Ponytail: A ruleset that makes AI coding agents write less code

Ponytail: Lazy Senior Engineer Skill

Ponytail is a ruleset for AI coding agents that pushes for the least code that works. It follows a decision ladder: check if the feature is needed, then look at the standard library and existing dependencies before writing anything. Across 12 feature tasks on a FastAPI + React repo, it cut code by 54% (median), tokens by 22%, cost by 20%, and latency by 27%, while keeping safety checks intact. It works with 14+ agents including Claude Code, Copilot CLI, and Gemini CLI, controlled via /ponytail commands.