Right, I never followed up on this. At some point, the POC became overly complicated when new stuff was added to the kit docs. The biggest issue is supporting the // ---cut--- comment as the script tag needs to be partly cut so source-map is harder. There is also some ts diagnostics error in svelte2tsx generated code that needs to be filtered out in a weird way and also requires a different sourcemap. So there are like a total of 3 or 4 kinds of sourcemap.

I assumed this was working when I saw the hover tooltips on variables for the new svelte site https://svelte.dev/docs/svelte/$state . I think I misunderstood since those blocks were JS only. Svelte blocks still don't have them.

Yeah. the library only works with ts/js so there isn't hover info in the svelte file. There is now a twoslash vue and eslint so maybe there would be more stuff added to the base library making it easier and not needing so many layers of source map.

I've made some efforts to build twoslash/svelte as a project for the upcoming Svelte hackathon:

• PR: Feat: twoslash-svelte twoslashes/twoslash#57
• Preview: https://deploy-preview-57--twoslash.netlify.app/packages/svelte

If this is something that you think will be valueable to the docs I will gladly submit a PR to add twoslash to .svelte blocks. It has 100% feature parity, so highlights, hovers, queries, cutted blocks etc all works.
Just note that the PR is still just a PR so the package isn't out yet.

This is how it looks for example:

@Hugos68 I have been patiently waiting for someone to build a Svelte integration for this for quite some time. This is incredible and will benefit not only the svelte.dev site but the entire ecosystem of Svelte libraries 💪 incredible job!

If this is something that you think will be valueable to the docs I will gladly submit a PR to add twoslash to .svelte blocks

This would be incredible, thank you!

Sure thing, once twoslash-svelte gets merged into twoslash I'll submit a PR 👍