Anjar,
Shadow tiddlers is quite a big subject since it relates to a large part of the core, plugins etc...
I do personally believe there are many opportunities to make use of this infrastructure for much more, which I think you question hints at. I have done quite a lot of exploration in this space and will share but a little in this response.
Shadow tiddlers are known as tiddlers inside a plugin, but a plugin is only a tiddler containing one or more tiddlers defined in JSON. This allows more than one tiddler to be packaged in another tiddler. Accessing such embedded tiddlers is via the shadow tiddler model.
There is already code to support converting tiddlers to JSON, and it is the import process. After dropping a set of tiddlers on a wiki (any wiki), rename the $:/import tiddler before importing, (remove its existing fields). It is then a JSON tiddler. However to convert it so it allows access to the tiddlers within as shadows, you need to change it into a plugin. This is not complex as it the case with most things in TiddlyWiki.
Changing a JSON Tiddler of tiddlers into a plugin and related shadow tiddlers.
- Edit the JSON tiddler and add or change the plugin-type field to have a value of plugin
You now have a plugin tiddlers, and you can find it in the list of plugins, bur it is not making use of all the features, it only has a contents tab.
You can now edit these to turn the shadows into real tiddlers, drag and drop between wikis and export it for import later.
Cool yes?
Tones