Optionalnavigation?: MobileProcessNavigationThe mutable navigation of this app process. Absent starts a new process: no screen in front and no chain. A caller that needs to observe or seed the process navigation (tests) passes its own object; the layer mutates it.
The production iOS service layer over a transport: device, session and application state, the request signature, the session-header parser and the plain API, Bloks, GraphQL and WebView request stacks with their iOS header layers. createIosIgpapi composes it over the native transport (with the runtime's request timeout); tests compose the same layer over a recording transport, so what they render is what the runtime sends.