# Biome @biomejs/biome@2.4.15 — Release & Upgrade Intelligence
- **Product:** Biome (https://biomejs.dev)
- **Version:** @biomejs/biome@2.4.15
- **Released:** May 09, 2026
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/biome/updates/biomejs-biome-2.4.15/

## Executive Summary (TL;DR)
Biome @biomejs/biome@2.4.15. Source highlight: Added the nursery rule `useTestHooksInOrder` in the `test` domain. The rule enforces that Jest/Vitest lifecycle hooks (`beforeAll`, `beforeEach`, `afterEach`, `afterAll`) are declared in the order they execute, making test setup and teardown easier to reason about.

## New Features
- feat(css_formatter): improve SCSS `@each` rule formatting
- feat(css_formatter): improve SCSS map formatting for parenthesized list keys
- feat(css_parser): parse scss interpolated nth arguments
- feat(css_formatter): improve SCSS map value and pair formatting for better readability
- feat(css_formatter): enhance SCSS map value formatting
- feat(css_formatter): improve formatting for parenthesized SCSS lists

## Improvements
- refactor(organizeImports): improve diagnostics
- perf: reduced queries in rules
- chore: improve agent behaviour
- perf(css): deduplicate rules information

## Bug Fixes
- Added the nursery rule `useTestHooksInOrder` in the `test` domain. The rule enforces that Jest/Vitest lifecycle hooks (`beforeAll`, `beforeEach`, `afterEach`, `afterAll`) are declared in the order they execute, making test setup and teardown easier to reason about.
- Added a new nursery rule `useVueNextTickPromise`, which enforces Promise syntax when using Vue `nextTick`.
- Added a new nursery rule `noVueVOnNumberValues`, that disallows deprecated number modifiers on Vue `v-on` directives.
- Added the new nursery rule `useVueValidVFor`, which validates Vue `v-for` directives and reports invalid aliases, missing component keys, and keys that do not use iteration variables.
- Added the recommended nursery rule `noVueImportCompilerMacros`, which disallows importing Vue compiler macros such as `defineProps` from `vue` because they are automatically available.
- Fixed #10193: `style/useReadonlyClassProperties` no longer reports class properties as readonly-able when they are assigned inside arrow callbacks nested in class property initializers.

## Upgrade Command
```bash
npm install --save-dev --save-exact @biomejs/biome@2.4.15
```