For manufacturing projects that take up work space (in addition to Runts): would it be feasible to modify default behavior so additional space is nullified when Runts working on said project are dropped to 0, but allowing the project to remain listed?
Since XPZ is a huge mod and lots of stuff is changing in production all the time it's quicker to drop Runts to 0, start another project until it completes, then return to original production - without going through laborious process of shutting down original production (to free up space) and restarting it. Another nice benefit over temporary abandoning project is that manufactured item count remains tracked by the game.
An example that made me suggest this: I setup Chemicals (infinite) & Plasasteel (sell) that runs continuously (until something else comes along). It works beautifully but takes a lot of extra space. Then I had to switch to Armor production and only two ways of doing it are to stop C&P -> start armor until done -> start C&P again; or keep C&P listed with 0 Runts and do Armor with a lot less Runt space. Kind of a drag.
Sounds like a great QoL in my head but I dunno how tricky it is to pull off. Mechanic doesn't look exploitable and seems also applicable to vanilla game (although unlikely ever be used due to game simplicity). Basically various checks would need to be shifted to when user increases Runts from 0 -> 1. Maybe a user switch in advanced options or something.
UPDATEGotta love it when stuff crawls into my mind just when I'm about to hit post button... I suddenly realized that paused projects (0 Runts) basically have 1 until allocated in production line at all times so my suggestion falls apart. UNLESS... a scheduled pause is coded, so that it occurs as one item is completed but before next one starts. Ah, who am I kiddin... maybe in next life