[Bug?]: @tailwindcss/vite v4 breaking after dev server restart

[birkskyum]

Current behavior 😯

In tailwind 4, which is still only in beta (but it would be good to fix this before they hit stable), there are now two ways to install tailwind.

• Traditional: Using a Postcss plugin - works as expected
• New: Using a Vite plugin (works in astro, but dev server struggle in solid-start)

The vite plugin works as expected when making a prod build, and for the dev server on a clean reload, but if the dev server is restart in solid-start, the style will be broken. To get it working again, it will be necessary to do either of the following:

• delete node_modules/.vinxi and then restart dev server
• modify/re-save ./src/app.css - triggering this file reload is enough to make it work again

With Astro (v5), there are no issues with restarting the dev server using @tailwindcss/vite with Solid.
With TanStack Start (vinxi 0.4.3/0.5.1), there are no issues either.

Expected behavior 🤔

I expected the tailwind plugin to load correctly on dev server restart.

Steps to reproduce 🕹

There's a repo here with multiple implementations:
https://github.com/birkskyum/tailwind-vite-repro

• Astro with Vite plugin (and solid) - working
• TanStack Start with Vite plugin (and vinxi) - working
• Solid Start with Postcss plugin - working
• Solid Start with Vite plugin - breaking after dev server restart

I can reproduce this issue with vinxi 0.4.3 / 0.5.0 / 0.5.1 and overrides with vite 5/6

The working output looks like this:

The broken output will look like this:

Context 🔦

No response

Your environment 🌎

No response

[atilafassina]

I'm not sure I followed all the way.

So Tanstack Start is on Vinxi 0.5.1 and Vite 5 -- and that works, right?
And we're on Vinxi 0.5.1 and Vite 6 -- which doesn't work.

Is that the takeaway? Should we pin down Vite to 5 would the issue goes away for us as well?

[birkskyum]

No, the takeaway here isn't related to vite/vinxi versions - i see same behavior across versions

The takeaway is that tailwindcss v4 doesn't work when installed through the vite plugin in solid-start, but it does work in astro (indicating the tailwind vite plugin is working) and it does work in tanstack start (indicating it might even be a solid-start rather than a vinxi problem)

[birkskyum]

Tailwind 4 is has been stable released:
https://tailwindcss.com/blog/tailwindcss-v4

So we better make sure it works with SolidStart

• https://www.npmjs.com/package/@tailwindcss/vite

[birkskyum]

Upstream ticket

• [v4] Tailwind CSS classes not updating in output when adding previously unused classes - requires server restart tailwindlabs/tailwindcss#14800

[mdynnl]

Should be fixed by tailwindlabs/tailwindcss#16052

[DaniGuardiola]

I can confirm this bug is fixed, I upgraded the example to v4 (with the nightly temporarily) and it works: #1747

However, there's a different problem now: #1749