List active sessions

[
  {
    "id": "session-1",
    "project_root": "/Users/example/project",
    "harness": "codex",
    "title": "Fix failing tests",
    "status": "running",
    "exit_code": null,
    "archived_at": null,
    "created_at": "2026-05-09T06:43:00.000Z",
    "updated_at": "2026-05-09T06:43:05.000Z"
  }
]

{
  "error": {
    "code": "internal_error",
    "message": "Unexpected internal daemon error.",
    "details": {}
  }
}