Do you have more of an idea how/when these would show? I'm wondering how far we can get by not showing Spaces UI when possible. ie, only if a user is a member of multiple Spaces and the say, search for all my tasks, which might cross two spaces?

Also another random 4am jetlagged thought, assigning a header-color to a space somehow seems like a reasonable idea.

Do you have more of an idea how/when these would show?

Here's my current thinking -- I can imagine a few rules we can consider using:

1. Don't show anything if the object is in the your current default space (whatever space new objects you create are created into).
2. Don't show anything if the object is in the global "default" space.
3. Don't show anything if you can only see one space.

I think (1) is probably a little too confusing. It also means that "no space shown" has different meanings at different times, assuming we let you switch which space you're creating into (I think we almost certainly will). However, it's maybe-possible that it's fine/natural depending on how the "switching" actually evolves.

I think (2) and (3) are pretty reasonable -- if we do them both it might be a little confusing, but probably fine. I think we could probably add both rules and be able to hide spaces most of the time as a result without any real issues. I'm a tiny bit worried about hiding UI in general when a user only has access to one space, but I think my fears about this being confusing are probably unfounded and/or the kind of thing that can be addressed by just documenting the behavior.

If we swap from names to icons we might want to continue always showing spaces, to avoid a ragged left edge. Let me look into that next and we can play around with it a bit and see how it feels.

Also another random 4am jetlagged thought, assigning a header-color to a space somehow seems like a reasonable idea.

I think we might not really need super-strong cues about space membership, but I'm not sure. Seems reasonable to leave on the table, at least.