{
  "type": "assistant",
  "sessionId": "cfa88393-fc66-480f-8762-fa85a33d1d9f",
  "timestamp": "2026-07-02T16:57:43.795Z",
  "uuid": "21fba4a4-f5e6-4420-a4e8-be64383362f9",
  "parentUuid": "6998eedd-1e25-4ad0-9325-bd2554ac4255",
  "isSidechain": false,
  "message": {
    "role": "assistant",
    "type": "message",
    "model": "claude-fable-5",
    "id": "msg_01UgmX8QWNGApwj8gFAK3EbW",
    "content": [
      {
        "type": "tool_use",
        "id": "toolu_01KFHHG1ptbGeZQK3epbQxhX",
        "name": "Artifact",
        "input": {
          "file_path": "/workspace/demo/artifact-shape-probe.html",
          "favicon": "🔬",
          "description": "Throwaway probe to capture the Artifact tool's JSONL wire format (issue #257).",
          "label": "shape-probe"
        }
      }
    ]
  }
}