Stateless Conversation State Management
Load Conversation History
async def load_conversation_history(
session: AsyncSession,
user_id: str,
conversation_id: int | None
) -> tuple[Conversation, list[dict]]:
"""Load or create conversation with message history."""
if conversation_id:
stmt = select(Conversation).where(
Conversation.id == conversation_id,
Conversation.user_id == user_id
)
result = await session.execute(stmt)
conversation = result.scalar_one_or_none()
if not conversation:
raise HTTPException(status_code=404, detail="Conversation not found")
else:
conversation = Conversation(user_id=user_id)
session.add(conversation)
await session.commit()
await session.refresh(conversation)
# Load messages
stmt = select(Message).where(
Message.conversation_id == conversation.id
).order_by(Message.created_at)
result = await session.execute(stmt)
db_messages = result.scalars().all()
messages = [{"role": msg.role, "content": msg.content} for msg in db_messages]
return conversation, messages
Complete Stateless Flow
@app.post("/api/{user_id}/chat")
async def chat(
user_id: str,
request: ChatRequest,
session: AsyncSession = Depends(get_db_session),
current_user: str = Depends(verify_jwt)
):
# 1. Load history from DB
conversation, messages = await load_conversation_history(
session, user_id, request.conversation_id
)
# 2. Save user message
user_msg = Message(
user_id=user_id,
conversation_id=conversation.id,
role="user",
content=request.message
)
session.add(user_msg)
await session.commit()
# 3. Add to history array
messages.append({"role": "user", "content": request.message})
# 4. Run agent
response, tool_calls = await run_agent(messages)
# 5. Save assistant response
assistant_msg = Message(
user_id=user_id,
conversation_id=conversation.id,
role="assistant",
content=response
)
session.add(assistant_msg)
await session.commit()
# 6. Return (server holds NO state)
return ChatResponse(
conversation_id=conversation.id,
response=response,
tool_calls=tool_calls
)
Benefits
- Horizontal scalability (any server handles any request)
- Resilience (server restart doesn't lose conversations)
- Testability (each request independent)
- No sticky sessions needed
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