You ask Claude Code to add input validation. It writes an abstract class, three subclasses, and a factory method. 200 lines. You needed 5. You ask it to fix a bug. It refactors three adjacent functions, adds type hints everywhere, and switches all single quotes to double quotes. Half the diff has nothing to do with the bug. This isn't a you problem. It's a fundamental LLM tendency. Andrej Karpathy — OpenAI co-founder, former Tesla AI lead — catalogued the same frustrations. In January 2026, he posted on X about four recurring failure modes in LLM-assisted coding. Someone turned those observations into a single CLAUDE.md file. Drop it in your project root, and Claude Code follows these rules automatically. The repo: forrestchang/andrej-karpathy-skills . Currently at 97.8k stars . Rule 1: Think Before Coding The most common failure mode: you say "write an export function," and the model silently decides on CSV format, all fields, overwrite existing files. You didn't specify any of that.…