Update app.py

app.py

@@ -286,10 +286,9 @@ async def chat(
             context_pieces.append(
                 f"Source: {src} (page {page}, chunk {chunk})\n{doc}"
             )
-        if not context_pieces:
-            return {"answer": "I don't know"}
+            
         context_text = "\n\n---\n\n".join(context_pieces) if context_pieces else ""
-
+        has_context = bool(context_pieces)
         # Parse history if provided
         history_msgs = []
         if history:
@@ -316,14 +315,13 @@ async def chat(
 
         # Core system prompt
         system_prompt = (
-            "You are a STRICT RAG chatbot. "
-            "Use ONLY the information in the provided context to answer factual questions. "
-            "Chat history is ONLY for understanding conversation flow, NOT for facts. "
-            "If the answer is not present in the context, reply EXACTLY with: 'I don't know'. "
-            "Do NOT guess. Do NOT use outside knowledge."
+            "You are a helpful study chatbot. "
+            "If context from uploaded documents is provided, use ONLY that context to answer. "
+            "If no relevant context is found, provide the best general answer using your own knowledge. "
+            "Never say 'I don't know' unless the question is unclear. "
+            "Chat history is ONLY for understanding conversation flow."
         )
 
-
         # ❗ STRICT: If no RAG context, answer immediately
         if not context_pieces:
             return {"answer": "I don't know"}
@@ -338,10 +336,11 @@ async def chat(
             messages_payload.extend(history_msgs)
         
         # Add RAG context once (NO DUPLICATES)
-        messages_payload.append({
-            "role": "system",
-            "content": f"Context:\n{context_text}"
-        })
+        if has_context:
+            messages_payload.append({
+                "role": "system",
+                "content": f"Context:\n{context_text}"
+            })
         
         # Add user's question
         messages_payload.append({