Add package command

[Rich-Harris]

If component libraries are to be a first-class use case for Kit, it stands to reason that npm run package should be available in new projects alongside npm run build.

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🦋 Changeset detected

Latest commit: 2b70f1e

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

This PR includes changesets to release 1 package

Name	Type
create-svelte	Patch

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[benmccann]

Or should it be part of svelte-create? An npm run package command wouldn't make as much sense if you're building a web app instead of a library. I wonder if it would end up confusing people because they think they're packaging their app for production deployment or something?

[Conduitry]

I agree about worrying that this might be confusing for people who are just writing an app and not a reusable library.

I'm not sure what @benmccann's suggesting though. That this become one of the prompts in the create-svelte CLI? Something else?

[dummdidumm]

Also in favor of a prompt "do you want to create a library or an app?"

[Rich-Harris]

I think npm run build is a widely-enough used convention that if someone opts to npm run package instead it's a definite case of PEBKAC. The docs (https://kit.svelte.dev/docs#command-line-interface) are fairly clear in any case.

Disagree that a prompt is appropriate — the whole point of this feature is that apps and libraries are the same thing (an app has an internal library, a library has a demo/docs app, the only difference is which bit is user-facing). If the only thing the prompt changes is whether or not "package": "svelte-kit package" gets added to the package.json, that's a pretty meagre payoff for adding another (potentially confusing) decision at project init time.

I think the solution here is something I've been meaning to get round to anyway — add some language when svelte-kit package completes along the following lines:

Successfully built library: src/lib -> package
To publish your package:
$ cd package
$ npm publish

[Conduitry]

👍 Adding that message when the package command completes would address my concerns in a tidy enough way, and does seem better than adding another prompt to the CLI.

[Rich-Harris]

Alright, added that. I really think we need to revisit this —

Cannot generate a "svelte" entry point because the "." entry in "exports" is missing. Please specify one or set a "svelte" entry point yourself

— it's very confusing and shouldn't be necessary. Will open a separate issue though as it will probably mean coordinating with the plugins