It seems to me that introducing a list of annotations (with their preview) on
- a) the list of papers (main app page) and
- b) in the citation plugin would be a great productivity booster.
a) would mimic existing Mendeley behaviour where you can browse through papers without opening them and immediately see what you have annotated (if anything). This really helps when you are looking for a particular annotation or a particular annotated paper, plus its great to refresh your memory when coming back to a project with lots of papers and annotations. This is what has kept me with Mendeley for so long.
b) when I find a paper in the citation plugin, I often need to go back to Paperpile, check the page of my highlights/annotations, remember the page numbers and go back to the plugin. Seeing the annotations directly in the plugin would allow us to find the paper and enter the page numbers into the citation without any loss of time and focus.