Most people don't notice their AI coding agent gets worse as their codebase grows. Not because the model degrades. Because the context does. The pattern 50 files: Claude Code or Cursor sees enough of the codebase to follow conventions, reuse utilities, avoid duplication. The output is coherent. 500 files: it can't. So it reimplements helpers that already exist three folders away. Introduces naming conventions that contradict the rest. Generates functions nobody will ever call. "Fixes" bugs by stacking workarounds on workarounds. The model didn't get dumber. It just stopped being able to hold the whole project in its head. The result: codebases that ship fast at first, then collapse under their own weight. Dead code. Hidden duplication. Best practices selectively applied. The exact opposite of what AI-assisted coding was supposed to give us. Why nothing catches it Linters catch syntax. Type checkers catch types. Test runners catch broken contracts.…