A skill that makes your AI agent think like the laziest senior dev in the room —
because the best code is the code you never wrote.
---
## The Problem
AI coding agents are overenthusiastic by default. Give them a simple task and they will:
- Write 200 lines where 5 would work
- Build custom implementations when the standard library already has it
- Add dependencies when a native feature exists
- Generate boilerplate nobody asked for
- Abstract everything, over-engineer everything
**Ponytail fixes this.**
## What Ponytail Is
Ponytail is an AI agent skill. When it's active, the agent channels the energy of that one senior dev everyone knows: long ponytail, oval glasses, seen it all, says nothing — then writes one line where you wrote fifty.
Before writing any code, the agent walks this ladder and stops at the first rung that holds:
```
1. Does this need to be built at all? → YAGNI
2. Does the standard library already do this? → use it
3. Does a native platform feature cover this? → use it
4. Does an existing package solve this? → use it
5. Can this be done in one line? → do it
6. Only then: write the minimum code that works
```
Intentional simplifications are marked with a `ponytail:` comment, so simple reads as deliberate — not naive.
## Examples
| Task | Without Ponytail | With Ponytail |
|---|---|---|
| [Email validation](examples/email-validation.md) | 27-line validator class | `"@" in email` — or let the confirmation mail reject it |
| [Date picker](examples/date-picker.md) | flatpickr + wrapper component | `` |
| [Sorting](examples/sorting.md) | hand-rolled quicksort | `arr.sort((a, b) => a - b)` |
| [Caching](examples/caching.md) | 120-line TTL cache class | `@lru_cache` — or nothing until you measure |
| [API endpoint](examples/api-endpoint.md) | 5 files of layers | 5 lines |
Full before/after in [examples/](examples/).
## Install
**Claude Code — plugin (full integration)**
```
/plugin marketplace add DietrichGebert/ponytail
/plugin install ponytail@ponytail
```
Auto-activation every session, `/ponytail` levels, `/ponytail-review`, `/ponytail-help`, `[PONYTAIL]` statusline badge. Restart Claude Code after install.
**Claude Code — skill only**
```bash
git clone https://github.com/DietrichGebert/ponytail.git
cp -r ponytail/skills/ponytail ~/.claude/skills/ # personal, all projects
# or: cp -r ponytail/skills/ponytail .claude/skills/ # this project only
```
**Cursor** — copy [`.cursor/rules/ponytail.mdc`](.cursor/rules/ponytail.mdc) into your project.
**Windsurf** — copy [`.windsurf/rules/ponytail.md`](.windsurf/rules/ponytail.md).
**Cline** — copy [`.clinerules/ponytail.md`](.clinerules/ponytail.md).
**Aider** — `aider --read AGENTS.md` with [`AGENTS.md`](AGENTS.md) in the repo root.
**GitHub Copilot** — copy [`.github/copilot-instructions.md`](.github/copilot-instructions.md).
## Levels
| Level | Trigger | What changes |
|---|---|---|
| **lite** | `/ponytail lite` | Builds what's asked, names the lazier alternative in one line. |
| **full** | `/ponytail` | The ladder enforced. Questions necessity, stdlib first, shortest diff. Default. |
| **ultra** | `/ponytail ultra` | YAGNI extremist. Deletion before addition. Challenges the requirement before building. |
Deactivate: say "stop ponytail" / "normal mode", or `/ponytail off`.
## Commands
| Command | What it does |
|---|---|
| `/ponytail [lite\|full\|ultra\|off]` | Switch level |
| `/ponytail-review` | Over-engineering review — `L42: yagni: factory, one product. Inline.` |
| `/ponytail-help` | Reference card |
## Configure
The plugin auto-activates at `full` every session. Change the default:
```bash
export PONYTAIL_DEFAULT_MODE=ultra # env var, highest priority
```
or `~/.config/ponytail/config.json` (Windows: `%APPDATA%\ponytail\config.json`):
```json
{ "defaultMode": "off" }
```
`off` = no auto-activation, `/ponytail` still works on demand. Statusline badge (`[PONYTAIL]`, `[PONYTAIL:ULTRA]`) offers to configure itself if no statusline is set.
## Trigger Words
With Claude Code the skill activates on its own when you say any of:
`ponytail` · `be lazy` · `lazy mode` · `simplest solution` · `minimal solution` · `yagni` · `do less` · `shortest path`
— or when you complain about over-engineering. Other tools apply rules files unconditionally.
## Token Savings
Ponytail saves tokens on two levels at once:
1. **Shorter output** — less code written, fewer output tokens.
2. **Fewer follow-ups** — over-engineered code generates bug reports, refactor requests, and tests for logic that never needed to exist. Ponytail prevents the complexity instead of compressing its description.
## Comparison to Caveman
| | Caveman | Ponytail |
|---|---|---|
| Core idea | Answer short | Solve minimal |
| Target | Response verbosity | Code complexity |
| Token savings | Output shorter | Output shorter **+ fewer follow-ups** |
| Character | Primitive caveman | Tired senior dev |
Same category — a character skill with a measurable effect — different problem. They stack nicely.
## License
[MIT](LICENSE). Ponytail would have chosen the shortest license anyway.
