[Bug]: /ask Q&A endpoint returns null due to duplicate ask_question function declaration

[Sandeep6135]

Summary

Summary

The endpoint handler for the /ask route in main.py is declared twice consecutively under the function name ask_question.
The first declaration (lines 3388-3389) is decorated with @app.post("/ask") but only performs session cleanup and returns nothing. The second declaration (starting at line 3392) contains the actual Q&A/inference implementation but has no route decorator.
In Python, redeclaring a function in the same scope overrides the previous name in the namespace. However, FastAPI registers the first decorated function during application startup. When a client calls /ask, FastAPI routes the request to the first (empty) implementation, which returns None/null to the client. The actual Q&A logic is unreachable and behaves as dead code.

Steps to reproduce

Steps to Reproduce

1. Start the backend RAG service and the Express gateway.
2. Upload a PDF and submit a question using the chat input.
3. Observe that the API returns 200 OK but a body of null (or empty JSON).
4. Inspect the RAG service logs: the Q&A pipeline and model inference never execute.

Expected behavior

Expected Behavior

The /ask endpoint should parse the question, verify the session secret, invoke the LLM model, and return a JSON response containing answer, sources, and mode.

Actual behavior

Actual Behavior

The endpoint returns null with a 200 OK status code, completely bypassing the question-answering logic.

Additional context

Additional Context

The duplicate function declaration in main.py:

@app.post("/ask")
def ask_question(data: Question, _ready: None = Depends(require_models_ready)):
    cleanup_expired_sessions()
def ask_question(data: Question):
    question = (data.question or "").strip()