adapter-auto: defer adapter installation until required

[gtm-nayan]

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🦋 Changeset detected

Latest commit: 84fa75a

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

This PR includes changesets to release 1 package

Name	Type
@sveltejs/adapter-auto	Patch

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[dummdidumm]

Makes sense to me and should probably resolve the "double package" problem one can run into - leaving this open so others can give their opinions on this

[Rich-Harris]

If we add new capabilities to adapters in future — for example, if they're allowed to control aspects of the dev environment — then this won't work

[Conduitry]

Probably we don't want the auto adapter to be affecting dev mode? It wouldn't have any of the env vars it looks at anyway. Presumably people should explicitly install their target adapter if they want to have it impact dev mode too.

[gtm-nayan]

To provide platform specific features in dev mode you'd have to know what platform you'd be deploying to, and at that point adapter-auto can be swapped out manually.

I thought the idea was that adapter-auto would serve as a minimal deployable setup for new users unfamiliar with adapters and users requiring more features can use specific ones for their platform. There's a warning in adapter-auto which reflects that sentiment: If you plan on staying on this deployment platform, consider replacing @sveltejs/adapter-auto with ${match.module}. This will give you faster and more robust installs, and more control over deployment configuration.

[Rich-Harris]

That's a fair point! I rescind my earlier comments. That said, I'm not 100% sure I understand what problem this solves?

[benmccann]

I'd make it clearer from the name that this is installing the adapter as get sounds side-effect free

Suggested change

	async function get_adapter() {
	async function install_adapter() {

[Rich-Harris]

In some cases it won't install anything though. We could make it get_or_install_adapter or whatever but i think it's clear enough from context

[benmccann]

I'm not 100% sure I understand what problem this solves?

Right now it's installing the adapter up-front, which seems to be doing the install in the middle of the Vite bundling causing two versions of SvelteKit to end up in the final bundle. By waiting until the bundle is written, hopefully that's fixed.

I'm not 100% sure how to test this other than merging it and updating the sites repo. There's probably a way, but I'd be just as happy to merge this even if it doesn't work as I think it's a nice way to structure the code, so I'd say we merge this and see if it works