Agent Skills: implement-with-test

Implements a task as production code plus tests, auto-detecting the test framework (jest, vitest, pytest, go test, cargo test) and following existing project patterns. Task information comes from an argument (description or task file path) or the current conversation. Use when user asks to implement a task, build a feature with tests, or says "implement", "구현", "구현해줘", "테스트와 함께 구현". Proactively trigger whenever the user wants to turn a task or requirement into working code with tests.