feat(admin-order): 订单管理列表恢复号主实际收入列

在金额左侧展示已结账/已仲裁订单的到手金额；整页一条批量 SQL 取最新结账行，避免 N+1。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/internal/modules/order/queries.go

@@ -173,9 +173,29 @@ func (r *Repository) ListAdmin(ctx context.Context, query AdminOrderQuery) (*Adm
 		}
 	}
 
+	// 号主实际收入：按需收集本页行号，一次性批量查询（单条 SQL），避免逐行查询的 N+1。
+	ownerIncome := make(map[uint64]int64)
+	incomeOrderIDs := make([]uint64, 0, len(rows))
+	for _, row := range rows {
+		if adminListItemNeedsOwnerIncome(row) {
+			incomeOrderIDs = append(incomeOrderIDs, row.ID)
+		}
+	}
+	if len(incomeOrderIDs) > 0 {
+		ownerIncome, err = r.latestOwnerIncomeByOrder(ctx, incomeOrderIDs)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	items := make([]AdminOrderListItemDTO, 0, len(rows))
 	for _, row := range rows {
-		items = append(items, row.toAdminListItem())
+		item := row.toAdminListItem()
+		if amount, ok := ownerIncome[row.ID]; ok {
+			value := amount
+			item.OwnerIncomeAmountCent = &value
+		}
+		items = append(items, item)
 	}
 
 	return &AdminOrderListPaginatedResult{
@@ -218,38 +238,57 @@ func (r *Repository) adminOrderCountQuery(ctx context.Context, query AdminOrderQ
 	return r.adminOrderJoinQuery(ctx)
 }
 
-// latestAdminCheckouts loads one latest checkout per order so the admin order
-// list can display finalized income without issuing one query per row.
-func (r *Repository) latestAdminCheckouts(ctx context.Context, rows []orderRow) (map[uint64]model.OrderCheckout, error) {
-	result := make(map[uint64]model.OrderCheckout, len(rows))
-	if len(rows) == 0 {
+// latestOwnerIncomeByOrder 批量读取每单「最新一次结账」的号主实际到手金额（分）。
+//
+// 后台订单列表专用：一次查询覆盖整页，不会退化为逐行查询的 N+1。
+// 只取结账表两列，不加载 content / evidence_urls 等大字段。
+//
+// 语义：多轮还价是原地更新同一行，但订单可能经历多次结账流程，
+// 因此按 order_id 取 MAX(id) 作为最终结账行。
+//
+// 执行计划（MySQL 8.4 实测，EXPLAIN FORMAT=TREE）：
+//
+//	-> Nested loop inner join
+//	    -> Materialize
+//	        -> Group aggregate: max(order_checkouts.id)
+//	            -> Covering index scan on order_checkouts using idx_order_checkouts_order_id
+//	    -> Single-row index lookup on oc using PRIMARY (id=latest.latest_id)
+//
+// 用 STRAIGHT_JOIN 固定连接顺序：先物化「每单最新结账 id」小集合（走
+// idx_order_checkouts_order_id 覆盖索引），再按主键逐行取金额。避免优化器
+// 在数据量增长后改选全表扫描；开销只与当前页订单数相关，与结账表总量无关。
+func (r *Repository) latestOwnerIncomeByOrder(ctx context.Context, orderIDs []uint64) (map[uint64]int64, error) {
+	result := make(map[uint64]int64, len(orderIDs))
+	if len(orderIDs) == 0 {
 		return result, nil
 	}
-	orderIDs := make([]uint64, 0, len(rows))
-	for _, row := range rows {
-		orderIDs = append(orderIDs, row.ID)
-	}
 	latest := r.db.WithContext(ctx).
 		Table("order_checkouts").
-		Select("MAX(id) AS id").
+		Select("order_id, MAX(id) AS latest_id").
 		Where("order_id IN ?", orderIDs).
 		Group("order_id")
-	var checkouts []model.OrderCheckout
+	var rows []struct {
+		OrderID               uint64
+		OwnerIncomeAmountCent int64
+	}
 	if err := r.db.WithContext(ctx).
-		Table("order_checkouts AS oc").
-		Joins("JOIN (?) AS latest ON latest.id = oc.id", latest).
-		Find(&checkouts).Error; err != nil {
+		Table("(?) AS latest", latest).
+		Select("oc.order_id, oc.owner_income_amount_cent").
+		Joins("STRAIGHT_JOIN order_checkouts AS oc ON oc.id = latest.latest_id").
+		Scan(&rows).Error; err != nil {
 		return nil, err
 	}
-	for _, checkout := range checkouts {
-		result[checkout.OrderID] = checkout
+	for _, row := range rows {
+		result[row.OrderID] = row.OwnerIncomeAmountCent
 	}
 	return result, nil
 }
 
-func shouldAttachAdminCheckout(row orderRow) bool {
-	return shouldAttachCheckout(row.Status) ||
-		row.SettlementStatus == settlementStatusSettled ||
+// adminListItemNeedsOwnerIncome 判断列表行是否需要附带号主实际收入。
+// 仅已结账/已仲裁时库中金额为最终值；协商中的金额会随后续还价变化，
+// 不作为列表结论展示（协商中的实时金额走详情接口）。
+func adminListItemNeedsOwnerIncome(row orderRow) bool {
+	return row.SettlementStatus == settlementStatusSettled ||
 		row.SettlementStatus == settlementStatusArbitrated
 }
 
@@ -415,15 +454,6 @@ func effectiveDisputeInitiatorType(row model.Dispute) string {
 	return "user"
 }
 
-func shouldAttachCheckout(status string) bool {
-	switch status {
-	case orderStatusPendingCheckoutConfirm, orderStatusPendingCheckoutAccept, orderStatusCheckoutDisputing, orderStatusCompleted:
-		return true
-	default:
-		return false
-	}
-}
-
 func (r *Repository) latestCheckoutDTOForUser(ctx context.Context, orderID uint64, userID uint64, order model.RentalOrder) *CheckoutDTO {
 	var checkout model.OrderCheckout
 	if err := r.db.WithContext(ctx).Where("order_id = ?", orderID).Order("id DESC").First(&checkout).Error; err != nil {