fix(parse/css): parse tailwind @utility with slash in the name

[dyc3]

Summary

Allows the css parser to parse @utility a/b {}.

fixes #8897

Test Plan

snapshots

Docs

[changeset-bot]

🦋 Changeset detected

Latest commit: 12f0722

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

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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[codspeed-hq]

Merging this PR will not alter performance

✅ 29 untouched benchmarks
⏩ 187 skipped benchmarks¹

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_{Comparing dyc3/tw-slash-utility-name (12f0722) with main (2cebc11)}

Footnotes

1. 187 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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Walkthrough

This PR addresses parsing errors when Tailwind @utility directives contain forward slashes in their names (e.g., @utility a/b). A new TailwindUtilityName lexical context was introduced to the CSS lexer, enabling it to recognise slashed identifiers in Tailwind utility contexts. The lexer's identifier consumption logic was generalised with an allow_slash parameter to permit slashes when parsing utility names. Test cases cover both valid and invalid scenarios.

Possibly related PRs

• fix(parse/css): improve parsing of @utility names #8850: Modifies Tailwind at-rule name parsing for wildcard/functional names alongside slashed-name handling
• fix(parse/css): fix parsing --*: initial; with tailwindDirectives enabled #7852: Modifies CSS lexer identifier parsing for Tailwind directives with similar contextual lexing approaches

Suggested labels

L-Tailwind

Suggested reviewers

• ematipico
• siketyan

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: enabling the CSS parser to handle Tailwind @utility directives with slashes in the name.
Description check	✅ Passed	The description clearly explains the motivation (parsing @utility a/b {}) and links to issue #8897, demonstrating relevance to the changeset.
Linked Issues check	✅ Passed	The PR directly addresses issue #8897 by implementing lexer changes to allow forward slashes in Tailwind utility names, with corresponding test cases validating the fix.
Out of Scope Changes check	✅ Passed	All changes are focused on supporting slash-containing Tailwind utility names: lexer modifications, parser updates, and test cases—nothing extraneous is present.

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✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch dyc3/tw-slash-utility-name

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