Function probe 

pub fn probe(url: &str, root: &Path) -> bool

Does a Majordomus server answer at url for the repository at root, as that repository’s server?

Three questions, and the third is the one a remembered address needs: it is a Majordomus server, it serves this root, and it still holds this checkout’s lease. Without the third, a process whose lease was taken over answers every probe exactly as the current server does — same name, same repository_id, its own peer board, its own generation of the layer — and a client holding an address from before the takeover is served plausible answers by a server nobody else is talking to. That was measured on 2026-09-10: two servers of one checkout, one lease, and the older one indistinguishable from the current one on this endpoint.

A server too old to answer the question is accepted. It cannot be told from a current one here, and refusing it would be the worse failure: a live server taken for dead is taken over, which is how one checkout comes to have two.