I think currently there is no way to mark an item in a checklist as failed?
I would like to have such an ability ... Something like:

- [F] task x

or:

- [0] task x

The use case is that I use checklists to remember and track doing some
important stuff at the start of the day; all the items are at first in a
neutral/todo state. Some of them get done (`[X]`), but some of them fail
during the day. For example, I have an item `- [ ] No sugar` which tracks
whether I have consumed artificial sugar during the day. I like to be able
to mark this as failed.

I know this can be simulated using headings, but checklists are visually
nicer and have cookies `[/]` etc.

PS: Please use reply to all, as I am not subscribed to the list.