Ponytail

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

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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

Six tasks: streaming log parser, atomic file sync, notification dispatcher, validation engine, auth module, concurrent money ledger. One spec each, one fresh agent per arm, same model. Three arms: no skill, the caveman skill, and ponytail. Every arm passes the same adversarial security and concurrency probes. Then the agreement ends:

47% fewer tokens than the no-skill agent. 3× faster. A seventh of the code. The 3,139 lines nobody wrote have never caused an incident. When a surprise feature request hit two of the tasks, ponytail extended in 96 changed lines; caveman needed 413, the no-skill agent 1,115. Every shortcut ponytail took is marked in the code with a ponytail: comment naming its upgrade path. Data: benchmarks/.

How it works

Before writing code, the agent stops at the first rung that holds:

1. Does this need to exist?   → no: skip it (YAGNI)
2. Stdlib does it?            → use it
3. Native platform feature?   → use it
4. Installed dependency?      → use it
5. One line?                  → one line
6. Only then: the minimum that works

Lazy, not negligent: trust-boundary validation, data-loss handling, security, and accessibility are never on the chopping block.

Install

The most effort ponytail will ever ask of you:

Claude Code

/plugin marketplace add DietrichGebert/ponytail
/plugin install ponytail@ponytail

Codex

codex plugin marketplace add DietrichGebert/ponytail
codex

Open /plugins, select the Ponytail marketplace, and install Ponytail. Then open /hooks, review and trust its two lifecycle hooks, and start a new thread.

That was it. He'd be proud. He won't say it.

Active every session. /ponytail-review finds what to delete in your diff. /ponytail ultra exists for when the codebase has wronged you personally. /ponytail-help explains the rest.

In Codex, invoke the skills as @ponytail, @ponytail-review, and @ponytail-help. Startup and mode-change text shows the current mode.

Cursor, Windsurf, Cline, Copilot, Aider, Kiro: copy the matching rules file from this repo (.cursor/rules/, .windsurf/rules/, .clinerules/, .github/copilot-instructions.md, AGENTS.md, .kiro/steering/).

Kiro: copy .kiro/steering/ponytail.md to ~/.kiro/steering/ (global) or .kiro/steering/ in your project.

Development

When changing the compact rule text, keep the agent copies aligned:

node scripts/check-rule-copies.js

FAQ

Does it need a config file? No.

What if I really need the 120-line cache class? You don't. Insist anyway and he'll build it. Slowly. Correctly. While looking at you.

Does it scale? The code you never wrote scales infinitely. Zero bugs, zero CVEs, 100% uptime since forever.

Why "ponytail"? You know exactly why.

License

MIT. The shortest license that works.