Agent Skills: blackbox-test-design

Turn an input specification into a minimal, high-coverage black-box test set using Equivalence Partitioning + 2-value Boundary Value Analysis. Use when designing or reviewing test cases for functions, forms, validators, or APIs from their input domains (ranges, formats, enums) — not from source code. Triggered by phrases like "design test cases", "what should I test for this input", "boundary tests", or "EP/BVA for this field".