Input Validation Skill

🔴 AI FIRST Quality Principle

Apply the AI FIRST principle: never accept first-pass quality. Minimum 2 iterations. Read all output, improve every section. No shortcuts.

Purpose

Defines input validation and sanitization patterns for preventing security vulnerabilities and ensuring data integrity.

Core Principles

1. Validate all input — Never trust user-supplied data
2. Allowlist over denylist — Define what IS allowed
3. Validate on server-side — Client-side validation is UX only
4. Encode output — Context-appropriate encoding
5. Fail securely — Reject invalid input with safe defaults