Purpose

Use this skill when creating a pull request for the Biome repository. It covers branch targeting, title formatting, the PR template, and AI disclosure requirements.

AI Assistance Disclosure

If AI was used in any capacity to produce the PR, you must disclose it in the PR description. Examples:

This PR was written primarily by Claude Code.

I consulted ChatGPT to understand the codebase but the solution was fully authored manually by myself.

This is mandatory. It helps reviewers apply appropriate scrutiny.

Choose the Target Branch

PR Title

Use conventional commit format. The title becomes the squash-merge commit message.

<type>(<scope>): <short description>

Supported prefixes:

• feat: — new feature
• fix: — bugfix
• docs: — documentation update
• refactor: — code refactor (no behavior change)
• test: — test update
• chore: — housekeeping
• perf: — performance improvement
• ci: — CI change
• build: — build system or dependency change
• revert: — revert a previous change

Examples:

feat(css): add noDuplicateSelectors rule
fix(linter): handle edge case in useOptionalChain
docs: update contributing guide
refactor(parser): simplify HTML attribute parsing

The CI runs action-semantic-pull-request to validate the title. Fix it if the workflow fails.

PR Template

The repository has a PR template at .github/PULL_REQUEST_TEMPLATE.md. Every PR description must follow this structure:

## Summary

<!-- Explain the motivation for this change. What problem does it solve? -->
<!-- Link relevant issues or Discord discussions. -->
<!-- If user-facing, mention the changeset. -->

## Test Plan

<!-- What demonstrates correctness? Mention tests added/updated. -->

## Docs

<!-- For new rules/actions/options: docs are inline in the code (rustdoc). -->
<!-- For other features: link a docs PR to the `next` branch of biomejs/website. -->

Writing a Good Summary

• Bug fixes: Explain the fix concisely. If the fix introduces exceptions or unusual code paths, call those out so reviewers know what to watch for.
• New concepts: If the PR adds new abstractions, types, or patterns to the codebase, explain the technical design so reviewers can evaluate it.
• General rule: Provide enough context for reviewers to understand how to review the PR. The summary serves the reviewer.
• Link related issues: Fixes #1234 or Related to #5678.
• A changeset description is a good starting point, but the summary should add context the changelog alone would not convey (design decisions, trade-offs, scope limitations).

Test Plan

Keep it brief. Examples:

• "Added new tests from the bug report."
• "Extended existing snapshot tests to cover the new edge case."

Do not list individual test files — the diff speaks for itself. If automated tests were not possible, state that manual testing is required.

Docs

• New features require documentation. This section is for linking the PR against the next branch of biomejs/website.
• Lint rules and helps to carry their own docs as rustdoc in the source code — no separate website PR needed.
• If the PR doesn't need for documentation changes, add N/A under the section.

Pre-PR Checklist

Before opening, ensure:

1. Code compiles: cargo check
2. Tests pass: cargo test (or just test-crate <crate> for scoped runs)
3. Code is formatted: just f
4. Lints pass: just l
5. Code generation is up to date (CI autofix handles this, but check if unsure):
   • Lint rules: just gen-rules && just gen-configuration
   • Grammar: just gen-grammar <lang>
   • Bindings: just gen-bindings
6. Changeset created (if user-facing change): just new-changeset-empty
7. Snapshot tests reviewed: cargo insta review

References

• Contribution guide: CONTRIBUTING.md sections "Commit messages" and "Creating pull requests"
• PR template: .github/PULL_REQUEST_TEMPLATE.md
• Conventional commits: https://www.conventionalcommits.org/en/v1.0.0-beta.2/
• Versioning policy: https://biomejs.dev/internals/versioning/