Universal drag-and-drop describes a proposed change to wiki-client behaviour enabling urls to be dropped anywhere on a wiki web-page, and not just the transporter concerned.
# Default behaviour
When an external url is dropped onto wiki a ghost page is created containing a simple external wiki-link to that dropped url ready to be dragged and dropped back into wiki.
This default behaviour can be enhanced (overridden) by supplying a new default global route (regular expression match) that adds for instance the ability to extract Twitter or Facebook cards should the metadata be supplied by the page page dropped on wiki. This is what the current Imagine Transport does.
This new transport imports Tweets, Flickr images, Pinterest pins, web images, research articles, and general web images. It also imports wikipedia articles.
# Customisation
It is proposed that this universal-drag-and-drop behaviour be extensible by an author by adding the relevant regular expression and associated api end-point to the Welcome Authors home page.
Exactly how the author wishes to add this Transport-proxy JSON to the site is up for debate. I have proposed using standard wiki workflows and plugins to enable a wide range of tools to offer such authoring capability. See Welcome Authors.