What problem does it solve? Writing a new Biome lint rule or assist requires navigating analyzer queries, semantic models, diagnostic design, fix safety, options, codegen, and fixture testing, and mistakes in any of these areas produce incorrect or unsafe rules. ## Core Features & Use Cases - Rule Scaffolding and Workflow: Provides the just new-*-lintrule and new-*-assistrule commands, nursery placement policy, and changeset targeting for new rules and assists. - Query, State, and Diagnostic Guidance: Explains how to choose between Ast, Semantic, service, and type-inference queries, keep State allocation-free, and structure messages, advice, and code actions. - Testing and Documentation: Covers fixture and snapshot testing, fix-safety verification, rule options with merge behavior, and end-user rustdoc conventions. - Use Case: A contributor adding a new JavaScript lint rule to Biome follows the workflow to scaffold the rule, implement a semantic query that handles global shadowing, add a safe autofix, write fixtures, and run just gen-rules and focused tests. ## Quick Start Ask the agent to scaffold and implement a new Biome lint rule named useMyRule following this skill's workflow.
