tdd or test-driven-development: which one should you install?
Install one of them, not both. They describe the same discipline from two publishers, so keeping both leaves two overlapping descriptions competing for the same task. Pick the one whose house style matches how your team already writes tests.
Matt Pocock's tdd skill drives red, green, refactor one vertical slice at a time, meaning each cycle delivers a thin but complete piece of behaviour. It is lighter than the superpowers version and fits teams that want the discipline without adopting a whole methodology. Choose one of the two, because running both produces contradictory instructions.
Best for
Feature work where you want working behaviour end to end early, and a light process.
Skip if
You already run superpowers, whose test-driven-development skill covers the same ground.
Which one to install
Choose tdd when you want the shorter instruction that leans on the model already knowing the loop. It is the lighter of the two and stays out of the way on codebases that have a test suite and a convention in place.
The test-driven-development skill in Jesse Vincent's superpowers collection drives the agent through a red, green, refactor cycle: a failing test first, the smallest change that passes it, then cleanup. With an agent the failing test does double duty, because it also proves the agent understood the requirement before it started writing code.
Best for
Features and bug fixes with checkable behaviour, especially in code you cannot manually verify quickly.
Skip if
You are exploring, prototyping or throwing the code away tomorrow.
Which one to install
Choose test-driven-development when you want the discipline enforced rather than suggested, including the part where the failing test has to be seen failing first. It is the better fit on a codebase where tests are written after the fact, or not at all.
Installing both is the clearest example of the overlap problem this catalogue keeps flagging. Two descriptions covering the same trigger means one wins every time and the other looks broken, so the decision is which to keep rather than how to combine them.