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

# SDK And Runtime Versions

> Understand local `cpsl` versions, hosted runtime versions, and deploy behavior.

Capsule apps are written with the local `cpsl` package, then run inside Capsule's managed runtime.

Most of the time you do not need to think about versioning. If local and hosted behavior diverge, check the points below.

## Local SDK

Your local environment controls what you import while editing and running CLI commands.

```bash theme={null}
python -c "import cpsl; print(cpsl.__version__)"
```

Upgrade locally with your package manager:

```bash theme={null}
uv add --upgrade cpsl
```

or:

```bash theme={null}
pip install --upgrade cpsl
```

## Runtime SDK

Hosted Capsule runtimes use the SDK version pinned by the Capsule platform.

That means a local-only SDK upgrade may not immediately change hosted runtime behavior. If you are testing a newly released SDK feature, confirm that the hosted runtime has the matching version available.

## Image dependencies

App dependencies belong in `cpsl.Image(...)`.

```python theme={null}
app = cpsl.App(
    name="my-app",
    image=cpsl.Image(python_packages=["openai", "requests"]),
)
```

Installing a dependency into your local virtual environment is not enough for the managed runtime.

## When to check versions

Check SDK/runtime versions when:

* code works locally but fails after deploy
* a new SDK method imports locally but is unavailable in hosted runtime
* generated UI metadata looks different between `serve` and `deploy`
* a dependency import fails in the managed runtime

## Related

* [Troubleshooting](/troubleshooting)
* [Deploy An App](/build/deploy-an-app)
* [Image, Theme, And Deployment Reference](/reference/image-theme-and-deployment)