@juranta +1 vote for this feature, this is something that’s really needed for now. Previously I explained my thoughts on how Drafts could share a note to an external Markdown rendering app like Marked 2 Feature suggestion: Split view for Markdown preview
I’m not familiar with MacOS app dev, but I’m guessing that representing a single draft as a file object (i.e. a temp file) is the requirement to achieve that.
If this feature is supported, then not limited to Taskpaper or Marked 2, all file related programs could be used in company with Draft, which would be so great to those who relies on external programs to process text while still wants to use Drafts as the central text management tool.