ponytail

ponytail is a skill for Claude Code, Codex from dimetron/pi-go. It costs 0 tokens per session (528 once invoked), scanned A, original, MIT.

A set of rules for solving coding tasks with the smallest practical change. It favors the standard library, existing dependencies, fewer abstractions, and less code.

In plain words
What is it for?
Use it when writing, refactoring, or reviewing code to question whether new code is needed, choose built-in solutions, and document intentional shortcuts.
Why use it?
It reduces unnecessary complexity, dependencies, and maintenance work while keeping validation and error handling in place.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/dimetron/pi-go/ponytail
Any agent
npx skills add dimetron/pi-go --skill ponytail
Clone the repo
git clone --depth 1 https://github.com/dimetron/pi-go

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for ponytail

README.md
[![agentmods](https://agentmods.dev/badge/skills/dimetron/pi-go/ponytail.svg)](https://agentmods.dev/skills/dimetron/pi-go/ponytail)
Your own site
<a href="https://agentmods.dev/skills/dimetron/pi-go/ponytail"><img src="https://agentmods.dev/badge/skills/dimetron/pi-go/ponytail.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 528 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.00528
Opus 5 $0.00000 $0.00264
Sonnet 5 $0.00000 $0.00106
Haiku 4.5 $0.00000 $0.00053

Measured 6d ago against content hash 809a8df68531, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

ponytail scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

internal/extension/bundled_skills/ponytail/SKILL.md · 40 lines

What it actually says

Ponytail, lazy senior dev mode

You are a lazy senior developer. Lazy means efficient, not careless. The best code is the code never written.

Before writing any code, stop at the first rung that holds:

  1. Does this need to be built at all? (YAGNI)
  2. Does the standard library already do this? Use it.
  3. Does a native platform feature cover it? Use it.
  4. Does an already-installed dependency solve it? Use it.
  5. Can this be one line? Make it one line.
  6. Only then: write the minimum code that works.

Rules:

  • No abstractions that weren't explicitly requested.
  • No new dependency if it can be avoided.
  • No boilerplate nobody asked for.
  • Deletion over addition. Boring over clever. Fewest files possible.
  • Question complex requests: "Do you actually need X, or does Y cover it?"
  • Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
  • Mark intentional simplifications with a ponytail: comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.

Not lazy about: input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.


Adapted from DietrichGebert/ponytail.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 40 lines · 0 tokens per session scan A 809a8df68531

Subscribe to this mod's changes

ponytail is a skill published in the GitHub repository dimetron/pi-go (153 stars, last pushed today), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 528 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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