ponytail: MIT YAGNI Skill Cuts AI Agent Code by 80–94%
Dietrich Gebert's ponytail hit v4.6.0 on 2026-06-15 with 17,921 GitHub stars, 761 forks, and 8 releases in four days. The ruleset teaches Claude Code, Codex, Gemini CLI, OpenCode, Cursor, Windsurf, Cline, Aider, Kiro, GitHub Copilot, and Pi agents to ask 'does this need to exist?' before they type — and ships with a reproducible promptfoo benchmark (median of 10 runs across Haiku, Sonnet, Opus) showing 80–94% less code, 47–77% lower cost, and 3–6× faster runs than a no-skill baseline. Five-task scope, MIT, every shortcut tagged for later.