要求结构化响应

{
  "type": "json_schema",
  "json_schema": {
    "name": "invoice_check",
    "strict": true,
    "schema": {
      "type": "object",
      "properties": {
        "status": { "type": "string", "enum": ["clear", "review"] },
        "amount": { "type": ["number", "null"] },
        "reason": { "type": "string" }
      },
      "required": ["status", "amount", "reason"],
      "additionalProperties": false
    }
  }
}