diff --git a/backend/app/services/common.go b/backend/app/services/common.go
index 7f0c567..2f03ee6 100644
--- a/backend/app/services/common.go
+++ b/backend/app/services/common.go
@@ -51,25 +51,6 @@ func (s *common) Options(ctx context.Context) (*common_dto.OptionsResponse, erro
 }
 
 func (s *common) CheckHash(ctx context.Context, tenantID, userID int64, hash string) (*common_dto.UploadResult, error) {
-	existing, err := models.MediaAssetQuery.WithContext(ctx).Where(models.MediaAssetQuery.Hash.Eq(hash)).First()
-	if err != nil {
-		return nil, nil // Not found, proceed to upload
-	}
-
-	// Found existing file (Global deduplication hit)
-
-	// Check if user already has it (Logic deduplication hit)
-	myQuery := models.MediaAssetQuery.WithContext(ctx).
-		Where(models.MediaAssetQuery.Hash.Eq(hash), models.MediaAssetQuery.UserID.Eq(userID))
-	if tenantID > 0 {
-		myQuery = myQuery.Where(models.MediaAssetQuery.TenantID.Eq(tenantID))
-	}
-	myExisting, err := myQuery.First()
-	if err == nil {
-		return s.composeUploadResult(myExisting), nil
-	}
-
-	// Create new record for this user reusing existing ObjectKey
 	// 优先使用路径租户，避免跨租户写入。
 	tenant, err := s.resolveTenant(ctx, tenantID, userID)
 	if err != nil {
@@ -80,6 +61,29 @@ func (s *common) CheckHash(ctx context.Context, tenantID, userID int64, hash str
 		tid = tenant.ID
 	}
 
+	query := models.MediaAssetQuery.WithContext(ctx).Where(models.MediaAssetQuery.Hash.Eq(hash))
+	if tid > 0 {
+		query = query.Where(models.MediaAssetQuery.TenantID.Eq(tid))
+	}
+	existing, err := query.First()
+	if err != nil {
+		return nil, nil // Not found, proceed to upload
+	}
+
+	// Found existing file (deduplication hit)
+
+	// Check if user already has it (Logic deduplication hit)
+	myQuery := models.MediaAssetQuery.WithContext(ctx).
+		Where(models.MediaAssetQuery.Hash.Eq(hash), models.MediaAssetQuery.UserID.Eq(userID))
+	if tid > 0 {
+		myQuery = myQuery.Where(models.MediaAssetQuery.TenantID.Eq(tid))
+	}
+	myExisting, err := myQuery.First()
+	if err == nil {
+		return s.composeUploadResult(myExisting), nil
+	}
+
+	// Create new record for this user reusing existing ObjectKey
 	asset := &models.MediaAsset{
 		TenantID:  tid,
 		UserID:    userID,
@@ -272,15 +276,19 @@ func (s *common) CompleteUpload(ctx context.Context, tenantID, userID int64, for
 	}
 
 	objectKey := s.buildObjectKey(tenant, hash, meta.Filename)
-	existing, err := models.MediaAssetQuery.WithContext(ctx).Where(models.MediaAssetQuery.Hash.Eq(hash)).First()
+	existingQuery := models.MediaAssetQuery.WithContext(ctx).Where(models.MediaAssetQuery.Hash.Eq(hash))
+	if tid > 0 {
+		existingQuery = existingQuery.Where(models.MediaAssetQuery.TenantID.Eq(tid))
+	}
+	existing, err := existingQuery.First()
 	var asset *models.MediaAsset
 
 	if err == nil {
 		os.Remove(mergedPath) // Delete duplicate
 		myQuery := models.MediaAssetQuery.WithContext(ctx).
 			Where(models.MediaAssetQuery.Hash.Eq(hash), models.MediaAssetQuery.UserID.Eq(userID))
-		if tenantID > 0 {
-			myQuery = myQuery.Where(models.MediaAssetQuery.TenantID.Eq(tenantID))
+		if tid > 0 {
+			myQuery = myQuery.Where(models.MediaAssetQuery.TenantID.Eq(tid))
 		}
 		myExisting, err := myQuery.First()
 		if err == nil {
@@ -422,7 +430,11 @@ func (s *common) Upload(
 	var asset *models.MediaAsset
 
 	// Deduplication Check
-	existing, err := models.MediaAssetQuery.WithContext(ctx).Where(models.MediaAssetQuery.Hash.Eq(hash)).First()
+	existingQuery := models.MediaAssetQuery.WithContext(ctx).Where(models.MediaAssetQuery.Hash.Eq(hash))
+	if tid > 0 {
+		existingQuery = existingQuery.Where(models.MediaAssetQuery.TenantID.Eq(tid))
+	}
+	existing, err := existingQuery.First()
 	if err == nil {
 		// Found existing file (Storage Deduplication)
 		os.Remove(tmpPath) // Delete the duplicate we just wrote
@@ -431,8 +443,8 @@ func (s *common) Upload(
 		// Check if user already has it (Logic Deduplication)
 		myQuery := models.MediaAssetQuery.WithContext(ctx).
 			Where(models.MediaAssetQuery.Hash.Eq(hash), models.MediaAssetQuery.UserID.Eq(userID))
-		if tenantID > 0 {
-			myQuery = myQuery.Where(models.MediaAssetQuery.TenantID.Eq(tenantID))
+		if tid > 0 {
+			myQuery = myQuery.Where(models.MediaAssetQuery.TenantID.Eq(tid))
 		}
 		myExisting, err := myQuery.First()
 		if err == nil {