Ponytail

Makes your AI agent think like the laziest senior dev in the room.
The best code is the code you never wrote.

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AI agents over-deliver. Ask for a date picker, get a component library.

With ponytail:

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

More before/afters in examples/.

How it works

Before writing code, the agent stops at the first rung that holds:

1. Does this need to exist?   → no: skip it (YAGNI)
2. Stdlib does it?            → use it
3. Native platform feature?   → use it
4. Installed dependency?      → use it
5. One line?                  → one line
6. Only then: the minimum that works

Never lazy about: validation at trust boundaries, error handling against data loss, security, accessibility.

Install

Claude Code:

/plugin marketplace add DietrichGebert/ponytail
/plugin install ponytail@ponytail

Active every session. /ponytail lite|full|ultra|off switches intensity, /ponytail-review hunts over-engineering, /ponytail-help explains the rest.

Cursor, Windsurf, Cline, Copilot, Aider: copy the matching rules file from this repo (.cursor/rules/, .windsurf/rules/, .clinerules/, .github/copilot-instructions.md, AGENTS.md).

Numbers

5 coding tasks, same agent with and without ponytail: −16% tokens, ~4× faster, 293 → 47 lines of code. Data: benchmarks/.

License

MIT. The shortest license that works.