fix(swap): 修复部分平仓后算尾利息计算问题(算头算尾T+0合约单利)

- 将测试方法改为数据驱动测试以覆盖不同利息模式
- 在测试中添加对不同利息模式的验证逻辑
- 修复平仓后EOD本金只携带剩余持仓的计算逻辑
- 添加对算尾部分平仓后EOD本金的断言验证
- 优化单利算尾当日按平仓前全额计提的处理逻辑

UnitTestProject/Modules/SwapModule/DealInterestsScenarioTest.cs

@@ -864,8 +864,10 @@ namespace YLErp.Modules.SwapModule
                 "预付金部分平仓待实现收益应为历史待实现+平仓后当日新增-平仓实现");
         }
 
-        [TestMethod]
-        public void DI_MANUAL_PARTIAL_CLOSE_CalcLastIncludesClosedPrincipalDailyInterest()
+        [DataTestMethod]
+        [DataRow((int)InterestModeEnum.合约名义本金规模)]
+        [DataRow((int)InterestModeEnum.标的期初全价)]
+        public void DI_MANUAL_PARTIAL_CLOSE_CalcLastIncludesClosedPrincipalDailyInterest(int interestMode)
         {
             var service = new StubEodPositionService();
             var td = CreateTrade();
@@ -876,6 +878,7 @@ namespace YLErp.Modules.SwapModule
                 SettlementRules = 0
             });
             var position = CreateInterestPosition();
+            position.InterestMode = interestMode;
             var previousEod = CreatePreEod(StartDate.AddDays(2), 100m);
             previousEod.TdInterestPrincipal = Principal;
             var closeFlow = CreateSwapFlowEvent(StartDate.AddDays(3), 50m);
@@ -887,6 +890,8 @@ namespace YLErp.Modules.SwapModule
 
             AssertDecimal(Principal * FixedRate / AnnualDays, result.TdInterestIncome,
                 "算尾部分平仓的当日新计利息应包含已平仓部分（按全额本金计提）");
+            AssertDecimal(500m, result.TdInterestPrincipal,
+                "算尾部分平仓后的 EOD 本金应只携带剩余持仓");
 
             // 补充：算尾部分平仓的待实现利息总额应满足递推
             //   InterestIncomeSum = 前日待实现 + 当日新计(全额本金，含被平仓部分) - 当日实现

YLErpDAL/Modules/SwapModule/SwapEodPositionService.cs

@@ -1453,6 +1453,16 @@ namespace YLErp.Modules.SwapModule
                     newEodPayPosition.TdInterestIncome /= tradeExtend.AnnualDays;
                 }
             }
+            if (!autoSwap
+                && closePercent > 0m && closePercent < 1m
+                && posiNotionalValue > 0m
+                && position.InterestType == (int)InterestTypeEnum.单利
+                && (position.InterestMode == (int)InterestModeEnum.合约名义本金规模
+                    || position.InterestMode == (int)InterestModeEnum.标的期初全价))
+            {
+                // 单利算尾当日仍按平仓前全额计提，跨日 EOD 本金只携带剩余持仓。
+                newEodPayPosition.TdInterestPrincipal = posiNotionalValue;
+            }
             Log.Info($"InterestIncomeSum is {lastInterestIncomeSum},TdInterestIncome is {newEodPayPosition.TdInterestIncome}" +
                      $",TdCloseInterest is {newEodPayPosition.TdCloseInterest}");
             Log.Info($"InterestFeeSum is {eodPayPosition.InterestFeeSum},TdInterestFee is {newEodPayPosition.TdInterestFee}" +