Cool, but system and user should probably stick to short, clear commands. E.g., I see you do some anaphora resolution (in particular: find what "it" refers to), but in a complex dialog, the human intention can differ from the machine's understanding. That will give problems when you end your dialog with "delete it".

Adding more sentences to your data set will slowly degrade performance. It's a delicate system.

Source: I have written software with similar functionality (NLP search) in SaaS form, a long time ago. It required quite a bit of work to configure.