Which component is affected?

Qwik Rollup / Vite plugin

Describe the bug

When a Vite plugin injects a virtual CSS module import (e.g. import "virtual:my-plugin:foo.css"), the dev SSR renders a <link> tag with the raw virtual module ID as the href:

<link rel="stylesheet" href="/virtual:my-plugin:/src/routes/index.tsx.css">

This returns a 404 because Vite's dev server serves virtual modules under the /@id/ prefix. The correct href should be:

<link rel="stylesheet" href="/@id/virtual:my-plugin:/src/routes/index.tsx.css">

Production builds work fine
Vite resolves the virtual module through its normal pipeline and emits a real CSS file

We use this pattern for next-yak to extract css from js

Reproduction

https://github.com/jantimon/qwik-virtual-css-repro

Steps to reproduce

1. npm install
2. npm run build && npm run preview — text is green (works correctly)
3. npm run dev — text is black (CSS not loaded, 404 on the <link> href)

The repro uses a minimal Vite plugin that:

• transform: detects a marker string and prepends import "virtual:repro-css:<id>.css"
• resolveId: maps virtual:repro-css:* → \0virtual:repro-css:*
• load: returns .example { color: green; } for the virtual module

System Info

System:
  OS: macOS 26.2
  CPU: (10) arm64 Apple M1 Max
  Memory: 91.50 MB / 64.00 GB
  Shell: 5.9 - /bin/zsh
Binaries:
  Node: 24.13.0 - /Users/jannicklas/.nvs/node/24.13.0/arm64/bin/node
  npm: 11.6.2 - /Users/jannicklas/.nvs/node/24.13.0/arm64/bin/npm
  pnpm: 10.15.0 - /Users/jannicklas/Library/pnpm/pnpm
Browsers:
  Chrome: 144.0.7559.133
  Safari: 26.2
npmPackages:
  @builder.io/qwik: ^1.19.0 => 1.19.0
  @builder.io/qwik-city: ^1.19.0 => 1.19.0
  typescript: 5.4.5 => 5.4.5
  vite: 7.3.1 => 7.3.1

Additional Information

I (claude) dug into the source and I believe the issue is in packages/qwik/src/optimizer/src/plugins/vite-dev-server.ts

The CSS collection logic iterates server.moduleGraph.fileToModulesMap and uses v.url directly in the href — this works for normal files but not for virtual modules:

Line ~199 (pre-render injection):

Line ~264 (post-render injection):

The file already defines VALID_ID_PREFIX = '/@id/' (line 375) but only uses it for request filtering, not for URL generation.

A possible fix might be to check for virtual module URLs before building the href:

if (url.startsWith('\0') || url.startsWith('virtual:')) {
  url = `/@id/${url.replace('\0', '')}`;
}