Parser and formatter coverage expanded across styles and markup
Biome broadened SCSS/CSS support in several directions: interpolation now works in more containers and property names, url() accepts conditional if() expressions, @root and @supports heads handle richer dynamic forms, and legacy vs modern if() syntax is distinguished more accurately. On the markup side, HTML parsing now rejects mismatched or stray closing tags, the formatter preserves spacing when joining inline content, and Vue slot props plus Svelte snippet formatting were tightened up for real-world component syntax.
Type inference and type-aware linting got noticeably more robust
The type system picked up multiple correctness fixes, including preserving generic bindings during member lookup, resolving mapped keyof types, and avoiding stack overflows in cyclic import graphs. Internal type-info/codegen work also continued to support these changes. In practice, this improves downstream type-aware rules like noFloatingPromises and reduces false positives in generic-heavy codebases.
New lint rules landed across JS, CSS, Vue, Svelte, Astro, and HTML
Biome added several new checks this week: useStrictBooleanExpressions, useBigintLiterals, noZeroFractions, noIteratorProperty, noProcessExit, noSvelteInspect, noVueBooleanDefault, noAstroConflictingSetDirectives, and noMisplacedListElements. Existing rules also gained coverage and compatibility updates, such as noUnknownAttribute recognizing React 19 transition events, noDuplicateFontNames exempting monospace, monospace, and useImportExtensions extending to HTML-backed Vue/Svelte/Astro modules.
Autofixes and diagnostics were made safer
Several fixes were hardened to avoid producing invalid code: noUselessReturn now avoids unsafe removals in unbraced bodies, noAdjacentSpacesInRegex skips character classes, and the test-title logic no longer misclassifies ordinary .test() calls. Biome also fixed migration metadata and unsupported-rule classification so ESLint-to-Biome conversion output is more accurate and reusable.
Performance and stability improvements
Performance work landed in semantic analysis, callable resolution, promise classification, HTML whitespace scanning, YAML lexing, and JSX attribute matching. The CLI was also hardened against broken pipes, and the Unix daemon socket is now restricted to the current user.
Other misc changes
- More migration mappings, schema updates, and documentation refreshes
- CI, benchmark, and fixture updates across parser and lint suites
- Internal refactors in rule metadata, type-info generation, and plugin/codegen plumbing