- 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.
+ Makes your AI agent think like the laziest senior dev in the room.
+ The best code is the code you never wrote.
---
-## The Problem
+AI agents over-deliver. Ask for a date picker, get a component library.
-AI coding agents are overenthusiastic by default. Give them a simple task and they will:
+With ponytail:
-- 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
+```html
+
+
```
-Intentional simplifications are marked with a `ponytail:` comment, so simple reads as deliberate — not naive.
+More before/afters in [examples/](examples/).
-## Examples
+## How it works
-| 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 |
+Before writing code, the agent stops at the first rung that holds:
-Full before/after in [examples/](examples/).
+```
+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 (full integration)**
+Claude Code:
```
/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.
+Active every session. `/ponytail lite|full|ultra|off` switches intensity, `/ponytail-review` hunts over-engineering, `/ponytail-help` explains the rest.
-**Claude Code — skill only**
+Cursor, Windsurf, Cline, Copilot, Aider: copy the matching rules file from this repo ([`.cursor/rules/`](.cursor/rules/), [`.windsurf/rules/`](.windsurf/rules/), [`.clinerules/`](.clinerules/), [`.github/copilot-instructions.md`](.github/copilot-instructions.md), [`AGENTS.md`](AGENTS.md)).
-```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
-```
+## Numbers
-**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.
-
-Measured (5 coding tasks, fresh agent per run, same model):
-
-| Config | Agent tokens | Time | Code written |
-|---|---|---|---|
-| No skill | 161,955 | 479s | ~293 lines |
-| Caveman | 138,410 | 136s | ~117 lines |
-| **Ponytail** | **135,709** | **127s** | **~47 lines** |
-
-The no-skill baseline produced a 190-line countdown "dashboard" where ponytail shipped 13 lines. Full data: [benchmarks/](benchmarks/).
-
-## 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.
+5 coding tasks, same agent with and without ponytail: **−16% tokens, ~4× faster, 293 → 47 lines of code.** Data: [benchmarks/](benchmarks/).
## License
-[MIT](LICENSE). Ponytail would have chosen the shortest license anyway.
+[MIT](LICENSE). The shortest license that works.