Hash API routes for static builds

[WaltzingPenguin]

Describe the problem

SvelteKit always fetches a new copy of a route's data when navigating to a new page or using sveltekit:prefetch. If the website was built using the static adaptor, we know the data is static and there is no need to refetch and check for updates.

If you visit https://svelte-demo.jamcart.io/, use dev tools to throttle the connection, and use the browser's back/forward buttons to navigate, then that delay becomes noticeable. This is not an issue for Next.js (https://react-demo.jamcart.io/), Nuxt.js (https://vue-demo.jamcart.io/), or even just static html (https://astro-demo.jamcart.io/).

Describe the proposed solution

Adopt Next/Nuxt's approach. Instead of writing files out to /api/my-endpoint.json, it could be instead rewritten to /_app/{ BUILD HASH OR TIMESTAMP }/api/my-endpoint.json. Then, developers can simply apply Cache-Control: public, immutable to everything inside of /_app.

Alternatives considered

For a static built, SvelteKit could just keep previous requests in memory and not force a refetch.

Importance

nice to have

Additional Information

No response