fixed dependencies issues

.gitignore

@@ -1,5 +1,5 @@
 .env
-vectorstore/
 myenv/
 __pycache__/
-*.py[cod]
+*.py[cod]
+vectorstore/

app.py

@@ -1,24 +1,32 @@
 from __future__ import annotations
 
+from contextlib import asynccontextmanager
 from fastapi import FastAPI, HTTPException
 from pydantic import BaseModel, Field
 import logging
-
 from google.genai.errors import ClientError, ServerError
-
 from rag.chain import aanswer
 from rag.retriever import get_retriever
 
 logger = logging.getLogger(__name__)
 
-app = FastAPI(
-    title="FAQ RAG Chatbot", 
-    version="1.0.0"
-)
 
-@app.on_event("startup")
-async def startup() -> None:
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """Pre-warm the retriever at startup so the first request is fast."""
+    logger.info("Pre-warming retriever (loading embeddings + FAISS index)...")
     get_retriever()
+    logger.info("Retriever ready.")
+    yield
+
+
+app = FastAPI(
+    title="FAQ RAG Chatbot",
+    version="1.0.0",
+    description="RAG-based chatbot for samagama internship portal - CSFAQ Project",
+    openapi_url="/openapi.json",
+    lifespan=lifespan,
+)
 
 
 class ChatRequest(BaseModel):

requirements.txt

@@ -7,9 +7,11 @@ numpy
 rank-bm25
 sentence-transformers
 google-genai
-langchain
-langchain-core
-langchain_community
+
+langchain-classic
+langchain-community>=0.4.0
+langchain-core>=1.2.5,<2.0.0
+
 faiss-cpu
 python-dotenv
 langchain_huggingface