HMR not working when triggered from vite plugin

[UstymUkhman]

What version of astro are you using?

1.9.0, 1.9.1

Are you using an SSR adapter? If so, which one?

None

What package manager are you using?

npm, yarn

What operating system are you using?

Windows

Describe the Bug

vite-plugin-glsl (for example) is using vite's server.restart method to trigger HMR when a shader file is changed and saved. When using this plugin with astro, after saving a file, dev server crashes unless the following setting is added to astro.config.mjs:

export default defineConfig({
  vite: {
    server: {
      port: 3000
    }
  }
});

Original bug report here;

Link to Minimal Reproducible Example

https://stackblitz.com/edit/github-ctfwyn?file=astro.config.mjs

Participation

• I am willing to submit a pull request for this issue.

[DaniloArantesF]

It also seems to work fine if you disable watch in the plugin's config. Not sure if it's standard behavior but my dev server also crashed silently and continued to update on file changes.

[UstymUkhman]

It also seems to work fine if you disable watch in the plugin's config.

@DaniloArantesF Yeah, good point, thanks for testing that. With watch: false option we don't rely on vite's server.restart and astro seems to handle file changes automatically. But I also don't know if that's a standard behavior.

...my dev server also crashed silently and continued to update on file changes.

Sorry, but I didn't get this. With plugin's watch: false option, it seems to be working just like with vite's server config, so in my tests I haven't see the dev server crashing, but it continued to fetch the latest version of the shader file just like if the plugin's watch option was set to true.

[bluwy]

#5849 should fix this. Note that the restart would cause a weird blank page between page reloads as vite-plugin-glsl isn't properly handling the changes. It should use handleHotUpdate instead of configureServer to detect the changes. Otherwise, handleHotUpdate would fallback to a full reload, while the server is still starting up, causing the weird interim blank page.

[UstymUkhman]

Thanks for the hint @bluwy ! I will take a look at handleHotUpdate on the plugin's side.