Update app.py

app.py

@@ -59,8 +59,8 @@ AVAILABLE_MODELS = {
 
 # Chat memory (in-memory)
 
-chat\_histories = defaultdict(list)
-MAX\_HISTORY = 100  # limit memory to avoid crashes
+chat_histories = defaultdict(list)
+MAX_HISTORY = 100  # limit memory to avoid crashes
 
 # Generate response stream