test(markdown): add minimal service plumbing for formatter integration by jfmcdowell · Pull Request #9070 · biomejs/biome

jfmcdowell · 2026-02-14T18:04:25Z

Note

AI Assistance Disclosure: This PR was developed with assistance from Claude Code.

Summary

This PR adds the minimum Markdown formatter plumbing needed so Markdown is recognized as a formattable language in Biome.

PR #8962 introduced formatter boilerplate. This PR focuses on the required syntax/service/formatter-option integration to make Markdown format-capable from the service layer.

Test corpus and comparison/snapshot-heavy formatter tests are handled separately in #9067

Continues work on #3718

Why

Markdown must be recognized by biome_service as a format-capable language before formatter infrastructure can be exercised end-to-end.

Scope

1) Markdown file source + service routing

Added MarkdownFileSource with:
- extension detection: md, markdown
- language ID detection: markdown
Added DocumentFileSource::Markdown support in service routing/capability dispatch.
Added markdown handler in biome_service with:
- parse + format capabilities
- debug syntax tree + formatter IR
- formatter/linter/assist enabled checks

2) Markdown formatter options plumbing

Added Display for MarkdownFormatOptions (required by service language trait
bounds).
Added option builders:
- with_indent_style
- with_indent_width
- with_line_ending
- with_trailing_newline

3) Service/settings integration

Added markdown language slot to LanguageListSettings.
Added markdown deps/schema wiring in biome_service Cargo config.

4) Exhaustive match maintenance

Added DocumentFileSource::Markdown arm in xtask/rules_check for exhaustive handling.

5) Follow-up consistency cleanup in this PR

Added DocumentFileSource::to_markdown_file_source() accessor for parity with other file source helpers.
Added TODOs in markdown service handler to explicitly mark override-pattern support as pending.

Not Included

No substantive Markdown formatting behavior changes yet.
No markdown fixture/snapshot corpus in this PR.
No Prettier markdown snapshot import in this PR.
Markdown override-pattern formatting settings are not implemented yet.

Those tests/corpus are being developed in #9067

Validation

just f
just l

changeset-bot · 2026-02-14T18:04:31Z

⚠️ No Changeset found

Latest commit: cf6326b

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codspeed-hq · 2026-02-14T18:08:18Z

Merging this PR will not alter performance

✅ 58 untouched benchmarks
⏩ 156 skipped benchmarks¹

_{Comparing jfmcdowell:feat/markdown-formatter-test-harness (cf6326b) with main (7f1e060)}

156 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 · 2026-02-14T18:10:09Z

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Walkthrough

This PR introduces Markdown language support to the Biome ecosystem alongside significant enhancements to CSS and SCSS parsing and formatting. It adds a new biome_markdown_syntax crate with file-source detection, integrates Markdown formatting and parsing capabilities into the service layer, and extends the CSS parser and formatter with support for unary expressions, SCSS qualified names, nesting declarations, parent selector values, and improved bracketed-value handling. Additionally, it includes fixes for Astro, HTML, Vue, and Svelte parsing edge cases, plus corresponding changelog entries.

Possibly related PRs

feat(css): support scss nesting declarations in declaration lists #9135: Adds SCSS nesting-declaration parsing and formatting across parser and formatter modules
feat(css): enhance SCSS qualified name detection #9159: Introduces SCSS qualified-name and parent-selector value detection and formatting
feat(css): add unary expression parsing #9093: Implements CSS unary-expression parsing and formatting support

Suggested labels

D-Vue, A-Linter

Suggested reviewers

ematipico

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: adding minimal service plumbing for Markdown formatter integration, which aligns with the changeset's primary objective.
Description check	✅ Passed	The description is comprehensive and directly related to the changeset, explaining the rationale, scope, and what's included/excluded.

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📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

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coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@crates/biome_service/Cargo.toml`:
- Line 74: The manifest uses an explicit version for the notify dependency
instead of the workspace reference; update the crate's Cargo.toml so the notify
dependency references the workspace-level declaration (use workspace = true) or
move notify into the root workspace [dependencies] and keep workspace = true
here; locate the notify entry (notify = { version = "8.2.0", features =
["crossbeam-channel"] }) and change it to a workspace reference consistent with
other dependencies or add notify to the workspace dependencies table and remove
the explicit version here.

🧹 Nitpick comments (2)

crates/biome_service/src/file_handlers/markdown.rs (1)

210-225: Parser metadata is discarded during AnyParse conversion.

parse_markdown_with_cache returns list_tightness, list_item_indents, and quote_indents alongside the syntax tree (see crates/biome_markdown_parser/src/lib.rs). These are lost when converting to AnyParse via NodeParse. This is fine for the current minimal plumbing, but will need addressing when substantive formatting logic lands — list tightness in particular affects Markdown rendering semantics.
crates/biome_service/src/file_handlers/mod.rs (1)
434-441: can_contain_embeds returns false for Markdown — worth a TODO?

Markdown files commonly contain fenced code blocks (e.g., ```js ... ```), which are semantically embedded snippets. Returning false is fine for this minimal plumbing PR, but it might be worth leaving a short comment or TODO so this isn't forgotten when embedded-language support lands.
Optional: leave a breadcrumb
             Self::Html(_) | Self::Js(_) => true,
             Self::Css(_)
             | Self::Graphql(_)
             | Self::Json(_)
             | Self::Grit(_)
+            // TODO: Markdown fenced code blocks may contain embeds — revisit when embedded support lands.
             | Self::Markdown(_)
             | Self::Ignore
             | Self::Unknown => false,

crates/biome_service/Cargo.toml

tidefield · 2026-02-15T03:17:15Z

crates/biome_service/src/file_handlers/markdown.rs

@@ -0,0 +1,267 @@
+use super::{


Hi @jfmcdowell . Sorry I'm afraid this will conflict with #9067 soon. :(

I was having this implementation in my local so I can verify the snapshots are correctly captured in the tests. I'm fixing some errors before pushing it to my PR.

FYI the reason I needed to implement what you had in this PR is because the tests need to have a TestFormatLanguage implementation which then requires ServiceLanguage implementation. So it overlaps with what you're doing in the PR.

ematipico

It looks good, however we need to gate the implementation under a cargo feature or Biome will start parsing the files

ematipico · 2026-02-16T09:30:00Z

crates/biome_markdown_syntax/src/file_source.rs

+
+    pub fn try_from_extension(extension: &str) -> Result<Self, FileSourceError> {
+        match extension {
+            "md" | "markdown" => Ok(Self::markdown()),


This will enable handling markdown to our users, and we're not ready for this yet. To prevent this, do the same thing I did for SCSS in this PR: #9091

ematipico · 2026-02-16T09:30:16Z

crates/biome_markdown_syntax/src/file_source.rs

+
+    pub fn try_from_language_id(language_id: &str) -> Result<Self, FileSourceError> {
+        match language_id {
+            "markdown" => Ok(Self::markdown()),


Same thing here, let's gate it under a cargo feature

ematipico · 2026-02-16T09:30:46Z

crates/biome_markdown_syntax/src/file_source.rs

+#[derive(
+    Debug, Clone, Default, Copy, Eq, PartialEq, Hash, serde::Serialize, serde::Deserialize,
+)]
+pub struct MarkdownFileSource {


nit: I would call it MdFileSource, just because it's shorter

jfmcdowell · 2026-02-16T15:18:16Z

@ematipico given @tidefield's comment on #9067 do you want me to hold off on this?

ematipico · 2026-02-16T15:34:23Z

@ematipico given @tidefield's comment on #9067 do you want me to hold off on this?

To be honest, I lack the context of the comment. I don't know what that's about. To me, this PR seems fine cc @tidefield

jfmcdowell · 2026-02-16T18:10:47Z

@ematipico given @tidefield's comment on #9067 do you want me to hold off on this?

To be honest, I lack the context of the comment. I don't know what that's about. To me, this PR seems fine cc @tidefield

#9067 and #9076 mention comments about potential clashes. I think you (@ematipico) gave a path forward but I want to make sure we are all aligned. Cc @tidefield

tidefield · 2026-02-17T03:54:04Z

Hi @jfmcdowell. Given @ematipico 's comment in #9076 (comment), I think we can prioritize your PR first (switching it to base on main and addressing the comments)

I'll rebase my branch to main after your PR is submitted. 🎉

Add the minimum markdown service integration so markdown is recognized as a formattable language and formatter tests can run against the standard service path. - Add MarkdownFileSource detection for md/markdown extensions and markdown language id. - Add DocumentFileSource::Markdown routing and markdown handler capabilities in biome_service. - Add markdown ServiceLanguage settings/format option resolution and formatter entry points. - Add MarkdownFormatOptions Display + missing option builder methods required by service plumbing. - Add focused service tests for markdown file-source detection and formatter capability routing. - Add markdown exhaustive match handling in xtask rules_check. Scope intentionally excludes Prettier markdown comparison tests (tracked separately).

- Added an experimental-markdown cargo feature to biome_markdown_syntax and gated Markdown detection in MdFileSource for: - file extensions (md, markdown) - language ID (markdown) - Renamed MarkdownFileSource to MdFileSource per maintainer feedback and updated all service/syntax references. - Updated biome_service markdown file-source capability tests to assert default feature-off behavior (Markdown stays Unknown unless the feature is enabled).

github-actions bot added A-Project Area: project A-Parser Area: parser A-Formatter Area: formatter A-Tooling Area: internal tools labels Feb 14, 2026

coderabbitai bot reviewed Feb 14, 2026

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tidefield reviewed Feb 15, 2026

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tidefield mentioned this pull request Feb 15, 2026

feat(markdown): port snapshots from prettier #9067

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ematipico requested changes Feb 16, 2026

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tidefield mentioned this pull request Feb 16, 2026

feat(markdown): add prettier tests for markdown formatter #9076

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jfmcdowell force-pushed the feat/markdown-formatter-test-harness branch from c9228e0 to f66e03d Compare February 20, 2026 20:55

jfmcdowell changed the base branch from next to main February 20, 2026 20:56

github-actions bot removed the A-Formatter Area: formatter label Feb 20, 2026

jfmcdowell added 2 commits February 20, 2026 16:02

jfmcdowell force-pushed the feat/markdown-formatter-test-harness branch from f66e03d to e676f78 Compare February 20, 2026 21:02

fix(markdown): remove service formatter wiring

e512804

jfmcdowell force-pushed the feat/markdown-formatter-test-harness branch from e676f78 to e512804 Compare February 20, 2026 22:27

[autofix.ci] apply automated fixes

cf6326b

jfmcdowell requested a review from ematipico February 20, 2026 22:59

ematipico approved these changes Feb 21, 2026

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ematipico merged commit b834078 into biomejs:main Feb 21, 2026
33 checks passed

coderabbitai bot mentioned this pull request Feb 23, 2026

feat(css): scss basic expressions #9212

Merged

jfmcdowell deleted the feat/markdown-formatter-test-harness branch February 24, 2026 10:22

coderabbitai bot mentioned this pull request Feb 28, 2026

feat(css): add support for @container scroll-state at-rule and associated queries #9273

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jfmcdowell commented Feb 14, 2026

Summary

Why

Scope

1) Markdown file source + service routing

2) Markdown formatter options plumbing

3) Service/settings integration

4) Exhaustive match maintenance

5) Follow-up consistency cleanup in this PR

Not Included

Validation

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Merging this PR will not alter performance

Footnotes

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Walkthrough

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