feat: 支持批量合成并收口不包邮运费规则

本次提交同时完成碎片批量合成与盒柜发货运费规则改造，减少用户重复操作，并确保不包邮商品在任何件数下都必须支付运费。

- 合成功能：新增批量合成接口与前端一键合成入口，按配方可合成上限批量消耗碎片并生成对应资产，同时补充批量合成测试
- 运费规则：后端新增统一运费判定逻辑，命中 category_id 14/15 的商品时整单强制收取运费，否则继续沿用少于 5 件收运费的旧规则
- 发货流程：新增运费检查接口，前端发货前先向后端确认是否需要支付运费，并根据“件数不足”或“包含不包邮商品”展示不同提示文案
- 接口校验：运费预下单与批量申请发货统一复用后端判定逻辑，避免前端规则被绕过

internal/api/user/request_shipping_batch_app.go

@@ -46,8 +46,13 @@ func (h *handler) RequestShippingBatch() core.HandlerFunc {
 		}
 		userID := int64(ctx.SessionUserInfo().Id)
 
-		// 运费校验：不满 5 件须已支付运费订单
-		if len(req.InventoryIDs) < shippingFeeThreshold {
+		needFee, reason, err := h.user.CheckShippingFeeRequirement(ctx.RequestContext(), userID, req.InventoryIDs)
+		if err != nil {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, 150004, err.Error()))
+			return
+		}
+
+		if needFee {
 			paid, _ := h.readDB.Orders.WithContext(ctx.RequestContext()).
 				Where(
 					h.readDB.Orders.UserID.Eq(userID),
@@ -55,7 +60,13 @@ func (h *handler) RequestShippingBatch() core.HandlerFunc {
 					h.readDB.Orders.Status.Eq(2),
 				).Count()
 			if paid == 0 {
-				ctx.AbortWithError(core.Error(http.StatusBadRequest, 150003, "不满5件需先支付运费"))
+				msg := "需先支付运费"
+				if reason == shippingFeeReasonContainsNonFreeShipping {
+					msg = "所选商品包含不包邮商品，需先支付运费"
+				} else if reason == shippingFeeReasonBelowThreshold {
+					msg = "不满5件需先支付运费"
+				}
+				ctx.AbortWithError(core.Error(http.StatusBadRequest, 150003, msg))
 				return
 			}
 		}

internal/api/user/shipping_fee_preorder_app.go

@@ -13,9 +13,11 @@ import (
 )
 
 const (
-	shippingFeeThreshold  = 5        // 低于此件数收运费
-	shippingFeeCents      = 1000     // 运费金额（分），10 元
-	shippingFeeSourceType = int32(5) // orders.source_type: 5 = 运费订单
+	shippingFeeThreshold                    = 5
+	shippingFeeCents                        = 1000     // 运费金额（分），10 元
+	shippingFeeSourceType                   = int32(5) // orders.source_type: 5 = 运费订单
+	shippingFeeReasonBelowThreshold          = "below_threshold"
+	shippingFeeReasonContainsNonFreeShipping = "contains_non_free_shipping_item"
 )
 
 type shippingFeePreorderRequest struct {
@@ -26,9 +28,40 @@ type shippingFeePreorderResponse struct {
 	OrderNo string `json:"order_no"`
 }
 
+type shippingFeeCheckResponse struct {
+	NeedFee  bool   `json:"need_fee"`
+	Reason   string `json:"reason,omitempty"`
+	FeeCents int64  `json:"fee_cents"`
+}
+
+func (h *handler) ShippingFeeCheck() core.HandlerFunc {
+	return func(ctx core.Context) {
+		req := new(shippingFeePreorderRequest)
+		rsp := &shippingFeeCheckResponse{FeeCents: shippingFeeCents}
+		if err := ctx.ShouldBindJSON(req); err != nil {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.ParamBindError, validation.Error(err)))
+			return
+		}
+		if len(req.InventoryIDs) == 0 {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.ParamBindError, "inventory_ids 不能为空"))
+			return
+		}
+
+		userID := int64(ctx.SessionUserInfo().Id)
+		needFee, reason, err := h.user.CheckShippingFeeRequirement(ctx.RequestContext(), userID, req.InventoryIDs)
+		if err != nil {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, 150002, err.Error()))
+			return
+		}
+		rsp.NeedFee = needFee
+		rsp.Reason = reason
+		ctx.Payload(rsp)
+	}
+}
+
 // ShippingFeePreorder 创建运费订单
 // @Summary 创建运费订单
-// @Description 选中件数不满 5 件时，创建 10 元运费订单并返回 order_no；前端再调用 /pay/wechat/jsapi/preorder 发起支付；满 5 件包邮无需调用
+// @Description 选中商品命中运费规则时，创建 10 元运费订单并返回 order_no；前端再调用 /pay/wechat/jsapi/preorder 发起支付；无需运费时不应调用
 // @Tags APP端.用户
 // @Accept json
 // @Produce json
@@ -50,12 +83,17 @@ func (h *handler) ShippingFeePreorder() core.HandlerFunc {
 			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.ParamBindError, "inventory_ids 不能为空"))
 			return
 		}
-		if len(req.InventoryIDs) >= shippingFeeThreshold {
-			ctx.AbortWithError(core.Error(http.StatusBadRequest, 150001, fmt.Sprintf("件数满 %d 件，无需支付运费", shippingFeeThreshold)))
-			return
-		}
 
 		userID := int64(ctx.SessionUserInfo().Id)
+		needFee, _, err := h.user.CheckShippingFeeRequirement(ctx.RequestContext(), userID, req.InventoryIDs)
+		if err != nil {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, 150002, err.Error()))
+			return
+		}
+		if !needFee {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, 150001, fmt.Sprintf("件数满 %d 件且均非不包邮分类商品，无需支付运费", shippingFeeThreshold)))
+			return
+		}
 
 		remarkBytes, _ := json.Marshal(req.InventoryIDs)
 

internal/api/user/synthesis_app.go

@@ -45,6 +45,23 @@ func (h *handler) DoSynthesis() core.HandlerFunc {
 	}
 }
 
+func (h *handler) DoBatchSynthesis() core.HandlerFunc {
+	return func(ctx core.Context) {
+		req := new(synthesizeRequest)
+		if err := ctx.ShouldBindJSON(req); err != nil || req.RecipeID <= 0 {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.ParamBindError, "invalid recipe_id"))
+			return
+		}
+		userID := int64(ctx.SessionUserInfo().Id)
+		result, err := h.synthesis.BatchSynthesize(ctx.RequestContext(), userID, req.RecipeID)
+		if err != nil {
+			ctx.AbortWithError(core.Error(http.StatusBadRequest, code.ServerError, err.Error()))
+			return
+		}
+		ctx.Payload(result)
+	}
+}
+
 func (h *handler) ListSynthesisLogsForUser() core.HandlerFunc {
 	return func(ctx core.Context) {
 		userID := int64(ctx.SessionUserInfo().Id)

internal/router/router.go

@@ -538,6 +538,7 @@ func NewHTTPMux(logger logger.CustomLogger, db mysql.Repo) (core.Mux, func(), er
 			lotteryGroup.POST("/users/:user_id/points/redeem-item-card", userHandler.RedeemPointsToItemCard())
 
 			// 资产操作（发货/回收）
+			lotteryGroup.POST("/users/:user_id/inventory/shipping-fee/check", userHandler.ShippingFeeCheck())
 			lotteryGroup.POST("/users/:user_id/inventory/shipping-fee/preorder", userHandler.ShippingFeePreorder())
 			lotteryGroup.POST("/users/:user_id/inventory/request-shipping", userHandler.RequestShippingBatch())
 			lotteryGroup.POST("/users/:user_id/inventory/cancel-shipping", userHandler.CancelShipping())
@@ -547,6 +548,7 @@ func NewHTTPMux(logger logger.CustomLogger, db mysql.Repo) (core.Mux, func(), er
 		// 碎片合成
 		appAuthApiRouter.GET("/users/:user_id/synthesis/recipes", userHandler.ListSynthesisRecipesForUser())
 		appAuthApiRouter.POST("/users/:user_id/synthesis/do", userHandler.DoSynthesis())
+		appAuthApiRouter.POST("/users/:user_id/synthesis/do-batch", userHandler.DoBatchSynthesis())
 		appAuthApiRouter.GET("/users/:user_id/synthesis/logs", userHandler.ListSynthesisLogsForUser())
 
 		// 对对碰其他接口（不需要严查黑名单，或者已在preorder查过）

internal/service/synthesis/synthesis.go

@@ -10,6 +10,7 @@ import (
 	"bindbox-game/internal/repository/mysql/model"
 
 	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
 )
 
 type Service interface {
@@ -20,6 +21,7 @@ type Service interface {
 	DeleteRecipe(ctx context.Context, id int64) error
 	GetAvailableRecipesForUser(ctx context.Context, userID int64) ([]*UserRecipeView, error)
 	Synthesize(ctx context.Context, userID int64, recipeID int64) (*model.UserInventory, error)
+	BatchSynthesize(ctx context.Context, userID int64, recipeID int64) (*BatchSynthesizeResult, error)
 	ListLogs(ctx context.Context, page, size int, userID *int64) (list []*SynthesisLogView, total int64, err error)
 }
 
@@ -51,12 +53,22 @@ type UserMaterialView struct {
 }
 
 type UserRecipeView struct {
-	ID              int64              `json:"id"`
-	Name            string             `json:"name"`
-	Description     string             `json:"description"`
-	TargetProduct   *model.Products    `json:"target_product"`
-	CanSynthesize   bool               `json:"can_synthesize"`
-	Materials       []UserMaterialView `json:"materials"`
+	ID                 int64              `json:"id"`
+	Name               string             `json:"name"`
+	Description        string             `json:"description"`
+	TargetProduct      *model.Products    `json:"target_product"`
+	CanSynthesize      bool               `json:"can_synthesize"`
+	MaxSynthesizeCount int64              `json:"max_synthesize_count"`
+	Materials          []UserMaterialView `json:"materials"`
+}
+
+type BatchSynthesizeResult struct {
+	RecipeID               int64   `json:"recipe_id"`
+	TargetProductID        int64   `json:"target_product_id"`
+	TargetProductName      string  `json:"target_product_name"`
+	SynthesizedCount       int64   `json:"synthesized_count"`
+	ProducedInventoryIDs   []int64 `json:"produced_inventory_ids"`
+	ConsumedInventoryCount int     `json:"consumed_inventory_count"`
 }
 
 type SynthesisLogView struct {
@@ -241,10 +253,11 @@ func (s *service) GetAvailableRecipesForUser(ctx context.Context, userID int64)
 			Name:          r.Name,
 			Description:   r.Description,
 			TargetProduct: &targetProduct,
-			CanSynthesize: true,
 			Materials:     make([]UserMaterialView, 0, len(materials)),
 		}
 
+		maxSynthesizeCount := int64(0)
+		initialized := false
 		for _, m := range materials {
 			var p model.Products
 			db.WithContext(ctx).Where("id = ?", m.FragmentProductID).First(&p)
@@ -254,9 +267,15 @@ func (s *service) GetAvailableRecipesForUser(ctx context.Context, userID int64)
 				Where("user_id = ? AND product_id = ? AND status = 1", userID, m.FragmentProductID).
 				Count(&ownedCount)
 
-			if ownedCount < int64(m.RequiredCount) {
-				view.CanSynthesize = false
+			currentCount := int64(0)
+			if m.RequiredCount > 0 {
+				currentCount = ownedCount / int64(m.RequiredCount)
 			}
+			if !initialized || currentCount < maxSynthesizeCount {
+				maxSynthesizeCount = currentCount
+				initialized = true
+			}
+
 			image := ""
 			if p.ImagesJSON != "" {
 				var imgs []string
@@ -272,12 +291,34 @@ func (s *service) GetAvailableRecipesForUser(ctx context.Context, userID int64)
 				OwnedCount:        ownedCount,
 			})
 		}
+		view.MaxSynthesizeCount = maxSynthesizeCount
+		view.CanSynthesize = maxSynthesizeCount > 0
 		result = append(result, view)
 	}
 	return result, nil
 }
 
 func (s *service) Synthesize(ctx context.Context, userID int64, recipeID int64) (*model.UserInventory, error) {
+	result, err := s.batchSynthesize(ctx, userID, recipeID, 1)
+	if err != nil {
+		return nil, err
+	}
+	if len(result.ProducedInventoryIDs) == 0 {
+		return nil, fmt.Errorf("synthesis_failed")
+	}
+
+	var newInv model.UserInventory
+	if err := s.repo.GetDbR().WithContext(ctx).Where("id = ?", result.ProducedInventoryIDs[0]).First(&newInv).Error; err != nil {
+		return nil, err
+	}
+	return &newInv, nil
+}
+
+func (s *service) BatchSynthesize(ctx context.Context, userID int64, recipeID int64) (*BatchSynthesizeResult, error) {
+	return s.batchSynthesize(ctx, userID, recipeID, 0)
+}
+
+func (s *service) batchSynthesize(ctx context.Context, userID int64, recipeID int64, limitTimes int64) (*BatchSynthesizeResult, error) {
 	db := s.repo.GetDbR()
 
 	var recipe model.FragmentSynthesisRecipes
@@ -302,16 +343,42 @@ func (s *service) Synthesize(ctx context.Context, userID int64, recipeID int64)
 		InventoryIDs []int64
 	}
 	toConsume := make([]materialConsume, 0, len(materials))
+	maxTimes := int64(0)
+	initialized := false
 
 	for _, m := range materials {
+		var ownedCount int64
+		db.WithContext(ctx).Model(&model.UserInventory{}).
+			Where("user_id = ? AND product_id = ? AND status = 1", userID, m.FragmentProductID).
+			Count(&ownedCount)
+
+		currentTimes := int64(0)
+		if m.RequiredCount > 0 {
+			currentTimes = ownedCount / int64(m.RequiredCount)
+		}
+		if !initialized || currentTimes < maxTimes {
+			maxTimes = currentTimes
+			initialized = true
+		}
+	}
+
+	if limitTimes > 0 && maxTimes > limitTimes {
+		maxTimes = limitTimes
+	}
+	if maxTimes <= 0 {
+		return nil, fmt.Errorf("insufficient_fragments")
+	}
+
+	for _, m := range materials {
+		requiredTotal := int(m.RequiredCount) * int(maxTimes)
 		var invList []*model.UserInventory
 		db.WithContext(ctx).
 			Where("user_id = ? AND product_id = ? AND status = 1", userID, m.FragmentProductID).
 			Order("id ASC").
-			Limit(int(m.RequiredCount)).
+			Limit(requiredTotal).
 			Find(&invList)
 
-		if int32(len(invList)) < m.RequiredCount {
+		if len(invList) < requiredTotal {
 			return nil, fmt.Errorf("insufficient_fragments")
 		}
 		ids := make([]int64, len(invList))
@@ -325,52 +392,84 @@ func (s *service) Synthesize(ctx context.Context, userID int64, recipeID int64)
 		})
 	}
 
-	var newInv model.UserInventory
+	result := &BatchSynthesizeResult{
+		RecipeID:          recipeID,
+		TargetProductID:   recipe.TargetProductID,
+		TargetProductName: targetProduct.Name,
+		SynthesizedCount:  maxTimes,
+	}
+
 	wdb := s.repo.GetDbW()
 	err := wdb.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
-		allConsumedIDs := make([]int64, 0)
+		consumedByRound := make([][]int64, int(maxTimes))
+		allConsumedCount := 0
+
 		for _, mc := range toConsume {
 			var locked []model.UserInventory
-			if err := tx.Raw("SELECT * FROM user_inventory WHERE id IN ? AND user_id = ? AND status = 1 FOR UPDATE", mc.InventoryIDs, userID).Scan(&locked).Error; err != nil {
+			query := tx.WithContext(ctx).Where("id IN ? AND user_id = ? AND status = 1", mc.InventoryIDs, userID)
+			if tx.Dialector.Name() != "sqlite" {
+				query = query.Clauses(clause.Locking{Strength: "UPDATE"})
+			}
+			if err := query.Find(&locked).Error; err != nil {
 				return err
 			}
-			if int32(len(locked)) < mc.Required {
+			if len(locked) < len(mc.InventoryIDs) {
 				return fmt.Errorf("insufficient_fragments")
 			}
-			if err := tx.Exec(
-				"UPDATE user_inventory SET status = 2, updated_at = NOW(3), remark = CONCAT(IFNULL(remark,''), '|synthesis_consumed:recipe_', ?) WHERE id IN ? AND user_id = ? AND status = 1",
-				recipeID, mc.InventoryIDs, userID,
-			).Error; err != nil {
+			updates := map[string]interface{}{
+				"status":     2,
+				"updated_at": time.Now(),
+			}
+			if tx.Dialector.Name() == "sqlite" {
+				updates["remark"] = gorm.Expr("COALESCE(remark, '') || ?", fmt.Sprintf("|synthesis_consumed:recipe_%d", recipeID))
+			} else {
+				updates["remark"] = gorm.Expr("CONCAT(IFNULL(remark,''), ?)", fmt.Sprintf("|synthesis_consumed:recipe_%d", recipeID))
+			}
+			if err := tx.Model(&model.UserInventory{}).
+				Where("id IN ? AND user_id = ? AND status = 1", mc.InventoryIDs, userID).
+				Updates(updates).Error; err != nil {
 				return err
 			}
-			allConsumedIDs = append(allConsumedIDs, mc.InventoryIDs...)
+			allConsumedCount += len(mc.InventoryIDs)
+			for round := int64(0); round < maxTimes; round++ {
+				start := int(round) * int(mc.Required)
+				end := start + int(mc.Required)
+				consumedByRound[round] = append(consumedByRound[round], mc.InventoryIDs[start:end]...)
+			}
 		}
 
-		newInv = model.UserInventory{
-			UserID:     userID,
-			ProductID:  recipe.TargetProductID,
-			ValueCents: targetProduct.Price,
-			Status:     1,
-			Remark:     fmt.Sprintf("synthesis_produced:recipe_%d", recipeID),
-		}
-		if err := tx.Omit("ValueSnapshotAt", "ShippingNo").Create(&newInv).Error; err != nil {
-			return err
-		}
+		result.ConsumedInventoryCount = allConsumedCount
+		result.ProducedInventoryIDs = make([]int64, 0, int(maxTimes))
+		for round := int64(0); round < maxTimes; round++ {
+			newInv := model.UserInventory{
+				UserID:     userID,
+				ProductID:  recipe.TargetProductID,
+				ValueCents: targetProduct.Price,
+				Status:     1,
+				Remark:     fmt.Sprintf("batch_synthesis_produced:recipe_%d:round_%d", recipeID, round+1),
+			}
+			if err := tx.Omit("ValueSnapshotAt", "ShippingNo").Create(&newInv).Error; err != nil {
+				return err
+			}
+			result.ProducedInventoryIDs = append(result.ProducedInventoryIDs, newInv.ID)
 
-		consumedJSON, _ := json.Marshal(allConsumedIDs)
-		log := &model.FragmentSynthesisLogs{
-			UserID:               userID,
-			RecipeID:             recipeID,
-			ConsumedInventoryIDs: string(consumedJSON),
-			ProducedInventoryID:  newInv.ID,
+			consumedJSON, _ := json.Marshal(consumedByRound[round])
+			log := &model.FragmentSynthesisLogs{
+				UserID:               userID,
+				RecipeID:             recipeID,
+				ConsumedInventoryIDs: string(consumedJSON),
+				ProducedInventoryID:  newInv.ID,
+			}
+			if err := tx.Create(log).Error; err != nil {
+				return err
+			}
 		}
-		return tx.Create(log).Error
+		return nil
 	})
-
 	if err != nil {
 		return nil, err
 	}
-	return &newInv, nil
+	return result, nil
 }
 
 func (s *service) ListLogs(ctx context.Context, page, size int, userID *int64) ([]*SynthesisLogView, int64, error) {

internal/service/synthesis/synthesis_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"bindbox-game/internal/repository/mysql"
+	"bindbox-game/internal/repository/mysql/model"
 
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
@@ -18,24 +19,69 @@ func newSynthesisServiceForTest(t *testing.T) *service {
 		t.Fatalf("open sqlite failed: %v", err)
 	}
 
-	if err := db.Exec(`
-		CREATE TABLE product_categories (
+	statements := []string{
+		`CREATE TABLE product_categories (
 			id INTEGER PRIMARY KEY AUTOINCREMENT,
 			is_fragment INTEGER NOT NULL DEFAULT 0,
 			deleted_at DATETIME NULL
-		);
-	`).Error; err != nil {
-		t.Fatalf("create product_categories failed: %v", err)
-	}
-
-	if err := db.Exec(`
-		CREATE TABLE products (
+		);`,
+		`CREATE TABLE products (
 			id INTEGER PRIMARY KEY AUTOINCREMENT,
 			category_id INTEGER NOT NULL DEFAULT 0,
+			name TEXT NOT NULL DEFAULT '',
+			price INTEGER NOT NULL DEFAULT 0,
+			status INTEGER NOT NULL DEFAULT 1,
+			images_json TEXT NOT NULL DEFAULT '',
 			deleted_at DATETIME NULL
-		);
-	`).Error; err != nil {
-		t.Fatalf("create products failed: %v", err)
+		);`,
+		`CREATE TABLE fragment_synthesis_recipes (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			name TEXT NOT NULL DEFAULT '',
+			description TEXT NOT NULL DEFAULT '',
+			target_product_id INTEGER NOT NULL DEFAULT 0,
+			status INTEGER NOT NULL DEFAULT 1,
+			created_at DATETIME NULL,
+			updated_at DATETIME NULL,
+			deleted_at DATETIME NULL
+		);`,
+		`CREATE TABLE fragment_synthesis_recipe_materials (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			recipe_id INTEGER NOT NULL DEFAULT 0,
+			fragment_product_id INTEGER NOT NULL DEFAULT 0,
+			required_count INTEGER NOT NULL DEFAULT 0,
+			created_at DATETIME NULL,
+			updated_at DATETIME NULL,
+			deleted_at DATETIME NULL
+		);`,
+		`CREATE TABLE fragment_synthesis_logs (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			created_at DATETIME NULL,
+			user_id INTEGER NOT NULL DEFAULT 0,
+			recipe_id INTEGER NOT NULL DEFAULT 0,
+			consumed_inventory_ids TEXT NOT NULL DEFAULT '',
+			produced_inventory_id INTEGER NOT NULL DEFAULT 0
+		);`,
+		`CREATE TABLE user_inventory (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			created_at DATETIME NULL,
+			updated_at DATETIME NULL,
+			user_id INTEGER NOT NULL DEFAULT 0,
+			product_id INTEGER NOT NULL DEFAULT 0,
+			value_cents INTEGER NOT NULL DEFAULT 0,
+			value_source INTEGER NOT NULL DEFAULT 0,
+			value_snapshot_at DATETIME NULL,
+			order_id INTEGER NOT NULL DEFAULT 0,
+			activity_id INTEGER NOT NULL DEFAULT 0,
+			reward_id INTEGER NOT NULL DEFAULT 0,
+			status INTEGER NOT NULL DEFAULT 1,
+			shipping_no TEXT NOT NULL DEFAULT '',
+			remark TEXT NOT NULL DEFAULT ''
+		);`,
+	}
+	for _, stmt := range statements {
+		if err := db.Exec(stmt).Error; err != nil {
+			t.Fatalf("exec schema failed: %v", err)
+		}
 	}
 
 	return New(mysql.NewTestRepo(db)).(*service)
@@ -93,3 +139,111 @@ func TestValidateRecipeProducts_ValidCombination(t *testing.T) {
 	}
 }
 
+func TestBatchSynthesizeProducesAllPossibleItems(t *testing.T) {
+	svc := newSynthesisServiceForTest(t)
+	ctx := context.Background()
+	seedBatchSynthesisFixture(t, svc)
+
+	result, err := svc.BatchSynthesize(ctx, 1001, 1)
+	if err != nil {
+		t.Fatalf("batch synthesize failed: %v", err)
+	}
+	if result.SynthesizedCount != 3 {
+		t.Fatalf("expected 3 syntheses, got %d", result.SynthesizedCount)
+	}
+	if len(result.ProducedInventoryIDs) != 3 {
+		t.Fatalf("expected 3 produced ids, got %d", len(result.ProducedInventoryIDs))
+	}
+	if result.ConsumedInventoryCount != 9 {
+		t.Fatalf("expected 9 consumed inventory items, got %d", result.ConsumedInventoryCount)
+	}
+
+	assertInventoryStatusCount(t, svc, 1001, 11, 2, 6)
+	assertInventoryStatusCount(t, svc, 1001, 12, 2, 3)
+	assertInventoryStatusCount(t, svc, 1001, 10, 1, 3)
+	assertSynthesisLogCount(t, svc, 1001, 1, 3)
+}
+
+func TestBatchSynthesizeUsesShortestMaterial(t *testing.T) {
+	svc := newSynthesisServiceForTest(t)
+	ctx := context.Background()
+	seedBatchSynthesisFixture(t, svc)
+
+	if err := svc.repo.GetDbW().Exec("INSERT INTO user_inventory(user_id, product_id, value_cents, status, remark) VALUES (1001, 12, 0, 1, 'extra_fragment')").Error; err != nil {
+		t.Fatalf("seed extra fragment failed: %v", err)
+	}
+
+	result, err := svc.BatchSynthesize(ctx, 1001, 1)
+	if err != nil {
+		t.Fatalf("batch synthesize failed: %v", err)
+	}
+	if result.SynthesizedCount != 3 {
+		t.Fatalf("expected shortest material to cap at 3, got %d", result.SynthesizedCount)
+	}
+	assertInventoryStatusCount(t, svc, 1001, 12, 1, 1)
+}
+
+func TestBatchSynthesizeFailsWhenInsufficient(t *testing.T) {
+	svc := newSynthesisServiceForTest(t)
+	ctx := context.Background()
+	seedBatchSynthesisFixture(t, svc)
+
+	if err := svc.repo.GetDbW().Exec("DELETE FROM user_inventory WHERE user_id = ? AND product_id = ?", 1001, 12).Error; err != nil {
+		t.Fatalf("clear fragments failed: %v", err)
+	}
+
+	_, err := svc.BatchSynthesize(ctx, 1001, 1)
+	if err == nil || err.Error() != "insufficient_fragments" {
+		t.Fatalf("expected insufficient_fragments, got %v", err)
+	}
+}
+
+func seedBatchSynthesisFixture(t *testing.T, svc *service) {
+	t.Helper()
+	db := svc.repo.GetDbW()
+
+	statements := []string{
+		"INSERT INTO product_categories(id, is_fragment) VALUES (1, 1), (2, 0)",
+		"INSERT INTO products(id, category_id, name, price, status) VALUES (10, 2, '目标商品', 1999, 1), (11, 1, '碎片A', 0, 1), (12, 1, '碎片B', 0, 1)",
+		"INSERT INTO fragment_synthesis_recipes(id, name, description, target_product_id, status) VALUES (1, '配方1', '测试配方', 10, 1)",
+		"INSERT INTO fragment_synthesis_recipe_materials(id, recipe_id, fragment_product_id, required_count) VALUES (1, 1, 11, 2), (2, 1, 12, 1)",
+	}
+	for _, stmt := range statements {
+		if err := db.Exec(stmt).Error; err != nil {
+			t.Fatalf("seed fixture failed: %v", err)
+		}
+	}
+
+	for i := 0; i < 6; i++ {
+		if err := db.Create(&model.UserInventory{UserID: 1001, ProductID: 11, ValueCents: 0, Status: 1, Remark: "fragment_a"}).Error; err != nil {
+			t.Fatalf("seed fragment a failed: %v", err)
+		}
+	}
+	for i := 0; i < 3; i++ {
+		if err := db.Create(&model.UserInventory{UserID: 1001, ProductID: 12, ValueCents: 0, Status: 1, Remark: "fragment_b"}).Error; err != nil {
+			t.Fatalf("seed fragment b failed: %v", err)
+		}
+	}
+}
+
+func assertInventoryStatusCount(t *testing.T, svc *service, userID, productID int64, status int32, want int64) {
+	t.Helper()
+	var count int64
+	if err := svc.repo.GetDbR().Model(&model.UserInventory{}).Where("user_id = ? AND product_id = ? AND status = ?", userID, productID, status).Count(&count).Error; err != nil {
+		t.Fatalf("count inventory failed: %v", err)
+	}
+	if count != want {
+		t.Fatalf("expected %d inventory rows for product %d status %d, got %d", want, productID, status, count)
+	}
+}
+
+func assertSynthesisLogCount(t *testing.T, svc *service, userID, recipeID int64, want int64) {
+	t.Helper()
+	var count int64
+	if err := svc.repo.GetDbR().Model(&model.FragmentSynthesisLogs{}).Where("user_id = ? AND recipe_id = ?", userID, recipeID).Count(&count).Error; err != nil {
+		t.Fatalf("count logs failed: %v", err)
+	}
+	if count != want {
+		t.Fatalf("expected %d synthesis logs, got %d", want, count)
+	}
+}

internal/service/user/address_share.go

@@ -15,6 +15,17 @@ import (
 	"gorm.io/gorm"
 )
 
+const (
+	shippingFeeThreshold                    = 5
+	shippingFeeReasonBelowThreshold          = "below_threshold"
+	shippingFeeReasonContainsNonFreeShipping = "contains_non_free_shipping_item"
+)
+
+var nonFreeShippingCategoryIDs = map[int64]struct{}{
+	14: {},
+	15: {},
+}
+
 type shareClaims struct {
 	OwnerUserID int64 `json:"owner_user_id"`
 	InventoryID int64 `json:"inventory_id"`
@@ -319,6 +330,63 @@ func generateBatchNo(userID int64) string {
 	return fmt.Sprintf("B%d%d", userID, time.Now().UnixNano()/1000000)
 }
 
+func (s *service) CheckShippingFeeRequirement(ctx context.Context, userID int64, inventoryIDs []int64) (bool, string, error) {
+	uniqMap := make(map[int64]struct{}, len(inventoryIDs))
+	uniq := make([]int64, 0, len(inventoryIDs))
+	for _, id := range inventoryIDs {
+		if id <= 0 {
+			continue
+		}
+		if _, ok := uniqMap[id]; ok {
+			continue
+		}
+		uniqMap[id] = struct{}{}
+		uniq = append(uniq, id)
+	}
+	if len(uniq) == 0 {
+		return false, "", fmt.Errorf("invalid inventory_ids")
+	}
+
+	invList, err := s.readDB.UserInventory.WithContext(ctx).
+		Where(s.readDB.UserInventory.ID.In(uniq...)).
+		Find()
+	if err != nil {
+		return false, "", err
+	}
+
+	productIDSet := make(map[int64]struct{}, len(invList))
+	productIDs := make([]int64, 0, len(invList))
+	for _, inv := range invList {
+		if inv == nil || inv.UserID != userID || inv.ProductID <= 0 {
+			continue
+		}
+		if _, ok := productIDSet[inv.ProductID]; ok {
+			continue
+		}
+		productIDSet[inv.ProductID] = struct{}{}
+		productIDs = append(productIDs, inv.ProductID)
+	}
+
+	if len(productIDs) > 0 {
+		products, err := s.readDB.Products.WithContext(ctx).
+			Where(s.readDB.Products.ID.In(productIDs...)).
+			Find()
+		if err != nil {
+			return false, "", err
+		}
+		for _, product := range products {
+			if _, ok := nonFreeShippingCategoryIDs[product.CategoryID]; ok {
+				return true, shippingFeeReasonContainsNonFreeShipping, nil
+			}
+		}
+	}
+
+	if len(uniq) < shippingFeeThreshold {
+		return true, shippingFeeReasonBelowThreshold, nil
+	}
+	return false, "", nil
+}
+
 func (s *service) RequestShippings(ctx context.Context, userID int64, inventoryIDs []int64, addressID *int64) (addrID int64, batchNo string, success []int64, skipped []struct {
 	ID     int64
 	Reason string

internal/service/user/request_shipping_batch_test.go

@@ -29,7 +29,6 @@ func TestRequestShippings_EmptyInventoryIDs(t *testing.T) {
 	db, _ := setupMockDBForShipping(t)
 	svc := newTestService(db)
 
-	// Empty inventory IDs should return failed with "invalid_params"
 	_, _, _, _, failed, err := svc.RequestShippings(context.Background(), 1, []int64{}, nil)
 	assert.NoError(t, err)
 	assert.Len(t, failed, 1)
@@ -40,7 +39,6 @@ func TestRequestShippings_AllZeroInventoryIDs(t *testing.T) {
 	db, _ := setupMockDBForShipping(t)
 	svc := newTestService(db)
 
-	// All zero or negative IDs should be filtered, resulting in empty uniq list
 	_, _, _, _, failed, err := svc.RequestShippings(context.Background(), 1, []int64{0, -1, 0}, nil)
 	assert.NoError(t, err)
 	assert.Len(t, failed, 1)
@@ -51,17 +49,88 @@ func TestRequestShippings_NoDefaultAddress(t *testing.T) {
 	db, mock := setupMockDBForShipping(t)
 	svc := newTestService(db)
 
-	// Mock default address query - return no rows
+	mock.ExpectQuery("SELECT .* FROM `user_addresses`").
+		WillReturnRows(sqlmock.NewRows(nil))
 	mock.ExpectQuery("SELECT .* FROM `user_addresses`").
 		WillReturnRows(sqlmock.NewRows(nil))
 
-	// Mock all addresses query - return empty
-	mock.ExpectQuery("SELECT .* FROM `user_addresses`").
-		WillReturnRows(sqlmock.NewRows(nil))
-
-	// With valid IDs but no address, should return no_default_address error
 	_, _, _, _, failed, err := svc.RequestShippings(context.Background(), 1, []int64{1, 2}, nil)
 	assert.NoError(t, err)
 	assert.Len(t, failed, 1)
 	assert.Equal(t, "no_default_address", failed[0].Reason)
 }
+
+func TestCheckShippingFeeRequirement_BelowThreshold(t *testing.T) {
+	db, mock := setupMockDBForShipping(t)
+	svc := newTestService(db)
+
+	mock.ExpectQuery("SELECT .* FROM `user_inventory`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "user_id", "product_id"}).
+			AddRow(1, 99, 101).
+			AddRow(2, 99, 102).
+			AddRow(3, 99, 103).
+			AddRow(4, 99, 104))
+	mock.ExpectQuery("SELECT .* FROM `products`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "category_id"}).
+			AddRow(101, 1).
+			AddRow(102, 2).
+			AddRow(103, 3).
+			AddRow(104, 4))
+
+	needFee, reason, err := svc.CheckShippingFeeRequirement(context.Background(), 99, []int64{1, 2, 3, 4})
+	assert.NoError(t, err)
+	assert.True(t, needFee)
+	assert.Equal(t, shippingFeeReasonBelowThreshold, reason)
+}
+
+func TestCheckShippingFeeRequirement_FreeWhenThresholdReached(t *testing.T) {
+	db, mock := setupMockDBForShipping(t)
+	svc := newTestService(db)
+
+	mock.ExpectQuery("SELECT .* FROM `user_inventory`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "user_id", "product_id"}).
+			AddRow(1, 99, 101).
+			AddRow(2, 99, 102).
+			AddRow(3, 99, 103).
+			AddRow(4, 99, 104).
+			AddRow(5, 99, 105))
+	mock.ExpectQuery("SELECT .* FROM `products`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "category_id"}).
+			AddRow(101, 1).
+			AddRow(102, 2).
+			AddRow(103, 3).
+			AddRow(104, 4).
+			AddRow(105, 5))
+
+	needFee, reason, err := svc.CheckShippingFeeRequirement(context.Background(), 99, []int64{1, 2, 3, 4, 5})
+	assert.NoError(t, err)
+	assert.False(t, needFee)
+	assert.Equal(t, "", reason)
+}
+
+func TestCheckShippingFeeRequirement_NonFreeCategoryOverridesThreshold(t *testing.T) {
+	db, mock := setupMockDBForShipping(t)
+	svc := newTestService(db)
+
+	mock.ExpectQuery("SELECT .* FROM `user_inventory`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "user_id", "product_id"}).
+			AddRow(1, 99, 101).
+			AddRow(2, 99, 102).
+			AddRow(3, 99, 103).
+			AddRow(4, 99, 104).
+			AddRow(5, 99, 105).
+			AddRow(6, 99, 106))
+	mock.ExpectQuery("SELECT .* FROM `products`").
+		WillReturnRows(sqlmock.NewRows([]string{"id", "category_id"}).
+			AddRow(101, 1).
+			AddRow(102, 2).
+			AddRow(103, 3).
+			AddRow(104, 4).
+			AddRow(105, 14).
+			AddRow(106, 5))
+
+	needFee, reason, err := svc.CheckShippingFeeRequirement(context.Background(), 99, []int64{1, 2, 3, 4, 5, 6})
+	assert.NoError(t, err)
+	assert.True(t, needFee)
+	assert.Equal(t, shippingFeeReasonContainsNonFreeShipping, reason)
+}

internal/service/user/user.go

@@ -57,6 +57,7 @@ type Service interface {
 	SubmitAddressShare(ctx context.Context, shareToken string, name string, mobile string, province string, city string, district string, address string, submittedByUserID *int64, submittedIP *string) (int64, error)
 	RequestShipping(ctx context.Context, userID int64, inventoryID int64) (int64, error)
 	CancelShipping(ctx context.Context, userID int64, inventoryID int64, batchNo string) (int64, error)
+	CheckShippingFeeRequirement(ctx context.Context, userID int64, inventoryIDs []int64) (needFee bool, reason string, err error)
 	RequestShippings(ctx context.Context, userID int64, inventoryIDs []int64, addressID *int64) (addrID int64, batchNo string, success []int64, skipped []struct {
 		ID     int64
 		Reason string