Ponytail is a skill ecosystem for AI coding agents that enforces a 'lazy senior developer' mindset through a priority ladder: YAGNI, reuse existing code, prefer stdlib/native features, avoid unrequested abstractions, and write minimal working code. It delivers this via platform-specific adapters (hooks, command files, plugin manifests) for agents like Claude Code, Codex, GitHub Copilot, OpenCode, Gemini CLI, and others. The core skill definition lives in skills/ponytail/SKILL.md, with companion skills for review, audit, debt tracking, gain scoring, and help. The system includes automated validation scripts to maintain consistency across platform-specific rule copies and version manifests, benchmark suites to measure code/token/cost reductions, and test coverage for hook behavior and plugin integrity.