Update app.py

app.py

@@ -129,7 +129,7 @@ class BasicAgent:
     def _call_llm(self, prompt: str, max_tokens: int = 256) -> str:
         try:
             resp = self.llm.chat.completions.create(
-                model="gpt-4o-mini",
+                model="gpt-4.1-mini",
                 messages=[
                     {"role": "system", "content": "You are a careful reasoning assistant."},
                     {"role": "user", "content": prompt},