Ponytail is an always-on ruleset and plugin for AI coding agents (Claude, Codex, Gemini, Copilot, etc.) that enforces a step-by-step “ladder” to include only necessary code. Benchmarks show 80–94% less code, 3–6× faster responses, and 42–75% lower cost by preferring built-ins and one-liner solutions before adding dependencies.

• Ponytail cuts AI-generated code by 80–94% while running 3–6× faster and costing 42–75% less, per Claude API benchmarks across Haiku, Sonnet, and Opus.
• It enforces a strict ladder—skip via YAGNI, use stdlib/native features, add dependencies only if essential, then compress to one-liners—without trimming validation, error handling, security, or accessibility.
• It installs as a plugin (e.g. via Claude Code or Codex commands) and works across Copilot CLI, OpenCode, Gemini/Antigravity, Cursor, Windsurf, Cline, and other agent hosts by copying matching rule files into each tool's config.
• Modes range from lite to full to ultra, adjustable via slash commands or an environment variable, giving control over how aggressively code gets minimized.

This project packages four principles—Think Before Coding, Simplicity First, Surgical Changes, and Goal-Driven Execution—into a Claude Code plugin or CLAUDE.md file to curb LLM code pitfalls like overengineering and hidden assumptions. It enforces explicit reasoning, minimal edits, and test-driven success criteria to produce cleaner, more accurate AI-generated code.

• A single CLAUDE.md file encodes four Karpathy-derived rules—think before coding, simplicity first, surgical changes, goal-driven execution—to fix common LLM coding failures.
• It explicitly bans unrequested abstractions, error handling, or flexibility, and restricts edits to only what was asked, leaving style and unrelated code untouched.
• It pushes test-first, criteria-based execution so the model loops until defined success conditions pass rather than coding aimlessly.
• Installable as a Claude Code plugin/marketplace package or via curl into CLAUDE.md, with a Cursor rule file and support for project-specific rule additions.