Awesome! I had been meaning to build something like this for a while now, but never got around to it.

Is it possible to annotate your text with extra 'stage directions' that influence how the book is read out?

> annotate your text with extra 'stage directions'

Good idea, not something I've considered yet. Wouldn't take much to add it since there's already a feature for selecting a quotation and assigning it an intonation. Same infrastructure could be reused to select arbitrary text and assign stage directions.