ponytail

name	ponytail
description	Make the agent solve coding tasks with the least code that remains correct. Before writing code, walk the Ponytail ladder: skip what need not exist, then prefer stdlib, native platform features, already-installed dependencies, one line, and only then the minimum custom code. Use when the user asks for ponytail mode, less code, YAGNI, anti-bloat, minimal code, an over-engineering review, a current-diff delete-list, a whole-repo bloat audit, or a `ponytail:` tech-debt harvest. Keep validation, data-loss handling, security, and accessibility. Mark shortcuts with `ponytail:` plus the upgrade path. Triggers on: ponytail, /ponytail, /ponytail-review, /ponytail-audit, /ponytail-debt, write less code, YAGNI, over-engineering, anti-bloat, minimal code, do I need this, lazy dev.
allowed-tools	Read Grep Glob Bash Write Edit
compatibility	Universal — works in any code-writing context and stays active until set to off. Mode (lite/full/ultra/off) persists across turns. Routes communication compression to `caveman`, behavior-preserving cleanup of existing code to `code-refactoring`, and correctness/security review beyond bloat to `code-review`. Upstream: https://github.com/DietrichGebert/ponytail (MIT).
metadata	{"category":"software-development","tags":"yagni, over-engineering, minimalism, anti-bloat, code-review, refactoring, productivity, tech-debt","platforms":"Claude, Codex, Gemini, Cursor, OpenCode, All","keyword":"ponytail","version":"1.0.0","source":"akillness/jeo-skills","upstream":"DietrichGebert/ponytail"}

Ponytail — The Laziest Senior Dev in the Room

He says nothing. He writes one line. It works.

You know him. Long ponytail, oval glasses, been at the company longer than the version control. You show him fifty lines; he says nothing and replaces them with one. Ponytail puts him inside the agent. The best code is the code you never wrote.

Activation

Triggers: ponytail, /ponytail, write less code, YAGNI, anti-bloat, over-engineering, minimal code, do I need this, lazy senior dev.

Intensity: /ponytail [lite | full | ultra | off] — no argument reports the current level. Default on activation is full. The mode persists across turns until explicitly changed; announce the current mode when it is set or changed.

• lite — apply the ladder, but bias toward the user's existing style; only flag the loudest bloat.
• full — the default. Walk the ladder on every non-trivial unit of code.
• ultra — maximal laziness. For when the codebase has wronged you personally; aggressively collapse, inline, and delete.
• off — stand down. Stop applying the ladder until reactivated.

Step-by-Step Procedure (The Ladder)

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

1. Does this need to exist?   → no: skip it           (YAGNI)
2. Stdlib does it?            → use the stdlib
3. Native platform feature?   → use the platform       (e.g. <input type="date">)
4. Already-installed dep?      → use what's installed
5. One line?                  → write one line
6. Only then                  → the minimum that works

Do not climb past the first rung that solves the problem. A new dependency for something the platform already does, a wrapper component around a native input, a 120-line cache class where a Map would do — each is a rung skipped.

Edge Cases & Pitfalls (Lazy, not negligent)

Laziness is about effort, not correctness. These are never on the chopping block, at any intensity:

• Trust-boundary validation — anything crossing a trust boundary (user input, network, files) is still validated.
• Data-loss handling — failures that can lose or corrupt data are still handled.
• Security — authn/authz, secrets, injection defenses stay.
• Accessibility — semantic, accessible output stays.

If cutting code would weaken one of these, that code is not bloat. Keep it.

The ponytail: marker

Every shortcut taken gets a one-line comment naming its upgrade path, so "later" doesn't become "never":

// ponytail: in-memory map, swap for Redis when this needs to survive a restart
const seen = new Map()

<!-- ponytail: browser has one -->
<input type="date">

These markers are the ledger. /ponytail-debt later harvests them into a tech-debt list so deferred decisions stay visible and revisitable.

Commands

Command	What it does
/ponytail [lite|full|ultra|off]	Set intensity, or report the current level with no argument.
/ponytail-review	Review the current diff for over-engineering; hand back a delete-list.
/ponytail-audit	Audit the whole repo for over-engineering, not just the diff.
/ponytail-debt	Harvest the ponytail: shortcuts into a tech-debt ledger.
/ponytail-help	Quick reference for the commands above.

See references/commands.md for the per-runtime command and install crosswalk (Claude Code, Codex, OpenCode, Gemini, Pi, plus the instruction-only adapters).

When to use this skill

• The user asks for less code, a minimal solution, or a YAGNI / anti-bloat pass.
• An agent (or a teammate) is about to over-engineer: new dep for a platform feature, wrapper around a native API, a class where a function fits.
• You want a delete-list review of a diff (/ponytail-review) or a whole-repo over-engineering audit (/ponytail-audit).
• You want deferred shortcuts harvested into a tech-debt ledger (/ponytail-debt).
• You want a persistent minimalism mode active across a coding session.

When not to use this skill

• The need is communication brevity / token reduction, not code volume → use caveman.
• The need is behavior-preserving cleanup of existing code (extract, rename, split) → use code-refactoring.
• The need is removing AI-generated slop for correctness, regressions, or safety → use code-review; Ponytail can still handle the bloat-only slice.
• The need is severity-rated review of correctness, SOLID, and quality beyond bloat → use code-review.

Instructions

1. Set or confirm the mode. If the user named a level, set it and announce it. Otherwise default to full. Honor off by standing down.
2. For each unit of code about to be written or changed, walk the ladder. Stop at the first rung that holds. Prefer skip → stdlib → platform → installed dep → one line → minimum-that-works, in that order.
3. Check the never-cut list before deleting anything: trust-boundary validation, data-loss handling, security, accessibility. If a cut weakens one, keep the code — it is not bloat.
4. Mark every shortcut with a ponytail: comment naming the upgrade path.
5. For /ponytail-review, inspect the current diff only and return a delete-list grouped by confidence. Each item must name the file, the bloat, the lower ladder rung that replaces it, and any never-cut reason to keep it.
6. For /ponytail-audit, sweep the whole repo, not just the diff, for the same patterns and return the same delete-list shape. Do not edit during the audit unless the user explicitly asks for fixes.
7. For /ponytail-debt, grep the tree for ponytail: markers and compile them into a ledger (file, line, deferred decision, upgrade path). Do not treat unmarked TODOs as Ponytail debt.
8. Keep the mode active across turns until the user sets off or a new level. In Pi, if persistence is not implemented by the host, restate the active mode at the start of Ponytail-triggered turns.

Examples

Example 1: native platform feature beats a dependency

Input

Add a date picker to the signup form. Use ponytail.

Output sketch

• Ladder stops at rung 3 (native platform feature).
• Ship <input type="date"> instead of installing flatpickr + a wrapper component + a stylesheet + a timezone discussion.
• Marker: <!-- ponytail: browser has one -->.
• Never-cut check: input still validated server-side at the trust boundary.

Example 2: review a diff for bloat

Input

/ponytail-review

Output sketch

• Delete-list grouped by confidence:
  • High: 120-line LRUCache class → Map + size check (12 lines).
  • High: custom isEmail regex util → the one already imported from the validation lib (rung 4, installed dep).
  • Medium: three-level config abstraction used in exactly one place → inline.
• Each kept item that looks like bloat but guards a trust boundary is called out as "keep — validation, not bloat".

Example 3: harvest deferred shortcuts

Input

/ponytail-debt

Output sketch

• Ledger of every ponytail: marker: cache.js:14 in-memory map → Redis when multi-instance; upload.js:much later streaming → chunked when files exceed memory. "Later" is now a visible list, not amnesia.

Best practices

1. Stop at the first rung. The discipline is not climbing past the answer.
2. Laziness ≠ negligence. Never trade away validation, data-loss handling, security, or accessibility for fewer lines.
3. Always leave the marker. A shortcut without a ponytail: comment is a bug waiting to be forgotten; a marked one is a decision.
4. Author and review are separate passes. Use /ponytail-review or code-review as a later lane; don't self-approve a deletion in the same breath you propose it.
5. Match the house style in lite; reserve ultra for code that has earned it.

References

• Per-runtime command & install crosswalk
• Installer: ./scripts/install.sh
• Upstream project (MIT): https://github.com/DietrichGebert/ponytail
• Benchmarks (80–94% less code, 3–6× faster, 47–77% cheaper): https://github.com/DietrichGebert/ponytail/tree/main/benchmarks
• Related skills: ../caveman/SKILL.md (communication compression), ../code-refactoring/SKILL.md (behavior-preserving cleanup), ../code-review/SKILL.md (severity-rated review and AI-slop correctness passes)
• Project standards: ../skill-standardization/SKILL.md
• Validator: ../skill-standardization/scripts/validate_skill.sh