Nice jazz collection
Currently the albums node can be sorted by:
album title
album artist
album artist and year
year
date added (mis-named, it is not the date the album was added to the library)
play count
last played
rating
userrating
Title, artist and year are all derrived from song file tags. Date added is a file property (timestamp). Playcount and lastplayed are set by Kodi automatically, userrating by the user via Kodi. Rating and userrating can also be set from NFO file.
But that list could easily be extended, and I guess that is the initial feature you are requesting? Genres (from song genres), Moods, Styles, Themes, Label, and Type are all possibilities. Label and Type both come initially from music file tags, all can be set by album NFO files. I guess the key question is could the list of sort criteria become too long and unuseable with another 6 items?
Also Kodi has to do sort combinations explicitly e.g. artist & year, which could become tedious very quickly. Providing a means for the user to specify sort combinations would need a complete redesign of how sorting is selected.
Most interesting is the rest of your idea shown by the image:
Miles Davis is the single album artist for a number of albums, he also collaborates with other album artists (multiple album artists), and he is also a featured artist on albums by other people, on some songs or even all. Sometimes tagged as one of the song artists, or given a musician credit as trumpet, or composer etc.
I agree it would be interesting to be able to sort the album results using that information too. A little unclear if you would want to group by role (how it was tagged) or by the other album artist. What makes one album an "appearence" rather than a "with XXX"?
I can see how to get that order in data, far less clear about how to get that out for a skin to display intelligently. Anyone else care to comment?