How do I get the outline/table of contents/toc to play nice with `show heading`?

Questions
3

You can just change the selector as shown in How to avoid ghost numbering in headers? - #5 by Andrew.

#show heading.where(outlined: true): it => {
  counter(heading).display(it.numbering)
}

This is a bit shorter too, though it’s 81 chars long, so it’s a bit too long to put on one line.