Purpose Use this skill when creating diagnostics - the error messages, warnings, and hints shown to users. Covers the trait, advice types, and best practices for clear, actionable messages. Prerequisites 1. Read for concepts 2. Understand Biome's Technical Principles 3. Follow the "show don't tell" philosophy Diagnostic Principles 1. Explain what - State what the error is (diagnostic message) 2. Explain why - Explain why it's an error (advice notes) 3. Tell how to fix - Provide actionable fixes (code actions, diff advice, command advice) Follow Technical Principles: - Informative: Explain, do…