[kovidgoyal]

Splitting and merging is trivial to implement. Splitting code already exists in calibre during conversions, it would be easy to adapt it, the only difference being that instead of automatically finding split points, we let the user specify them.

This is the major advantage of re-writing things within calibre, lots of code to do common ebook related tasks already exists and is either ready to use or can be easily adapted given the dynamic nature of python.

However, we are still waiting for someone to commit to building an editor component, with or without WYSIWYG. I think that we should start with code view + preview and worry about WYSIWYG later, but that is upto whoever writes the code.