Update app.py

app.py

@@ -91,6 +91,16 @@ class SimpleRetriever(BaseRetriever):
 
         ranked_docs = sorted(zip(similarities, self.documents), reverse=True)
         return [doc for _, doc in ranked_docs[:5]]
+documents, embeddings = build_pdf_index()
+retriever = SimpleRetriever(documents=documents, embeddings=embeddings)
+
+# بعد chain را بساز
+chain = RetrievalQA.from_chain_type(
+    llm=llm,
+    retriever=retriever,
+    chain_type="stuff",
+    input_key="question"
+)
 # ----------------- استیت برای چت -----------------
 if 'messages' not in st.session_state:
     st.session_state.messages = []