This is strictly a solo project, though I occasionally use and modify (with permission) code from other mods, to save time. As such I don't use an online repository/versioning system for Starsector+, but the source is included in the jars folder. Was there a feature you wanted to request I add?
P.S. Citadel, BRDY, and Exigency being unavailable in the campaign is not the fault of SS+ but rather an artifact of those mods' world generation scripts. In the past, SS+ would have a separate version of the world generation but for logistical reasons I stopped this practice to avoid forking; Citadel, BRDY, and Exigency have not updated to reflect this, yet.