Monospace · CraftNº 005 · Executive Cut

The Case for
Writing Less Code

Ponytail is an anti-overengineering skill that teaches coding agents to reach for the standard library before the framework — and its corrected benchmark counts diff lines, not promises.

DIFF DISCIPLINE

DietrichGebert/ponytail · MIT · MarkdownThe five-minute cut · full deck alongside

The Premise02

A behavior patch that changes what the agent reaches for first.

Before it writes anything, the agent stops at the first rung of a six-step ladder that already solves the problem: skip the work, use the standard library, use the platform, reuse a dependency, write one line, or write the minimum. What lifts it above a slogan is the carve-out — validation, data loss, security, and accessibility are never simplified away.

35kstars, mostly Markdown

10agent families

62/62unit tests, our bench

0declared dependencies

One skill file · a fallback · two hook scriptsThe Case for Writing Less Code

Play 01Demonstrated An Afternoon

Put every diff on a diet.

The scenario → the move

Your agents solve small problems with large code — a framework where a function would do. Install the skill, hand the agent ordinary tickets, and let the ladder argue for the standard library first.

The receipt

The repo's corrected agentic benchmark — real Claude Code sessions against twelve tickets, scored by added lines in git diff — cut code 54%, cost 20%, and time 27% at a 100% safety rate.

Boundary — turn it off when the task genuinely is architecture.

Scored by lines added, not by the model's own claimsThe Case for Writing Less Code

Play 02Verified An Afternoon

Run one ruleset across ten agents.

The scenario → the move

A team spread across Claude Code, Codex, Cursor, and Copilot drifts into ten different coding temperaments. Install the ladder once; thin adapters carry the same eight rules to every agent family.

The receipt

The ladder's eight rules validated identical across every adapter, and all 62 of the repo's unit tests passed on our bench — one rulebook, ten front doors.

Boundary — the rules are identical, but the effect still rides on each model's instruction-following.

Your review bar stops depending on which tool wrote the diffThe Case for Writing Less Code

Play 03Demonstrated An Afternoon

Keep the guardrail, skip the slogan.

The scenario → the move

A one-line "YAGNI" system prompt looks like a free substitute for the whole skill. What you're actually installing is the ladder's explicit carve-outs — the rules that refuse to simplify the wrong thing away.

The receipt

In the repo's own control run, the bare YAGNI one-liner got respectable reduction numbers — and then quietly dropped a path-traversal guard. The full skill kept it.

Boundary — the one-liner isn't useless; it's just missing the carve-outs that matter.

The slogan is the wrapper; the carve-outs are the productThe Case for Writing Less Code

The Fine Print06

Quiet scan. Two caveats worth naming.

Clean scan: no critical issues in what ships, no real credentials anywhere; zero dependencies to audit.
Needs a strong model: the effect rides on instruction-following; on small local models it disappears into noise.
No universal savings: OpenAI reasoning models can cost more, not less — measure before you promise.
Two operational caveats: the missing lockfile hurts reproducibility, and the benchmark's graders run the code they grade — throwaway environments only.

Full report: security scan in the study archiveThe Case for Writing Less Code

The Kicker07

Best for halving the code your agents write.

If you run one play tonight, put your next ticket on a diet — install the skill, hand the agent an ordinary backend task, and read the diff. The ladder makes its case for the standard library before you've written a line, and the guardrails stay up while it does.

git clone https://github.com/DietrichGebert/ponytail
# drop the skill into your agent, then diff your next ticket

MONOSPACE · monospacemag.comField-tested reviews of trending repositories

The Case forWriting Less Code

A behavior patch that changes what the agent reaches for first.

Put every diff on a diet.

Run one ruleset across ten agents.

Keep the guardrail, skip the slogan.

Quiet scan. Two caveats worth naming.

Best for halving the code your agents write.

The Case for
Writing Less Code