What’s new here

Ponytail tells the agent to write only what the task needs. The core is one prompt, skills/ponytail/SKILL.md, and a compact AGENTS.md version for agents that read a rules file. Before writing code, the agent stops at the first rung of a ladder that holds:

• Does this need to exist?
• Is it already in this codebase?
• Does the standard library do it?
• Is there a native platform feature?
• Is there an installed dependency?
• Can it be one line?

Only then does it write the minimum.

What it does

The README’s own example is a date picker. Without the skill, the agent builds 335 lines. With it, the agent reuses the repo’s Input component with type=date and lets the browser supply the calendar, in 10 lines. The rule is not fewest tokens. Validation, error handling, security and accessibility are never cut, and logic with a branch, loop, parser, money or security gets one small test. Every reply ends with what was skipped or not checked.

On top of the prompt there are commands:

• /ponytail [lite | full | ultra | off] sets the intensity.
• /ponytail-review reviews the current diff plus the code it touches.
• /ponytail-audit ranks problems across the whole repo.
• /ponytail-debt collects deferred shortcut: comments into a ledger.
• /ponytail-gain shows the benchmark scoreboard.

Version 5.3 adds a band above the prompt in Claude Code. It shows task cost, tokens, agent time, how often existing code was reused, and whether tests passed after the last change. A local board page keeps this history, by default in ~/.config/ponytail/band/.

Who it’s for

People who use Claude Code, Codex or another coding agent and are tired of 300-line answers to 10-line problems. It also suits teams that want a review or audit pass written from the point of view of whoever gets paged when it breaks. If you want an agent to build big things from scratch in one go, this pushes the other way.

Try it

Needs a supported coding agent. The band needs Claude Code 2.1.290 or later. No config file is required. In Claude Code, run these as two separate prompts:

/plugin marketplace add DietrichGebert/ponytail

/plugin install ponytail@ponytail

In Codex:

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

Then open /hooks in Codex, trust its two lifecycle hooks, and start a new thread. For any other agent, copy AGENTS.md into your project or install skills/ponytail/SKILL.md as a skill. INSTALL.md covers Copilot, Cursor, OpenCode, Gemini and others. The README says to install only from DietrichGebert/ponytail on GitHub or @dietrichgebert/ponytail on npm.

How mature is it

Created 2026-06-12 and pushed 2026-10-18. It has 176,581 stars, 9,643 forks, 29 releases (latest v5.3.2 on 2026-10-16) and at least 100 contributors. The API count is capped at 100 for both contributors and commits in the last 90 days. It has 61 open issues and 76 open PRs. The license is MIT. The headline numbers (53% less code, 41% less time, 98% of risky logic shipping with a test versus 68%) come from the author’s own benchmark: 39 tasks in Claude Code on Opus 5.5, 5 runs each. Treat them as the author’s claim, not independent results.