The idea of building a TiddlyWiki style app from off the shelf components is really interesting I think. For Feather Wiki, a lot of the functionality is handled by its three dependencies, the pell (wysiwyg) , snarkdown (markdown), and choo (app framework) npm packages.
Ps, I’m pleased to announce there is now support for Feather Wiki on https://tiddlyhost.com/ . If you click “Show advanced settings” when creating a site you’ll see Feather Wiki as an option. If you’re interested in using Feather Wiki on Tiddlyhost please give it try there and report any bugs you find.