* fix(scss): preprocess SCSS CSS-module composes deps via SassAwareFileSystemLoader
postcss-modules' built-in FileSystemLoader reads files referenced by
`composes: className from './other.module.scss'` as raw text — without
Sass preprocessing. For .scss files this leaves SCSS variables and bare
@import directives in the CSS output, causing LightningCSS to crash with
"Invalid empty selector" during production builds.
Fix: introduce SassAwareFileSystemLoader that delegates to Vite's
`preprocessCSS` API for every `composes:` dependency, so Sass compilation
runs before CSS-module scoping. Register it via `css.modules.Loader` in
vinext's Vite config hook and thread the resolved config through via a new
`setSassLoaderResolvedConfig` call in the `configResolved` hook.
Fixes the following deploy-suite tests (both sass and sass-embedded variants):
- test/e2e/app-dir/scss/nm-module/nm-module.test.ts
- test/e2e/app-dir/scss/nm-module-nested/nm-module-nested.test.ts
- test/e2e/app-dir/scss/composes-external/composes-external.test.ts
Part of #1825 (non-tilde CSS-module/composes cases; complements #1881)
* fix(scss): address review feedback on SassAwareFileSystemLoader
- Guard the css.modules.Loader injection: respect a user's explicit
css.modules: false (mergeConfigRecursively would otherwise re-enable
CSS Modules with an object override) and never clobber a
user-provided custom Loader. The override is precomputed as a typed
const so the conditional spread doesn't disturb the config literal's
contextual typing.
- Surface composes preprocessing failures via config.logger.warn
instead of a bare catch {}, so missing composed classes are
observable; a missing/unreadable dependency file now rejects like
postcss-modules' FileSystemLoader did.
- Use Vite's exported preprocessCSS + PreprocessCSSResult type via a
top-level import instead of the lazy dynamic import and stringly
typed casts.
- Preserve parity for composes from non-*.module.* files: hand
preprocessCSS a virtual *.module.* filename so plain '.css' deps are
still scoped and export tokens extracted, matching the built-in
FileSystemLoader.
- Port the three failing Next.js fixtures (composes-external,
nm-module, nm-module-nested) as production-build regression tests in
tests/scss-composes.test.ts, plus a plain .module.css / non-module
.css parity test. All three SCSS tests reproduce the original
"[lightningcss minify] Invalid empty selector" crash when the
Loader injection is disabled.
- Add sass as a root devDependency so the SCSS tests (including the
previously always-skipped tests/scss.test.ts) actually run in CI;
drop the now-redundant knip ignore entry. Installing sass makes
Vite's SassPreprocessorOptions resolve to the concrete sass types
(previously any), so the tilde-importer's importers array now
carries an explicit SassPreprocessorOptions["importers"] cast.
* fix(scss): bind composes-loader config per plugin instance; scope extensionless deps
- Replace the module-level resolved-config singleton with a per-vinext-
instance binding (createSassAwareFileSystemLoader), so multiple builds in
one process never preprocess composes deps with another build's config.
- Cover extensionless composes deps in the virtual *.module.* rename
(append .module.css) so their tokens are scoped instead of silently
dropped; add a parity test case.
- Pin url() pass-through behaviour for composed deps in the parity test
(verbatim, never mangled into placeholders — matches the built-in
FileSystemLoader, verified against a vanilla Vite build).
* docs(scss): document the per-subtree recursion boundary of the composes loader
Notes the two structural consequences of delegating nested composes
recursion to preprocessCSS (per-subtree duplicate inlining collapsed by
LightningCSS, and no cross-boundary cycle short-circuit for invalid
circular composes), per review.
* fix(scss): fail the build on composed-dep preprocessing errors
Only a missing Sass implementation is downgraded to a logged warning;
any other preprocessCSS error (e.g. a Sass syntax error in the composed
dependency) now propagates and fails the build, matching postcss-modules'
built-in FileSystemLoader instead of shipping a green build with
silently-missing classes. Docstrings updated to accurately describe the
silent empty-token path when no resolved config is bound. Adds a
regression test for the fail-loudly path.
* chore(deps): move sass to the workspace catalog; drop the now-dead dynamic skip in scss.test.ts
Review feedback on #1882: sass belongs in the pnpm workspace catalog
rather than pinned inline in the root package.json. With sass now a
guaranteed root devDependency, the runtime describeIfSass skip in
tests/scss.test.ts is dead code — the suite always runs — so make the
unskip explicit by removing the conditional machinery.
* rebuild lockfile
James Anderson