Every engineering team has two codebases. The first is the one in your repository — versioned, reviewed, deployed. The second lives in your engineers' heads: which patterns are preferred, which shortcuts are acceptable, what "clean code" means in this project specifically. New hires absorb it over months. It shapes every PR comment. It's the reason two experienced engineers on your team produce recognizably similar code even when working independently. This second codebase — tacit knowledge — is invisible to your AI assistant. What Tacit Knowledge Actually Is There's a concept from philosophy of knowledge that describes exactly this problem. Michael Polanyi called it tacit knowledge: "we know more than we can tell." In software teams, it shows up as patterns that everyone enforces but no one has written down. Pull from a real Next.js project: "We don't use useEffect for data fetching." Never written down. Every senior dev enforces it in code review. New hires learn it by getting the comment.…