feat(ponytail): introduce "Ponytail" feature for minimalistic code generation

README.md

@@ -409,6 +409,7 @@ Default URLs:
 | 🚀 **RTK Token Saver** ([RTK](https://github.com/rtk-ai/rtk) ⭐40K) | Compress tool outputs (`git diff`, `grep`, `ls`, `tree`...) before sending to LLM | Save **20-40% input tokens** per request |
 | 🧠 **Headroom Token Saver** ([Headroom](https://github.com/chopratejas/headroom)) | Optional external `/v1/compress` proxy before provider routing | Save more context tokens without changing clients |
 | 🪨 **Caveman Mode** ([Caveman](https://github.com/JuliusBrussee/caveman) ⭐52K) | Inject caveman-speak prompt → LLM replies terse, technical substance preserved | Save **up to 65% output tokens** |
+| 🐴 **Ponytail** ([Ponytail](https://github.com/DietrichGebert/ponytail)) | Inject "lazy senior dev" prompt → LLM writes minimal, YAGNI-first code (Lite/Full/Ultra) | **Fewer output tokens, less refactoring** |
 | 🎯 **Smart 3-Tier Fallback** | Auto-route: Subscription → Cheap → Free | Never stop coding, zero downtime |
 | 📊 **Real-Time Quota Tracking** | Live token count + reset countdown | Maximize subscription value |
 | 🔄 **Format Translation** | OpenAI ↔ Claude ↔ Gemini ↔ Cursor ↔ Kiro ↔ Vertex | Works with any CLI tool |
@@ -467,6 +468,21 @@ http://host.docker.internal:8787
 
 If Headroom is down or returns an error, 9Router fails open and sends the original request.
 
+### 🐴 Ponytail (Lazy Senior Dev)
+
+Ponytail injects a *"lazy senior dev"* system prompt into every request, biasing the LLM toward minimal, YAGNI-first code — deletion over addition, stdlib over new deps, one-liners over abstractions. Adapted from [DietrichGebert/ponytail](https://github.com/DietrichGebert/ponytail).
+
+- **Lite** — Build what's asked, name the lazier alternative.
+- **Full** — YAGNI ladder enforced: stdlib → native → existing deps → one-liner → minimal code.
+- **Ultra** — YAGNI extremist: deletion first, ship the one-liner, challenge the rest of the requirement in the same response.
+
+```
+Without Ponytail: verbose code, extra abstractions, "just in case" scaffolding
+With Ponytail:    shortest working diff, no unrequested abstractions, fewer tokens
+```
+
+Never trades away: input validation, error handling that prevents data loss, security, accessibility, or anything explicitly requested. Enable in Dashboard → Endpoint → Ponytail. Stacks with Caveman (output terseness) and RTK (input compression).
+
 ### 🎯 Smart 3-Tier Fallback
 
 Create combos with automatic fallback:
@@ -1348,6 +1364,7 @@ Built on the shoulders of giants:
 - **[CLIProxyAPI](https://github.com/router-for-me/CLIProxyAPI)** — original Go implementation that inspired this JavaScript port.
 - **[RTK](https://github.com/rtk-ai/rtk)** ![Stars](https://img.shields.io/github/stars/rtk-ai/rtk?style=flat&color=yellow) — Rust token-saver. 9Router ports its compression pipeline to JS → **−20-40% input tokens** on every request.
 - **[Caveman](https://github.com/JuliusBrussee/caveman)** ![Stars](https://img.shields.io/github/stars/JuliusBrussee/caveman?style=flat&color=yellow) by **[@JuliusBrussee](https://github.com/JuliusBrussee)** — viral *"why use many token when few token do trick"*. 9Router adapts its prompt → **−65% output tokens**.
+- **[Ponytail](https://github.com/DietrichGebert/ponytail)** ![Stars](https://img.shields.io/github/stars/DietrichGebert/ponytail?style=flat&color=yellow) by **[@DietrichGebert](https://github.com/DietrichGebert)** — *"lazy senior dev"* skill. 9Router injects its YAGNI-first ladder → **fewer tokens, less code, shorter diffs**.
 
 Huge thanks to these authors — without their work, 9Router's token-saving features wouldn't exist. ⭐ them on GitHub!