Code duplication piles up after weeks of vibe coding

The fix

GitClear measured 4x more duplication in AI-assisted codebases. The model doesn't know your existing helpers exist unless you point at them. Two habits: (1) Keep a `CLAUDE.md` or `AGENTS.md` listing utilities and where to find them. (2) After every feature, ask the agent: "Did this duplicate logic from anywhere? Show me the closest existing helper." Even imperfect dedup beats the default behavior.