feat(backend): 入库每行新建独立产品发独立序列号(product 加生产日期/批次列)

入库 Create/Update 改为对每条明细新建独立 product（createIndependentProduct，
nextProductCode 自增 + uk_shop_code 唯一约束兜底），回填 product_id；不再按名称复用。
product 表加 production_date/batch_no。向后兼容：保留明细/库存快照列。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YZ4DskSRKsSiheQonFtQvx

backend/internal/handler/product.go

@@ -85,6 +85,42 @@ func nextProductCode(tx *gorm.DB, shopID uint64) (string, error) {
 	return fmt.Sprintf("P%03d", maxN+1), nil
 }
 
+// createIndependentProduct 为入库明细新建一个独立产品（特有产品/序列号），返回新 product。
+// "入库每行 = 一个特有产品"模型:每条明细建一个独立 product、发新序列号,不按名称复用。
+// 含 nextProductCode 自增 + 撞 uk_shop_code 唯一约束时重试。必须在事务内调用。
+func createIndependentProduct(tx *gorm.DB, shopID uint64, name, series, spec, batchNo string, prodDate *model.Date, price float64) (model.Product, error) {
+	namePinyin, nameInitials := util.ToPinyin(name)
+	var prod model.Product
+	var err error
+	for attempt := 0; attempt < 5; attempt++ {
+		code, e := nextProductCode(tx, shopID)
+		if e != nil {
+			return model.Product{}, e
+		}
+		prod = model.Product{
+			TenantBase:     model.TenantBase{ShopID: shopID},
+			PublicID:       uuid.New().String(),
+			Code:           code,
+			Name:           name,
+			Series:         series,
+			Spec:           spec,
+			BatchNo:        batchNo,
+			ProductionDate: prodDate,
+			PurchasePrice:  price,
+			NamePinyin:     namePinyin,
+			NameInitials:   nameInitials,
+		}
+		prod.ID = 0
+		if err = tx.Create(&prod).Error; err == nil || !errors.Is(err, gorm.ErrDuplicatedKey) {
+			break
+		}
+	}
+	if err != nil {
+		return model.Product{}, err
+	}
+	return prod, nil
+}
+
 // Create POST /api/v1/products
 func (h *ProductHandler) Create(c *gin.Context) {
 	shopID := middleware.GetShopID(c)

backend/internal/handler/stock_in.go

@@ -106,19 +106,28 @@ func (h *StockInHandler) Create(c *gin.Context) {
 	}
 	req.OrderNo = orderNo
 
-	// 计算总金额；自动生成批次号
-	var total float64
-	for i := range req.Items {
-		req.Items[i].ShopID = shopID
-		req.Items[i].TotalPrice = req.Items[i].Quantity * req.Items[i].UnitPrice
-		total += req.Items[i].TotalPrice
-		if req.Items[i].BatchNo == "" {
-			req.Items[i].BatchNo = fmt.Sprintf("%s-%02d", req.OrderNo, i+1)
+	// 事务内：每条明细新建一个独立产品（特有产品/序列号，不按名称复用），回填 product_id，再建单。
+	err = h.db.Transaction(func(tx *gorm.DB) error {
+		var total float64
+		for i := range req.Items {
+			it := &req.Items[i]
+			it.ShopID = shopID
+			if it.BatchNo == "" {
+				it.BatchNo = fmt.Sprintf("%s-%02d", req.OrderNo, i+1)
+			}
+			prod, e := createIndependentProduct(tx, shopID, it.ProductName, it.Series, it.Spec, it.BatchNo, it.ProductionDate, it.UnitPrice)
+			if e != nil {
+				return e
+			}
+			it.ProductID = prod.ID
+			it.ProductCode = prod.Code // 保留快照,兼容现有查询(瘦身阶段再去)
+			it.TotalPrice = it.Quantity * it.UnitPrice
+			total += it.TotalPrice
 		}
-	}
-	req.TotalAmount = total
-
-	if err := h.db.Create(&req).Error; err != nil {
+		req.TotalAmount = total
+		return tx.Create(&req).Error
+	})
+	if err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
 	}
@@ -148,13 +157,20 @@ func (h *StockInHandler) Update(c *gin.Context) {
 		}
 		var total float64
 		for i := range req.Items {
-			req.Items[i].ShopID = shopID
-			req.Items[i].OrderID = order.ID
-			req.Items[i].TotalPrice = req.Items[i].Quantity * req.Items[i].UnitPrice
-			total += req.Items[i].TotalPrice
-			if req.Items[i].BatchNo == "" {
-				req.Items[i].BatchNo = fmt.Sprintf("%s-%02d", order.OrderNo, i+1)
+			it := &req.Items[i]
+			it.ShopID = shopID
+			it.OrderID = order.ID
+			if it.BatchNo == "" {
+				it.BatchNo = fmt.Sprintf("%s-%02d", order.OrderNo, i+1)
 			}
+			// 编辑草稿:旧明细已删,每条按新模型重建独立产品（旧草稿 product 无库存,暂留待后续清理）
+			prod, e := createIndependentProduct(tx, shopID, it.ProductName, it.Series, it.Spec, it.BatchNo, it.ProductionDate, it.UnitPrice)
+			if e != nil {
+				return e
+			}
+			it.ProductID = prod.ID
+			it.ProductCode = prod.Code
+			it.TotalPrice = it.Quantity * it.UnitPrice
 		}
 		updates := map[string]interface{}{
 			"warehouse_id": req.WarehouseID,

backend/internal/handler/stock_in_test.go

@@ -28,9 +28,11 @@ func TestStockInHandler_FullFlow(t *testing.T) {
 		"order_date":   time.Now().Format(time.RFC3339),
 		"items": []map[string]interface{}{
 			{
-				"product_id": product.ID,
-				"quantity":   10.0,
-				"unit_price": 5.0,
+				"product_name": "Test Beer",
+				"series":       "普通",
+				"spec":         "500ml",
+				"quantity":     10.0,
+				"unit_price":   5.0,
 			},
 		},
 	})
@@ -57,15 +59,17 @@ func TestStockInHandler_FullFlow(t *testing.T) {
 	w = makeRequest(r, "PUT", fmt.Sprintf("/api/v1/stock-in/orders/%d/approve", orderID), token, nil)
 	require.Equal(t, http.StatusOK, w.Code)
 
-	// 5. 验证库存变化
+	// 5. 验证库存变化：入库为明细新建了独立产品，库存指向它（不是预设的 product）
 	var inv model.Inventory
-	db.Where("shop_id = ? AND warehouse_id = ? AND product_id = ?",
-		shop.ID, warehouse.ID, product.ID).First(&inv)
+	db.Where("shop_id = ? AND warehouse_id = ?",
+		shop.ID, warehouse.ID).First(&inv)
 	assert.Equal(t, float64(10), inv.Quantity)
+	assert.NotZero(t, inv.ProductID)
+	assert.NotEqual(t, product.ID, inv.ProductID)
 
 	// 6. 验证库存流水
 	var logs []model.InventoryLog
-	db.Where("shop_id = ? AND product_id = ?", shop.ID, product.ID).Find(&logs)
+	db.Where("shop_id = ? AND product_id = ?", shop.ID, inv.ProductID).Find(&logs)
 	require.Len(t, logs, 1)
 	assert.Equal(t, "in", logs[0].Direction)
 	assert.Equal(t, float64(10), logs[0].Quantity)

backend/internal/model/product.go

@@ -22,6 +22,9 @@ type Product struct {
 	Brand         string  `gorm:"size:100" json:"brand"`
 	PurchasePrice float64 `gorm:"type:decimal(12,2)" json:"purchase_price"`
 	SalePrice     float64 `gorm:"type:decimal(12,2)" json:"sale_price"`
+	// 特有产品的批次属性：每个 product = 一个特有产品/序列号，生产日期/批次归此（单一来源）
+	ProductionDate *Date  `gorm:"type:date" json:"production_date"`
+	BatchNo        string `gorm:"size:50" json:"batch_no"`
 	MinStock      int     `gorm:"default:0" json:"min_stock"`
 	Description   string  `gorm:"type:text" json:"description"`
 	CustomFields    JSON    `gorm:"type:json" json:"custom_fields,omitempty"`

backend/testutil/setup.go

@@ -188,6 +188,8 @@ func SetupTestDB() *gorm.DB {
 			brand TEXT,
 			purchase_price REAL,
 			sale_price REAL,
+			production_date DATETIME,
+			batch_no TEXT,
 			min_stock INTEGER DEFAULT 0,
 			description TEXT,
 			custom_fields TEXT,