{
    "round_id": 0,
    "plan_agent_input": "...", 
    "plan_agent_output": [{
      "thought": "...",
      "aspect": "Subject‑consistency"
    }],
    "promptgen_input": "...",
    "promptgen_output": {
      "thought": "...",
      "prompt": "Generate a 3‑sec video of ..."
    },
    "eval_results": {...}
  }