I had not seen your project before: it is very interesting and exciting. It looks as if we have adopted some of the same techniques (not to mention, javascript framework).
I will read over your project's documentation - indeed it seems as if we could collaborate and settle on some best practices as well!
Thank you for your comment; I think these are good suggestions.
In fact I think Biblios should allow callbacks at all important events in the record life cycle: on retrieval from z3950 server, on record editing, on record saving (or "send"ing to a remote ils). This way plugins will have the opportunity to modify things as needed.
This also goes hand in hand with the concept of editor plugins, whereby someone could write an editor for another kind of metadata record, like MODS.