`@sveltejs/package` Customize behavior of copying `package.json` and other essential files to the output directory when packaging a Svelte library

[bryanmylee]

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
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• [x] Ideally, include a test that fails without this PR but passes with it.

This resolves #6824.

For context, I'm building a cross-framework component library so I've set up a standard package structure for each framework in my monorepo with npm workspaces.

I'm using Vite with @sveltejs/package to develop and build my components. However, @sveltejs/package breaks my toolchain because it creates a copy of package.json in my dist folder.

npm workspaces picks up both the original package.json and dist/package.json, causing other dependent packages to break due to the duplication.

This PR adds a metadata filter function to allow disabling the copy feature for metadata files like package.json and other whitelisted essential files.

Tests

• [x] Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

All existing tests for @sveltejs/package pass and I added a test for the new config option.

Changesets

• [x] If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpm changeset and following the prompts. All changesets should be patch until SvelteKit 1.0

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🦋 Changeset detected

Latest commit: 2e086685adac0c6aa6bc4225f74a4c671cc3b2a1

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

This PR includes changesets to release 1 package

Name	Type
@sveltejs/package	Minor

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[dominikg]

fyi: the test fail in create-svelte is unrelated to this issue and a fix for that is pending in #6866

[dummdidumm]

Not 100% sure about the API yet but it's definitely going in the right direction. In the meantime, could you remove some of the unnecessary files from the tests? We don't need to have multiple Svelte files in there, copying them over and generating types for them is already checked in other tests. It should be enough to just have one index.js file.

[bryanmylee]

Any updates on this? I would love to have this merged into the package itself.

[vercel[bot]]

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[bryanmylee]

The failing test seems to be unrelated to svelte-package

[Rich-Harris]

Thank you for the PR. We ended up going in a different direction (#8825) — closing in favour of #8922