Ponytail 5: reuse what exists before writing

/plugin marketplace add DietrichGebert/ponytail

/plugin install ponytail@ponytail

The new Ponytail 5 is a complete rewrite. Same request, “add a date picker to the frontend”: without it, the agent wrote 335 lines. With it, just 10 lines, using the repo’s existing Input component and letting the browser supply the calendar.

In the maker’s own benchmark, 39 tasks in Claude Code with Opus 5.5, the agent with Ponytail wrote 53% less code, took 41% less time and cost 26% less. It wrote less, yet 98% of its risky logic shipped with a test, against 68% without.

Before writing code, it reads the parts the change touches, then asks these in order and stops at the first one that holds:

• Does this have to be written at all?
• Is it already in the repo?
• Is the standard library enough?
• Does the browser or the OS already have it?
• Can an installed dependency cover it?
• Can it be one line?
• If none of that works, write the smallest version that runs, plus one small test if it has logic

Input validation, error handling, security and accessibility never get cut.

Two commands were rebuilt too. /ponytail-review used to look only for code to delete; now it also reads the code your change touches. Rename a field and break a file you never touched, and it catches that. In the maker’s tests it found every problem outside the diff, against 78% without the skill. /ponytail-audit runs the same checks across the whole repo and ranks what to fix first.

Ponytail 5.3 also adds a bar above the Claude Code prompt: what the task cost, its tokens, how long it ran, how much existing code it reused, and whether the tests passed (needs Claude Code 2.1.290 or later).

It’s MIT licensed.

In Codex, run these two:

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

Then trust its two hooks in /hooks and start a new thread.