Can someone explain to me how I'm supposed to develop an Enterprise web app, that requires a regular "liveliness" check-in and to continue to receive timely notifications without internet access (internal only)?

Between all the creative ways they're finding to decide they should throttle a tab or put it to sleep, and the ways they keep screwing with timers/intervals, I feel like I'm being forced back to pushing for a fat client. Is there web technology I'm missing that will allow me to achieve this without having to use internet access and pushing notifications through a third party?