arbtt

arbtt is the “automatic, rule-based time tracker”. It is a time-tracking program that runs in the background, recording which windows are open, which window has focus, and so on. It has a separate arbtt-stats command that displays the recorded information in various ways – the user is expected to write suitable rules so that the summary is interesting.

The documentation is pretty good, and will give an idea of what it can do:

As gwern’s guide mentions, setting informative window titles is important. Most of my time on the computer is spent in a web browser or on a terminal. Both Firefox and Google Chrome already set good titles, so for me the challenge was mostly trying to make sure the terminal application I use sets titles correctly.

The configuration is split across three programs:

Shorten tmux pane titles with this answer.

Potentially relevant is this.

Some problems:

See also