The mixes can be drawn from chosen libraries only.
A new setting, libraries: comma separated Navidrome library ids (the number in the library's URL in Navidrome's own settings). Leave it empty and the mixes draw from every library the account can see, which is what every install did until now. Set it when one library keeps landing in mixes it does not belong in, a study playlist library or the children's music, and only the tracks from the listed libraries are candidates. The listening clock still counts every play, so the time-of-day mixes keep leaning the way you listen; only which tracks they can pick is narrowed.
Install: download navibeat-mixes.ndp below and upload it on the Navidrome Plugins page, replacing 0.9.12.