Ah, it is Vim's todo list, not using Vim as a todo app.

I was looking for more pointers on the later, I wrote a little on using Vim Wiki for managing todo list, always on the look out for more tips.

Here's the TLDR;

- Install Vim wiki plugin

- Convert line to checkboxes using ctrl-space

- Use ctrl-space to mark complete

- Use gln to toggle partial complete (glp for previous)

- gl<Space> to remove checkbox

A little more at: https://mkaz.blog/working-with-vim/vimwiki/