The Silent Killer in AI Coding—And How CLAUDE.md Fixes It

AI coding agents fail not due to model limitations, but from unconstrained decision-making that fills ambiguity with unnecessary changes. CLAUDE.md transforms this by replacing vague guidance with concrete behavioral rules—Karpathy's original four rules cut error rates from 40% to 11%, while the extended 12-rule framework achieves 3%, a 13-fold improvement. For production Claude Code deployments, this represents a shift from managing failures to preventing them systematically.