# models/chat.py
from pydantic import BaseModel
from datetime import datetime
from typing import List, Optional

class ChatRequest(BaseModel):
    user_id: str        # identifier for the user (can be same as session if desired)
    session_id: Optional[str] = None # new: multi-session handling
    message: str        # user input text
    model_name: Optional[str] = None  # <-- Add this

class ChatResponse(BaseModel):
    response: str       # assistant's reply
    session_id: str       # <-- now included in every response