diff --git a/YLErpDAL/Modules/SwapModule/Penalty/PenaltyInterestFeeMerger.cs b/YLErpDAL/Modules/SwapModule/Penalty/PenaltyInterestFeeMerger.cs
index 91ab256f..aa0b4ce0 100644
--- a/YLErpDAL/Modules/SwapModule/Penalty/PenaltyInterestFeeMerger.cs
+++ b/YLErpDAL/Modules/SwapModule/Penalty/PenaltyInterestFeeMerger.cs
@@ -141,16 +141,29 @@ public static class PenaltyInterestFeeMerger
         if (unwindOnResetDay)
         {
             capitalized = (preEod?.InterestIncomeSum ?? 0m) * share;
+            if (preEod != null)
+                trace?.Note(
+                    $"PENALTY|p{position.id} 承接①推导 重置日平仓+有快照：快照{preEod.ValueDate:yyyy-MM-dd} " +
+                    $"昨日待实现利息InterestIncomeSum={preEod.InterestIncomeSum:F4} ×share={share:P4} → ①={capitalized:F4}");
             if (preEod == null && (unwindDate - position.PosiStartDate).Days >= periodDays)
                 trace?.Note($"PENALTY|p{position.id} 注意 无preEod且平仓日=重置日：①退化0（此前重置并入额缺失，请核对日终归档完整性）");
         }
         else if (preEod != null)
         {
-            capitalized = Math.Max(0m, preEod.TdInterestPrincipal * share - closePrincipal);
+            // 段中平仓+有快照（复利承接主路径）：① = 快照滚动基数×份额 − 平仓本金。全程留推导——
+            // ①异常时凭此行即可区分"快照基数错 / share错 / 平仓本金错"三因，不必反推。
+            var rawCarry = preEod.TdInterestPrincipal * share - closePrincipal;
+            capitalized = Math.Max(0m, rawCarry);
+            trace?.Note(
+                $"PENALTY|p{position.id} 承接①推导 段中平仓+有快照：快照{preEod.ValueDate:yyyy-MM-dd} " +
+                $"滚动基数TdInterestPrincipal={preEod.TdInterestPrincipal:F4} ×share={share:P4} −平仓本金{closePrincipal:F4} = {rawCarry:F4} → ①={capitalized:F4}" +
+                (rawCarry < 0m ? "（原始差为负已钳0：快照滚动基数×份额小于平仓本金，疑部分平仓比例与快照归档口径不一致，请核对eod_swap_position.TdInterestPrincipal）" : ""));
         }
         else
         {
             capitalized = Math.Max(0m, normalEvent.InterestPrincipal - closePrincipal);
+            trace?.Note(
+                $"PENALTY|p{position.id} 承接①推导 段中平仓+无快照兜底：事件基数InterestPrincipal={normalEvent.InterestPrincipal:F4} −平仓本金{closePrincipal:F4} → ①={capitalized:F4}");
             // 兜底①=0 但账龄已过重置周期：复利每周期并本，理应 ①>0——多为 interestWindowEmpty
             // (当日已结息)早退未重放覆盖种子值、或日终归档缺失。留痕含两侧基数与账龄，供直接定位根因。
             var ageDays = (unwindDate - position.PosiStartDate).Days;