# Create, seal, and read a checkpoint

Prerequisite: [configuration ownership](posture.md). These entry lessons introduce
recording without requiring the complete [Expert persistence guide](../expert/persistence.md).

Configure and activate Crystallizer before creating checkpoints. The creation
lesson gets a checkpoint ID, lists it, describes it, and confirms that another
checkpoint receives a different ID.

## Know which operation completed

| Operation | What you can conclude |
| --- | --- |
| `create_checkpoint(...)` | A checkpoint exists in the running record |
| `flush_checkpoint(...)` | The checkpoint is sealed locally; inspect remote delivery separately |
| `list_cached_checkpoint_ids()` | Which checkpoint IDs remain in the bounded local cache |
| `reload_cached_checkpoint(...)` | A cached record is read back into the record system |
| `verify_checkpoint_chain(...)` | A report about the recorded lineage |

A bounded cache can evict older entries. A successful local seal does not establish
remote durability. Reloading a record is also different from rebuilding its runtime
objects: use [restore and cold boot](../expert/restore.md) for that next step.


## The workflow in code

These are the core steps from the saved example. Use its complete linked script for all class definitions and setup.

```{literalinclude} ../downloads/03_advanced/17_taking_a_checkpoint.py
:language: python
:pyobject: main
:linenos:
```


## Runnable examples

- [Taking a checkpoint](../examples/advanced/17-taking-a-checkpoint.md) — Advanced 17
- [Loading it back](../examples/advanced/18-loading-it-back.md) — Advanced 18

[All advanced examples](../examples/advanced/index.md) · [Level contents](index.md) · [Full contents](../contents.md)

[Canonical page source](https://github.com/Synaptic724/melder/blob/1211e838099a342c9dde48f064b1e772b6060e13/docs/advanced/checkpoints.md)