per environment `cssMinify: false` doesn't work when `sharedPlugins: true`

[hi-ogawa]

Describe the bug

For the following config, both client build and ssr build generates minified css:

export default defineConfig({
  build: {
    // cssMinify: false, // [works]
  },
  environments: {
    client: {
      build: {
        outDir: 'dist/client',
        cssMinify: false, // [not working]
        rollupOptions: {
          input: './src/client.ts',
        },
      },
    },
    ssr: {
      build: {
        outDir: 'dist/ssr',
        cssMinify: false, // [not working]
        emitAssets: true,
        rollupOptions: {
          input: './src/ssr.ts',
        },
      },
    },
  },
  builder: {
    sharedPlugins: true,
  },
});

I'm not sure practically any people should switch between environments though, so setting top-level build.cssMinify is a workaround.

Reproduction

https://stackblitz.com/edit/github-go4wdecj-no7tad8l?file=vite.config.ts

Steps to reproduce

• open stackblitz
• check generated css files are minified
  • dist/ssr/assets/ssr-xxx.css
  • dist/ssr/assets/ssr-xxx.css

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 20.19.1 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.8.2 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vite: ^7.1.2 => 7.1.5

Used Package Manager

npm

Logs

No response

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

[ValentinYoushkevich]

Opened #23243 for this.

cssPostPlugin captures the root ResolvedConfig at plugin creation and reads build.cssMinify from it, so with sharedPlugins: true the per-environment value never applies. The PR resolves it from this.environment.config instead, matching how the surrounding code already handles cssCodeSplit and chunkImportMap.