Constant SESSION_DISCOVER_DEADLINE 

pub const SESSION_DISCOVER_DEADLINE: Duration;

How long sessions.discover gets before its caller is answered an error instead. Discovery reads each harness’s own store, and a store on a cold or unavailable mount answers at the filesystem’s pace rather than its own.

Deliberately shorter than the clients’ own request deadline (30s): the server’s answer names the store that did not answer, and it is only read if it lands before the client stops listening.