fix(ledger): 修復分紅業務邏輯與成本算法，支持攤薄成本為負數的極端場景

src/actions/portfolio.ts

@@ -25,6 +25,7 @@ interface Position {
   dilutedCost: string;
   holdingDays: number;
   exchange: string;
+  totalDividendCny: string;
 }
 
 interface RawRate {
@@ -179,6 +180,7 @@ export async function getPortfolioPositions(): Promise<Position[]> {
         totalBuyCostNative: new Big('0'),
         totalBuyQuantity: new Big('0'),
         realizedPnlCny: new Big('0'),
+        totalDividendCny: new Big('0'),
         firstBuyDate: null,
       });
     }
@@ -228,7 +230,10 @@ export async function getPortfolioPositions(): Promise<Position[]> {
     } else if (tx.txType === 'AIRDROP') {
       holding.quantity = holding.quantity.plus(new Big(tx.quantity));
     } else if (tx.txType === 'DIVIDEND') {
-      holding.quantity = holding.quantity.plus(new Big(tx.quantity));
+      const dividendAmountNative = new Big(tx.quantity).times(new Big(tx.price));
+      const dividendCny = dividendAmountNative.times(new Big(tx.exchangeRate || '1'));
+      holding.realizedPnlCny = holding.realizedPnlCny.plus(dividendCny);
+      holding.totalDividendCny = holding.totalDividendCny.plus(dividendCny);
     }
 
     if (tx.assetLatestPrice) {
@@ -263,10 +268,10 @@ export async function getPortfolioPositions(): Promise<Position[]> {
       avgCost = holding.totalBuyCostCny.div(holding.totalBuyQuantity);
     }
 
-    // 摊薄成本 = (总买入成本 - 已实现盈亏) / 当前持仓数量
+    // 摊薄成本 = (总买入成本 - 已实现盈亏 - 总分红) / 当前持仓数量
     let dilutedCost = new Big('0');
     if (holding.quantity.gt(0)) {
-      dilutedCost = holding.totalBuyCostCny.minus(holding.realizedPnlCny).div(holding.quantity);
+      dilutedCost = holding.totalBuyCostCny.minus(holding.realizedPnlCny).minus(holding.totalDividendCny).div(holding.quantity);
     }
 
     // 持仓天数
@@ -295,6 +300,7 @@ export async function getPortfolioPositions(): Promise<Position[]> {
       dilutedCost: dilutedCost.toString(),
       holdingDays,
       exchange: holding.exchange,
+      totalDividendCny: holding.totalDividendCny.toString(),
     });
   }