adapter types

[Rich-Harris]

In #5081, we ask people to manually update their src/app.d.ts to include the relevant platform types for their adapter. It's confusing and brittle (people who already have adapter-cloudflare installed won't see env.caches magically appear, even though it's now there).

In an ideal world we'd somehow magically inject these types, but failing that, asking people to add a triple-slash directive is probably reasonable.

Marking as draft because we should do this for all adapters.

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

• 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
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• 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

[changeset-bot]

🦋 Changeset detected

Latest commit: 76b60a7

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

This PR includes changesets to release 3 packages

Name	Type
@sveltejs/adapter-cloudflare	Patch
@sveltejs/adapter-cloudflare-workers	Patch
@sveltejs/adapter-auto	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Rich-Harris]

Netlify and Vercel are actually a little tricky, since you might use edge: true or edge: false and the platform object would differ. Not immediately sure of the best solution to that. No reason for it to hold this up though so I'm marking the PR ready

[dummdidumm]

Idea: have two ambient type definitions which are in separate files and importable through @sveltejs/adapter-vercel/edge and @sveltejs/adapter-vercel/noedge or sth like that (this means the ambient file import needs to be removed from the other files)

[Rich-Harris]

The challenge will be that one day we want to allow some endpoints (or even handlers) to run on the edge and others to run in a lambda, depending on their data requirements. Not sure how to reconcile that with a global App.Platform interface...

[dummdidumm]

Oh yeah that sounds impossible to solve correctly with one global type definition. We kind of have the same problem with stuff, not everything in there will be available at the same time

[Rich-Harris]

Perhaps it's an argument for normalizing/abstracting platform in those environments. Anyway we can cross that bridge later