Yesterday I posted about Codex turning small tasks into big systems. Several people in the replies pointed to the same tool: 𝗣𝗼𝗻𝘆𝘁𝗮𝗶𝗹.

Besides adding rules to AGENTS.md, you can install this ready-made Skill. It’s like giving Codex / Claude Code a senior developer who’s too lazy to reinvent the wheel.

An example from the repo: you ask for a date picker, and the agent starts installing a library, writing a wrapper, and adding styles. Ponytail’s solution is one line:

<input type="date">

If the browser’s built-in control does the job, you can skip all that extra work.

Before writing new code, Ponytail tells the agent to check these options in order:

→ Reuse an existing implementation in the codebase
→ Prefer the standard library and built-in platform features
→ Use an installed dependency if it solves the problem
→ If none of those are enough, write only what the current task needs

If the agent has already written a pile of code, you can also use 𝗽𝗼𝗻𝘆𝘁𝗮𝗶𝗹-𝗿𝗲𝘃𝗶𝗲𝘄 to check the current diff.

It flags unnecessary abstractions, duplicate implementations, and dependencies you don’t need. Each finding includes the file, line number, what to delete, and what to use instead. It returns a review checklist without changing the code.

Try it on the diff that keeps growing with every change.

𝗙𝗿𝗲𝗲 𝗮𝗻𝗱 𝗼𝗽𝗲𝗻 𝘀𝗼𝘂𝗿𝗰𝗲, with support for Codex, Claude Code, and Pi:
github.com/DietrichGebert/ponytail