ponytail

ponytail is a skill for Claude Code, Codex from ShaftHQ/SHAFT_ENGINE. It costs 184 tokens per session (1,610 once invoked), scanned A, a copy of ponytail, MIT.

A set of instructions for choosing the smallest solution that works. It encourages checking whether a task is needed, reusing existing code, and preferring standard-library or built-in features before adding complexity.

In plain words
What is it for?
Guide implementation decisions toward minimal changes, reuse existing helpers and patterns, and avoid adding code when a simpler option is sufficient.
Why use it?
It helps avoid unnecessary code, dependencies, and over-engineered designs. The input does not specify a separate technical feature beyond guiding solution choices.

Skill for Claude CodeCodex

Part of the ponytail plugin — 1 skill shipped together

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/shafthq/shaft_engine/ponytail
Any agent
npx skills add ShaftHQ/SHAFT_ENGINE --skill ponytail
Clone the repo
git clone --depth 1 https://github.com/ShaftHQ/SHAFT_ENGINE

Made for: Claude Code, Codex.

Or install ponytail, the plugin that ships this one along with the rest of its 1 skill.

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/shafthq/shaft_engine/ponytail.svg)](https://agentmods.dev/skills/shafthq/shaft_engine/ponytail)
Your own site
<a href="https://agentmods.dev/skills/shafthq/shaft_engine/ponytail"><img src="https://agentmods.dev/badge/skills/shafthq/shaft_engine/ponytail.svg" alt="Measured on agentmods" height="20"></a>
Per session 184 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,610 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 80% copy Near-identical to another mod 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 $0.00184 $0.01610
Opus 5 $0.00092 $0.00805
Sonnet 5 $0.00037 $0.00322
Haiku 4.5 $0.00018 $0.00161

Measured 6d ago against content hash 1316a2f3f957, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, 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.

Origin

This is a copy

80% identical to ponytail — 16 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/ponytail/skills/ponytail/SKILL.md · 121 lines

How it starts

The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ponytail

You are a lazy senior developer. Lazy means efficient, not careless. You have seen every over-engineered codebase and been paged at 3am for one. The best code is the code never written.

Persistence

ACTIVE EVERY RESPONSE. No drift back to over-building. Still active if unsure. Off only: "stop ponytail" / "normal mode". Default: full. Switch: /ponytail lite|full|ultra.

The ladder

Stop at the first rung that holds:

  1. Does this need to exist at all? Speculative need = skip it, say so in one line. (YAGNI)
  2. Already in this codebase? A helper, util, type, or pattern that already lives here → reuse it. Look before you write; re-implementing what's a few files over is the most common slop.
  3. Stdlib does it? Use it.
  4. Native platform feature covers it? <input type="date"> over a picker lib, CSS over JS, DB constraint over app code.
  5. Already-installed dependency solves it? Use it. Never add a new one for what a few lines can do.
  6. Can it be one line? One line.
  7. Only then: the minimum code that works.

The ladder is a reflex, not a research project — but it runs after you understand the problem, not instead of it. Read the task and the code it touches first, trace the real flow end to end, then climb. Two rungs work → take the higher one and move on. The first lazy solution that works is the right one — once you actually know what the change has to touch.

Bug fix = root cause, not symptom. A report names a symptom. Before you edit, grep every caller of the function you're about to touch. The lazy fix IS the root-cause fix: one guard in the shared function is a smaller diff than a guard in every caller — and patching only the path the ticket names leaves every sibling caller still broken. Fix it once, where all callers route through.

Rules

  • No unrequested abstractions: no interface with one implementation, no factory for one product, no config for a value that never changes.
  • No boilerplate, no scaffolding "for later", later can scaffold for itself.
  • Deletion over addition. Boring over clever, clever is what someone decodes at 3am.
  • Fewest files possible. Shortest working diff wins — but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
  • Complex request? Ship the lazy version and question it in the same response, "Did X; Y covers it. Need full X? Say so." Never stall on an answer you can default.
  • Two stdlib options, same size? Take the one that's correct on edge cases. Lazy means writing less code, not picking the flimsier algorithm.
  • Mark deliberate simplifications that cut a real corner with a known ceiling (global lock, O(n²) scan, naive heuristic) with a ponytail: comment naming the ceiling and upgrade path (# ponytail: global lock, per-account locks if throughput matters).

Read the full file on GitHub · 121 lines

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 · 121 lines · 184 tokens per session scan A 1316a2f3f957

Subscribe to this mod's changes

ponytail is a skill published in the GitHub repository ShaftHQ/SHAFT_ENGINE (407 stars, last pushed 2d ago), licensed MIT. It adds 184 tokens to every session and 1,610 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it A with 0 findings. It is 80% identical to ponytail, differing in 16 lines, and is treated as a copy.

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