feat(chat): add background task for updating chat title from message content

api/routers/chats.py

@@ -1,7 +1,7 @@
 import uuid
 from typing import List
 
-from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi import APIRouter, Depends, HTTPException, status, BackgroundTasks 
 from sqlmodel.ext.asyncio.session import AsyncSession
 
 # --- LangChain Imports ---
@@ -110,6 +110,7 @@ async def post_message_and_get_response(
     *,
     chat_id: uuid.UUID,
     message_in: MessageCreate,
+    background_tasks: BackgroundTasks,
     user_id: uuid.UUID = Depends(get_current_user),
     db: AsyncSession = Depends(get_db)
 ):
@@ -149,7 +150,10 @@ async def post_message_and_get_response(
 
     # 8. If this was the first message, generate and set a title for the chat
     if is_first_user_message:
-        new_title = await generate_chat_title(message_in.content)
-        await chat_crud.update_chat_title(db=db, chat=chat, chat_update=ChatUpdate(title=new_title))
-
+        background_tasks.add_task(
+            chat_crud.update_chat_title_from_message,
+            db=db,
+            chat_id=chat.id,
+            message_content=message_in.content
+        )
     return final_ai_message

db/crud/chat.py

@@ -4,10 +4,12 @@ from typing import Optional
 
 from sqlmodel import Session, select
 from sqlmodel.ext.asyncio.session import AsyncSession
-from sqlalchemy.orm import selectinload
+from sqlalchemy.orm import selectinload, raiseload
 from db.models.chat import Chat
 from db.schemas.chat import ChatUpdate
 
+from workflow.title_generator import generate_chat_title
+
 async def create_chat(db: AsyncSession, user_id: uuid.UUID) -> Chat:
     """Creates a new, empty chat for a specific user asynchronously."""
     db_chat = Chat(user_id=user_id)
@@ -18,7 +20,12 @@ async def create_chat(db: AsyncSession, user_id: uuid.UUID) -> Chat:
 
 async def get_chats_by_user(db: AsyncSession, user_id: uuid.UUID) -> list[Chat]:
     """Retrieves all chats for a specific user, sorted by the most recently updated."""
-    statement = select(Chat).where(Chat.user_id == user_id).order_by(Chat.updated_at.desc())
+    statement = (
+        select(Chat)
+        .where(Chat.user_id == user_id)
+        .order_by(Chat.updated_at.desc())
+        .options(raiseload(Chat.messages)) # Proactively block loading of messages
+    )
     result = await db.exec(statement)
     return result.all()
 
@@ -41,6 +48,28 @@ async def update_chat_title(db: AsyncSession, chat: Chat, chat_update: ChatUpdat
     await db.refresh(chat)
     return chat
 
+async def update_chat_title_from_message(db: AsyncSession, chat_id: uuid.UUID, message_content: str):
+    """
+    Generates a title from a message and updates the chat record.
+    Designed to be run as a background task.
+    """
+    try:
+        chat = await db.get(Chat, chat_id)
+        if not chat or chat.title != "New Chat":
+            # Chat doesn't exist or has already been titled, so we exit.
+            return
+
+        new_title = await generate_chat_title(message_content)
+        if new_title:
+            chat.title = new_title
+            db.add(chat)
+            await db.commit()
+            print(f"INFO:     Background task updated title for chat {chat_id} to '{new_title}'")
+    except Exception as e:
+        print(f"ERROR:    Background task failed for chat {chat_id}: {e}")
+    finally:
+        await db.close() # Ensure the session is closed.
+
 async def delete_chat(db: AsyncSession, chat: Chat) -> None:
     """Deletes a chat from the database."""
     await db.delete(chat)