feat(fragment): 商品成本价 + 活动奖品单次产出数量

- products 表新增 cost_price 字段（成本价/分）
- activity_reward_settings 新增 drop_quantity（单次产出数量，默认1）
  和 cost_snapshot_cents（成本价快照）
- 奖品创建/修改时自动快照成本价，drop_quantity 限制 1-100
- 抽奖发放逻辑按 drop_quantity 循环创建多个库存项
- 抽奖结果接口按 drop_quantity 返回多条 item，前端自动合并显示
- 抽奖记录接口返回 drop_quantity 字段
- 商品管理 API 全链路支持 cost_price

internal/api/activity/draw_logs_app.go

@@ -32,6 +32,7 @@ type drawLogItem struct {
 	IsWinner     int32     `json:"is_winner"`
 	Level        int32     `json:"level"`
 	CurrentLevel int32     `json:"current_level"`
+	DropQuantity int32     `json:"drop_quantity"`
 	CreatedAt    time.Time `json:"created_at"`
 }
 
@@ -142,6 +143,7 @@ func (h *handler) ListDrawLogs() core.HandlerFunc {
 		// 批量查询奖品与商品信息
 		rewardNameMap := make(map[int64]string)
 		rewardImageMap := make(map[int64]string)
+		rewardDropQtyMap := make(map[int64]int32)
 		if len(rewardIDs) > 0 {
 			rewards, err := h.readDB.ActivityRewardSettings.WithContext(ctx.RequestContext()).ReadDB().Where(h.readDB.ActivityRewardSettings.ID.In(rewardIDs...)).Find()
 			if err == nil {
@@ -150,6 +152,7 @@ func (h *handler) ListDrawLogs() core.HandlerFunc {
 				rewardProductMap := make(map[int64]int64)
 
 				for _, r := range rewards {
+					rewardDropQtyMap[r.ID] = r.DropQuantity
 					// 不再使用 r.Name，只通过 ProductID 关联查询商品名称
 					if r.ProductID > 0 {
 						if _, ok := productSet[r.ProductID]; !ok {
@@ -208,6 +211,7 @@ func (h *handler) ListDrawLogs() core.HandlerFunc {
 				IsWinner:     v.IsWinner,
 				Level:        v.Level,
 				CurrentLevel: v.CurrentLevel,
+				DropQuantity: rewardDropQtyMap[v.RewardID],
 				CreatedAt:    v.CreatedAt,
 			}
 		}
@@ -257,7 +261,9 @@ func (h *handler) ListDrawLogsByLevel() core.HandlerFunc {
 		// 收集所有 ProductID 用于批量查询商品名称
 		productIDs := make([]int64, 0, len(rewards))
 		rewardProductMap := make(map[int64]int64) // rewardID -> productID
+		rewardDropQtyMap2 := make(map[int64]int32)
 		for _, r := range rewards {
+			rewardDropQtyMap2[r.ID] = r.DropQuantity
 			if r.ProductID > 0 {
 				productIDs = append(productIDs, r.ProductID)
 				rewardProductMap[r.ID] = r.ProductID
@@ -304,6 +310,7 @@ func (h *handler) ListDrawLogsByLevel() core.HandlerFunc {
 					IsWinner:     v.IsWinner,
 					Level:        v.Level,
 					CurrentLevel: v.CurrentLevel,
+					DropQuantity: rewardDropQtyMap2[v.RewardID],
 				}
 				groupsMap[v.Level] = append(groupsMap[v.Level], item)
 			}

internal/api/activity/lottery_result_order_app.go

@@ -159,7 +159,11 @@ func (h *handler) LotteryResultByOrder() core.HandlerFunc {
 			drawLogIDs = append(drawLogIDs, lg.ID)
 			image := ""
 			name := ""
+			dropQty := int32(1)
 			if rw, ok := rewardMap[lg.RewardID]; ok {
+				if rw.DropQuantity > 1 {
+					dropQty = rw.DropQuantity
+				}
 				if p, ok := productMap[rw.ProductID]; ok {
 					name = p.Name
 					if p.ImagesJSON != "" {
@@ -171,13 +175,15 @@ func (h *handler) LotteryResultByOrder() core.HandlerFunc {
 				}
 			}
 
-			items = append(items, orderResultItem{
+			for q := int32(0); q < dropQty; q++ {
-				RewardID:   lg.RewardID,
+				items = append(items, orderResultItem{
-				RewardName: name,
+					RewardID:   lg.RewardID,
-				Level:      lg.Level,
+					RewardName: name,
-				DrawIndex:  int32(lg.DrawIndex + 1),
+					Level:      lg.Level,
-				Image:      image,
+					DrawIndex:  int32(lg.DrawIndex + 1),
-			})
+					Image:      image,
+				})
+			}
 		}
 
 		// 处理翻倍奖励

internal/api/activity/rewards_app.go

@@ -24,6 +24,7 @@ type rewardItem struct {
 	IsBoss       int32  `json:"is_boss"`
 	ProductImage string `json:"product_image"`
 	MinScore     int64  `json:"min_score"`
+	DropQuantity int32  `json:"drop_quantity"`
 }
 
 type listRewardsResponse struct {
@@ -130,6 +131,7 @@ func (h *handler) ListIssueRewards() core.HandlerFunc {
 				IsBoss:       v.IsBoss,
 				ProductImage: imageMap[v.ProductID],
 				MinScore:     v.MinScore,
+				DropQuantity: v.DropQuantity,
 			}
 		}
 		ctx.Payload(res)

internal/api/admin/product_create.go

@@ -15,6 +15,7 @@ type createProductRequest struct {
 	CategoryID    int64  `json:"category_id" binding:"required"`
 	ImagesJSON    string `json:"images_json"`
 	Price         int64  `json:"price" binding:"required"`
+	CostPrice     int64  `json:"cost_price"`
 	Stock         int64  `json:"stock" binding:"required"`
 	Status        int32  `json:"status"`
 	Description   string `json:"description"`
@@ -48,7 +49,7 @@ func (h *handler) CreateProduct() core.HandlerFunc {
 			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.CreateAdminError, "禁止操作"))
 			return
 		}
-		item, err := h.product.CreateProduct(ctx.RequestContext(), prodsvc.CreateProductInput{Name: req.Name, CategoryID: req.CategoryID, ImagesJSON: req.ImagesJSON, Price: req.Price, Stock: req.Stock, Status: req.Status, Description: req.Description, ShowInMiniapp: req.ShowInMiniapp})
+		item, err := h.product.CreateProduct(ctx.RequestContext(), prodsvc.CreateProductInput{Name: req.Name, CategoryID: req.CategoryID, ImagesJSON: req.ImagesJSON, Price: req.Price, CostPrice: req.CostPrice, Stock: req.Stock, Status: req.Status, Description: req.Description, ShowInMiniapp: req.ShowInMiniapp})
 		if err != nil {
 			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.CreateAdminError, err.Error()))
 			return
@@ -64,6 +65,7 @@ type modifyProductRequest struct {
 	CategoryID    *int64  `json:"category_id"`
 	ImagesJSON    *string `json:"images_json"`
 	Price         *int64  `json:"price"`
+	CostPrice     *int64  `json:"cost_price"`
 	Stock         *int64  `json:"stock"`
 	Status        *int32  `json:"status"`
 	Description   *string `json:"description"`
@@ -94,7 +96,7 @@ func (h *handler) ModifyProduct() core.HandlerFunc {
 			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.CreateAdminError, "禁止操作"))
 			return
 		}
-		if err := h.product.ModifyProduct(ctx.RequestContext(), id, prodsvc.ModifyProductInput{Name: req.Name, CategoryID: req.CategoryID, ImagesJSON: req.ImagesJSON, Price: req.Price, Stock: req.Stock, Status: req.Status, Description: req.Description, ShowInMiniapp: req.ShowInMiniapp}); err != nil {
+		if err := h.product.ModifyProduct(ctx.RequestContext(), id, prodsvc.ModifyProductInput{Name: req.Name, CategoryID: req.CategoryID, ImagesJSON: req.ImagesJSON, Price: req.Price, CostPrice: req.CostPrice, Stock: req.Stock, Status: req.Status, Description: req.Description, ShowInMiniapp: req.ShowInMiniapp}); err != nil {
 			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.CreateAdminError, err.Error()))
 			return
 		}
@@ -143,6 +145,7 @@ type productItem struct {
 	CategoryID    int64  `json:"category_id"`
 	ImagesJSON    string `json:"images_json"`
 	Price         int64  `json:"price"`
+	CostPrice     int64  `json:"cost_price"`
 	Stock         int64  `json:"stock"`
 	Sales         int64  `json:"sales"`
 	Status        int32  `json:"status"`
@@ -188,7 +191,7 @@ func (h *handler) ListProducts() core.HandlerFunc {
 		res.Total = total
 		res.List = make([]productItem, len(items))
 		for i, it := range items {
-			res.List[i] = productItem{ID: it.ID, Name: it.Name, CategoryID: it.CategoryID, ImagesJSON: it.ImagesJSON, Price: it.Price, Stock: it.Stock, Sales: it.Sales, Status: it.Status, Description: it.Description, ShowInMiniapp: it.ShowInMiniapp}
+			res.List[i] = productItem{ID: it.ID, Name: it.Name, CategoryID: it.CategoryID, ImagesJSON: it.ImagesJSON, Price: it.Price, CostPrice: it.CostPrice, Stock: it.Stock, Sales: it.Sales, Status: it.Status, Description: it.Description, ShowInMiniapp: it.ShowInMiniapp}
 		}
 		ctx.Payload(res)
 	}

internal/api/admin/rewards_admin.go

@@ -21,11 +21,13 @@ type rewardItem struct {
 	Sort                 int32   `json:"sort"`
 	IsBoss               int32   `json:"is_boss"`
 	MinScore             int64   `json:"min_score"`
+	DropQuantity         int32   `json:"drop_quantity"`
 	ProductName          string  `json:"product_name"`
 	ProductImageUrl      string  `json:"product_image_url"`
 	ProductPrice         float64 `json:"product_price"` // 兼容：返回配置快照价
 	ProductPriceSnapshot float64 `json:"product_price_snapshot"`
 	ProductPriceCurrent  float64 `json:"product_price_current"`
+	CostSnapshotCents    int64   `json:"cost_snapshot_cents"`
 }
 
 type createRewardsRequest struct {
@@ -73,15 +75,16 @@ func (h *handler) CreateIssueRewards() core.HandlerFunc {
 		var rewards []activitysvc.CreateRewardInput
 		for _, r := range req.Rewards {
 			rewards = append(rewards, activitysvc.CreateRewardInput{
-				ProductID:   r.ProductID,
+				ProductID:    r.ProductID,
-				Name:        "", // Name 不再从前端传递，后续可从商品表获取
+				Name:         "", // Name 不再从前端传递，后续可从商品表获取
-				Weight:      int32(r.Weight),
+				Weight:       int32(r.Weight),
-				Quantity:    r.Quantity,
+				Quantity:     r.Quantity,
-				OriginalQty: r.OriginalQty,
+				OriginalQty:  r.OriginalQty,
-				Level:       r.Level,
+				Level:        r.Level,
-				Sort:        r.Sort,
+				Sort:         r.Sort,
-				IsBoss:      r.IsBoss,
+				IsBoss:       r.IsBoss,
-				MinScore:    r.MinScore,
+				MinScore:     r.MinScore,
+				DropQuantity: r.DropQuantity,
 			})
 		}
 
@@ -138,15 +141,17 @@ func (h *handler) ListIssueRewards() core.HandlerFunc {
 		res.List = make([]rewardItem, len(items))
 		for i, v := range items {
 			it := rewardItem{
-				ID:          v.ID,
+				ID:                v.ID,
-				ProductID:   v.ProductID,
+				ProductID:         v.ProductID,
-				Weight:      float64(v.Weight),
+				Weight:            float64(v.Weight),
-				Quantity:    v.Quantity,
+				Quantity:          v.Quantity,
-				OriginalQty: v.OriginalQty,
+				OriginalQty:       v.OriginalQty,
-				Level:       v.Level,
+				Level:             v.Level,
-				Sort:        v.Sort,
+				Sort:              v.Sort,
-				IsBoss:      v.IsBoss,
+				IsBoss:            v.IsBoss,
-				MinScore:    v.MinScore,
+				MinScore:          v.MinScore,
+				DropQuantity:      v.DropQuantity,
+				CostSnapshotCents: v.CostSnapshotCents,
 			}
 
 			if v.ProductID > 0 {
@@ -165,14 +170,15 @@ func (h *handler) ListIssueRewards() core.HandlerFunc {
 }
 
 type modifyRewardRequest struct {
-	ProductID   *int64   `json:"product_id"`
+	ProductID    *int64   `json:"product_id"`
-	Weight      *float64 `json:"weight"`
+	Weight       *float64 `json:"weight"`
-	Quantity    *int64   `json:"quantity"`
+	Quantity     *int64   `json:"quantity"`
-	OriginalQty *int64   `json:"original_qty"`
+	OriginalQty  *int64   `json:"original_qty"`
-	Level       *int32   `json:"level"`
+	Level        *int32   `json:"level"`
-	Sort        *int32   `json:"sort"`
+	Sort         *int32   `json:"sort"`
-	IsBoss      *int32   `json:"is_boss"`
+	IsBoss       *int32   `json:"is_boss"`
-	MinScore    *int64   `json:"min_score"`
+	MinScore     *int64   `json:"min_score"`
+	DropQuantity *int32   `json:"drop_quantity"`
 }
 
 // ModifyIssueReward 更新期数奖励
@@ -206,15 +212,16 @@ func (h *handler) ModifyIssueReward() core.HandlerFunc {
 			return
 		}
 		in := activitysvc.ModifyRewardInput{
-			ProductID:   req.ProductID,
+			ProductID:    req.ProductID,
-			Name:        "", // Name 不再使用
+			Name:         "", // Name 不再使用
-			Weight:      req.Weight,
+			Weight:       req.Weight,
-			Quantity:    req.Quantity,
+			Quantity:     req.Quantity,
-			OriginalQty: req.OriginalQty,
+			OriginalQty:  req.OriginalQty,
-			Level:       req.Level,
+			Level:        req.Level,
-			Sort:        req.Sort,
+			Sort:         req.Sort,
-			IsBoss:      req.IsBoss,
+			IsBoss:       req.IsBoss,
-			MinScore:    req.MinScore,
+			MinScore:     req.MinScore,
+			DropQuantity: req.DropQuantity,
 		}
 		if err := h.activity.ModifyIssueReward(ctx.RequestContext(), rewardID, in); err != nil {
 			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.CreateIssueRewardsError, err.Error()))

internal/repository/mysql/model/activity_reward_settings.gen.go

@@ -28,7 +28,9 @@ type ActivityRewardSettings struct {
 	Sort               int32          `gorm:"column:sort;comment:排序" json:"sort"`                                                      // 排序
 	IsBoss             int32          `gorm:"column:is_boss;comment:Boss 1 是 0 不是" json:"is_boss"`                                     // Boss 1 是 0 不是
 	DeletedAt          gorm.DeletedAt `gorm:"column:deleted_at" json:"deleted_at"`
-	MinScore           int64          `gorm:"column:min_score;not null;comment:最低得分/碰数要求" json:"min_score"` // 最低得分/碰数要求
+	MinScore           int64          `gorm:"column:min_score;not null;comment:最低得分/碰数要求" json:"min_score"`                              // 最低得分/碰数要求
+	DropQuantity       int32          `gorm:"column:drop_quantity;not null;default:1;comment:单次抽中产出数量" json:"drop_quantity"`                // 单次抽中产出数量
+	CostSnapshotCents  int64          `gorm:"column:cost_snapshot_cents;not null;default:0;comment:奖品配置时成本价快照（分）" json:"cost_snapshot_cents"` // 奖品配置时成本价快照（分）
 }
 
 // TableName ActivityRewardSettings's table name

internal/repository/mysql/model/products.gen.go

@@ -21,6 +21,7 @@ type Products struct {
 	CategoryID    int64          `gorm:"column:category_id;comment:单一主分类ID（product_categories.id）" json:"category_id"`           // 单一主分类ID（product_categories.id）
 	ImagesJSON    string         `gorm:"column:images_json;comment:商品图片JSON（数组）" json:"images_json"`                             // 商品图片JSON（数组）
 	Price         int64          `gorm:"column:price;not null;comment:商品售价（分）" json:"price"`                                     // 商品售价（分）
+	CostPrice     int64          `gorm:"column:cost_price;not null;default:0;comment:成本价（分）" json:"cost_price"`                   // 成本价（分）
 	Stock         int64          `gorm:"column:stock;not null;comment:可售库存" json:"stock"`                                        // 可售库存
 	Sales         int64          `gorm:"column:sales;not null;comment:已售数量" json:"sales"`                                        // 已售数量
 	Status        int32          `gorm:"column:status;not null;default:1;comment:上下架状态：1上架 2下架" json:"status"`                   // 上下架状态：1上架 2下架

internal/service/activity/activity.go

@@ -232,6 +232,8 @@ type CreateRewardInput struct {
 	// IsBoss 是否Boss奖励
 	IsBoss   int32
 	MinScore int64
+	// DropQuantity 单次抽中产出数量（默认1）
+	DropQuantity int32
 }
 
 type ModifyRewardInput struct {
@@ -252,4 +254,6 @@ type ModifyRewardInput struct {
 	// IsBoss 是否Boss奖励
 	IsBoss   *int32
 	MinScore *int64
+	// DropQuantity 单次抽中产出数量
+	DropQuantity *int32
 }

internal/service/activity/lottery_process.go

@@ -168,8 +168,20 @@ func (s *service) ProcessOrderLottery(ctx context.Context, orderID int64) error
 	var effectLogs []*model.ActivityDrawLogs // 需要处理道具卡效果的日志
 
 	// 无限赏模式下使用总数检测（因为inventory.RewardID=0）
-	// 如果已发放总数已达到开奖数量，说明已完成发放，跳过后续逻辑
+	// 计算期望发放总数（考虑 drop_quantity）
-	if invTotalCount >= dc {
+	expectedTotal := int64(0)
+	for _, lg := range existingLogs {
+		if rw, ok := rewardMap[lg.RewardID]; ok {
+			dq := int64(rw.DropQuantity)
+			if dq < 1 {
+				dq = 1
+			}
+			expectedTotal += dq
+		} else {
+			expectedTotal++
+		}
+	}
+	if invTotalCount >= expectedTotal && expectedTotal > 0 {
 		// s.logger.Info("奖励已全部发放，跳过重复发放", zap.Int64("order_id", orderID), zap.Int64("dc", dc), zap.Int64("invTotalCount", invTotalCount))
 	} else {
 		for i := int64(0); i < dc; i++ {
@@ -178,19 +190,29 @@ func (s *service) ProcessOrderLottery(ctx context.Context, orderID int64) error
 				continue
 			}
 
-			// 统计该 RewardID 应得数量
+			rw := rewardMap[log.RewardID]
-			needed := int64(0)
+			if rw == nil {
+				continue
+			}
+
+			dropQty := int64(rw.DropQuantity)
+			if dropQty < 1 {
+				dropQty = 1
+			}
+
+			// 统计该 RewardID 应得库存数量（命中次数 × 单次产出数量）
+			hitCount := int64(0)
 			for j := int64(0); j <= i; j++ {
 				if l, ok := logMap[j]; ok && l.RewardID == log.RewardID {
-					needed++
+					hitCount++
 				}
 			}
+			needed := hitCount * dropQty
 
 			// 检查是否需要发放
 			if invCountMap[log.RewardID] < needed {
-				rw := rewardMap[log.RewardID]
+				rewardIDRef := &log.RewardID
-				if rw != nil {
+				for q := int64(0); q < dropQty; q++ {
-					rewardIDRef := &log.RewardID
 					batchItems = append(batchItems, usersvc.BatchRewardItem{
 						ProductID:         rw.ProductID,
 						RewardID:          rewardIDRef,
@@ -198,12 +220,12 @@ func (s *service) ProcessOrderLottery(ctx context.Context, orderID int64) error
 						ActivityID:        aid,
 						Remark:            productNameMap[rw.ProductID],
 					})
-					invCountMap[log.RewardID]++ // 内存计数同步
+				}
+				invCountMap[log.RewardID] += dropQty // 内存计数同步
 
-					// 记录需要处理道具卡效果的日志
+				// 记录需要处理道具卡效果的日志
-					if act != nil && act.AllowItemCards && icID > 0 {
+				if act != nil && act.AllowItemCards && icID > 0 {
-						effectLogs = append(effectLogs, log)
+					effectLogs = append(effectLogs, log)
-					}
 				}
 			}
 		}

internal/service/activity/rewards_create.go

@@ -20,6 +20,7 @@ func (s *service) CreateIssueRewards(ctx context.Context, issueID int64, rewards
 			}
 		}
 		productPriceMap := make(map[int64]int64)
+		productCostMap := make(map[int64]int64)
 		if len(productIDs) > 0 {
 			ids := make([]int64, 0, len(productIDs))
 			for id := range productIDs {
@@ -31,15 +32,25 @@ func (s *service) CreateIssueRewards(ctx context.Context, issueID int64, rewards
 			}
 			for _, p := range products {
 				productPriceMap[p.ID] = p.Price
+				productCostMap[p.ID] = p.CostPrice
 			}
 		}
 
 		for _, r := range rewards {
+			dropQty := r.DropQuantity
+			if dropQty < 1 {
+				dropQty = 1
+			}
+			if dropQty > 100 {
+				dropQty = 100
+			}
 			item := &model.ActivityRewardSettings{
 				IssueID:            issueID,
 				ProductID:          r.ProductID,
 				PriceSnapshotCents: productPriceMap[r.ProductID],
 				PriceSnapshotAt:    time.Now(),
+				CostSnapshotCents:  productCostMap[r.ProductID],
+				DropQuantity:       dropQty,
 				Weight:             r.Weight,
 				Quantity:           r.Quantity,
 				OriginalQty:        r.OriginalQty,

internal/service/activity/rewards_modify.go

@@ -18,14 +18,17 @@ func (s *service) ModifyIssueReward(ctx context.Context, rewardID int64, in Modi
 	if in.ProductID != nil {
 		item.ProductID = *in.ProductID
 		priceSnapshot := int64(0)
+		costSnapshot := int64(0)
 		if *in.ProductID > 0 {
 			product, err := s.readDB.Products.WithContext(ctx).Where(s.readDB.Products.ID.Eq(*in.ProductID)).First()
 			if err != nil {
 				return err
 			}
 			priceSnapshot = product.Price
+			costSnapshot = product.CostPrice
 		}
 		item.PriceSnapshotCents = priceSnapshot
+		item.CostSnapshotCents = costSnapshot
 		item.PriceSnapshotAt = time.Now()
 	}
 	if in.Weight != nil {
@@ -49,6 +52,16 @@ func (s *service) ModifyIssueReward(ctx context.Context, rewardID int64, in Modi
 	if in.MinScore != nil {
 		item.MinScore = *in.MinScore
 	}
+	if in.DropQuantity != nil {
+		dq := *in.DropQuantity
+		if dq < 1 {
+			dq = 1
+		}
+		if dq > 100 {
+			dq = 100
+		}
+		item.DropQuantity = dq
+	}
 	item.UpdatedAt = time.Now()
 	return s.writeDB.ActivityRewardSettings.WithContext(ctx).Save(item)
 }

internal/service/product/product.go

@@ -128,6 +128,7 @@ type CreateProductInput struct {
 	CategoryID    int64
 	ImagesJSON    string
 	Price         int64
+	CostPrice     int64
 	Stock         int64
 	Status        int32
 	Description   string
@@ -139,6 +140,7 @@ type ModifyProductInput struct {
 	CategoryID    *int64
 	ImagesJSON    *string
 	Price         *int64
+	CostPrice     *int64
 	Stock         *int64
 	Status        *int32
 	Description   *string
@@ -192,7 +194,7 @@ func (s *service) CreateProduct(ctx context.Context, in CreateProductInput) (*mo
 	if in.ShowInMiniapp != nil {
 		showInMiniapp = *in.ShowInMiniapp
 	}
-	m := &model.Products{Name: in.Name, CategoryID: in.CategoryID, ImagesJSON: normalizeJSON(in.ImagesJSON), Price: in.Price, Stock: in.Stock, Status: in.Status, Description: in.Description, ShowInMiniapp: showInMiniapp}
+	m := &model.Products{Name: in.Name, CategoryID: in.CategoryID, ImagesJSON: normalizeJSON(in.ImagesJSON), Price: in.Price, CostPrice: in.CostPrice, Stock: in.Stock, Status: in.Status, Description: in.Description, ShowInMiniapp: showInMiniapp}
 	if err := s.writeDB.Products.WithContext(ctx).Create(m); err != nil {
 		return nil, err
 	}
@@ -214,6 +216,9 @@ func (s *service) ModifyProduct(ctx context.Context, id int64, in ModifyProductI
 	if in.Price != nil {
 		set["price"] = *in.Price
 	}
+	if in.CostPrice != nil {
+		set["cost_price"] = *in.CostPrice
+	}
 	if in.Stock != nil {
 		set["stock"] = *in.Stock
 	}

migrations/20260323_fragment_cost_and_drop_qty.sql

@@ -0,0 +1,8 @@
+-- 1. products 表新增成本价
+ALTER TABLE products
+  ADD COLUMN cost_price BIGINT NOT NULL DEFAULT 0 COMMENT '成本价（分）';
+
+-- 2. activity_reward_settings 新增单次产出数量 + 成本价快照
+ALTER TABLE activity_reward_settings
+  ADD COLUMN drop_quantity INT NOT NULL DEFAULT 1 COMMENT '单次抽中产出数量',
+  ADD COLUMN cost_snapshot_cents BIGINT NOT NULL DEFAULT 0 COMMENT '奖品配置时成本价快照（分）';