Add a restricted set of built-ins

app.py

@@ -124,8 +124,29 @@ Rules:
         # Prepare sandbox
         local_vars = {"df1": df1, "df2": df2, "pd": pd}
 
+        # Define a restricted set of built-ins
+        safe_builtins = {
+            "abs": abs,
+            "all": all,
+            "any": any,
+            "bool": bool,
+            "dict": dict,
+            "float": float,
+            "int": int,
+            "len": len,
+            "list": list,
+            "max": max,
+            "min": min,
+            "range": range,
+            "str": str,
+            "sum": sum,
+            "round": round,
+            "KeyError": KeyError,
+            "ValueError": ValueError,
+        }
+
         # Execute code
-        exec(safe_code, {"__builtins__": {}}, local_vars)
+        exec(safe_code, {"__builtins__": safe_builtins}, local_vars)
 
         # Fetch result
         result = local_vars.get("result", "No result produced")