Mark a test server (the rehearsal)

Before an app reaches production, Fodide rehearses it on a test server: the same release with the same production keys, its checks, then it is removed from there. If a rehearsal fails, production is not touched. To use it, connect a second, small server the same way, then under Settings → Connectors → Servers open its ⋮ and tap Use as test server.

A test server holds rehearsals only, so it must have no apps on it. It can serve all your apps. Without one, Fodide says so in the chat and asks you; if you go ahead, the deployment card says NO rehearsal.