| name | changeset |
| description | Guide for creating and writing proper changesets for Biome PRs. Use when a PR introduces user-visible changes (bug fixes, new features, rule changes, formatter changes, parser changes) that need a changeset entry for the CHANGELOG. Trigger when creating changesets, writing changeset descriptions, or choosing the correct change type. |
| compatibility | Designed for coding agents working on the Biome codebase (github.com/biomejs/biome). |
Purpose
Use this skill when a PR introduces user-facing changes that require a changeset. Changesets drive CHANGELOG generation and release automation. Internal-only changes (refactors with no user-visible effect) do not need changesets.
Create a Changeset
Do not create changeset files manually. Use:
just new-changeset-empty
The command will create an empty file .changeset/. Edit it directly to add detail.
Requires pnpm — run pnpm i from repo root first.
Choose the Correct Change Type
patch — Bug fixes.minor — New features. PR must target the next branch.major — Breaking user API changes. PR must target the next branch. These are rare and strictly controlled.
Refer to the versioning page when unsure.
Changeset Format
---
"@biomejs/biome": patch
---
Description here.
If you need headers inside the description, use #### or ##### only. Other header levels break the CHANGELOG tooling.
Writing Guidelines
General Rules
- Write about user-facing changes only. No changeset needed for pure refactoring. Describe how the change affects the user.
- Be concise and clear — 1 to 3 sentences. Longer entries signal to users that the change deserves attention.
- Past tense for what you did: "Added", "Fixed", "Changed".
- Present tense for Biome behavior: "Biome now supports...", "The rule now detects...".
- End every sentence with a full stop (
.).
Bug Fixes
Start with a link to the issue:
Fixed [#4444](https://github.com/biomejs/biome/issues/4444): [`useOptionalChain`](https://biomejs.dev/linter/rules/use-optional-chain/) now detects negated logical OR chains.
New Lint Rules
Show an example of an invalid case. Use inline code for simple things, a code block for complex ones:
Added a new nursery rule [`noDuplicateSelectors`](https://biomejs.dev/linter/rules/no-duplicate-selectors/), that disallows duplicate selector lists within the same at-rule context.
For example, the following snippet triggers the rule:
` ` `css
.foo {}
.foo {}
` ` `
Changes to Existing Rules
Clearly show what is now invalid that was not before (or vice versa). Show both sides if helpful:
Fixed [#7211](https://github.com/biomejs/biome/issues/7211): [`useOptionalChain`](https://biomejs.dev/linter/rules/use-optional-chain/) now detects negated logical OR chains. The following code is now considered invalid:
` ` `js
!foo || !foo.bar
` ` `
Formatter Changes
Show the formatting diff:
Changed formatting of arrow function parameters. Example:
` ` `diff
- const fn = ( a, b ) => {};
+ const fn = (a, b) => {};
` ` `
Parser Changes
Brief inline example of what can now be parsed:
Added support for parsing `using` declarations in JavaScript.
Use a code block if multiline clarity helps.
Linking Rules and Assists
Always link to the website, even if the page does not exist yet (it will after merge):
- Rules:
[`useConst`](https://biomejs.dev/linter/rules/use-const/)
- Assists:
[`organizeImports`](https://biomejs.dev/assist/actions/organize-imports/)
Tips
- Create the changeset before opening the PR; you can edit it after.
- Look at existing files in
.changeset/ or recent CHANGELOG.md entries for reference.
- One changeset per PR is typical. Multiple changesets are allowed if the PR addresses multiple, distinct bugs.
References
