Biome 2.5.8

Biome 2.5.8 ships today. Here's what changed.

New Lint Rules

• useReactCompiler (nursery) — Reports diagnostics straight from React Compiler lint mode, so compiler-level feedback lands in your editor.
• noSvelteLegacyConst (nursery) — Flags legacy Svelte {@const} tags and points you to declaration tags with $derived().
• noInvalidPropertyInitValue (nursery) — Catches CSS @property rules whose initial-value doesn't match the declared syntax descriptor.

HTML Style Attributes Are Now CSS

HTML style attribute values are parsed as CSS in this release. Every Biome CSS lint rule now applies inside style attributes, closing a long-standing coverage gap.

Fixes

• useAwait no longer reports async functions containing await using declarations.
• noUselessUndefined stops flagging return undefined when the enclosing function has a non-undefined return type.
• noUselessFragments panic fixed when an unsafe fix removes a fragment used as a JSX attribute value.
• noUndeclaredVariables now understands Vue's $slots, $attrs, and $event in templates.
• Svelte parsing fixed for expressions beginning with object literals; {{ is no longer misread as interpolation.
• CSS formatter preserves comment placement in functional pseudo-classes and indentation between declaration colons and values.

Performance

• noImportCycles skips node_modules.
• noMisusedPromises faster on async class methods calling through this.
• noFloatingPromises skips type inference for assignment statements.
• Console diagnostic printing sped up.

Biome 2.5.8 is available now via npm and the Biome installer. Update when you can.