diff --git a/YLErpDAL/Modules/SwapModule/ClosePercentMath.cs b/YLErpDAL/Modules/SwapModule/ClosePercentMath.cs
new file mode 100644
index 00000000..9269a449
--- /dev/null
+++ b/YLErpDAL/Modules/SwapModule/ClosePercentMath.cs
@@ -0,0 +1,65 @@
+using YLErp.DBModels;
+
+namespace YLErp.Modules.SwapModule;
+
+/// <summary>
+/// 平仓比例(ClosePercent) 数学——占期初(A) / 占剩余(B) 两种口径的转换。
+/// 从 SwapDealService 提取为共享模块，两个 service 均可引用。
+/// </summary>
+public static class ClosePercentMath
+{
+    /// <summary>
+    /// 取上一日终的浮动端名义本金（orginPv 的来源）。
+    /// 优先取浮动腿 PosiNotionalValue 之和，取不到用 eod_swap 多空绝对值之和，都没有用 currentNotional 兜底。
+    /// </summary>
+    public static decimal ResolveUnwindPreviousNotional(
+        eod_swap lastEod,
+        IEnumerable<eod_swap_position> lastEodPositions,
+        decimal currentNotional)
+    {
+        var floatingPositions = lastEodPositions?.Where(x => x.PosiDirection > 0).ToList();
+        decimal previousNotional;
+        if (floatingPositions?.Count > 0)
+        {
+            previousNotional = floatingPositions.Sum(x => x.PosiNotionalValue);
+        }
+        else
+        {
+            previousNotional = lastEod == null
+                ? currentNotional
+                : Math.Abs(lastEod.NotionalValueLong) + Math.Abs(lastEod.NotionalValueShort);
+        }
+
+        return previousNotional == 0m && currentNotional != 0m
+            ? currentNotional
+            : previousNotional;
+    }
+
+    /// <summary>
+    /// A(占期初) → B(占剩余)，用于把前端传入的占期初比例换算成后端计算用的占剩余比例。
+    /// </summary>
+    public static decimal ToRemainingClosePercent(decimal originalClosePercent, decimal notionalValue, decimal posiNotionalValue)
+    {
+        if (posiNotionalValue <= 0) return originalClosePercent;
+        var remaining = originalClosePercent * notionalValue / posiNotionalValue;
+        return remaining > 1 ? 1 : remaining;
+    }
+
+    /// <summary>
+    /// B(占剩余) → A(占期初)，用于落库 / 事件列表展示还原。见 ToRemainingClosePercent。
+    /// </summary>
+    public static decimal ToOriginalClosePercent(decimal remainingClosePercent, decimal notionalValue, decimal posiNotionalValue)
+    {
+        if (notionalValue <= 0) return remainingClosePercent;
+        return remainingClosePercent * posiNotionalValue / notionalValue;
+    }
+
+    /// <summary>
+    /// 计算 InitUnwind 默认占期初(A)平仓比例 = PosiNotionalValue / NotionalValue。
+    /// 未平仓时 =1（平100%）；部分平仓后自动变为剩余比例。
+    /// </summary>
+    public static decimal CalcDefaultInitClosePercent(decimal notionalValue, decimal posiNotionalValue)
+    {
+        return notionalValue > 0 ? posiNotionalValue / notionalValue : 1;
+    }
+}
diff --git a/YLErpDAL/Modules/SwapModule/SwapDealService.cs b/YLErpDAL/Modules/SwapModule/SwapDealService.cs
index eab142cc..8a3f0796 100644
--- a/YLErpDAL/Modules/SwapModule/SwapDealService.cs
+++ b/YLErpDAL/Modules/SwapModule/SwapDealService.cs
@@ -625,24 +625,7 @@ namespace YLErp.Modules.SwapModule
             eod_swap lastEod,
             IEnumerable<eod_swap_position> lastEodPositions,
             decimal currentNotional)
-        {
-            var floatingPositions = lastEodPositions?.Where(x => x.PosiDirection > 0).ToList();
-            decimal previousNotional;
-            if (floatingPositions?.Count > 0)
-            {
-                previousNotional = floatingPositions.Sum(x => x.PosiNotionalValue);
-            }
-            else
-            {
-                previousNotional = lastEod == null
-                    ? currentNotional
-                    : Math.Abs(lastEod.NotionalValueLong) + Math.Abs(lastEod.NotionalValueShort);
-            }
-
-            return previousNotional == 0m && currentNotional != 0m
-                ? currentNotional
-                : previousNotional;
-        }
+            => ClosePercentMath.ResolveUnwindPreviousNotional(lastEod, lastEodPositions, currentNotional);
 
         /// <summary>
         /// 获取利息腿"已通过历史互换结出的累计利息"（用于复利重算时扣除，类比分红的 CalcConsumedDividend）。
@@ -822,32 +805,19 @@ namespace YLErp.Modules.SwapModule
         /// 分母为 0（无持仓等异常场景）时原样返回，避免除零。
         /// </summary>
         public static decimal ToRemainingClosePercent(decimal originalClosePercent, decimal notionalValue, decimal posiNotionalValue)
-        {
-            if (posiNotionalValue <= 0) return originalClosePercent;
-            var remaining = originalClosePercent * notionalValue / posiNotionalValue;
-            return remaining > 1 ? 1 : remaining;
-        }
+            => ClosePercentMath.ToRemainingClosePercent(originalClosePercent, notionalValue, posiNotionalValue);
 
         /// <summary>
         /// B(占剩余) → A(占期初)，用于落库 / 事件列表展示还原。见 ToRemainingClosePercent。
         /// </summary>
         public static decimal ToOriginalClosePercent(decimal remainingClosePercent, decimal notionalValue, decimal posiNotionalValue)
-        {
-            if (notionalValue <= 0) return remainingClosePercent;
-            return remainingClosePercent * posiNotionalValue / notionalValue;
-        }
+            => ClosePercentMath.ToOriginalClosePercent(remainingClosePercent, notionalValue, posiNotionalValue);
 
         /// <summary>
-        /// 计算 InitUnwind 默认占期初(A)平仓比例 = "平掉剩余全部持仓"对应的占期初比例。
-        /// 即：ClosePercent(A) = PosiNotionalValue / NotionalValue。
-        /// 未平仓时 PosiNotionalValue==NotionalValue → 1（平100%）；
-        /// 部分平仓后自动变为剩余比例（如已平 30% 则默认 0.7）。
-        /// 与互换/提前终止 InitIncome 保持一致。抽出为纯函数以支持无库单测。
+        /// 计算 InitUnwind 默认占期初(A)平仓比例 = PosiNotionalValue / NotionalValue。
         /// </summary>
         public static decimal CalcDefaultInitClosePercent(decimal notionalValue, decimal posiNotionalValue)
-        {
-            return notionalValue > 0 ? posiNotionalValue / notionalValue : 1;
-        }
+            => ClosePercentMath.CalcDefaultInitClosePercent(notionalValue, posiNotionalValue);
 
         /// <summary>
         /// 读取"上一收盘日"浮动腿的待实现分红（eod_swap_position.PosiDividendSum），