Where AGENTS.md breaks at scale
- Zero visibility — you never really know which rules the AI picked up
- Rule duplication hell — 3 repos means 3 copies to keep in sync
- No cross-repo management — updates happen manually, slowly, inconsistently
- Folder-structure lock-in — behavior depends on where markdown is placed
- Multi-tool nightmare — CLAUDE.md vs .cursorrules vs copilot-instructions.md