# Context Duplication - Final Fix

## 🐛 Root Cause Analysis

The duplication was happening because:

1. **Flutter sends `conversation_history`** when starting a new session
   - This history might contain study material from a previous attempt
   - Could be from a crashed session or user restarting

2. **Server adds fresh `study_context`** on top
   - Not checking if material already exists in history
   - Results in DOUBLE the content in prompt

## ✅ Solution Applied

### 1. **Skip Duplicate Study Material on Session Init**
```python
# When receiving conversation_history from Flutter
if data.get('conversation_history'):
    for msg in data['conversation_history']:
        # Skip system messages with study material
        if msg.get('role') == 'system' and '[STUDY MATERIAL PROVIDED]' in msg.get('content', ''):
            logger.info("Skipping study material from previous session")
            session.context_sent_to_ai = True  # Mark as already sent
            continue
        session.conversation_history.append(msg)
```

### 2. **Check Before Sending Context**
```python
async def create_simple_context(session, user_input):
    # Check if study material already in history
    has_study_material = any(
        '[STUDY MATERIAL PROVIDED]' in str(msg.get('content', '')) 
        for msg in session.conversation_history 
        if msg.get('role') == 'system'
    )
    
    # Only send if NOT already in history
    if session.study_context and not session.context_sent_to_ai and not has_study_material:
        return session.study_context  # Send fresh context
    else:
        return ""  # Don't duplicate
```

### 3. **Prevent Double Addition to History**
```python
# Only add to history if not already there
if context and not any('[STUDY MATERIAL PROVIDED]' in str(msg.get('content', '')) 
                      for msg in session.conversation_history 
                      if msg.get('role') == 'system'):
    session.conversation_history.appendleft({
        'role': 'system',
        'content': f"[STUDY MATERIAL PROVIDED]\n{context}"
    })
```

### 4. **Clean Prompt Building**
```python
if context:  # First interaction with NEW material
    # Use ONLY the context, no history
    prompt = f"""
STUDY MATERIAL PROVIDED:
{context}

Student's Current Question: "{user_input}"
"""
else:  # Subsequent or when material in history
    # Use conversation history (includes material)
    history_context = build_conversation_context(session.conversation_history)
    prompt = f"""
Conversation History (includes study material from earlier):
{history_context}

Student's Current Question: "{user_input}"
"""
```

## 📊 Expected Results

### **Scenario 1: Fresh Session (No History)**
```
Context: 20,673 chars
Prompt: ~21,000 chars (context + instructions)
```

### **Scenario 2: Session with History from Flutter**
```
Flutter sends: conversation_history with study material
Server detects: Study material already in history
Context sent: 0 chars (skipped)
Prompt: ~22,000 chars (history + new question)
```

### **Scenario 3: Subsequent Interactions**
```
Context: 0 chars (already in history)
Prompt: ~24,000 chars (growing with conversation)
```

## 🔍 Debug Logs to Verify

You should now see:
```bash
# When Flutter sends history with material:
"Skipping study material from previous session to avoid duplication"
"Study material already in conversation history, not resending"
"Sending prompt to AI model: 21000 chars total"  # NOT doubled

# Fresh session:
"FIRST TIME: Passing FULL original context: 20673 chars"
"Sending prompt to AI model: 21000 chars total"  # NOT doubled

# Subsequent:
"Subsequent interaction #2: Using conversation history only"
"Sending prompt to AI model: 23000 chars total"  # Growing normally
```

## ✅ Summary

The fix ensures:
1. **No duplicate study material** when Flutter sends existing history
2. **Smart detection** of existing material in conversation
3. **Clean separation** between fresh context and historical context
4. **Optimal prompt sizes** without redundancy

This completely eliminates the doubling issue while maintaining full context availability!
