CLAUDE.md Rules: How to Cut AI Coding Mistakes from 40% to 3% in 2026

CLAUDE.md Rules: How to Cut AI Coding Mistakes from 40% to 3% in 2026 TL;DR Summary Andrej Karpathy's original 4-rule CLAUDE.md cut Claude coding errors from ~40% to ~11% by enforcing clarification, simplicity, surgical scope, and verification The 12-rule extension (claude-code-pro-pack) adds 8 more rules targeting agent-orchestration failures and pushes error rates to ~3% — a ~10x improvement over no rules Two leading open-source implementations exist: the 12-Rule Pro Pack (~700 t...