Architecture: WiFi support for WiFi enabled boards ...

I'm not sure I grasp the signifcance of the save() and restore() methods. Do these not overlap espruino save() and onInit() functions i.e the espruino program (which includes wifi configuration) must start at boot time for ESP8266 to do anything useful?

The Wifi.save() method saves the Wifi config independent of any JS program that may or may not be loaded. I think you should move away from configuring the wifi in each program and instead configure it on each module once. This will become more useful when the IDE connects via wifi, at that point it's nice to have a stable connection whether you have a program loaded that works or not. Also, I want to add a "failsafe" mode to the Wifi that makes it turn on AP mode if it hasn't made a STA connection a minute after power-up. This way when you take your module to a different location it doesn't become unreachable.