Update app.py

app.py

@@ -31,12 +31,14 @@ async def evaluate_code(request: EvalRequest):
         messages=[
             {
                 "role": "system", 
-                "content": "You are a friendly, positive Python grading assistant. You strictly output valid JSON only. The score you provide must strictly be an integer from 0 to 100."
+                "content": "You are a friendly Python grader. Output ONLY valid JSON."
             },
             {"role": "user", "content": prompt}
         ],
         max_tokens=250, 
-        temperature=0.1 
+        temperature=0.1,
+        # THIS IS THE MAGIC LINE:
+        response_format={"type": "json_object"} 
     )
         
     return {"evaluation": response['choices'][0]['message']['content']}