Update app.py

app.py

@@ -976,6 +976,61 @@ def rag_search(query, subject, k=5):
     
     return "\n\n".join(results)
 
+# ------------------------------
+# Topic Validation (Check if topic belongs to subject)
+# ------------------------------
+def validate_topic_subject(topic, subject):
+    """
+    Validate if the topic belongs to the selected subject using LLM
+    Returns True if valid, False otherwise
+    """
+    if not groq_client:
+        return True  # Skip validation if API not available
+    
+    validation_prompt = f"""You are a Class 12 PCB subject expert. Determine if the following topic belongs to {subject.title()}.
+
+Topic: "{topic}"
+Subject: {subject.title()}
+
+Class 12 {subject.title()} covers:
+{"- Reproduction, Genetics, Evolution, Plant Physiology, Human Systems, Ecology, Biotechnology" if subject == "biology" else ""}
+{"- Solid State, Solutions, Thermodynamics, Electrochemistry, Organic Chemistry, Coordination Compounds" if subject == "chemistry" else ""}
+{"- Rotational Dynamics, Fluids, Thermodynamics, Waves, Optics, Electromagnetism, Modern Physics, Semiconductors" if subject == "physics" else ""}
+
+Answer ONLY with "YES" if the topic belongs to {subject.title()}, or "NO" if it belongs to a different subject.
+
+Answer:"""
+    
+    try:
+        response = groq_client.chat.completions.create(
+            messages=[
+                {
+                    "role": "system",
+                    "content": f"You are an expert at identifying which subject a topic belongs to. Answer only YES or NO."
+                },
+                {
+                    "role": "user",
+                    "content": validation_prompt
+                }
+            ],
+            model="llama-3.3-70b-versatile",
+            temperature=0.1,
+            max_tokens=10
+        )
+        
+        result = response.choices[0].message.content.strip().upper()
+        
+        if "YES" in result:
+            print(f"✓ Topic '{topic}' validated for {subject}")
+            return True
+        else:
+            print(f"❌ Topic '{topic}' does NOT belong to {subject}")
+            return False
+            
+    except Exception as e:
+        print(f"⚠️ Validation failed: {e}")
+        return True  # Allow on error to avoid blocking
+
 # ------------------------------
 # Chapter Detection (Using Actual Chapter Names)
 # ------------------------------
@@ -1502,8 +1557,22 @@ def generate():
         if subject not in SUBJECTS:
             return jsonify({"error": "Invalid subject"}), 400
         
-        print(f"\n🔍 Searching {subject} for: {topic}")
+        print(f"\n🔍 Validating topic for {subject}...")
+        
+        # STEP 1: Validate if topic belongs to subject (BEFORE RAG search)
+        if not validate_topic_subject(topic, subject):
+            subject_names = {
+                "biology": "Biology",
+                "chemistry": "Chemistry", 
+                "physics": "Physics"
+            }
+            error_msg = f"The topic '{topic}' does not appear to be related to {subject_names[subject]}.\n\nPlease either:\n• Enter a {subject_names[subject]}-related topic, or\n• Select the correct subject for this topic"
+            return jsonify({"error": error_msg}), 400
+        
+        print(f"✓ Topic validated for {subject}")
+        print(f"🔍 Searching {subject} for: {topic}")
         
+        # STEP 2: RAG search
         context = rag_search(topic, subject, k=5)
         
         if not context or len(context.strip()) < 50:
@@ -1511,6 +1580,7 @@ def generate():
         
         print(f"✓ Context found ({len(context)} chars)")
         
+        # STEP 3: Generate MCQs
         mcqs, chapter = generate_mcqs(context, topic, subject)
         
         # Check if there was a subject mismatch