From e2133cd76f69aca74f807fab208044e292e7898c Mon Sep 17 00:00:00 2001
From: truewhile <62226914+truewhile@users.noreply.github.com>
Date: Sat, 17 Oct 2026 23:24:48 +0800
Subject: [PATCH] =?UTF-8?q?app=E5=85=BC=E5=AE=B9=E6=8E=A5=E5=8F=A3?=
 =?UTF-8?q?=E5=BC=80=E5=8F=91?=
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---
 internal/service/favorites_sync.go      | 18 +++++++++++++++---
 internal/service/favorites_sync_test.go | 13 +++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/internal/service/favorites_sync.go b/internal/service/favorites_sync.go
index cc72d5d..4b6e446 100644
--- a/internal/service/favorites_sync.go
+++ b/internal/service/favorites_sync.go
@@ -35,16 +35,28 @@ func IsUserFavorite(ctx context.Context, repo *repository.Container, userID, med
 func setLocalFavorite(ctx context.Context, repo *repository.Container, userID, mediaID string, favorite bool) error {
 	if favorite {
 		var existing model.Favorite
-		err := repo.DB.WithContext(ctx).
+		// 收藏行的删除是软删除；重新收藏时必须连已软删除的行一起查出来，
+		// 否则会再次插入同一 (user_id, media_id)，撞上唯一索引后稳定返回
+		// 500，用户表现为“取消收藏后无法再收藏”。
+		err := repo.DB.WithContext(ctx).Unscoped().
 			Where("user_id = ? AND media_id = ?", userID, mediaID).
 			First(&existing).Error
-		if errors.Is(err, gorm.ErrRecordNotFound) {
+		switch {
+		case errors.Is(err, gorm.ErrRecordNotFound):
 			return repo.DB.WithContext(ctx).Create(&model.Favorite{
 				UserID:  userID,
 				MediaID: mediaID,
 			}).Error
+		case err != nil:
+			return err
+		case existing.DeletedAt.Valid:
+			return repo.DB.WithContext(ctx).Unscoped().
+				Model(&model.Favorite{}).
+				Where("id = ?", existing.ID).
+				Update("deleted_at", nil).Error
+		default:
+			return nil
 		}
-		return err
 	}
 	return repo.DB.WithContext(ctx).
 		Where("user_id = ? AND media_id = ?", userID, mediaID).
diff --git a/internal/service/favorites_sync_test.go b/internal/service/favorites_sync_test.go
index 0c7e85c..64366c1 100644
--- a/internal/service/favorites_sync_test.go
+++ b/internal/service/favorites_sync_test.go
@@ -44,6 +44,19 @@ func TestSyncUserFavoriteWritesLocalForRemoteID(t *testing.T) {
 	if favorite {
 		t.Fatal("expected remote favourite to be removed locally")
 	}
+
+	// 软删除后重新收藏必须恢复原行：唯一索引 (user_id, media_id) 不允许
+	// 再插入一条，旧的实现会在这里返回约束错误。
+	if err := SyncUserFavorite(context.Background(), repos, nil, userID, remoteMediaID, true); err != nil {
+		t.Fatalf("SyncUserFavorite re-favorite: %v", err)
+	}
+	favorite, err = IsUserFavorite(context.Background(), repos, userID, remoteMediaID)
+	if err != nil {
+		t.Fatalf("IsUserFavorite after re-favorite: %v", err)
+	}
+	if !favorite {
+		t.Fatal("expected re-favourite to restore the soft-deleted row")
+	}
 }
 
 func TestFavoriteItemsIncludesRemoteFavourites(t *testing.T) {