It'd be a lot more useful if it captured the websites visited in the browser, the files edited in the text editor, the current directories in the shells, etc.
It's not complete, but it's already working great for myself:
https://github.com/phiresky/timetrackrs
I've added a comparison to Arbtt and ActivityWatch in the readme.
https://chrome.google.com/webstore/detail/url-in-title/ignpa...
Edit: seems like ActivityWatch (mentioned below) does