Launch a draft session

Example response

{
  "data": {
    "id": "sess_abcdef123456",
    "run_id": "run_xyz789",
    "claude_session_id": "claude_sess_123",
    "parent_session_id": "sess_parent123",
    "query": "Help me refactor this code",
    "summary": "Refactored authentication module",
    "title": "My Important Task",
    "model": "sonnet",
    "model_id": "claude-opus-4-1-20250805",
    "working_dir": "/home/user/project",
    "additional_directories": [
      "~/.humanlayer/logs",
      "/var/log/myapp"
    ],
    "cost_usd": 0.05,
    "input_tokens": 1000,
    "output_tokens": 500,
    "cache_creation_input_tokens": 100,
    "cache_read_input_tokens": 50000,
    "effective_context_tokens": 51100,
    "context_limit": 168000,
    "duration_ms": 45000,
    "proxy_base_url": "https://openrouter.ai/api/v1",
    "proxy_model_override": "openai/gpt-oss-120b",
    "editor_state": "{\"content\":\"console.log(\\\"hello\\\");\",\"cursorPosition\":24}"
  }
}