Type-aware analysis got more accurate and faster
Biome spent much of the week refactoring its JS/TS inference engine to reduce false positives and improve performance. Rules like noMisusedPromises, noMisleadingReturnType, useAwaitThenable, and useExhaustiveSwitchCases now avoid diagnostics when inference is incomplete, while type consumers were rewritten to request only the information they need and cache export resolution. The result is both broader coverage for inferred async/Promise cases and less repeated type work in hot lint paths.
Formatter support expanded significantly, especially for YAML
YAML saw the biggest user-facing formatter changes: support landed for document markers and directives, flow mappings, block scalars, cleaner comment indentation, node-property placement, and better handling of multiline/comment-heavy structures. On the CSS side, Biome fixed selector-boundary comment placement, escaped newlines in attribute selectors, SCSS parent-selector parsing, and commented function arguments, improving stability across tricky stylesheet inputs. HTML/Svelte formatting also got several correctness fixes, including comment deduplication, idempotent embedded reformatting, and support for Svelte declaration tags.
Parser and analyzer coverage broadened across web frameworks
HTML and template support improved in a few notable ways: shorthand attributes now participate correctly in ARIA role inference, mixed-case doctypes are accepted, and Svelte-specific constructs like {let ...} and {const ...} are now parsed, formatted, and linted. These changes close several real-world gaps in Astro/Svelte/Vue-style markup handling and reduce false positives in accessibility and formatting workflows.
New lint capability and CLI output improvements
Biome added a nursery noRestrictedProperties rule, along with migration/config support so ESLint conversions preserve options. On the CLI side, reviewdog-compatible rdjson output now includes explicit severities for every diagnostic, making downstream integrations more reliable.
Performance and infrastructure work rounded out the week
The formatter picked up hot-path optimizations that the team reports as roughly 7% faster overall, and noMisusedPromises avoids unnecessary repeated inference on some expressions. Biome also added benchmark coverage for lint rules in CI, updated some dependencies, and made smaller maintenance changes around audit ignores, release metadata, and test snapshots.
Other misc changes
- Tailwind class sorting now orders utilities by name more consistently
- Canonical inferred globals and
Symbolglobal type plumbing were refactored - Misc dependency bumps, lockfile updates, docs, and test/snapshot refreshes