If I have a list that stores my game level map data, and I have a level editor that allows someone to change and add levels, will I see their changes appear in my scratch project? That is, are list values shared between whoever is running the project at the time? Or do the values reset to whatever I made them during project design?

I'd like to know this, because I foresee concurrency issues and people losing work if two of them happen to edit the same level in parallel. If this is the case, then they will simply need to fork my project and edit levels within their fork to avoid potential problems?

Thanks a lot for any insight!

Nope. Lists are all local and temporary – as soon as you refresh the page their data is reset.

But, if it were cloud lists (although they don't exist yet) you could have people editing the same world.

I hope this helps!

Some scratchers have created and shared easy blocks that code cloud lists.
You just have to search for cloud list and will find one project very quickly.

That answers my question perfectly, thanks!