I want to use header-includes: in a defaults file, so assuming it is metadata (i.e. converted to variables for the template) do this in my typst.yaml defaults file:
metadata:
header-includes: |
```{=typst}
#set heading(numbering: "(I)")
```
mainfont: "Alegreya Sans"
But the output is escaped. The same header-includes text works when added to the document metadata header directly. I'm probably doing something stupid but didn't yet grok what that is... Any help appreciated!