# Phase 2 Completion Summary

## Goal
Add cycle persistence to work_orders table with 5-second throttling

## Changes Made

### Modified Files
1. **flows.json** - Updated "Machine cycles" function node (ID: 0d023d87a13bf56f)

### Code Modifications

#### Machine Cycles Function (/home/mdares/projects/Plastico/flows.json:1180)

**Added throttling logic:**
- Added `lastWorkOrderDbWrite` global variable to track last DB write timestamp
- Implemented 5-second throttle (5000ms) for work_orders persistence
- Only sends DB update when `timeSinceLastWrite >= 5000`
- Added debug logging for DB writes

**Updated SQL query on 4th output:**
```sql
UPDATE work_orders
SET cycle_count = ?,
    good_parts = ?,
    progress_percent = ?,
    updated_at = NOW()
WHERE work_order_id = ?
```

**4th Output now sends** (when throttle allows):
```javascript
{
    topic: "UPDATE work_orders SET cycle_count = ?, good_parts = ?, progress_percent = ?, updated_at = NOW() WHERE work_order_id = ?",
    payload: [cycles, produced, progress, activeOrder.id]
}
```

### Wiring Verification

✅ Output 1 (port 0): Scrap prompt → link out + debug
✅ Output 2 (port 1): Production state → multiple consumers
✅ Output 3 (port 2): KPI trigger → multiple consumers
✅ Output 4 (port 3): **DB persistence** → DB Guard (Cycles) → mariaDB

### How It Works

1. Every machine cycle increments `cycleCount` and calculates `good_parts`
2. On every cycle, check if 5 seconds have passed since last DB write
3. If yes:
   - Send UPDATE message on output 4
   - Set `lastWorkOrderDbWrite` to current timestamp
   - Log the DB write operation
4. If no:
   - Send `null` on output 4 (no DB write)

### Data Loss Prevention

- **Maximum data loss on crash**: 5 seconds of cycles (typically 1-2 cycles depending on cycle time)
- Balances between:
  - Data persistence (resume work orders)
  - Database load (not writing every 3-15 second cycle)
  - Recovery granularity (acceptable for manufacturing use case)

### Backup Created

`flows.json.backup_phase2_20251129_055629`

## Risk Assessment

**Risk Level**: LOW
- Only adds throttled writes to existing logic
- Doesn't modify existing UI or state management
- Default values (0) won't break existing work orders
- DB writes use parameterized queries (SQL injection safe)

## Dependencies Met

✅ Phase 1 complete (schema has cycle_count, good_parts columns)
✅ Existing 4th output wiring to DB Guard intact
✅ MariaDB node configured and connected

## Next Steps

Ready for Phase 3: Implement Resume/Restart prompt on Load