I have noticed that hitting Alt-Up to demote the first node in a list does nothing. If this isnāt a problem of my setup (I can only use TiddlyWiki on mobile), consider what follows below a feature request. Making it possible to push the first node to the bottom of the list would make the management of nodes more flexible. Same for making it possible to push the last node to the top of the list by hitting Alt-Down.
An use case of this is using Streams as checklist manager. When marking the first item done, one usually wants items that are not done still at the top of the list, so quickly pushing the most recenly done item to the bottom of the list achieves that.
An evolution of this idea is to make it possible to push any given node in the list to the top or to the bottom, by hitting Alt-t / Alt-b for example. Unlike Alt-Up and Alt-Down, which are complementary and simply turn a list into a double linked list, Alt-t and Alt-b are more complex: pushing an item from the middle of the list to either the top or the bottom of it, completely changes the ordering, so having a one level undo (Alt-u) here could help to quick fix accidental typing mistakes.
PS: I donāt know if these suggestions fit the philosophy of Streams. My impression is that Streams is primarily advertised for fluid, distraction free, yet linear writing. My intention is to use it as outliner (tree-like structure) and having rich node management options is essential.