{
  "all_documents": 20,
  "selected_ids": [
    "policy-2026",
    "shipping",
    "noise-0"
  ],
  "answer_evidence": {
    "id": "policy-2026",
    "text": "现行政策：退款期限为签收后14天。",
    "date": "2026-05-01"
  },
  "answer": "14天"
}