ponytail

A skill that makes your agent code like the laziest senior dev: YAGNI enforced — ~54% less code, ~20% cheaper, ~27% faster on measured Claude Code sessions. Works with 20 agents.

122,688 6,634 JavaScript MITupdated 1 months ago

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Curator's take

One opinion, installed: the best code is the code you never wrote. Where every other add-on gives your agent MORE — more context, more tools, more process — ponytail gives it restraint, and the benchmarking is unusually honest: ~54% mean code reduction across 12 real tasks (94% is the over-building ceiling, not the average), with the safety-guard regression of a naive 'write one-liners' prompt explicitly tested and avoided. Works across 20 agents. NOT for codebases where verbosity is the convention (enterprise Java won't thank you), and watch the trajectory: 88k stars, a waitlist banner and ponytail.dev — the skill is free today, the product is coming.

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README.md1 min read

Ponytail

He says nothing. He writes one line. It works.

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~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 (a date picker) and is near zero where the code is already minimal. ponytail keeps every safety guard while a bare "write one-liners" prompt drops one. (The earlier single-shot benchmark reported 80-94% as a flat figure; against a fair agentic baseline that is the per-task ceiling, not the average.) Full writeup · reproduce it.}

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You know him. Long ponytail. Oval glasses. Has been at the company longer than the version control. You show him fifty lines; he looks at them, says nothing, and replaces them with one.

Ponytail puts him inside your AI agent.

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">

More survivors in examples/.

Numbers

The honest measurement is a real agent doing real work: a headless Claude Code session editing tiangolo's full-stack-fastapi-template (a real FastAPI + React repo), scored on the git diff it leaves behind. Twelve feature tickets, the same agent with and without the skill, n=4, Haiku 4.5.

Each arm as a percent of the no-skill baseline across LOC, tokens, cost and time (Haiku 4.5). ponytail is lowest on every metric (LOC 46%, tokens 78%, cost 80%, time 73%); caveman rises above 100% on tokens, cost and time; yagni-oneliner LOC 67%. Safety, separate adversarial tier: baseline, caveman and ponytail 100%, yagni-oneliner 95%.

vs no-skill baseline	LOC	tokens	cost	time	safe
ponytail	-54%	-22%	-20%	**-2