When the person who built your AI-assisted systems leaves, git keeps every line of code. What leaves with them is everything git never recorded: why the third approach was chosen after the first two failed, which vendor’s API silently drops requests under load, the setting that looks safe to change and is not.
That knowledge normally lives in one head and in chat transcripts nobody will reopen. Most companies discover this the week after someone leaves, when the next person hits the same wall the last one already found a way around.
Two different payoffs, in the order they actually show up
The instinct is to treat this as a departure problem and stop there. Two things get solved the same way but arrive on a different schedule.
The first is ordinary and constant. Two people on different projects, or the same person three months apart, hit the same gotcha and solve it twice. That happens weekly, not on someone’s last day. A shared, searchable record of what was learned pays for itself here alone.
The second is the sharper claim. When someone does leave, the next person’s first session with an AI coding tool is already informed. Not because they went looking for documentation, which requires knowing it exists and where. Because the record is put in front of the tool automatically, at the start of every session, the same way it would have been for the person who left.
What makes this different from a wiki
A wiki has to be known about and searched, and someone leaving does not leave a note explaining what to search for. The fix is to make the record ambient rather than searchable: a short index of what has been learned, loaded into every AI session automatically, so a new task connects to a relevant lesson the way an experienced colleague would, without anyone asking.
That only works if people wrote things down as they went, not only in a handover document at the end. A rule that “the last thing decided gets written down before the session closes, and mid-session when it matters” is what makes the record real rather than aspirational.
What a team version needs that a personal one does not
Three things change once more than one person is contributing.
Someone owns it. Not enforcement, just the monthly pass that merges near-duplicates and catches entries that have gone stale. The same way someone owns the backlog.
Contradictions get resolved, not argued. Two entries that look like they disagree are usually both true under different conditions; state the boundary and move on. When they are a genuine contradiction, it goes to whoever wrote the entry, because they know why they wrote it, and title is not the deciding factor. If that person is gone, a named owner decides. Never left unresolved, and never resolved silently: record who decided and why.
No approval step. The obvious instinct for a company is to add review before anything gets recorded. Do not. The moment writing something down requires someone else’s sign-off, people stop doing it in the moment and the knowledge goes back to living only in chat history, which is the exact failure this is meant to fix.
The other half: what git cannot see
Knowledge is one side of the bus-factor problem. The other is work in progress that has not landed anywhere yet. Push what you are working on daily, even unfinished, because anything that only exists on one laptop is invisible to everyone else and to any process trying to help.
A quarterly drill, where someone other than the usual owner picks up a piece of work cold, is the only honest test of whether either half is working. Whatever they get stuck on is the real gap, not whatever the documentation claims to cover.
Where to start
This is the same method as the learning loop, run by more than one person. If a company has none of this yet, the fastest way in is the same one: ten notes, written this afternoon, by whoever is about to make its first real decision.