DiscoJuice do have hooks to communicate with rich clients (Browsers with custom extensions).
Browser extensions with a fixed pre-defined preferred institusion may be pre-installed on computer systems on campus. Other uses are individuals that uses federated service a lot, which may get an more effective user experience by installing a browser extension.
Currently the browser extension to DiscoJuice is experimental. How much effort are put into this depends on the feedback we get from our users.
The Safari browser extension allows you to store your preferred IdP in browser preferences, and your preferences will popup on top on all DiscoJuice instances, even though you have never vistited them before.
You may even use the auto-login option, which will automatically selects your preference, instead of floating your preferred IdP on top.
The Safari DiscoJuice is currently in version 0.1.5 and is experimental.
The Safari DiscoJuice Extension is also supporting a few other Discovery Services, such as SWITCH Wayf.