1 files changed, 46 insertions, 0 deletions
diff --git a/frontend/src/lib/capitalMetrics.ts b/frontend/src/lib/capitalMetrics.ts
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+// 投入口径 reporting（任务 A）：纯前端推导，不触后端与 worker 容器。
+// 口径（在结果页注明"不含初始账户闲置现金"）：
+//   累计投入 = 首日 cash − 末日 cash（保留 2 位）
+//   最终持仓估值 = Σ 末日 positions[k] × closes[k]
+//   投入回报率 = 估值 / 投入 − 1（带正负号与百分号）
+// 未建仓/无数据返回 null，由 UI 以 "—" 占位，不编造数字。
+import type { BacktestResult } from './types';
+
+export interface CapitalReporting {
+  invested: number | null;
+  holdingValue: number | null;
+  returnPct: string | null;
+}
+
+/** round(v, 2) with fixed exponent (avoids FP drift vs Number(v.toFixed(2))) */
+function r2(v: number): number {
+  return Number(v.toFixed(2));
+}
+
+export function fmtInvestmentPct(x: number): string {
+  return `${x >= 0 ? '+' : ''}${(x * 100).toFixed(2)}%`;
+}
+
+export function capitalReporting(
+  result: Pick<BacktestResult, 'equity'> | { equity?: BacktestResult['equity'] | undefined }
+): CapitalReporting {
+  const eq = result?.equity ?? [];
+  const first = eq[0];
+  const last = eq[eq.length - 1];
+  if (!first || !last || eq.length < 2) return { invested: null, holdingValue: null, returnPct: null };
+
+  const invested = r2(first.cash - last.cash);
+  let holdingValue = 0;
+  const pos = (last as { positions?: Record<string, number> }).positions;
+  const cls = (last as { closes?: Record<string, number> }).closes;
+  if (pos && cls) {
+    for (const sym of Object.keys(pos)) {
+      holdingValue += (pos[sym] ?? 0) * (cls[sym] ?? 0);
+    }
+  }
+  const investedOut = eq.length >= 2 ? invested : null;
+  const holdingValueOut = r2(holdingValue);
+  const returnPct =
+    investedOut !== null && investedOut > 0 ? fmtInvestmentPct(holdingValueOut / investedOut - 1) : null;
+  return { invested: investedOut, holdingValue: holdingValueOut, returnPct };
+}