curl "http://localhost:18080/api/history?user_id=user_123&session_id=session_abc&limit=20"

{
  "history": [
    {
      "role": "user",
      "content": "How many steps did I take yesterday?",
      "timestamp": "2024-01-15T10:30:00Z"
    },
    {
      "role": "assistant",
      "content": "Based on your Garmin data, you took 10,543 steps yesterday.",
      "timestamp": "2024-01-15T10:30:02Z"
    }
  ],
  "session_id": "session_abc",
  "total_messages": 2
}