Hi, I really like what you are doing in Hall, congrats! So as soon as I can, I will try to contribute to its improvement. :)

When you create a new space you can add a description. In my case it is important because the title of the space is very brief, but I miss that this description is visible to users, because they explain the short title of the space. I don't know if I'm missing something...

For example it could be shown as a title attribute of the link to the space in the sidebar, and below or next to the title in the central column when you enter the space so that it is visible once you are inside.

But are just my suggestions.

Keep it up.