fix(ledger): 修复历史净值双重汇率折算 bug 与汇率时间查询边界

app/api/debug/snapshot/route.ts

@@ -48,10 +48,10 @@ async function buildDailyRatesMap(targetDateStr: string): Promise<Record<string,
   function getClosestRateForDate(currencyPair: string): string | null {
     const records = ratesCache.get(currencyPair);
     if (!records || records.length === 0) return null;
-    const targetDt = new Date(targetDateStr + 'T00:00:00Z');
+    const endOfDay = new Date(targetDateStr + 'T23:59:59.999');
     let closest: RateRecord | null = null;
     for (const rec of records) {
-      if (rec.fetchTime <= targetDt) {
+      if (rec.fetchTime <= endOfDay) {
         closest = rec;
       } else {
         break;
@@ -222,7 +222,7 @@ export async function GET(req: Request) {
       const fxNum = snapshotFxRate;
 
       const calcMarketValueCny = holding.quantity.times(priceNum).times(fxNum);
-      const calcCostCny = holding.totalCost.times(fxNum);
+      const calcCostCny = holding.totalCost;
 
       totalMarketValue = totalMarketValue.plus(calcMarketValueCny);
       totalCost = totalCost.plus(calcCostCny);