| What I can't decide is how I think these links should render into the | page -- perhaps as "article; fragment-text"?
Another question immediately arises: how should a broken link be rendered? What HTML is generated by [[article#subhead]], if "article" exists but does not contain "subhead"?
The latter question is really a no-brainer: the link is generated containing the fragment identifier, and is marked as broken or not solely based on whether or not the page exists. Browsers routinely accept links to non-existent fragments and just silently drop the fragment, going to the page.
The question of whether or not to include the fragment id in the default text is really one of style; I'm inclined to just drop it.