2 files changed, 118 insertions, 0 deletions
diff --git a/frontend/src/lib/capitalMetrics.test.ts b/frontend/src/lib/capitalMetrics.test.ts
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+++ b/frontend/src/lib/capitalMetrics.test.ts
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+// 投入口径 reporting 推导函数测试（Leader 第二轮返工后追加任务 A3）。
+// 断言锚点 = 生产现网 run 26e9c9ab-2fad-4a7d-8190-2a7134a11f76 的真实账目：
+//   累计投入 12029.09 / 最终持仓估值 10846.00 / 投入回报率 -9.84%。
+// 口径：投入 = 首日 cash − 末日 cash；估值 = Σ 末日 positions × closes；
+// 回报 = 估值 / 投入 − 1。不含初始账户闲置现金。
+import { describe, expect, it } from 'vitest';
+import { capitalReporting, fmtInvestmentPct } from './capitalMetrics';
+
+// 忠实于现网该 run 的首末两行（中间行与本口径无关）。
+const fixture = {
+  equity: [
+    { date: '2025-09-18', equity: 100000.0, cash: 100000.0, closes: { '159399': 1.127 }, positions: { '159399': 0 } },
+    { date: '2026-09-17', equity: 98816.91045543, cash: 87970.91045543001, closes: { '159399': 0.986 }, positions: { '159399': 11000 } }
+  ]
+} as const;
+
+describe('capitalReporting（现网 run 26e9c9ab 真实账目锚点）', () => {
+  it('累计投入 = 首日 cash − 末日 cash，保留 2 位', () => {
+    const c = capitalReporting(fixture as never);
+    expect(c.invested).toBeCloseTo(12029.09, 2);
+  });
+
+  it('最终持仓估值 = Σ 末日 positions × closes（10846.00）', () => {
+    const c = capitalReporting(fixture as never);
+    expect(c.holdingValue).toBeCloseTo(10846.0, 2);
+  });
+
+  it('投入回报率 = 估值 / 投入 − 1，带正负号与百分号（-9.84%）', () => {
+    const c = capitalReporting(fixture as never);
+    expect(c.returnPct).toBe('-9.84%');
+  });
+
+  it('多持仓键：多个 symbol 的市值求和', () => {
+    const multi = {
+      equity: [
+        { date: 'd0', equity: 50000, cash: 50000 },
+        { date: 'd1', equity: 50600, cash: 30000, closes: { A: 10.0, B: 2.0 }, positions: { A: 2000, B: 300 } }
+      ]
+    } as never;
+    const c = capitalReporting(multi);
+    expect(c.invested).toBeCloseTo(20000, 2);
+    expect(c.holdingValue).toBeCloseTo(20000 + 600, 2);
+    expect(c.returnPct).toBe('+3.00%');
+  });
+
+  it('无投入（未建仓）时回报为 null，不除零', () => {
+    const flat = { equity: [{ date: 'd0', equity: 100000, cash: 100000 }] } as never;
+    const c = capitalReporting(flat);
+    expect(c.invested).toBeCloseTo(0, 2);
+    expect(c.holdingValue).toBeCloseTo(0, 2);
+    expect(c.returnPct).toBeNull();
+  });
+
+  it('空 equity 返回全 null，UI 可渲染占位', () => {
+    const c = capitalReporting({ equity: [] } as never);
+    expect(c.invested).toBeNull();
+    expect(c.holdingValue).toBeNull();
+    expect(c.returnPct).toBeNull();
+  });
+});
+
+describe('fmtInvestmentPct（正负号与百分号）', () => {
+  it('负值带负号', () => {
+    expect(fmtInvestmentPct(-0.098435)).toBe('-9.84%');
+  });
+  it('正值带加号', () => {
+    expect(fmtInvestmentPct(0.03)).toBe('+3.00%');
+  });
+  it('四舍五入两位', () => {
+    expect(fmtInvestmentPct(0.045849)).toBe('+4.58%');
+  });
+});
diff --git a/frontend/src/lib/capitalMetrics.ts b/frontend/src/lib/capitalMetrics.ts
new file mode 100644
index 0000000..cd062a8
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+++ 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 };
+}