global-validation

Implement comprehensive input validation with server-side validation (security), client-side validation (UX), fail-early patterns (KISS), specific error messages, allowlists over blocklists, and reusable validators (DRY). Use this skill when validating user input in forms, API endpoints, or data processing functions. Use when implementing validation rules for data types, formats, ranges, required fields, or business rules (SRP). Use when creating validator functions, validation schemas (Zod, Joi, Yup), form validation logic, or input sanitization to prevent injection attacks (SQL, XSS). Use when working with backend validators, frontend form libraries (React Hook Form, Formik), or consistent validation across web forms, API endpoints, and background jobs. Apply validation at multiple layers for defense in depth.