vite, compiler: Add cssFileFilter option to customize VE module detection

[o-alexandrov]

Summary

Adds an optional cssFileFilter option to vanillaExtractPlugin (@vanilla-extract/vite-plugin) and createCompiler (@vanilla-extract/compiler) so consumers can customize which files are treated as Vanilla Extract modules.

Today the filter is a hardcoded const in @vanilla-extract/integration:

export const cssFileFilter = /\.css\.(js|cjs|mjs|jsx|ts|tsx)(\?used)?$/;

It's imported directly by the Vite plugin and the compiler, with no way to override it. The new option threads a caller-provided RegExp through both, defaulting to the existing filter so nothing changes when it's omitted.

vanillaExtractPlugin({
  // e.g. treat `css.ts` as the VE module convention instead of `*.css.ts`
  cssFileFilter: /(?:^|[/\\])css\.(js|cjs|mjs|jsx|ts|tsx)(\?used)?$/,
});

Motivation

We use a single-filename convention (css.ts) rather than the *.css.ts suffix across a large codebase. With no public way to change the filter, our only option has been to patch @vanilla-extract/integration on disk after every install (rewriting the regex), which is fragile: a missed copy in a multi-repo/workspace setup silently leaves css.ts files untransformed, which surfaces later as Styles were unable to be assigned to a file at runtime. A first-class option removes the need for that patch.

Changes

• @vanilla-extract/vite-plugin: new cssFileFilter?: RegExp option; used in the transform gate and HMR invalidation, and passed to createCompiler.
• @vanilla-extract/compiler: new cssFileFilter?: RegExp on CreateCompilerOptions; used by the module scanner and the internal file-scope transform.
• Both default to the existing cssFileFilter, so it's fully backwards compatible.
• Added a compiler unit test with a .vanilla.ts fixture that is only recognized via a custom filter, plus a changeset (minor for both packages).

Notes

I've read the contributing guide's note that non-trivial changes are ideally discussed first: happy to move this to a discussion/issue if preferred. The change is small, additive, and non-breaking, so I've opened it as a PR to make the proposal concrete. Existing unit tests pass and the changed files are Prettier/oxlint clean.

[changeset-bot]

🦋 Changeset detected

Latest commit: 7e14133

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@vanilla-extract/vite-plugin	Minor
@vanilla-extract/compiler	Minor
@vanilla-extract/turbopack-plugin	Patch

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