Taxonomies in themes

It doesn’t seem to be possible to provide taxonomies in a theme. This is something I’d like to do in a theme that I’m working on - specifically, I’m using a series taxonomy to group articles into series and render a series ToC on each page.

Is this by design? If acceptable, I’d be happy to work on implementing support for taxonomies in themes. I would expect it to be an error for the site to (re)define a taxonomy that is defined in the theme.

Thoughts?

I think it makes sense not include them in the theme. Having them baked in it would make it harder for example if a user wants to use the theme but in another language.