> ## Documentation Index
> Fetch the complete documentation index at: https://docs.meter.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# Change Detection Workflow

> Build custom change detection logic on top of Meter

# Change Detection Workflow

Learn how to build custom change detection workflows using Meter's job comparison and history features.

## Overview

While Meter's schedules include automatic change detection, you can build custom workflows for specific needs using job comparison APIs.

**Use custom change detection when:**

* Need custom change thresholds
* Comparing non-adjacent jobs
* Building complex diff logic
* Generating change reports

## Basic comparison

```python theme={null}
from meter_sdk import MeterClient

client = MeterClient(api_key="sk_live_...")

# Get last two jobs for a strategy
jobs = client.list_jobs(strategy_id="your-strategy-id", limit=2)

if len(jobs) >= 2:
    # Compare latest with previous
    comparison = client.compare_jobs(jobs[0]['job_id'], jobs[1]['job_id'])

    print(f"Content hash match: {comparison['content_hash_match']}")
    print(f"Structural match: {comparison['structural_match']}")

    if not comparison['content_hash_match']:
        print("Content has changed!")
        for change in comparison.get('changes', []):
            print(f"  - {change}")
```

## Custom workflows

### Track specific field changes

**TODO: Implement field-level change detection**

```python theme={null}
def detect_price_changes(strategy_id):
    """Detect price changes specifically"""
    jobs = client.list_jobs(strategy_id=strategy_id, limit=2, status='completed')

    if len(jobs) < 2:
        return []

    old_results = jobs[1]['results']
    new_results = jobs[0]['results']

    changes = []

    # TODO: Implement comparison logic
    # for old, new in zip(old_results, new_results):
    #     if old.get('price') != new.get('price'):
    #         changes.append({
    #             'product': new.get('name'),
    #             'old_price': old.get('price'),
    #             'new_price': new.get('price')
    #         })

    return changes
```

### Generate change reports

**TODO: Create change reporting**

```python theme={null}
def generate_change_report(strategy_id, days=7):
    """Generate report of changes over time"""
    history = client.get_strategy_history(strategy_id)

    report = {
        "total_jobs": len(history),
        "jobs_with_changes": sum(1 for j in history if j['has_changes']),
        "change_rate": 0,
        "recent_changes": []
    }

    # TODO: Implement reporting logic
    # Calculate change rate, find patterns, etc.

    return report
```

### Alert on specific changes

**TODO: Implement alerting logic**

```python theme={null}
def monitor_with_alerts(strategy_id, alert_threshold=10):
    """Monitor and alert on significant changes"""
    comparison = client.compare_jobs(job_id_1, job_id_2)

    if not comparison['content_hash_match']:
        # TODO: Implement alert logic based on change magnitude
        # if change_magnitude > alert_threshold:
        #     send_alert(...)
        pass
```

## See also

* [Change Detection Concept](/concepts/change-detection) - How Meter detects changes
* [Job Comparison API](/api-reference/python/jobs#compare_jobs) - API reference
* [Pull-Based Monitoring](/guides/pull-based-monitoring) - Polling for changes

## Need help?

Email me at [mckinnon@meter.sh](mailto:mckinnon@meter.sh)