perf: shorten file names

[benmccann]

This shortens references to assets in SSR, JS, and HTTP headers. It actually reduced the size of the JS on my image-heavy page by 6.5% after brotli compression.

[changeset-bot]

🦋 Changeset detected

Latest commit: 248da93

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[Rich-Harris]

preview: https://svelte-dev-git-preview-kit-13003-svelte.vercel.app/

this is an automated message

[dominikg]

this could be a breaking change.it's going to bust existing users caches due to the change in output names, and if they used those somewhere without resolution through manifest, those references break too.

[benmccann]

it's going to bust existing users caches due to the change in output names

it wouldn't be the first time we've changed it and no one's ever complained before. static assets are incredibly cheap to serve

if they used those somewhere without resolution through manifest, those references break too

the filenames already change everytime a single character changes and I don't know what you can do referencing an individual file anyway

[dominikg]

assets don't change that often. this will force all users to download everything again they already had far future cached. images, fonts, everything...

how often did we change it? if we offer immutable asset caching as a feature, we should be mindful not to bust that

[benmccann]

Yeah, we've changed it very rarely