# Plan Enforcement Implementation Summary

**Date:** 2026-03-31  
**Issue:** GPT-5.4 creating duplicate plans  
**Solution:** Tool-level enforcement

## What Changed

### 1. Hard-Block Duplicate Plans

The `create_plan` tool now checks for existing active plans **before** creating a new one:

```typescript
// If active plan exists, return it instead of creating duplicate
const activePlans = await planService.getActivePlansForChat(chatId);
if (activePlans.length > 0) {
  return {
    success: false,
    existingPlan: true,
    message: "⚠ Active plan already exists: 'Task Name' (2/5 steps complete)...",
    data: existingPlan
  };
}
```

### 2. New `delete_plan` Tool

Agents can now explicitly delete plans when needed:

```typescript
delete_plan({ planId: "plan-123" })
// Returns: "✓ Plan deleted. You can now create a new plan."
```

### 3. Updated Guidance

System prompt changed from:
- ❌ "Check before calling create_plan" (prompt-based)

To:
- ✅ "System automatically prevents duplicates" (enforcement-based)

## Impact

| Before | After |
|--------|-------|
| 3-6 duplicate plans per task | **Zero duplicates possible** |
| Relies on model following prompts | Hard-blocked at tool level |
| Works inconsistently with GPT-5.4 | Works with **any model** |

## Testing

Run the test script:

```bash
npm run build
node scripts/test-plan-enforcement.mjs
```

Expected output:
```
✅ Create first plan: PASS
✅ Block duplicate plan: PASS
✅ Update plan: PASS
✅ Delete plan: PASS
✅ Create after delete: PASS

✅ All tests PASSED!
```

## Verification

Check database for duplicates (should be 0):

```bash
sqlite3 ~/Papr/data/plans.db "
  SELECT chat_id, COUNT(*) as plan_count
  FROM plans 
  WHERE status = 'active'
  GROUP BY chat_id
  HAVING plan_count > 1
"
```

## Files Changed

1. `src/core/tools/planning.ts` - Enforcement logic + delete tool
2. `src/core/tools/index.ts` - Export delete tool
3. `src/core/agents/SystemPrompt.ts` - Updated guidance
4. `scripts/test-plan-enforcement.mjs` - Test script
5. `docs/GPT_5_4_DUPLICATE_PLANS_FIX.md` - Documentation
6. `CLAUDE.md` - Issue 30 entry

## Why This is Better

**Prompt-based approach:**
- Depends on model following instructions
- Fails with extended reasoning (GPT-5.4)
- Requires constant prompt tuning

**Tool-level enforcement:**
- **Impossible** to create duplicates
- Works with any model, any reasoning length
- Future-proof, zero maintenance

## Next Steps

1. Build and test: `npm run build && node scripts/test-plan-enforcement.mjs`
2. Restart app: `npm start`
3. Test with GPT-5.4 Thinking on a multi-step task
4. Verify no duplicate plans appear in UI

## Success Criteria

✅ Test script passes all 5 tests  
✅ Database shows 0 duplicate active plans  
✅ UI shows single plan card per task  
✅ GPT-5.4 Thinking cannot create duplicates  
