How about just a phone call (or two, to break through “do not disturb”), or tapping on their shoulder to get their attention? That's what we do when we really

How about just a phone call (or two, to break through “do not disturb”), or tapping on their shoulder to get their attention? That's what we do when we really need someone right now rather than when they come back up for air in the next hour or two. That, plus simply being mindful of the meaning of “deep work” and people working in roles that need that kind of concentration. I don't need an app for this.