Claude Code，有了界面。

src/cart.ts

 export function applyCoupon(total: number, percent: number): number {-  return total - total * (percent / 100);+  const discount = Math.round(total * percent) / 100;+  return Math.round((total - discount) * 100) / 100; }

tests/cart.test.ts

   });++  it("rounds a percent coupon to whole cents", () => {+    expect(total([{ sku: "mug", price: 19.99, qty: 1 }], 15)).toBe(16.99);+  }); });