[
  {
    "timestamp": "2026-03-11T05:59:44.031Z",
    "dev_id": "DEV-004",
    "steps": {
      "portrait": "✅",
      "pca": "✅",
      "sync": "✅"
    },
    "duration_ms": 1,
    "pca": {
      "score": 73,
      "grade": "A"
    },
    "suggestion": "🎯 可进更高难度：EL-9 挑战",
    "status": "completed"
  },
  {
    "timestamp": "2026-03-11T05:53:04.004Z",
    "dev_id": "DEV-004",
    "steps": {
      "portrait": "✅",
      "pca": "✅",
      "sync": "✅"
    },
    "duration_ms": 7,
    "pca": {
      "score": 66,
      "grade": "B"
    },
    "suggestion": "📚 继续当前模块：巩固 Phase4 基础",
    "status": "completed"
  }
]