Major new capabilities
TypeScript plugins are now supported — Biome’s JS plugin runtime can load .ts plugins, expanding authoring options and tightening syntax validation.
TypeScript type stripping lands as a new JS transform — A new stripTypes transformation erases TS annotations across classes, enums, imports/exports, namespaces, and more.
Markdown frontmatter parsing is now supported — Markdown files can preserve YAML-style frontmatter end-to-end through parsing and formatting.
Safety and linting improvements
New Astro and CSS safety rules — The week added useAstroClientOnlyDirectiveValue, noAstroSetHtmlDirective, useNamedLayer, and noUndeclaredCustomProperties, covering invalid Astro directives, XSS-prone HTML injection, anonymous cascade layers, and undeclared CSS variables.
New TypeScript correctness checks — noUnsafeTypeAssertion now flags unsound as assertions, while useStrictMode and Vue-related rules were refined to reduce false positives and avoid unsafe autofixes.
Parser, resolver, and analyzer fixes
Astro, Svelte, Vue, YAML, and JS parsing got major cleanup — Biome fixed multiple edge cases around Astro expressions/frontmatter, incomplete Svelte declarations, Vue bindings, YAML indentation and mapping parsing, and parenthesized object expressions in JS.
TypeScript path resolution and inference improved — Path aliases without ./ now resolve correctly, and local inference was tightened for dependent class members to improve analysis quality and performance.
Plugin and GritQL tooling became more capable — JS plugins can query nodes by kind, GritQL handles metavariables in quoted strings and richer export patterns, and WASM builds can opt into JS plugins.
Performance and internal refactors
Analyzer, deserializer, and markdown hot paths were optimized — Several internal refactors reduced monomorphization, narrowed lint queries, improved cache eviction, and trimmed markdown lexer/formatter overhead.
Other misc changes
Maintenance and cleanup — CI and dependency updates, release housekeeping, changeset cleanup, and assorted test/snapshot refreshes landed throughout the week.