chore(core): add CSS variant information to the source file

[ematipico]

Summary

This is an internal code change that doesn't effect formatting and lint rules yet.

This PR updates the CssFileSource type to new variants: CssModules and TailwindCss. These variants are computed when opening the file from the Workspace.

This information will allow us to better target lint rules, such as #8083

Test Plan

CI should stay green

Docs

[changeset-bot]

⚠️ No Changeset found

Latest commit: e17d3b7

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[coderabbitai]

Walkthrough

This PR establishes CSS variant support infrastructure by introducing a CssVariant enum with CssModules and TailwindCss variants, adding query methods on CssFileSource, implementing a From<&CssFileSource> conversion to CssParserOptions, and updating the workspace server to set CSS variants based on configuration. The changes enable the parser to derive configuration from file source characteristics at runtime.

Possibly related PRs

• feat(format/css): implement formatters for new tailwind nodes #7241 — Shares Tailwind directive support configuration paths and modifies CSS file-source handling in tandem with this variant infrastructure.
• fix(parse/css): parse tailwind @source inline(...) #7921 — Implements parsing and formatting for Tailwind @source inline directives that directly relies on the tailwindDirectives option set by this PR's From implementation.

Suggested reviewers

• dyc3

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The PR title accurately describes the main change: adding CSS variant information (CssModules and TailwindCss variants) to the CssFileSource type.
Description check	✅ Passed	The description clearly explains the internal change to CssFileSource with new variants and their purpose for targeted lint rules, directly related to the changeset.
Docstring Coverage	✅ Passed	Docstring coverage is 88.89% which is sufficient. The required threshold is 80.00%.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch chore/add-variants-to-css

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📜 Recent review details

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Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between b406db6 and 1049fe3.

📒 Files selected for processing (4)

• crates/biome_css_parser/src/parser.rs (2 hunks)
• crates/biome_css_syntax/src/file_source.rs (3 hunks)
• crates/biome_css_syntax/src/lib.rs (1 hunks)
• crates/biome_service/src/workspace/server.rs (2 hunks)

🧰 Additional context used

🧠 Learnings (3)

📚 Learning: 2025-08-20T16:24:59.781Z

Learnt from: arendjr
Repo: biomejs/biome PR: 7266
File: crates/biome_js_type_info/src/type.rs:94-102
Timestamp: 2025-08-20T16:24:59.781Z
Learning: In crates/biome_js_type_info/src/type.rs, the flattened_union_variants() method returns TypeReference instances that already have the correct module IDs applied to them. These references should be used directly with resolver.resolve_reference() without applying additional module ID transformations, as variant references may originate from nested unions in different modules.

Applied to files:

• crates/biome_css_syntax/src/lib.rs
• crates/biome_service/src/workspace/server.rs

📚 Learning: 2025-11-09T12:47:46.298Z

Learnt from: ematipico
Repo: biomejs/biome PR: 8031
File: crates/biome_html_parser/src/syntax/svelte.rs:140-147
Timestamp: 2025-11-09T12:47:46.298Z
Learning: In the Biome HTML parser, `expect` and `expect_with_context` consume the current token and then lex the next token. The context parameter in `expect_with_context` controls how the next token (after the consumed one) is lexed, not the current token being consumed. For example, in Svelte parsing, after `bump_with_context(T!["{:"], HtmlLexContext::Svelte)`, the next token is already lexed in the Svelte context, so `expect(T![else])` is sufficient unless the token after `else` also needs to be lexed in a specific context.

Applied to files:

• crates/biome_css_parser/src/parser.rs

📚 Learning: 2025-10-25T07:22:18.540Z

Learnt from: ematipico
Repo: biomejs/biome PR: 7852
File: crates/biome_css_parser/src/syntax/property/mod.rs:161-168
Timestamp: 2025-10-25T07:22:18.540Z
Learning: In the Biome CSS parser, lexer token emission should not be gated behind parser options like `is_tailwind_directives_enabled()`. The lexer must emit correct tokens regardless of parser options to enable accurate diagnostics and error messages when the syntax is used incorrectly.

Applied to files:

• crates/biome_css_parser/src/parser.rs

🧬 Code graph analysis (1)

crates/biome_service/src/workspace/server.rs (1)

crates/biome_css_syntax/src/file_source.rs (1)

• css (35-39)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (9)

• GitHub Check: Bench (biome_css_formatter)
• GitHub Check: Bench (biome_css_parser)
• GitHub Check: Bench (biome_css_analyze)
• GitHub Check: Check Dependencies
• GitHub Check: autofix
• GitHub Check: Test (depot-ubuntu-24.04-arm-16)
• GitHub Check: Test (depot-windows-2022-16)
• GitHub Check: Lint project (depot-windows-2022)
• GitHub Check: Test Node.js API

🔇 Additional comments (8)

crates/biome_service/src/workspace/server.rs (2)

25-25: LGTM!

Import added to support CSS variant handling below.

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356-377: CSS variant selection looks good.

The if-else structure means CSS Modules takes precedence if both css_modules_enabled and tailwind_directives are true. This is likely intentional since these represent different tooling approaches, but worth confirming.

crates/biome_css_syntax/src/lib.rs (1)

15-15: LGTM!

Public export enables external usage of the CSS variant API.

crates/biome_css_parser/src/parser.rs (2)

4-4: LGTM!

Imports added to support the From implementation below.

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174-186: Clean conversion implementation.

The From trait correctly derives parser options from file source characteristics, enabling the appropriate CSS variant features.

crates/biome_css_syntax/src/file_source.rs (3)

25-32: LGTM!

CssVariant is now public with new variants properly documented. This establishes the foundation for CSS variant support.

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41-57: Helper methods look good.

The constructors and predicates follow consistent naming patterns and provide a clean API for working with CSS variants.

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83-83: LGTM!

Language ID mapping for "tailwindcss" is a useful addition for LSP integration.

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[codspeed-hq]

CodSpeed Performance Report

Merging #8095 will not alter performance

_{Comparing chore/add-variants-to-css (e17d3b7) with main (963dbaf)}

Summary

✅ 29 untouched
⏩ 126 skipped¹

Footnotes

1. 126 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. ↩

[dyc3]

Makes sense to me