Isn't a Solo Developer a Bus Factor of One?

Yes. With one developer, the bus factor is one. Every honest answer starts there. The useful part is what comes next.

What the Bus Factor Means

The bus factor is how many people would have to disappear before a project stalls. Hit by a bus, or in the kinder version, the lottery factor: they win and quit. Some teams say truck factor.

• Low bus factor: knowledge sits with too few people.
• High bus factor: the work survives anyone leaving.

In software engineering, it's the plainest name for key person risk.

Why Headcount Doesn't Fix It

Solo Model counts one person holding the full context as the advantage. No handoffs, no standups, no "I thought you were handling that." The same sentence is the risk.

A team of three raises the number on paper. It still loses context in the gaps between people. So the better question isn't how many developers. It's what the next one finds on day one.

What the Next Developer Finds

Four principles answer that, and each closes one gap.

• Access. Client Owns Everything: the repo, the cloud bills and every API key sit with the client from the start. Nothing is locked.
• Knowledge. Documentation: pull requests explain why, issues capture decisions, decision records live in the repo. Knowledge transfer happens as a side effect, not in a handover week.
• History. Transparency and Async Updates: a written update after every session, a shared board, owner access. The client has been reading the trail all along.
• Exit. Exit Freedom and Pause, Not End: leave any week, resume where it stopped. Nothing to extract.

What It Still Costs

Response time. Incident Response has no on-call rotation: when something breaks, the developer gets to a computer as soon as physically possible. If the developer can't, the fix waits for someone new to read in.

The setup turns that wait from reverse engineering into reading. It doesn't remove it. When a product can't afford the wait, that's the limit Solo Model names: time for a team.

Judge a solo setup by how cheap the replacement is, not by the headcount.