# 🤖 Assets

`rastrillo.Assets` fingerprints your static files so they can be cached
forever and still update on an ordinary reload.

```go
assets := rastrillo.NewAssets(app.StaticFS)
mux.Handle("GET /static/", assets.Handler())
```

`Path` maps a file to a URL carrying its content hash, and `Handler`
serves that URL with an immutable `Cache-Control`. Because the hash
changes whenever the content does, your HTML always links a URL the
browser has never cached stale. No cache-busting query string, no
version constant to remember to bump.

The FS is served with `http.FileServerFS` semantics — URL path is `/`
plus the FS path — which matches how the scaffold embeds `static/`.
Mount at `GET /static/` with no `StripPrefix`.

## Delivered once, yours afterwards

Two files arrive in your `static/` directory from `rastrillo new`
rather than from an import: `tokens.css`
([the design tokens](/docs/templates)) and `rastrillo.js`
([the progressive-enhancement shim](/docs/jobs)). The scaffolded icons
package works the same way.

Edit them freely. Nothing in the framework will overwrite them, and no
upgrade will change them under you.

## The pin test

The scaffold ships a `vendored_test.go` asserting the delivered copies
are byte-identical to the library's.

It is a tripwire, not a prohibition on editing. It tells you that you
have drifted, so drift is something you chose rather than something you
discover much later while debugging a component that no longer matches
its stylesheet.

When you do mean to diverge, say so in the same commit as the edit: add
the file's name to `vendoredIsMine` at the top of that test. A pin test
everybody knows is failing protects nothing.

`rastrillo doctor` reads the same list, so a file you have recorded as
yours is one it leaves alone too — and it will re-copy the ones you have
not. See [The CLI](/docs/cli).