turns out osx has a handy option cmd drag ecancrusher from applications to the finder sidebar. you need the cmd to allow apps there. drag across an epub its unpacked drag the folder its packed. Might try Sigil and brackets in the sidebar too
Brackets is perfect in the sidebar once epub has been cracked open with the ecancrusher dragging the folder into the side bar onto the brackets app makes the folder open as the project folder. which is ideal