[sxzz]

Description

css.lightningcss.cssModules was overwritten by the internally resolved CSS Modules configuration, so options such as animation: false had no effect. Merge these options in resolveCssModulesConfig, preserving tsdown's naming overrides and applying them only to CSS modules. Ordinary CSS and final minification do not enable module scoping.

Add eight regression cases covering CSS and SCSS, minification, naming precedence, ordinary CSS, and disabled CSS Modules.

Linked Issues

Closes #1083

Additional context

Validation: pnpm lint, pnpm typecheck, and Prettier checks passed. CSS tests: 134 passed, with 3 existing expected failures.

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tsdown

pnpm add https://pkg.pr.new/rolldown/tsdown@1103 -D

npm i https://pkg.pr.new/rolldown/tsdown@1103 -D

yarn add https://pkg.pr.new/rolldown/tsdown@1103.tgz -D

create-tsdown

pnpm add https://pkg.pr.new/rolldown/tsdown/create-tsdown@1103 -D

npm i https://pkg.pr.new/rolldown/tsdown/create-tsdown@1103 -D

yarn add https://pkg.pr.new/rolldown/tsdown/create-tsdown@1103.tgz -D

@tsdown/css

pnpm add https://pkg.pr.new/rolldown/tsdown/@tsdown/css@1103 -D

npm i https://pkg.pr.new/rolldown/tsdown/@tsdown/css@1103 -D

yarn add https://pkg.pr.new/rolldown/tsdown/@tsdown/css@1103.tgz -D

@tsdown/exe

pnpm add https://pkg.pr.new/rolldown/tsdown/@tsdown/exe@1103 -D

npm i https://pkg.pr.new/rolldown/tsdown/@tsdown/exe@1103 -D

yarn add https://pkg.pr.new/rolldown/tsdown/@tsdown/exe@1103.tgz -D

tsdown-migrate

pnpm add https://pkg.pr.new/rolldown/tsdown/tsdown-migrate@1103 -D

npm i https://pkg.pr.new/rolldown/tsdown/tsdown-migrate@1103 -D

yarn add https://pkg.pr.new/rolldown/tsdown/tsdown-migrate@1103.tgz -D

commit: 99986e5

[Copilot]

🟢 Approval recommended

The focused change preserves naming precedence and module boundaries, with regression coverage for the affected paths and no unresolved findings.

No open issues 🎉

What changed in this PR

Fixes #1083 by preserving Lightning CSS module options such as animation: false in tsdown’s CSS processing, while retaining tsdown’s naming precedence.

Changes:

• Merge Lightning CSS module options into the resolved module configuration.
• Preserve existing scoping boundaries for ordinary CSS and disabled CSS Modules.
• Add eight regression cases and snapshots covering CSS, SCSS, minification, and naming precedence.

File	Description
tests/​css-modules.test.ts	Adds eight regression cases for module options and scoping.
tests/​__snapshots__/​lightningcss-css-modules-options/​preserves-animation-names-with-scss-and-minify-true.snap.md	Records preserved animation names in minified SCSS output.
tests/​__snapshots__/​lightningcss-css-modules-options/​preserves-animation-names-with-scss-and-minify-false.snap.md	Records preserved animation names in unminified SCSS output.
tests/​__snapshots__/​lightningcss-css-modules-options/​preserves-animation-names-with-css-and-minify-true.snap.md	Records preserved animation names in minified CSS output.
tests/​__snapshots__/​lightningcss-css-modules-options/​preserves-animation-names-with-css-and-minify-false.snap.md	Records preserved animation names in unminified CSS output.
tests/​__snapshots__/​lightningcss-css-modules-options/​prefers-tsdown-modules-options-for-fade.snap.md	Records global naming precedence.
tests/​__snapshots__/​lightningcss-css-modules-options/​prefers-tsdown-modules-options-for-custom_fade.snap.md	Records custom naming precedence.
tests/​__snapshots__/​lightningcss-css-modules-options/​does-not-scope-app-module-css-with-modules-false.snap.md	Records unscoped output when modules are disabled.
tests/​__snapshots__/​lightningcss-css-modules-options/​does-not-scope-app-css-with-modules-undefined.snap.md	Records unscoped ordinary CSS output.
packages/​css/​src/​plugin.ts	Merges Lightning CSS options before applying tsdown naming overrides.

_{Review effort: Balanced}