Ponytail

What it is

A free, MIT-licensed prompt, packaged as a skill, that makes your AI coding agent think like "the laziest senior dev in the room" (the repo's own description). Before writing anything it takes the simplest option that fully works: does this need to exist at all, is it already in the codebase, does the standard library or a native platform feature cover it, does an installed dependency solve it, and only then the minimum code. The README's example (v5): asked for a date picker, the agent reuses the repo's own Input with type date, 10 lines instead of 335 by hand. The README says it never cuts validation at trust boundaries, data-loss handling, security or accessibility.

Setup

1. Claude Code, first prompt. Send it on its own:

   /plugin marketplace add DietrichGebert/ponytailCopy

2. Second prompt, separately (the README says both must be sent as separate prompts):

   /plugin install ponytail@ponytailCopy

3. In a new thread, check it. With no argument it reports the current level. The levels are lite, full (the default) and ultra; turn it off with /ponytail off.

   /ponytailCopy

4. Codex: add the marketplace, then the plugin. Open /hooks, trust its hooks and start a new thread.

   codex plugin marketplace add DietrichGebert/ponytailCopy
   codex plugin add ponytail@ponytailCopy

5. Other agents: copy AGENTS.md into your project, or add the skills only. The repo's INSTALL.md has step-by-step instructions for each agent.

   npx skills add DietrichGebert/ponytailCopy

Cheat sheet

• Repository and README and the install guide.
• Install only from DietrichGebert/ponytail on GitHub or @dietrichgebert/ponytail on npm. The README says it never ships .exe or .dll files; a copy that does is not the author's.
• The hooks need node on your PATH. Without it the skills still work, but each hook prints a harmless node: command not found.
• Commands: /ponytail-review reviews your diff for bugs, security, load, missing tests and what to cut; /ponytail-audit does the same for the whole repo, most important first; /ponytail-debt collects the shortcut: comments you deferred.
• Start on full. Lite names the smaller option and lets you pick; ultra also questions the request itself.
• The numbers are the maker's. The older "about 54% less code" counts lines added in the git diff, comments included, across 12 tickets (from about 0% to 94% per task), on Haiku 4.5 and one repo, and its file says the safety check "is not a proof of security". The newer headline (-53% lines) covers 39 tasks on Opus 5.5 with 5 runs each. Both are on Claude Code only. Review the diff anyway.
• If you do need the long version, ask for it and it will build it.
• Uninstall: /plugin remove ponytail (Codex: codex plugin remove ponytail). A little state stays behind outside the plugin folder, such as ~/.claude/.ponytail-active and ~/.config/ponytail/config.json; the install guide's Uninstall section says how to clear it.
• Not verified by Axo: either benchmark (we did not rerun them), and how it behaves on your setup.

Axo's take

AXO

Haven't run it myself: this page comes from the maker's README and benchmark files. Try it if your agent keeps shipping a 400-line component where one native HTML tag would do. The headline saving is lines of code, and the maker also reports checks on correctness, but they are the maker's own, so keep reading the diff.