Automatically [suggest to] stop timer when idle for a long time

When I close the app without stopping the focus time, I want the app to suggest me discarding all the idle time, so that I can see the actual time I spent on a task, and not the time I’ve been forgetting to stop the focus time :)

This is how it works in Toggl — it suggest to stop timer when I’ve been idle for some [configurable] time + it suggests to discard time when a timer is running and I've been idle.