# Use app artifacts

## Goal

Pass a model file, dataset, or other file that ships *with* an app — for example, DeepSite's trained model — as an argument to that app.

## Minimal example

```python
from playmolecule.apps import deepsite

print(deepsite.artifacts)         # show what's bundled with this app

deepsite(
    outdir="out",
    pdbid="3ptb",
    model=deepsite.artifacts.default,
).run()
```

`deepsite.artifacts.default` is a file handle bundled with the app. You pass it where the app expects a file path; PlayMolecule resolves it to the right location in the container.

## How artifacts work

App manifests can declare a list of `artifacts` (sometimes called `datasets` — they're synonymous). PlayMolecule attaches them to the app module as attributes named after each artifact:

```python
deepsite.artifacts                       # container of bundled file handles
deepsite.artifacts.default               # one specific artifact
deepsite.artifacts.default.path          # path inside the container
deepsite.artifacts.default.description
```

Each artifact is also addressable for a specific version: `deepsite.v1.artifacts.<NAME>`.

## Download an artifact to disk

If you want to keep an app artifact outside its container:

```python
local_path = deepsite.artifacts.default.download("./models/deepsite-default.ckpt")
```

Whether this copies from a local install, extracts from a Docker / Apptainer image, or downloads from an HTTP backend depends on which registry the app came from — the call is the same in all cases.

## Gotchas

- Artifact names must start with a letter and contain no dots. The loader skips invalid names silently — if `deepsite.artifacts.X` doesn't exist, check the spelling in the app manifest.
- The handle is *not* a string path. Don't `str(...)` it before passing it in; PlayMolecule does the resolution itself based on the active execution backend.
- A pinned-version artifact (`deepsite.v1.artifacts.X`) may not exist in `deepsite.v2.artifacts` — artifacts are versioned together with the app.

## See also

- [Apps and manifests](../explanation/apps-and-manifests.md)
- [Artifacts and files](../explanation/artifacts-and-files.md)
- [Pass input files to an app](pass-input-files-to-an-app.md)