Biome Agent Skills

Use only for reviewing completed Biome PRs, branches, commit ranges, diffs, or working trees against business logic and requirements. Excludes broad code-quality and process audits, triage, reproduction, and implementation.

Use this skill when a Biome change may affect users and you must decide whether it needs a changeset, choose the release level, or create and edit `.changeset/*.md` release-note text. Do not use for implementation details or PR descriptions.

Use this skill when designing or implementing Biome user-facing diagnostic presentation or APIs, including messages, advice, markup, details, code frames, categories, severity, and standalone `Diagnostic` types. Do not use for lint matching logic or code-action mutations.

Use this skill whenever writing or editing Rust `//`, `///`, or `//!` comments in Biome, including comments added incidentally and end-user rustdoc inside lint/assist declarations. For lint/assist rustdoc, also load lint-rule-development for content requirements. Do not use for formatter handling of comments in user code.

Use this skill when `biome migrate eslint` must preserve configurable ESLint rule options through source-option models, Biome conversions, typed rule variants, and migration fixtures. Do not use for generated severity-only mapping or general rule-option design.

Use this skill whenever implementing or debugging Biome formatter behavior, IR composition, node rules, layout selection, source-comment handling, verbatim formatting, idempotency, internal specs, or Prettier comparison. Do not use it for generic snapshot commands or parser changes.

Use this skill when creating or modifying Biome lint rules or assists, including analyzer queries, semantic bindings, rule state, code actions, fix safety, options, registration, and end-user rule rustdoc. Also load diagnostics-development for substantial message/advice design and testing-codegen for fixture or snapshot mechanics.

Use this skill when implementing or modifying Biome parser behavior, including `.ungram` grammars, lexers, token sources, parse rules, separated lists, error recovery, and parser fixtures. Do not use merely for consuming an existing AST/CST.

Use this skill when extracting or storing Biome AST/CST source text, working with any `SyntaxNode`, `SyntaxToken`, `TokenText`, quoted strings, token-relative ranges, or embedded-language attribute values, or diagnosing trivia, allocation, range, and temporary-borrow problems. Do not use for parser implementation or formatter comment placement.

Use this skill when selecting or running Biome test fixtures, quick tests, `insta` snapshot workflows, expectation comments, orphan checks, or required code generators. Do not use for subsystem implementation design.

Use this skill when working on Biome's Salsa-backed JavaScript and TypeScript inference, including type-aware lint rules, raw collection or inferred representations, analyzer requests, tracked queries, import or cycle resolution, profiling, and Salsa invalidation tests. Do not use for standalone CSS/HTML module-graph data unrelated to JS/TS inference or for ordinary semantic binding analysis.