feat(v2): RefundStore(建单/求和/条件翻转/人工待办)+ Order 退款态机(PaidAttempt/ApplyRefundToOrder)

internal/store/order_query.go

@@ -62,3 +62,35 @@ func (s *OrderStore) ExpirePendingAttempts(outTradeNo string) (int64, error) {
 	}
 	return res.RowsAffected, nil
 }
+
+// PaidAttempt returns the settled (paid) attempt of an order — the payment a
+// refund reverses (channel + provider_ref for the original transaction).
+func (s *OrderStore) PaidAttempt(outTradeNo string) (*model.Attempt, error) {
+	var a model.Attempt
+	err := s.db.Where("out_trade_no = ? AND status = ?", outTradeNo, model.AttemptPaid).First(&a).Error
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, ErrAttemptNotFound
+		}
+		return nil, fmt.Errorf("store.PaidAttempt: %w", err)
+	}
+	return &a, nil
+}
+
+// ApplyRefundToOrder advances a settled order's status per cumulative refunds:
+// fully refunded → refunded, else → partially_refunded. Guard: only from a
+// post-paid, non-fully-refunded state (paid / partially_refunded / refunding).
+func (s *OrderStore) ApplyRefundToOrder(outTradeNo string, fully bool) (bool, error) {
+	next := model.OrderPartRefundedV2
+	if fully {
+		next = model.OrderRefundedV2
+	}
+	res := s.db.Model(&model.OrderV2{}).
+		Where("out_trade_no = ? AND status IN ?", outTradeNo,
+			[]model.OrderStatusV2{model.OrderPaidV2, model.OrderPartRefundedV2, model.OrderRefundingV2}).
+		Update("status", next)
+	if res.Error != nil {
+		return false, fmt.Errorf("store.ApplyRefundToOrder: %w", res.Error)
+	}
+	return res.RowsAffected > 0, nil
+}