Ponytail
A coding-agent skill that replaces over-built code with the one minimal line that works.
Ponytail puts the grizzled senior dev inside your AI agent — the one who looks at fifty lines, says nothing, and replaces them with one. It's a minimal-code skill: YAGNI first, stdlib and language natives before custom code.
Repository: github.com/DietrichGebert/ponytail
Works with 16 coding agents. Published on npm as @dietrichgebert/ponytail.
Before / after
You ask for a date picker. Your agent installs flatpickr, writes a wrapper component, adds a stylesheet, and starts a discussion about timezones. With Ponytail:
<!-- ponytail: browser has one -->
<input type="date">Numbers
~54% less code (up to 94%) · ~20% cheaper · ~27% faster · 100% safe.
Measured on real Claude Code sessions editing a real open-source repo (FastAPI + React), against the same agent with no skill. ~54% is the mean across 12 feature tasks (Haiku 4.5, n=4); it reaches 94% where an agent over-builds and is near zero where the code is already minimal. Ponytail keeps every safety guard that a bare "write one-liners" prompt would drop.