ponytail

Apply a decision ladder that checks whether the feature is needed at all, whether existing code or the standard library already solves it, and whether native platform features cover it before writing new code. This Skill enforces that hierarchy on every coding task.

Prefer the standard library first, then native platform features, then already-installed dependencies. Only add a new dependency when a few lines of code genuinely cannot solve the problem, which reduces maintenance and supply-chain risk.

Lite builds what is asked but names a lazier alternative. Full, the default, enforces the ladder with the shortest working diff. Ultra is YAGNI-extremist, preferring deletion over addition and challenging the requirement itself.

Never simplify away input validation at trust boundaries, error handling that prevents data loss, security measures, accessibility basics, or anything explicitly requested. Minimal code also never justifies skipping problem comprehension before editing.

Non-trivial logic such as branches, loops, parsers, or money and security paths should ship with one small runnable check, like an assert-based self-check or a single test file. Trivial one-liners need no test, and full test frameworks are avoided unless requested.