Fix Chapter 11 quiz inference routing and failure handling

app.py

@@ -10,6 +10,7 @@ import black  # Add black import
 # Initialize the inference client
 client = InferenceClient(
     api_key=os.getenv("HF_TOKEN"),  # Make sure to set this environment variable
+    provider="auto",  # Use the current Inference Providers routing layer
 )
 
 # Load questions from Hugging Face dataset
@@ -98,11 +99,18 @@ def check_code(
 
     except Exception as e:
         gr.Warning(f"Error checking code: {str(e)}")
-        # Fall back to simple string comparison if LLM fails
+        # Fall back to exact comparison if LLM fails. A mismatch is
+        # inconclusive while the automated grader is unavailable.
         is_correct = formatted_user_code.strip() == formatted_solution.strip()
-        status = "✅ Correct!" if is_correct else "❌ Incorrect!"
-        gr.Info(f"{status} (Fallback comparison)")
-        return is_correct
+        if is_correct:
+            gr.Info("✅ Correct! (Exact-match fallback)")
+            return True
+
+        gr.Warning(
+            "The automated grader is temporarily unavailable. "
+            "Your answer was not marked incorrect. Please try again."
+        )
+        return None
 
 
 def on_user_logged_in(token: gr.OAuthToken | None):
@@ -226,6 +234,27 @@ def handle_quiz(question_idx, user_answers, submitted_code, is_start):
                 current_q["challenge"],
                 current_q["assessment_criteria"],
             )
+            # Keep the current question and score unchanged if the grader is
+            # unavailable, so an infrastructure failure is not recorded as wrong.
+            if is_correct is None:
+                return (
+                    f"## Question {question_idx + 1} \n### {current_q['challenge']}",
+                    gr.update(value=formatted_code, visible=True),
+                    (
+                        "The automated grader is temporarily unavailable. "
+                        "Your answer was not marked incorrect. Please try again."
+                    ),
+                    question_idx,
+                    user_answers,
+                    gr.update(visible=False),
+                    gr.update(visible=True),
+                    gr.update(visible=False),
+                    gr.update(visible=False),
+                    gr.update(
+                        value=current_q["image"],
+                        visible=True if current_q["image"] else False,
+                    ),
+                )
             user_answers.append(
                 {
                     "challenge": current_q["challenge"],

requirements.txt

@@ -34,7 +34,7 @@ gradio-client==1.7.0
 h11==0.14.0
 httpcore==1.0.7
 httpx==0.28.1
-huggingface-hub==0.28.1
+huggingface-hub==1.4.1
 idna==3.10
 ipykernel==6.29.5
 ipython==8.32.0