refine response instructions for unanswered queries in RAGService

app/services/RAG_service.py

@@ -9,7 +9,6 @@ from app.utils.metadata_utils import MetadataService
 from langchain_core.documents import Document
 import json
 from langchain_community.retrievers import BM25Retriever
-from langchain.schema import Document
 
 # Global model instances (loaded once)
 _embedding_model = None
@@ -155,7 +154,8 @@ class RAGService:
         prompt = f"""
         You are a legal/insurance domain expert and policy analyst. 
         Use the following extracted clauses from policy documents to answer the question.  
-        If you can't find the answer, say "I don't know".
+        If you can't find the answer, either say it is not available in the provided context or respond with whatever you can find gracefully. 
+        Provide a concise and clear answer based on the context.
         Context clauses:
         {"".join(context_clauses)}
         Question: {raw_query}