A customer waiting does not care which device you are near. One application, built once, wrapped natively — so a screen improved on the web is improved everywhere the same afternoon, and push tells you somebody is waiting while the laptop is shut.
A real Mac app with a Dock badge, notifications and a session that survives being quit. Downloads and file attachments behave the way they do everywhere else on your Mac.
Push notifications for a customer message on a thread that is yours or nobody's — naming the company, so somebody looking after two stores knows which before they decide to open it.
The same shell, on the other desktop. The application inside it already runs there today in a browser; this is about the badge, the notifications and the session.
After Windows. The web application is already built for a phone — one gutter, a bottom bar, a reply drawer — so this is the wrapper and the push, not the product.
Nothing is exclusive to an app. Every screen works in a browser on any device, today.
The inbox below is the real application at a phone's width. One gutter, a bottom bar under your thumb, and a reply drawer that opens rather than swallowing the conversation you are answering.
The reason to have this on a phone is not that it is possible. It is that a contractor asking at four on a Friday gets an answer at four on a Friday.