[
  {
    "id": "c1",
    "title": "Hello",
    "create_time": 1700000000.0,
    "update_time": 1700000100.0,
    "mapping": {
      "root": { "id": "root", "message": null, "children": ["m1"] },
      "m1": {
        "id": "m1",
        "message": {
          "id": "m1",
          "author": { "role": "user" },
          "create_time": 1700000010.0,
          "content": { "content_type": "text", "parts": ["Hello, world"] }
        },
        "children": ["m2"]
      },
      "m2": {
        "id": "m2",
        "message": {
          "id": "m2",
          "author": { "role": "assistant" },
          "create_time": 1700000020.0,
          "content": { "content_type": "text", "parts": ["Hi!"] }
        },
        "children": []
      }
    }
  }
]