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.
npx agentmods add skills/0xbeycan/genesis/ponytailnpx skills add 0xBeycan/genesis --skill ponytailgit clone --depth 1 https://github.com/0xBeycan/genesisWrote 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.
[](https://agentmods.dev/skills/0xbeycan/genesis/ponytail)<a href="https://agentmods.dev/skills/0xbeycan/genesis/ponytail"><img src="https://agentmods.dev/badge/skills/0xbeycan/genesis/ponytail.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00126 | $0.01732 |
| Opus 5 | $0.00063 | $0.00866 |
| Sonnet 5 | $0.00025 | $0.00346 |
| Haiku 4.5 | $0.00013 | $0.00173 |
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.
How it starts
The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Ponytail — write the least code that works
Vendored from DietrichGebert/ponytail (MIT). Adapted to Genesis — see Notes for what was reconciled.
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.
When to use
Always, while writing or changing code — the always-on sibling of clean-code:
clean-code governs the shape of the code, ponytail governs how much
of it exists. Active every response; no drift back to over-building. Off only
when the user says "stop ponytail" / "normal mode". Default intensity: full
(see Intensity).
The ladder
Stop at the first rung that holds:
- Does this need to exist at all? Speculative need = skip it, say so in one line. (YAGNI)
- 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.
- Stdlib does it? Use it.
- Native platform feature covers it?
<input type="date">over a picker lib, CSS over JS, DB constraint over app code. - Already-installed dependency solves it? Use it. Never add a new one for what a few lines can do.
- Can it be one line? One line.
- 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, check 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.
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.
- 6d ago First seen · 119 lines · 126 tokens per session scan A ece9955c2780
ponytail is a skill published in the GitHub repository 0xBeycan/genesis (11 stars, last pushed 1mo ago), licensed MIT. It adds 126 tokens to every session and 1,732 once invoked, about $0.0006 per session on Opus 5. 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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