>
> ,----
> | #+name: project-root
> | #+header: :var buf-file=(buffer-file-name)
> | #+begin_src emacs-lisp
> | (file-name-directory
> |  (directory-file-name
> |   (file-name-directory buf-file)))
> | #+end_src
> `----
>
> #+results: project-root
> : /home/tj/News/drafts/
>
> ,----
> | #+name: project-name
> | #+header: :exports none
> | #+header: :var root-dir=project-root(buf-file=(buffer-file-name))
> | #+begin_src emacs-lisp
> |   (mapconcat
> |    'capitalize
> |    (split-string
> |     (file-name-nondirectory root-dir)
> |     "-" 'OMIT-NULLS)
> |    " ")
> | #+end_src
> `----
>
> #+results: project-name
>
> Wrong usage of :var or limitations of header arguments?

This is to be expected.  The two blocks above compose to something like

    #+begin_src emacs-lisp
      (file-name-nondirectory
       (file-name-directory
        (directory-file-name
         (file-name-directory
          (buffer-file-name)))))
    #+end_src

Calling `file-name-nondirectory' on the results of `file-name-directory'
seems like it should give you an empty string.

Best,

-- 
Eric Schulte
https://cs.unm.edu/~eschulte
PGP: 0x614CA05D (see https://u.fsf.org/yw)