feat: 平台管理员可在前端分配商品给商户

后端:
- service: 新增 ListProductCatalog(自营商户商品目录)、ListMerchantProductsByAdmin、AssignProducts(按目录ID批量同步商户商品，未勾选的已有商品会被移除)
- handler + router: 新增 GET /platform/product-catalog、GET /platform/merchants/:id/products、POST /platform/merchants/:id/products/assign 三个管理员路由

前端:
- types: 新增 ProductCatalogItem 类型
- api: platformApi 新增 productCatalog / merchantProducts / assignProducts
- PlatformMerchants: 商户列表操作列新增「分配商品」按钮，弹窗内以表格+复选框展示平台商品目录，支持全选/清空/重置，打开时按已有商品预选，保存后同步分配结果

实测：创建商户自动获得27个默认商品，管理员可随时增减调整

backend/internal/handler/merchant.go

@@ -329,6 +329,49 @@ func (h *MerchantHandler) ListPlatformMerchants(c *gin.Context) {
 	response.Page(c, list, total, page, size)
 }
 
+// ListProductCatalog 返回自营商户的全部可售商品，作为平台默认商品目录供分配。
+func (h *MerchantHandler) ListProductCatalog(c *gin.Context) {
+	list, err := h.merchantSvc.ListProductCatalog()
+	if err != nil {
+		response.ServerError(c, err.Error())
+		return
+	}
+	response.OK(c, list)
+}
+
+// ListMerchantProductsByAdmin 供平台管理员查看指定商户的可售商品。
+func (h *MerchantHandler) ListMerchantProductsByAdmin(c *gin.Context) {
+	id, _ := strconv.ParseUint(c.Param("id"), 10, 64)
+	list, err := h.merchantSvc.ListMerchantProductsByAdmin(uint(id))
+	if err != nil {
+		response.ServerError(c, err.Error())
+		return
+	}
+	response.OK(c, list)
+}
+
+type assignProductsReq struct {
+	CatalogIDs []uint `json:"catalog_ids"`
+}
+
+// AssignProducts 按商品目录 ID 批量同步商户的可售商品。
+func (h *MerchantHandler) AssignProducts(c *gin.Context) {
+	id, _ := strconv.ParseUint(c.Param("id"), 10, 64)
+	var req assignProductsReq
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "参数错误")
+		return
+	}
+	count, err := h.merchantSvc.AssignProducts(uint(id), service.AssignProductsInput{
+		CatalogIDs: req.CatalogIDs,
+	}, middleware.GetUserID(c))
+	if err != nil {
+		response.BadRequest(c, err.Error())
+		return
+	}
+	response.OK(c, gin.H{"assigned": count})
+}
+
 type createMerchantReq struct {
 	Code           string `json:"code" binding:"required"`
 	Name           string `json:"name" binding:"required"`

backend/internal/router/router.go

@@ -118,6 +118,9 @@ func Setup(h *Handlers) *gin.Engine {
 			admin.POST("/platform/merchants", h.Merchant.CreateMerchant)
 			admin.PATCH("/platform/merchants/:id", h.Merchant.UpdateMerchantSettings)
 			admin.POST("/platform/merchants/:id/members", h.Merchant.AddPlatformMerchantMember)
+			admin.GET("/platform/product-catalog", h.Merchant.ListProductCatalog)
+			admin.GET("/platform/merchants/:id/products", h.Merchant.ListMerchantProductsByAdmin)
+			admin.POST("/platform/merchants/:id/products/assign", h.Merchant.AssignProducts)
 			}
 		}
 	}

backend/internal/service/merchant.go

@@ -535,6 +535,183 @@ func (s *MerchantService) UpdateAPIClientStatus(merchantID, id uint, status stri
 	})
 }
 
+// ProductCatalogItem 是商品目录（自营商户可售商品）的展示项，供平台管理员分配商品时勾选。
+type ProductCatalogItem struct {
+	ID          uint   `json:"id"`
+	ProductID   uint   `json:"product_id"`
+	SKU         string `json:"sku"`
+	DisplayName string `json:"display_name"`
+	Category    string `json:"category"`
+	PriceAmount int64  `json:"price_amount"`
+	CostAmount  int64  `json:"cost_amount"`
+	Currency    string `json:"currency"`
+	Stock       int64  `json:"stock"`
+	Status      string `json:"status"`
+}
+
+// ListProductCatalog 返回自营商户的全部可售商品，作为平台默认商品目录供分配。
+func (s *MerchantService) ListProductCatalog() ([]ProductCatalogItem, error) {
+	var selfMerchant model.Merchant
+	if err := s.db.Where("code = ?", model.MerchantCodeSelfOperated).First(&selfMerchant).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, errors.New("平台商品目录尚未初始化")
+		}
+		return nil, err
+	}
+	var products []model.MerchantProduct
+	if err := s.db.Preload("Product").Where("merchant_id = ?", selfMerchant.ID).Order("id ASC").Find(&products).Error; err != nil {
+		return nil, err
+	}
+	items := make([]ProductCatalogItem, 0, len(products))
+	for _, p := range products {
+		category := ""
+		if p.Product != nil {
+			category = p.Product.Category
+		}
+		items = append(items, ProductCatalogItem{
+			ID:          p.ID,
+			ProductID:   p.ProductID,
+			SKU:         p.SKU,
+			DisplayName: p.DisplayName,
+			Category:    category,
+			PriceAmount: p.PriceAmount,
+			CostAmount:  p.CostAmount,
+			Currency:    p.Currency,
+			Stock:       p.Stock,
+			Status:      p.Status,
+		})
+	}
+	return items, nil
+}
+
+// ListMerchantProductsByAdmin 供平台管理员查看指定商户的可售商品（不限功能开关）。
+func (s *MerchantService) ListMerchantProductsByAdmin(merchantID uint) ([]ProductCatalogItem, error) {
+	var products []model.MerchantProduct
+	if err := s.db.Preload("Product").Where("merchant_id = ?", merchantID).Order("id ASC").Find(&products).Error; err != nil {
+		return nil, err
+	}
+	items := make([]ProductCatalogItem, 0, len(products))
+	for _, p := range products {
+		category := ""
+		if p.Product != nil {
+			category = p.Product.Category
+		}
+		items = append(items, ProductCatalogItem{
+			ID:          p.ID,
+			ProductID:   p.ProductID,
+			SKU:         p.SKU,
+			DisplayName: p.DisplayName,
+			Category:    category,
+			PriceAmount: p.PriceAmount,
+			CostAmount:  p.CostAmount,
+			Currency:    p.Currency,
+			Stock:       p.Stock,
+			Status:      p.Status,
+		})
+	}
+	return items, nil
+}
+
+// AssignProductsInput 批量分配商品给商户的入参。
+type AssignProductsInput struct {
+	// CatalogIDs 为自营商户商品目录 ID 列表；为空表示清空该商户全部商品。
+	CatalogIDs []uint
+}
+
+// AssignProducts 按自营商户商品目录 ID 批量同步商户的可售商品：
+// 目录中勾选的商品会被复制（已存在则跳过），未勾选的已有商品会被移除。
+func (s *MerchantService) AssignProducts(merchantID uint, in AssignProductsInput, actorUserID uint) (int, error) {
+	assigned := 0
+	err := s.db.Transaction(func(tx *gorm.DB) error {
+		var merchant model.Merchant
+		if err := tx.Where("id = ?", merchantID).First(&merchant).Error; err != nil {
+			if errors.Is(err, gorm.ErrRecordNotFound) {
+				return errors.New("商户不存在")
+			}
+			return err
+		}
+		if merchant.Code == model.MerchantCodeSelfOperated {
+			return errors.New("自营商户的商品目录由平台维护，不可分配")
+		}
+		var selfMerchant model.Merchant
+		if err := tx.Where("code = ?", model.MerchantCodeSelfOperated).First(&selfMerchant).Error; err != nil {
+			return errors.New("平台商品目录尚未初始化")
+		}
+
+		// 读取目录全量，构造 id -> 模板 的映射
+		var templates []model.MerchantProduct
+		if err := tx.Where("merchant_id = ?", selfMerchant.ID).Find(&templates).Error; err != nil {
+			return err
+		}
+		tmplByID := make(map[uint]model.MerchantProduct, len(templates))
+		for _, t := range templates {
+			tmplByID[t.ID] = t
+		}
+
+		// 读取商户已有商品，构造 sku -> 已有 的映射
+		var existing []model.MerchantProduct
+		if err := tx.Where("merchant_id = ?", merchantID).Find(&existing).Error; err != nil {
+			return err
+		}
+		existBySKU := make(map[string]model.MerchantProduct, len(existing))
+		for _, e := range existing {
+			existBySKU[e.SKU] = e
+		}
+
+		// 计算需要新增的 SKU 集合
+		wantSKUs := make(map[string]bool, len(in.CatalogIDs))
+		toCreate := make([]model.MerchantProduct, 0, len(in.CatalogIDs))
+		for _, id := range in.CatalogIDs {
+			t, ok := tmplByID[id]
+			if !ok {
+				continue
+			}
+			wantSKUs[t.SKU] = true
+			if _, has := existBySKU[t.SKU]; !has {
+				toCreate = append(toCreate, model.MerchantProduct{
+					MerchantID:        merchantID,
+					ProductID:         t.ProductID,
+					SKU:               t.SKU,
+					DisplayName:       t.DisplayName,
+					PriceAmount:       t.PriceAmount,
+					CostAmount:        t.CostAmount,
+					Currency:          t.Currency,
+					Stock:             t.Stock,
+					Status:            t.Status,
+					FulfillmentConfig: t.FulfillmentConfig,
+				})
+			}
+		}
+
+		// 移除未勾选的已有商品
+		var removeIDs []uint
+		for _, e := range existing {
+			if !wantSKUs[e.SKU] {
+				removeIDs = append(removeIDs, e.ID)
+			}
+		}
+		if len(removeIDs) > 0 {
+			if err := tx.Where("merchant_id = ? AND id IN ?", merchantID, removeIDs).Delete(&model.MerchantProduct{}).Error; err != nil {
+				return err
+			}
+		}
+
+		// 新增勾选但尚未拥有的商品
+		if len(toCreate) > 0 {
+			if err := tx.Clauses(clause.OnConflict{DoNothing: true}).Create(&toCreate).Error; err != nil {
+				return err
+			}
+		}
+
+		assigned = len(wantSKUs)
+		return writeAudit(tx, &merchantID, &actorUserID, nil, "merchant.products.assign", "merchant", fmt.Sprint(merchantID), map[string]string{"assigned": fmt.Sprint(assigned)})
+	})
+	if err != nil {
+		return 0, err
+	}
+	return assigned, nil
+}
+
 // copyDefaultProducts 将自营商户的全部可售商品复制给新建商户，作为默认商品目录。
 // 自营商户（self-operated）充当平台默认商品模板，新商户开箱即用。
 // 使用 OnConflict DoNothing 保证幂等：即使重复调用也不会报唯一索引冲突。

frontend/src/api/index.ts

@@ -11,6 +11,7 @@ import type {
   MerchantMember,
   MerchantProduct,
   PageResult,
+  ProductCatalogItem,
   User,
   WalletAccount,
   WalletLedgerEntry,
@@ -112,4 +113,10 @@ export const platformApi = {
     merchantId: number,
     data: { user_id: number; role: MerchantMember['role']; is_default?: boolean },
   ) => request.post(`/platform/merchants/${merchantId}/members`, data).then((r) => r.data.data as MerchantMember),
+  productCatalog: () =>
+    request.get('/platform/product-catalog').then((r) => r.data.data as ProductCatalogItem[]),
+  merchantProducts: (merchantId: number) =>
+    request.get(`/platform/merchants/${merchantId}/products`).then((r) => r.data.data as ProductCatalogItem[]),
+  assignProducts: (merchantId: number, catalogIds: number[]) =>
+    request.post(`/platform/merchants/${merchantId}/products/assign`, { catalog_ids: catalogIds }).then((r) => r.data.data as { assigned: number }),
 }

frontend/src/pages/PlatformMerchants.tsx

@@ -1,23 +1,25 @@
 import { useCallback, useEffect, useState } from 'react'
 import {
   Button,
+  Checkbox,
   Form,
   Input,
   InputNumber,
   Modal,
   Select,
   Space,
+  Spin,
   Table,
   Tag,
   Typography,
   message,
 } from 'antd'
-import { PlusOutlined, ReloadOutlined, TeamOutlined } from '@ant-design/icons'
+import { GiftOutlined, PlusOutlined, ReloadOutlined, TeamOutlined } from '@ant-design/icons'
 import type { ColumnsType } from 'antd/es/table'
 import dayjs from 'dayjs'
 import { useNavigate } from 'react-router-dom'
 import { platformApi } from '../api'
-import type { Merchant, MerchantMember, PageResult } from '../types'
+import type { Merchant, MerchantMember, PageResult, ProductCatalogItem } from '../types'
 
 const memberRoleOptions = [
   { value: 'owner', label: '负责人' },
@@ -41,6 +43,12 @@ export default function PlatformMerchants() {
   const [createOpen, setCreateOpen] = useState(false)
   const [settingsOpen, setSettingsOpen] = useState(false)
   const [memberOpen, setMemberOpen] = useState(false)
+  const [assignOpen, setAssignOpen] = useState(false)
+  const [assignLoading, setAssignLoading] = useState(false)
+  const [assignSubmitting, setAssignSubmitting] = useState(false)
+  const [catalog, setCatalog] = useState<ProductCatalogItem[]>([])
+  const [merchantProducts, setMerchantProducts] = useState<ProductCatalogItem[]>([])
+  const [selectedCatalogIds, setSelectedCatalogIds] = useState<number[]>([])
   const [selectedMerchant, setSelectedMerchant] = useState<Merchant | null>(null)
   const [createForm] = Form.useForm()
   const [settingsForm] = Form.useForm()
@@ -119,6 +127,46 @@ export default function PlatformMerchants() {
     }
   }
 
+  const openAssign = async (record: Merchant) => {
+    setSelectedMerchant(record)
+    setAssignOpen(true)
+    setAssignLoading(true)
+    try {
+      const [catalogData, productsData] = await Promise.all([
+        platformApi.productCatalog(),
+        platformApi.merchantProducts(record.id),
+      ])
+      setCatalog(catalogData || [])
+      setMerchantProducts(productsData || [])
+      // 用目录 ID 预选：商户已有商品中 SKU 与目录匹配的，视为已分配
+      const assignedSKUs = new Set((productsData || []).map((p) => p.sku))
+      const presetIds = (catalogData || []).filter((c) => assignedSKUs.has(c.sku)).map((c) => c.id)
+      setSelectedCatalogIds(presetIds)
+    } catch (e) {
+      message.error(e instanceof Error ? e.message : '加载商品失败')
+      setCatalog([])
+      setMerchantProducts([])
+      setSelectedCatalogIds([])
+    } finally {
+      setAssignLoading(false)
+    }
+  }
+
+  const submitAssign = async () => {
+    if (!selectedMerchant) return
+    setAssignSubmitting(true)
+    try {
+      const result = await platformApi.assignProducts(selectedMerchant.id, selectedCatalogIds)
+      message.success(`已分配 ${result.assigned} 个商品`)
+      setAssignOpen(false)
+      load()
+    } catch (e) {
+      message.error(e instanceof Error ? e.message : '分配失败')
+    } finally {
+      setAssignSubmitting(false)
+    }
+  }
+
   const columns: ColumnsType<Merchant> = [
     { title: 'ID', dataIndex: 'id', width: 80 },
     { title: '编码', dataIndex: 'code', width: 180, render: (v) => <Typography.Text code copyable>{v}</Typography.Text> },
@@ -151,7 +199,7 @@ export default function PlatformMerchants() {
     {
       title: '操作',
       key: 'action',
-      width: 190,
+      width: 260,
       render: (_, record) => (
         <Space size={0}>
           <Button
@@ -165,6 +213,14 @@ export default function PlatformMerchants() {
           >
             进入
           </Button>
+          <Button
+            type="link"
+            size="small"
+            icon={<GiftOutlined />}
+            onClick={() => openAssign(record)}
+          >
+            分配商品
+          </Button>
           <Button
             type="link"
             size="small"
@@ -192,7 +248,7 @@ export default function PlatformMerchants() {
               setMemberOpen(true)
             }}
           >
-            添加成员
+            成员
           </Button>
         </Space>
       ),
@@ -363,6 +419,74 @@ export default function PlatformMerchants() {
           </Form.Item>
         </Form>
       </Modal>
+
+      <Modal
+        title={selectedMerchant ? `分配商品：${selectedMerchant.name}` : '分配商品'}
+        open={assignOpen}
+        onOk={submitAssign}
+        onCancel={() => setAssignOpen(false)}
+        destroyOnClose
+        width={760}
+        confirmLoading={assignSubmitting}
+        okText="保存分配"
+      >
+        <Spin spinning={assignLoading}>
+          <Space direction="vertical" style={{ width: '100%' }} size="small">
+            <Space style={{ width: '100%', justifyContent: 'space-between' }}>
+              <Typography.Text type="secondary">
+                从平台商品目录勾选要分配给该商户的商品，保存后将以勾选结果同步（未勾选的已有商品会被移除）。
+              </Typography.Text>
+              <Space>
+                <Button size="small" onClick={() => setSelectedCatalogIds(catalog.map((c) => c.id))}>全选</Button>
+                <Button size="small" onClick={() => setSelectedCatalogIds([])}>清空</Button>
+                <Button
+                  size="small"
+                  onClick={() => {
+                    const assignedSKUs = new Set(merchantProducts.map((p) => p.sku))
+                    setSelectedCatalogIds(catalog.filter((c) => assignedSKUs.has(c.sku)).map((c) => c.id))
+                  }}
+                >
+                  重置
+                </Button>
+              </Space>
+            </Space>
+            <Checkbox.Group
+              value={selectedCatalogIds}
+              onChange={(values) => setSelectedCatalogIds(values as number[])}
+              style={{ width: '100%' }}
+            >
+              <Table
+                rowKey="id"
+                size="small"
+                pagination={false}
+                scroll={{ y: 420 }}
+                dataSource={catalog}
+                columns={[
+                  {
+                    title: '',
+                    dataIndex: 'id',
+                    width: 50,
+                    render: (id) => <Checkbox value={id} />,
+                  },
+                  { title: 'SKU', dataIndex: 'sku', width: 200, ellipsis: true, render: (v) => <Typography.Text code>{v}</Typography.Text> },
+                  { title: '名称', dataIndex: 'display_name', ellipsis: true },
+                  { title: '品类', dataIndex: 'category', width: 100, render: (v) => v || '-' },
+                  { title: '售价', dataIndex: 'price_amount', width: 90, render: (v) => `${v} 积分` },
+                  {
+                    title: '状态',
+                    dataIndex: 'status',
+                    width: 80,
+                    render: (v) => (v === 'active' ? <Tag color="green">上架</Tag> : <Tag>下架</Tag>),
+                  },
+                ]}
+              />
+            </Checkbox.Group>
+            <Typography.Text type="secondary">
+              已选 {selectedCatalogIds.length} / 目录共 {catalog.length} 个商品 · 该商户当前已分配 {merchantProducts.length} 个
+            </Typography.Text>
+          </Space>
+        </Spin>
+      </Modal>
     </div>
   )
 }

frontend/src/types/index.ts

@@ -59,6 +59,19 @@ export interface MerchantProduct {
   created_at: string
 }
 
+export interface ProductCatalogItem {
+  id: number
+  product_id: number
+  sku: string
+  display_name: string
+  category: string
+  price_amount: number
+  cost_amount: number
+  currency: string
+  stock: number
+  status: 'active' | 'inactive'
+}
+
 export interface WalletAccount {
   id: number
   merchant_id: number