Excellent, I’m glad that you’ve all been thinking about it already.
One comment I’ll make about the ticket (here, rather than add too much noise there):
the question i still have is, what’s better - getting people to use good lua code style, or making a sort of complex environment that will protect them from the consequences of bad style?
good style is probably best, and we should suggest this in the short term given the sandboxing isn’t going to happen overnight 
good style is totally a hostage to fortune!
One other thing that I think may end up causing support issues in the future is the existence of the lib folder in the Dust repo.
Code re-use is good, but… it’s not unreasonable to suggest that in a years time we could have 50-100 apps/scripts in the Dust repo, not to mention countless other scripts not in the repo. That will make it really hard to make changes to anything in the lib folder for fear of breaking scripts (even fixing bugs can be problematic).
Also users may end up tweaking a Lua or Supercollider script in the lib folder for something they’re working on, not realising the consequences to other scripts.
Ultimately I guess it comes down to how curated we expect the Dust repo to be, and how we want the burden of keeping all the scripts working to fall.
It could be that we can find a system to move the library files to each users’ script folder, e.g. lib/lua/pattern_time.lua would move to scripts/tehn/lib/pattern_time.lua. I like this as it shows ownership, and even if we provided a way to require scripts from another user’s folder, there is an implication that you shouldn’t rely on it not changing.