{
  "nested_json_columns": [
    "action_history",
    "cost_or_steps",
    "failure_state",
    "final_state",
    "goal",
    "initial_state",
    "oracle",
    "provenance",
    "recovery_action",
    "recovery_sequence"
  ],
  "reason": "Heterogeneous cross-domain structures are losslessly encoded as JSON strings for a stable Arrow schema. Raw original JSONL remains available.",
  "records": 22573
}