feat: 支持从失败状态重新发起退款，添加相关逻辑和测试用例

backend/app/services/order_test.go

@@ -942,6 +942,77 @@ func (s *OrderTestSuite) Test_AdminRefundOrder() {
 			So(len(ledgers), ShouldEqual, 1)
 		})
 
+		Convey("failed 状态允许重新发起退款（paid/failed -> refunding）", func() {
+			s.truncate(
+				ctx,
+				models.TableNameTenantLedger,
+				models.TableNameContentAccess,
+				models.TableNameOrderItem,
+				models.TableNameOrder,
+				models.TableNameTenantUser,
+				models.TableNameUser,
+			)
+			s.seedTenantUser(ctx, tenantID, buyerUserID, 0, 0)
+
+			contentID := int64(123)
+			orderModel := &models.Order{
+				TenantID:       tenantID,
+				UserID:         buyerUserID,
+				Type:           consts.OrderTypeContentPurchase,
+				Status:         consts.OrderStatusPaid,
+				Currency:       consts.CurrencyCNY,
+				AmountOriginal: 300,
+				AmountDiscount: 0,
+				AmountPaid:     300,
+				Snapshot:       newLegacyOrderSnapshot(),
+				PaidAt:         now,
+				CreatedAt:      now,
+				UpdatedAt:      now,
+			}
+			So(orderModel.Create(ctx), ShouldBeNil)
+
+			item := &models.OrderItem{
+				TenantID:      tenantID,
+				UserID:        buyerUserID,
+				OrderID:       orderModel.ID,
+				ContentID:     contentID,
+				ContentUserID: 999,
+				AmountPaid:    300,
+				Snapshot:      types.NewJSONType(fields.OrderItemsSnapshot{}),
+				CreatedAt:     now,
+				UpdatedAt:     now,
+			}
+			So(item.Create(ctx), ShouldBeNil)
+
+			access := &models.ContentAccess{
+				TenantID:  tenantID,
+				UserID:    buyerUserID,
+				ContentID: contentID,
+				OrderID:   orderModel.ID,
+				Status:    consts.ContentAccessStatusActive,
+				CreatedAt: now,
+				UpdatedAt: now,
+				RevokedAt: time.Time{},
+			}
+			So(access.Create(ctx), ShouldBeNil)
+
+			// 先发起一次退款进入 refunding，再模拟异步失败进入 failed。
+			refunding, err := Order.AdminRefundOrder(ctx, tenantID, operatorUserID, orderModel.ID, false, "原因", "", now.Add(time.Minute))
+			So(err, ShouldBeNil)
+			So(refunding.Status, ShouldEqual, consts.OrderStatusRefunding)
+
+			So(Order.MarkRefundFailed(ctx, tenantID, orderModel.ID, now.Add(2*time.Minute)), ShouldBeNil)
+
+			var failed models.Order
+			So(_db.WithContext(ctx).Where("tenant_id = ? AND id = ?", tenantID, orderModel.ID).First(&failed).Error, ShouldBeNil)
+			So(failed.Status, ShouldEqual, consts.OrderStatusFailed)
+
+			// failed -> refunding 允许重新发起，并再次入队（幂等）。
+			refunding2, err := Order.AdminRefundOrder(ctx, tenantID, operatorUserID, orderModel.ID, false, "原因2", "", now.Add(3*time.Minute))
+			So(err, ShouldBeNil)
+			So(refunding2.Status, ShouldEqual, consts.OrderStatusRefunding)
+		})
+
 		Convey("不可重试错误分类应稳定", func() {
 			So(IsRefundJobNonRetryableError(nil), ShouldBeFalse)
 			So(IsRefundJobNonRetryableError(errors.New("x")), ShouldBeFalse)