Como validar JSON estruturado com Pydantic?

import json
import os

from openai import OpenAI
from pydantic import BaseModel, ValidationError


class Ticket(BaseModel):
    category: str
    summary: str


client = OpenAI(
    api_key=os.environ["BETTERTOKEN_API_KEY"],
    base_url="https://bettertoken.ai/v1",
)

response = client.chat.completions.create(
    model="YOUR_MODEL_ID",
    messages=[
        {
            "role": "user",
            "content": (
                "Return only a JSON object with string fields "
                "category and summary for this support request: "
                "The API request timed out."
            ),
        }
    ],
)

raw = response.choices[0].message.content or ""

try:
    payload = json.loads(raw)
    ticket = Ticket.model_validate(payload)
except (json.JSONDecodeError, ValidationError) as error:
    # Store raw only in a protected debug record allowed by your data policy.
    raise RuntimeError("Model output failed validation") from error

print(ticket.model_dump())