 .perspective(perspective)
-                .userId(userId)
+                .user(user)
                 .build());
         perspective.incrementLikeCount();
 
diff --git a/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveService.java b/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveService.java
index 4e75278..f910766 100644
--- a/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveService.java
+++ b/src/main/java/com/swyp/app/domain/perspective/service/PerspectiveService.java
@@ -1,9 +1,12 @@
 package com.swyp.app.domain.perspective.service;
 
+import com.swyp.app.domain.battle.entity.Battle;
 import com.swyp.app.domain.battle.entity.BattleOption;
 import com.swyp.app.domain.battle.enums.BattleOptionLabel;
 import com.swyp.app.domain.battle.service.BattleService;
 import com.swyp.app.domain.perspective.enums.PerspectiveStatus;
+import com.swyp.app.domain.user.entity.User;
+import com.swyp.app.domain.user.repository.UserRepository;
 import com.swyp.app.domain.perspective.dto.request.CreatePerspectiveRequest;
 import com.swyp.app.domain.perspective.dto.request.UpdatePerspectiveRequest;
 import com.swyp.app.domain.perspective.dto.response.CreatePerspectiveResponse;
@@ -38,22 +41,25 @@ public class PerspectiveService {
     private final BattleService battleService;
     private final VoteService voteService;
     private final UserService userQueryService;
+    private final UserRepository userRepository;
     private final GptModerationService gptModerationService;
 
     @Transactional
     public CreatePerspectiveResponse createPerspective(Long battleId, Long userId, CreatePerspectiveRequest request) {
-        battleService.findById(battleId);
+        Battle battle = battleService.findById(battleId);
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
 
         if (perspectiveRepository.existsByBattleIdAndUserId(battleId, userId)) {
             throw new CustomException(ErrorCode.PERSPECTIVE_ALREADY_EXISTS);
         }
 
-        Long optionId = voteService.findPreVoteOptionId(battleId, userId);
+        BattleOption option = voteService.findPreVoteOption(battleId, userId);
 
         Perspective perspective = Perspective.builder()
-                .battleId(battleId)
-                .userId(userId)
-                .optionId(optionId)
+                .battle(battle)
+                .user(user)
+                .option(option)
                 .content(request.content())
                 .build();
 
@@ -84,8 +90,8 @@ public PerspectiveListResponse getPerspectives(Long battleId, Long userId, Strin
 
         List<PerspectiveListResponse.Item> items = perspectives.stream()
                 .map(p -> {
-                    UserSummary user = userQueryService.findSummaryById(p.getUserId());
-                    BattleOption option = battleService.findOptionById(p.getOptionId());
+                    UserSummary user = userQueryService.findSummaryById(p.getUser().getId());
+                    BattleOption option = p.getOption();
                     boolean isLiked = perspectiveLikeRepository.existsByPerspectiveAndUserId(p, userId);
                     return new PerspectiveListResponse.Item(
                             p.getId(),
@@ -154,7 +160,7 @@ private Perspective findPerspectiveById(Long perspectiveId) {
     }
 
     private void validateOwnership(Perspective perspective, Long userId) {
-        if (!perspective.getUserId().equals(userId)) {
+        if (!perspective.getUser().getId().equals(userId)) {
             throw new CustomException(ErrorCode.PERSPECTIVE_FORBIDDEN);
         }
     }
diff --git a/src/main/java/com/swyp/app/domain/reward/service/AdMobRewardServiceImpl.java b/src/main/java/com/swyp/app/domain/reward/service/AdMobRewardServiceImpl.java
index 70114fa..365a6c1 100644
--- a/src/main/java/com/swyp/app/domain/reward/service/AdMobRewardServiceImpl.java
+++ b/src/main/java/com/swyp/app/domain/reward/service/AdMobRewardServiceImpl.java
@@ -52,9 +52,6 @@ public String processReward(AdMobRewardRequest request) {
 
         adRewardHistoryRepository.save(history);
 
-        // 6. TODO: 작업 중인 포인트 합산 로직 호출 지점
-        // user.addPoint(request.reward_amount());
-
         log.info("보상 지급 완료: user={}, amount={}", user.getId(), request.reward_amount());
         return "OK";
     }
diff --git a/src/main/java/com/swyp/app/domain/scenario/controller/ScenarioController.java b/src/main/java/com/swyp/app/domain/scenario/controller/ScenarioController.java
index 59c7d98..926b048 100644
--- a/src/main/java/com/swyp/app/domain/scenario/controller/ScenarioController.java
+++ b/src/main/java/com/swyp/app/domain/scenario/controller/ScenarioController.java
@@ -3,7 +3,7 @@
 import com.swyp.app.domain.scenario.dto.request.ScenarioCreateRequest;
 import com.swyp.app.domain.scenario.dto.request.ScenarioStatusUpdateRequest;
 import com.swyp.app.domain.scenario.dto.response.AdminDeleteResponse;
-import com.swyp.app.domain.scenario.dto.response.AdminScenarioDetailResponse; // 🚀 추가 (상세 조회용)
+import com.swyp.app.domain.scenario.dto.response.AdminScenarioDetailResponse;
 import com.swyp.app.domain.scenario.dto.response.AdminScenarioResponse;
 import com.swyp.app.domain.scenario.dto.response.UserScenarioResponse;
 import com.swyp.app.domain.scenario.service.ScenarioService;
diff --git a/src/main/java/com/swyp/app/domain/scenario/service/ScenarioServiceImpl.java b/src/main/java/com/swyp/app/domain/scenario/service/ScenarioServiceImpl.java
index 8dadc05..a5d4b4e 100644
--- a/src/main/java/com/swyp/app/domain/scenario/service/ScenarioServiceImpl.java
+++ b/src/main/java/com/swyp/app/domain/scenario/service/ScenarioServiceImpl.java
@@ -8,7 +8,7 @@
 import com.swyp.app.domain.scenario.dto.request.ScenarioCreateRequest;
 import com.swyp.app.domain.scenario.dto.request.ScriptRequest;
 import com.swyp.app.domain.scenario.dto.response.AdminDeleteResponse;
-import com.swyp.app.domain.scenario.dto.response.AdminScenarioDetailResponse; // 🚀 추가
+import com.swyp.app.domain.scenario.dto.response.AdminScenarioDetailResponse;
 import com.swyp.app.domain.scenario.dto.response.AdminScenarioResponse;
 import com.swyp.app.domain.scenario.dto.response.UserScenarioResponse;
 import com.swyp.app.domain.scenario.entity.InteractiveOption;
diff --git a/src/main/java/com/swyp/app/domain/user/entity/CreditHistory.java b/src/main/java/com/swyp/app/domain/user/entity/CreditHistory.java
index ceeea05..e3000ff 100644
--- a/src/main/java/com/swyp/app/domain/user/entity/CreditHistory.java
+++ b/src/main/java/com/swyp/app/domain/user/entity/CreditHistory.java
@@ -6,7 +6,10 @@
 import jakarta.persistence.Entity;
 import jakarta.persistence.EnumType;
 import jakarta.persistence.Enumerated;
+import jakarta.persistence.FetchType;
 import jakarta.persistence.Index;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
 import jakarta.persistence.Table;
 import lombok.AccessLevel;
 import lombok.Builder;
@@ -22,8 +25,9 @@
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class CreditHistory extends BaseEntity {
 
-    @Column(name = "user_id", nullable = false)
-    private Long userId;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = false)
+    private User user;
 
     @Enumerated(EnumType.STRING)
     @Column(name = "credit_type", nullable = false, length = 30)
@@ -36,8 +40,8 @@ public class CreditHistory extends BaseEntity {
     private Long referenceId;
 
     @Builder
-    private CreditHistory(Long userId, CreditType creditType, int amount, Long referenceId) {
-        this.userId = userId;
+    private CreditHistory(User user, CreditType creditType, int amount, Long referenceId) {
+        this.user = user;
         this.creditType = creditType;
         this.amount = amount;
         this.referenceId = referenceId;
diff --git a/src/main/java/com/swyp/app/domain/user/repository/CreditHistoryRepository.java b/src/main/java/com/swyp/app/domain/user/repository/CreditHistoryRepository.java
index a860eef..775b23c 100644
--- a/src/main/java/com/swyp/app/domain/user/repository/CreditHistoryRepository.java
+++ b/src/main/java/com/swyp/app/domain/user/repository/CreditHistoryRepository.java
@@ -8,7 +8,7 @@
 
 public interface CreditHistoryRepository extends JpaRepository<CreditHistory, Long> {
 
-    @Query("SELECT COALESCE(SUM(c.amount), 0) FROM CreditHistory c WHERE c.userId = :userId")
+    @Query("SELECT COALESCE(SUM(c.amount), 0) FROM CreditHistory c WHERE c.user.id = :userId")
     int sumAmountByUserId(@Param("userId") Long userId);
 
     boolean existsByUserIdAndCreditTypeAndReferenceId(Long userId, CreditType creditType, Long referenceId);
diff --git a/src/main/java/com/swyp/app/domain/user/service/CreditService.java b/src/main/java/com/swyp/app/domain/user/service/CreditService.java
index a9c9ce3..7704791 100644
--- a/src/main/java/com/swyp/app/domain/user/service/CreditService.java
+++ b/src/main/java/com/swyp/app/domain/user/service/CreditService.java
@@ -5,6 +5,7 @@
 import com.swyp.app.domain.user.entity.User;
 import com.swyp.app.domain.user.enums.CreditType;
 import com.swyp.app.domain.user.repository.CreditHistoryRepository;
+import com.swyp.app.domain.user.repository.UserRepository;
 import com.swyp.app.global.common.exception.CustomException;
 import com.swyp.app.global.common.exception.ErrorCode;
 import lombok.RequiredArgsConstructor;
@@ -18,6 +19,7 @@
 public class CreditService {
 
     private final CreditHistoryRepository creditHistoryRepository;
+    private final UserRepository userRepository;
     private final UserService userService;
 
     /**
@@ -50,8 +52,11 @@ public void addCredit(Long userId, CreditType creditType, Long referenceId) {
     public void addCredit(Long userId, CreditType creditType, int amount, Long referenceId) {
         validateReferenceId(referenceId);
 
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
+
         CreditHistory history = CreditHistory.builder()
-                .userId(userId)
+                .user(user)
                 .creditType(creditType)
                 .amount(amount)
                 .referenceId(referenceId)
diff --git a/src/main/java/com/swyp/app/domain/user/service/MypageService.java b/src/main/java/com/swyp/app/domain/user/service/MypageService.java
index fa45e85..3fcd2ba 100644
--- a/src/main/java/com/swyp/app/domain/user/service/MypageService.java
+++ b/src/main/java/com/swyp/app/domain/user/service/MypageService.java
@@ -193,7 +193,7 @@ private ContentActivityListResponse buildCommentActivities(User user, int pageOf
                 .map(comment -> {
                     Perspective p = comment.getPerspective();
                     return toActivityItem(comment.getId().toString(), ActivityType.COMMENT, p,
-                            battleMap.get(p.getBattleId()), optionMap.get(p.getOptionId()),
+                            battleMap.get(p.getBattle().getId()), optionMap.get(p.getOption().getId()),
                             comment.getContent(), comment.getCreatedAt());
                 })
                 .toList();
@@ -215,7 +215,7 @@ private ContentActivityListResponse buildLikeActivities(User user, int pageOffse
                 .map(like -> {
                     Perspective p = like.getPerspective();
                     return toActivityItem(like.getId().toString(), ActivityType.LIKE, p,
-                            battleMap.get(p.getBattleId()), optionMap.get(p.getOptionId()),
+                            battleMap.get(p.getBattle().getId()), optionMap.get(p.getOption().getId()),
                             p.getContent(), like.getCreatedAt());
                 })
                 .toList();
@@ -229,7 +229,7 @@ private ContentActivityListResponse.ContentActivityItem toActivityItem(
             String activityId, ActivityType activityType, Perspective perspective,
             Battle battle, BattleOption option, String content, LocalDateTime createdAt) {
 
-        UserSummary author = userService.findSummaryById(perspective.getUserId());
+        UserSummary author = userService.findSummaryById(perspective.getUser().getId());
         ContentActivityListResponse.AuthorInfo authorInfo = new ContentActivityListResponse.AuthorInfo(
                 author.userTag(), author.nickname(), CharacterType.from(author.characterType())
         );
@@ -237,7 +237,7 @@ private ContentActivityListResponse.ContentActivityItem toActivityItem(
         return new ContentActivityListResponse.ContentActivityItem(
                 activityId, activityType,
                 perspective.getId().toString(),
-                perspective.getBattleId().toString(),
+                perspective.getBattle().getId().toString(),
                 battle != null ? battle.getTitle() : null,
                 authorInfo,
                 option != null ? option.getStance() : null,
@@ -248,12 +248,12 @@ private ContentActivityListResponse.ContentActivityItem toActivityItem(
     }
 
     private Map<Long, Battle> loadBattles(List<Perspective> perspectives) {
-        List<Long> battleIds = perspectives.stream().map(Perspective::getBattleId).distinct().toList();
+        List<Long> battleIds = perspectives.stream().map(p -> p.getBattle().getId()).distinct().toList();
         return battleQueryService.findBattlesByIds(battleIds);
     }
 
     private Map<Long, BattleOption> loadOptions(List<Perspective> perspectives) {
-        List<Long> optionIds = perspectives.stream().map(Perspective::getOptionId).distinct().toList();
+        List<Long> optionIds = perspectives.stream().map(p -> p.getOption().getId()).distinct().toList();
         return battleQueryService.findOptionsByIds(optionIds);
     }
 
diff --git a/src/main/java/com/swyp/app/domain/vote/controller/VoteController.java b/src/main/java/com/swyp/app/domain/vote/controller/VoteController.java
index 1d703fd..4bdb9b8 100644
--- a/src/main/java/com/swyp/app/domain/vote/controller/VoteController.java
+++ b/src/main/java/com/swyp/app/domain/vote/controller/VoteController.java
@@ -9,6 +9,7 @@
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import lombok.RequiredArgsConstructor;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.web.bind.annotation.*;
 
 @Tag(name = "투표 (Vote)", description = "사전/사후 투표 실행 및 통계, 내 투표 내역 조회 API")
@@ -23,9 +24,8 @@ public class VoteController {
     @PostMapping("/battles/{battleId}/votes/pre")
     public ApiResponse<VoteResultResponse> preVote(
             @PathVariable Long battleId,
+            @AuthenticationPrincipal Long userId,
             @RequestBody VoteRequest request) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(voteService.preVote(battleId, userId, request));
     }
 
@@ -33,9 +33,8 @@ public ApiResponse<VoteResultResponse> preVote(
     @PostMapping("/battles/{battleId}/votes/post")
     public ApiResponse<VoteResultResponse> postVote(
             @PathVariable Long battleId,
+            @AuthenticationPrincipal Long userId,
             @RequestBody VoteRequest request) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
         return ApiResponse.onSuccess(voteService.postVote(battleId, userId, request));
     }
 
@@ -47,9 +46,9 @@ public ApiResponse<VoteStatsResponse> getVoteStats(@PathVariable Long battleId)
 
     @Operation(summary = "내 투표 내역 조회", description = "특정 배틀에 대한 내 사전/사후 투표 내역과 현재 상태를 조회합니다.")
     @GetMapping("/battles/{battleId}/votes/me")
-    public ApiResponse<MyVoteResponse> getMyVote(@PathVariable Long battleId) {
-        // TODO: Security 적용 후 @AuthenticationPrincipal로 userId 교체
-        Long userId = 1L;
+    public ApiResponse<MyVoteResponse> getMyVote(
+            @PathVariable Long battleId,
+            @AuthenticationPrincipal Long userId) {
         return ApiResponse.onSuccess(voteService.getMyVote(battleId, userId));
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/java/com/swyp/app/domain/vote/entity/Vote.java b/src/main/java/com/swyp/app/domain/vote/entity/Vote.java
index fe9a24b..2c469b1 100644
--- a/src/main/java/com/swyp/app/domain/vote/entity/Vote.java
+++ b/src/main/java/com/swyp/app/domain/vote/entity/Vote.java
@@ -2,6 +2,7 @@
 
 import com.swyp.app.domain.battle.entity.Battle;
 import com.swyp.app.domain.battle.entity.BattleOption;
+import com.swyp.app.domain.user.entity.User;
 import com.swyp.app.domain.vote.enums.VoteStatus;
 import com.swyp.app.global.common.BaseEntity;
 import jakarta.persistence.Column;
@@ -9,9 +10,6 @@
 import jakarta.persistence.EnumType;
 import jakarta.persistence.Enumerated;
 import jakarta.persistence.FetchType;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
 import jakarta.persistence.Table;
@@ -26,9 +24,9 @@
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
 public class Vote extends BaseEntity {
 
-    // TODO: User 엔티티 병합 후 @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "user_id") 로 교체
-    @Column(name = "user_id", nullable = false)
-    private Long userId;
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "user_id", nullable = false)
+    private User user;
 
     @ManyToOne(fetch = FetchType.LAZY)
     @JoinColumn(name = "battle_id", nullable = false)
@@ -47,28 +45,26 @@ public class Vote extends BaseEntity {
     private VoteStatus status;
 
     @Builder
-    private Vote(Long userId, Battle battle, BattleOption preVoteOption,
+    private Vote(User user, Battle battle, BattleOption preVoteOption,
                  BattleOption postVoteOption, VoteStatus status) {
-        this.userId = userId;
+        this.user = user;
         this.battle = battle;
         this.preVoteOption = preVoteOption;
         this.postVoteOption = postVoteOption;
         this.status = status;
     }
 
-    // 사전 투표 생성 팩토리 메서드
-    public static Vote createPreVote(Long userId, Battle battle, BattleOption option) {
+    public static Vote createPreVote(User user, Battle battle, BattleOption option) {
         return Vote.builder()
-                .userId(userId)
+                .user(user)
                 .battle(battle)
                 .preVoteOption(option)
                 .status(VoteStatus.PRE_VOTED)
                 .build();
     }
 
-    // 사후 투표 실행 상태 변경 메서드
     public void doPostVote(BattleOption postOption) {
         this.postVoteOption = postOption;
         this.status = VoteStatus.POST_VOTED;
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/java/com/swyp/app/domain/vote/repository/VoteRepository.java b/src/main/java/com/swyp/app/domain/vote/repository/VoteRepository.java
index da6a67e..cd0ed29 100644
--- a/src/main/java/com/swyp/app/domain/vote/repository/VoteRepository.java
+++ b/src/main/java/com/swyp/app/domain/vote/repository/VoteRepository.java
@@ -5,6 +5,7 @@
 import com.swyp.app.domain.battle.enums.BattleOptionLabel;
 import com.swyp.app.domain.user.entity.User;
 import com.swyp.app.domain.vote.entity.Vote;
+import com.swyp.app.domain.vote.enums.VoteStatus;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
@@ -15,11 +16,9 @@
 
 public interface VoteRepository extends JpaRepository<Vote, Long> {
 
-    // ScenarioService : Battle 엔티티 조회 없이 ID만으로 투표 내역 확인
     Optional<Vote> findByBattleIdAndUserId(Long battleId, Long userId);
 
-    // VoteService : 이미 조회된 Battle 엔티티를 활용하여 투표 내역 확인
-    Optional<Vote> findByBattleAndUserId(Battle battle, Long userId);
+    Optional<Vote> findByBattleAndUser(Battle battle, User user);
 
     long countByBattle(Battle battle);
 
@@ -27,36 +26,29 @@ public interface VoteRepository extends JpaRepository<Vote, Long> {
 
     Optional<Vote> findTopByBattleOrderByUpdatedAtDesc(Battle battle);
 
-    // MypageService: 사용자 투표 기록 조회 (offset 페이지네이션)
     @Query("SELECT v FROM Vote v JOIN FETCH v.battle JOIN FETCH v.preVoteOption " +
-           "WHERE v.userId = :userId ORDER BY v.createdAt DESC")
+           "WHERE v.user.id = :userId ORDER BY v.createdAt DESC")
     List<Vote> findByUserIdOrderByCreatedAtDesc(@Param("userId") Long userId, Pageable pageable);
 
-    // MypageService: 사용자 투표 기록 - voteSide(PRO/CON) 필터
     @Query("SELECT v FROM Vote v JOIN FETCH v.battle JOIN FETCH v.preVoteOption " +
-           "WHERE v.userId = :userId AND v.preVoteOption.label = :label ORDER BY v.createdAt DESC")
+           "WHERE v.user.id = :userId AND v.preVoteOption.label = :label ORDER BY v.createdAt DESC")
     List<Vote> findByUserIdAndPreVoteOptionLabelOrderByCreatedAtDesc(
             @Param("userId") Long userId, @Param("label") BattleOptionLabel label, Pageable pageable);
 
-    // MypageService: 사용자 투표 전체 수
     long countByUserId(Long userId);
 
-    // MypageService: 사용자 투표 수 - voteSide 필터
-    @Query("SELECT COUNT(v) FROM Vote v WHERE v.userId = :userId AND v.preVoteOption.label = :label")
+    @Query("SELECT COUNT(v) FROM Vote v WHERE v.user.id = :userId AND v.preVoteOption.label = :label")
     long countByUserIdAndPreVoteOptionLabel(@Param("userId") Long userId, @Param("label") BattleOptionLabel label);
 
-    // MypageService (recap): 사후 투표 완료 수
-    long countByUserIdAndStatus(Long userId, com.swyp.app.domain.vote.enums.VoteStatus status);
+    long countByUserIdAndStatus(Long userId, VoteStatus status);
 
-    // MypageService (recap): 입장 변경 수 (사전/사후 투표 옵션이 다른 경우)
-    @Query("SELECT COUNT(v) FROM Vote v WHERE v.userId = :userId AND v.status = 'POST_VOTED' " +
+    @Query("SELECT COUNT(v) FROM Vote v WHERE v.user.id = :userId AND v.status = 'POST_VOTED' " +
            "AND v.preVoteOption <> v.postVoteOption")
     long countOpinionChangesByUserId(@Param("userId") Long userId);
 
-    // MypageService (recap): 사용자가 참여한 모든 투표 (배틀 목록 추출용)
     List<Vote> findByUserId(Long userId);
 
     // MypageService: 철학자 유형 산출용 - 최초 N개 투표 조회 (생성순)
-    @Query("SELECT v FROM Vote v JOIN FETCH v.battle WHERE v.userId = :userId ORDER BY v.createdAt ASC")
+    @Query("SELECT v FROM Vote v JOIN FETCH v.battle WHERE v.user.id = :userId ORDER BY v.createdAt ASC")
     List<Vote> findByUserIdOrderByCreatedAtAsc(@Param("userId") Long userId, Pageable pageable);
 }
diff --git a/src/main/java/com/swyp/app/domain/vote/service/VoteService.java b/src/main/java/com/swyp/app/domain/vote/service/VoteService.java
index ba47ef5..70e95a7 100644
--- a/src/main/java/com/swyp/app/domain/vote/service/VoteService.java
+++ b/src/main/java/com/swyp/app/domain/vote/service/VoteService.java
@@ -1,5 +1,6 @@
 package com.swyp.app.domain.vote.service;
 
+import com.swyp.app.domain.battle.entity.BattleOption;
 import com.swyp.app.domain.vote.dto.request.VoteRequest;
 import com.swyp.app.domain.vote.dto.response.MyVoteResponse;
 import com.swyp.app.domain.vote.dto.response.VoteResultResponse;
@@ -7,7 +8,7 @@
 
 public interface VoteService {
 
-    Long findPreVoteOptionId(Long battleId, Long userId);
+    BattleOption findPreVoteOption(Long battleId, Long userId);
 
     VoteStatsResponse getVoteStats(Long battleId);
 
diff --git a/src/main/java/com/swyp/app/domain/vote/service/VoteServiceImpl.java b/src/main/java/com/swyp/app/domain/vote/service/VoteServiceImpl.java
index df70224..c76898b 100644
--- a/src/main/java/com/swyp/app/domain/vote/service/VoteServiceImpl.java
+++ b/src/main/java/com/swyp/app/domain/vote/service/VoteServiceImpl.java
@@ -4,6 +4,8 @@
 import com.swyp.app.domain.battle.entity.BattleOption;
 import com.swyp.app.domain.battle.repository.BattleOptionRepository;
 import com.swyp.app.domain.battle.service.BattleService;
+import com.swyp.app.domain.user.entity.User;
+import com.swyp.app.domain.user.repository.UserRepository;
 import com.swyp.app.domain.vote.converter.VoteConverter;
 import com.swyp.app.domain.vote.dto.request.VoteRequest;
 import com.swyp.app.domain.vote.dto.response.MyVoteResponse;
@@ -29,18 +31,21 @@ public class VoteServiceImpl implements VoteService {
     private final VoteRepository voteRepository;
     private final BattleService battleService;
     private final BattleOptionRepository battleOptionRepository;
+    private final UserRepository userRepository;
 
     @Override
-    public Long findPreVoteOptionId(Long battleId, Long userId) {
+    public BattleOption findPreVoteOption(Long battleId, Long userId) {
         Battle battle = battleService.findById(battleId);
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
 
-        Vote vote = voteRepository.findByBattleAndUserId(battle, userId)
+        Vote vote = voteRepository.findByBattleAndUser(battle, user)
                 .orElseThrow(() -> new CustomException(ErrorCode.VOTE_NOT_FOUND));
 
         if (vote.getPreVoteOption() == null) {
             throw new CustomException(ErrorCode.PRE_VOTE_REQUIRED);
         }
-        return vote.getPreVoteOption().getId();
+        return vote.getPreVoteOption();
     }
 
     @Override
@@ -70,8 +75,10 @@ public VoteStatsResponse getVoteStats(Long battleId) {
     @Override
     public MyVoteResponse getMyVote(Long battleId, Long userId) {
         Battle battle = battleService.findById(battleId);
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
 
-        Vote vote = voteRepository.findByBattleAndUserId(battle, userId)
+        Vote vote = voteRepository.findByBattleAndUser(battle, user)
                 .orElseThrow(() -> new CustomException(ErrorCode.VOTE_NOT_FOUND));
 
         return VoteConverter.toMyVoteResponse(vote);
@@ -81,15 +88,16 @@ public MyVoteResponse getMyVote(Long battleId, Long userId) {
     @Transactional
     public VoteResultResponse preVote(Long battleId, Long userId, VoteRequest request) {
         Battle battle = battleService.findById(battleId);
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
         BattleOption option = battleOptionRepository.findById(request.optionId())
                 .orElseThrow(() -> new CustomException(ErrorCode.BATTLE_OPTION_NOT_FOUND));
 
-        // 이미 투표 내역이 존재하는지 검증
-        if (voteRepository.findByBattleAndUserId(battle, userId).isPresent()) {
+        if (voteRepository.findByBattleAndUser(battle, user).isPresent()) {
             throw new CustomException(ErrorCode.VOTE_ALREADY_SUBMITTED);
         }
 
-        Vote vote = Vote.createPreVote(userId, battle, option);
+        Vote vote = Vote.createPreVote(user, battle, option);
         voteRepository.save(vote);
 
         return VoteConverter.toVoteResultResponse(vote);
@@ -99,13 +107,14 @@ public VoteResultResponse preVote(Long battleId, Long userId, VoteRequest reques
     @Transactional
     public VoteResultResponse postVote(Long battleId, Long userId, VoteRequest request) {
         Battle battle = battleService.findById(battleId);
+        User user = userRepository.findById(userId)
+                .orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND));
         BattleOption option = battleOptionRepository.findById(request.optionId())
                 .orElseThrow(() -> new CustomException(ErrorCode.BATTLE_OPTION_NOT_FOUND));
 
-        Vote vote = voteRepository.findByBattleAndUserId(battle, userId)
+        Vote vote = voteRepository.findByBattleAndUser(battle, user)
                 .orElseThrow(() -> new CustomException(ErrorCode.VOTE_NOT_FOUND));
 
-        // 사전 투표 상태일 때만 사후 투표 가능
         if (vote.getStatus() != VoteStatus.PRE_VOTED) {
             throw new CustomException(ErrorCode.INVALID_VOTE_STATUS);
         }
diff --git a/src/main/java/com/swyp/app/global/config/S3Config.java b/src/main/java/com/swyp/app/global/config/S3Config.java
index f2ae86f..cac7a59 100644
--- a/src/main/java/com/swyp/app/global/config/S3Config.java
+++ b/src/main/java/com/swyp/app/global/config/S3Config.java
@@ -8,7 +8,6 @@
 import software.amazon.awssdk.regions.Region;
 import software.amazon.awssdk.services.s3.presigner.S3Presigner;
 
-// TODO: S3 Presigned URL 정식 구현 시 교체 필요 (임시 구현)
 @Configuration
 public class S3Config {
 
diff --git a/src/main/java/com/swyp/app/global/infra/s3/dto/FileUploadResponse.java b/src/main/java/com/swyp/app/global/infra/s3/dto/FileUploadResponse.java
index beaf366..4a510ac 100644
--- a/src/main/java/com/swyp/app/global/infra/s3/dto/FileUploadResponse.java
+++ b/src/main/java/com/swyp/app/global/infra/s3/dto/FileUploadResponse.java
@@ -1,4 +1,3 @@
 package com.swyp.app.global.infra.s3.dto;
 
-// TODO: S3 Presigned URL 정식 구현 시 교체 필요 (임시 구현)
 public record FileUploadResponse(String s3Key, String presignedUrl) {}
diff --git a/src/main/java/com/swyp/app/global/infra/s3/service/S3PresignedUrlService.java b/src/main/java/com/swyp/app/global/infra/s3/service/S3PresignedUrlService.java
index ca1fe2e..fc7b0be 100644
--- a/src/main/java/com/swyp/app/global/infra/s3/service/S3PresignedUrlService.java
+++ b/src/main/java/com/swyp/app/global/infra/s3/service/S3PresignedUrlService.java
@@ -11,7 +11,6 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 
-// TODO: S3 Presigned URL 정식 구현 시 교체 필요 (임시 구현)
 @Service
 @RequiredArgsConstructor
 public class S3PresignedUrlService {
diff --git a/src/test/java/com/swyp/app/domain/user/service/CreditServiceTest.java b/src/test/java/com/swyp/app/domain/user/service/CreditServiceTest.java
index a82f810..2a53ae9 100644
--- a/src/test/java/com/swyp/app/domain/user/service/CreditServiceTest.java
+++ b/src/test/java/com/swyp/app/domain/user/service/CreditServiceTest.java
@@ -5,6 +5,7 @@
 import com.swyp.app.domain.user.entity.User;
 import com.swyp.app.domain.user.enums.CreditType;
 import com.swyp.app.domain.user.repository.CreditHistoryRepository;
+import com.swyp.app.domain.user.repository.UserRepository;
 import com.swyp.app.global.common.exception.CustomException;
 import com.swyp.app.global.common.exception.ErrorCode;
 import org.junit.jupiter.api.DisplayName;
@@ -16,6 +17,8 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.dao.DataIntegrityViolationException;
 
+import java.util.Optional;
+
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.ArgumentMatchers.any;
@@ -30,6 +33,9 @@ class CreditServiceTest {
     @Mock
     private CreditHistoryRepository creditHistoryRepository;
 
+    @Mock
+    private UserRepository userRepository;
+
     @Mock
     private UserService userService;
 
@@ -42,6 +48,7 @@ void addCredit_forCurrentUser_savesDefaultAmount() {
         User user = org.mockito.Mockito.mock(User.class);
         when(user.getId()).thenReturn(1L);
         when(userService.findCurrentUser()).thenReturn(user);
+        when(userRepository.findById(1L)).thenReturn(Optional.of(user));
 
         creditService.addCredit(CreditType.BATTLE_VOTE, 10L);
 
@@ -49,7 +56,7 @@ void addCredit_forCurrentUser_savesDefaultAmount() {
         verify(creditHistoryRepository).saveAndFlush(captor.capture());
 
         CreditHistory saved = captor.getValue();
-        assertThat(saved.getUserId()).isEqualTo(1L);
+        assertThat(saved.getUser().getId()).isEqualTo(1L);
         assertThat(saved.getCreditType()).isEqualTo(CreditType.BATTLE_VOTE);
         assertThat(saved.getAmount()).isEqualTo(CreditType.BATTLE_VOTE.getDefaultAmount());
         assertThat(saved.getReferenceId()).isEqualTo(10L);
@@ -69,6 +76,8 @@ void addCredit_withoutReferenceId_throwsException() {
     @Test
     @DisplayName("중복 적립 충돌이면 조용히 무시한다")
     void addCredit_duplicateInsert_ignoresConflict() {
+        User user = org.mockito.Mockito.mock(User.class);
+        when(userRepository.findById(1L)).thenReturn(Optional.of(user));
         when(creditHistoryRepository.saveAndFlush(any(CreditHistory.class)))
                 .thenThrow(new DataIntegrityViolationException("duplicate"));
         when(creditHistoryRepository.existsByUserIdAndCreditTypeAndReferenceId(1L, CreditType.BATTLE_VOTE, 10L))
@@ -82,6 +91,8 @@ void addCredit_duplicateInsert_ignoresConflict() {
     @Test
     @DisplayName("중복이 아닌 데이터 무결성 오류는 그대로 던진다")
     void addCredit_nonDuplicateIntegrityFailure_rethrows() {
+        User user = org.mockito.Mockito.mock(User.class);
+        when(userRepository.findById(1L)).thenReturn(Optional.of(user));
         when(creditHistoryRepository.saveAndFlush(any(CreditHistory.class)))
                 .thenThrow(new DataIntegrityViolationException("broken"));
         when(creditHistoryRepository.existsByUserIdAndCreditTypeAndReferenceId(1L, CreditType.BATTLE_VOTE, 10L))
diff --git a/src/test/java/com/swyp/app/domain/user/service/MypageServiceTest.java b/src/test/java/com/swyp/app/domain/user/service/MypageServiceTest.java
index 5ce1473..08908ac 100644
--- a/src/test/java/com/swyp/app/domain/user/service/MypageServiceTest.java
+++ b/src/test/java/com/swyp/app/domain/user/service/MypageServiceTest.java
@@ -166,7 +166,7 @@ void getBattleRecords_returns_paginated_records() {
         Battle battle = createBattle("배틀 제목");
         BattleOption optionA = createOption(battle, BattleOptionLabel.A);
         Vote vote = Vote.builder()
-                .userId(1L)
+                .user(user)
                 .battle(battle)
                 .preVoteOption(optionA)
                 .build();
@@ -192,7 +192,7 @@ void getBattleRecords_returns_no_next_when_last_page() {
         Battle battle = createBattle("제목");
         BattleOption optionA = createOption(battle, BattleOptionLabel.A);
         Vote vote = Vote.builder()
-                .userId(1L)
+                .user(user)
                 .battle(battle)
                 .preVoteOption(optionA)
                 .build();
@@ -227,29 +227,27 @@ void getBattleRecords_applies_vote_side_filter() {
     @DisplayName("COMMENT 타입으로 댓글활동을 반환한다")
     void getContentActivities_returns_comments() {
         User user = createUser(1L, "tag");
-        Long battleId = generateId();
-        Long optionId = generateId();
+        Battle battle = createBattle("배틀");
+        Long battleId = battle.getId();
+        BattleOption option = createOption(battle, BattleOptionLabel.A);
+        Long optionId = option.getId();
+
         Perspective perspective = Perspective.builder()
-                .battleId(battleId)
-                .userId(1L)
-                .optionId(optionId)
+                .battle(battle)
+                .user(user)
+                .option(option)
                 .content("관점 내용")
                 .build();
         ReflectionTestUtils.setField(perspective, "id", generateId());
 
         PerspectiveComment comment = PerspectiveComment.builder()
                 .perspective(perspective)
-                .userId(1L)
+                .user(user)
                 .content("댓글")
                 .build();
         ReflectionTestUtils.setField(comment, "id", generateId());
         ReflectionTestUtils.setField(comment, "createdAt", LocalDateTime.now());
 
-        Battle battle = createBattle("배틀");
-        ReflectionTestUtils.setField(battle, "id", battleId);
-        BattleOption option = createOption(battle, BattleOptionLabel.A);
-        ReflectionTestUtils.setField(option, "id", optionId);
-
         when(userService.findCurrentUser()).thenReturn(user);
         when(perspectiveQueryService.findUserComments(1L, 0, 20)).thenReturn(List.of(comment));
         when(perspectiveQueryService.countUserComments(1L)).thenReturn(1L);
@@ -268,28 +266,26 @@ void getContentActivities_returns_comments() {
     @DisplayName("LIKE 타입으로 좋아요활동을 반환한다")
     void getContentActivities_returns_likes() {
         User user = createUser(1L, "tag");
-        Long battleId = generateId();
-        Long optionId = generateId();
+        Battle battle = createBattle("배틀");
+        Long battleId = battle.getId();
+        BattleOption option = createOption(battle, BattleOptionLabel.B);
+        Long optionId = option.getId();
+
         Perspective perspective = Perspective.builder()
-                .battleId(battleId)
-                .userId(1L)
-                .optionId(optionId)
+                .battle(battle)
+                .user(user)
+                .option(option)
                 .content("관점 내용")
                 .build();
         ReflectionTestUtils.setField(perspective, "id", generateId());
 
         PerspectiveLike like = PerspectiveLike.builder()
                 .perspective(perspective)
-                .userId(1L)
+                .user(user)
                 .build();
         ReflectionTestUtils.setField(like, "id", generateId());
         ReflectionTestUtils.setField(like, "createdAt", LocalDateTime.now());
 
-        Battle battle = createBattle("배틀");
-        ReflectionTestUtils.setField(battle, "id", battleId);
-        BattleOption option = createOption(battle, BattleOptionLabel.B);
-        ReflectionTestUtils.setField(option, "id", optionId);
-
         when(userService.findCurrentUser()).thenReturn(user);
         when(perspectiveQueryService.findUserLikes(1L, 0, 20)).thenReturn(List.of(like));
         when(perspectiveQueryService.countUserLikes(1L)).thenReturn(1L);