
learn-agent
A collection of notes on building coding agents, derived from the production development of the desktop agent Reina, with each mechanism simplified into a zero-dependency, single-file Node.js demo.
It provides a unique, structured approach to combat over-engineering in AI-generated code by systematically checking if the problem can be solved with existing code, standard libraries, or platform features before writing anything.
Ponytail
He says nothing. He writes one line. It works.
Install · Before / after · How it works · Numbers · Commands · FAQ
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 your AI agent. Skills plus two lifecycle hooks, installed in one command.
You ask for a date picker.
Before writing code, the agent stops at the first rung that holds.
Text version
1 does this need to exist? → no. skip it (yagni)
2 is it already in this repo? → reuse it
3 does the stdlib do it? → use it
4 does the platform do it? → use it
5 does an installed dep do it? → use it
6 can it be one line? → write the line
7 nothing above held → the minimum that works
The ladder runs after it understands the problem, not instead of it. Lazy about the solution, never about reading.
Lazy, not negligent. Validation, error handling, security, and accessibility are never on the chopping block.
Real Claude Code sessions on a real repo.
| Code written | ~54% less (up to 94% where the agent over-builds) |
| Cost | ~20% cheaper |
| Time | ~27% faster |
| Safety guards kept | 100% |
node ponytail.js -i
Pick your agent, copy the commands, done.
Works with Claude Code Codex Copilot CLI OpenCode Pi Antigravity Hermes OpenClaw and more.
The plugins run two tiny Node.js lifecycle hooks, so node needs to be on your PATH. If it isn't, the skills still work and the always-on activation just stays quiet.
Once installed, in a skill-capable host:
| Command | What it does |
|---|---|
/ponytail [lite | full | ultra | off] | Set the intensity, or turn it off. |
/ponytail-review | Review the current diff for over-engineering. |
/ponytail-audit | Audit the whole repo, not just the diff. |
/ponytail-debt | Collect the shortcuts you deferred into a ledger. |
/ponytail-help | Quick reference. |
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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