Vite 8.2.x leaves CSS asset URLs stale after PostCSS transforms

[Razunter]

Describe the bug

most of the issue is written by AI

Vite 8.2.x can emit hashed CSS assets while leaving the original source-relative url() unchanged. The generated CSS then points at a source path that is not present beside the output CSS file.

The regression reproduces in two independent configurations:

1. Sass with postcss-lightningcss.
2. @tailwindcss/vite with an empty PostCSS configuration.

Both fixtures produce the expected asset URLs with Vite 8.1.5. With Vite 8.2.2, the asset files are still emitted but the CSS references stale relative URLs.

Reproduction

https://github.com/Razunter/vite-82-css-bug-repro

Steps to reproduce

1. Clone the reproduction repo.

2. Install dependencies:

   npm install

3. Run the four comparison builds:

   npm run build:postcss:8.1.5
   npm run build:postcss:8.2.2
   npm run build:tailwind:8.1.5
   npm run build:tailwind:8.2.2

4. Inspect the generated CSS files under the four dist-* directories.

Each script invokes its Vite version through npx --yes; the fixture manifest itself remains pinned to Vite 8.2.2.

System Info

System:
  OS: Linux 6.18.33.1-microsoft-standard-WSL2 x64
  Environment: DDEV on WSL2
Binaries:
  Node: 24.18.0
  npm: 11.16.0
Packages:
  vite: 8.2.2
  rolldown: 1.2.5
  @tailwindcss/vite: 4.3.3
  postcss-lightningcss: 1.1.1
  sass: 1.103.0
  tailwindcss: 4.3.3

Used Package Manager

npm

Logs

The builds complete successfully; the failure is visible in the emitted CSS.

Vite 8.1.5 / PostCSS:
  url(/assets/Roboto-Regular-BKwBj7lc.ttf)
  url(/vite-css-url-repro.webp)

Vite 8.2.2 / PostCSS:
  url(../fonts/Roboto-Regular.ttf)
  url(/vite-css-url-repro.webp)

Vite 8.1.5 / Tailwind:
  url(/assets/vite-css-url-repro-HxSRdrt5.webp)
  url(/vite-css-url-repro.webp)

Vite 8.2.2 / Tailwind:
  url(../images/vite-css-url-repro.webp)
  url(/vite-css-url-repro.webp)

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[Razunter]

Vite 8.1.5 registers its CSS URL rewriter with a PostCSS Once visitor. Vite 8.2.2 changes it to OnceExit in the change associated with vitejs/vite#22983.