# Engine.diff
URL: https://lsd.tools/docs/api-engine-diff
Updated: 2026-07-17

## Parameters

| name | type | default | description |
|---|---|---|---|
| `target` | `str \| Entity \| None` | `None` | one entity by name or instance; `None` diffs every entity |

## Example

```python
for change in engine.diff():
    print(change["step_class"], change["current_params"])
```

## Notes

Compares current parameter values against the `param_snapshot` stored in the manifest after each
successful run. Returns an **empty list** when nothing changed or there is no prior snapshot. Each
dict has `entity_name`, `step_id`, `step_class`, `current_params`, and `old_params`.

## See also

**API:** [plan](/docs/api-engine-plan) · [run](/docs/api-engine-run) · [Engine](/docs/api-engine)