Yeah, I wouldn't plan to keep the tag on it. Other stuff off the top of my head:

• Icon in the header has whack spacing.
• TODO about alterning descendants.
• You can probably reorder these but it won't actually work? I didn't actually try.
• Names are probably editable but I don't think that really makes sense.
• Header should maybe be linked to iteration project page / workboard?
• If sub-thing is disabled maybe column auto-hides? Might be messy-ish / have weird interactions with milestones.

I'm probably not going to make too much more progress tonight so I'm going to hold this until I get started tomorrow, since some of the edges here are still a bit rough.

After sleeping on this, I'm a little bit unsatisfied about the approach I'm taking to set up column positions.

The big issue is that a lot of logic is happening at read time (i.e., when you look at the board), and it has a lot of potential side-effect writes, and none of that logic is separated or isolated. There's also an existing, similar block of logic in PhabricatorProjectColumnPositionQuery which isn't integrated with the new stuff, and feels a bit awkward now.

I think about 90% of this change is good, but I want to chew on my approach a bit more and develop a clearer picture of the path forward, since I'm not completely confident in this approach. In particular, I think a better approach might be:

• Pull the layout/write logic out of PhabricatorProjectColumnPositionQuery (make it a simple dumb query like most other queries).
• Pull the layout/write logic out of the board view.
• Put all the layout/write logic in some new FancyBoardLayoutThing.
• Don't actually do writes when looking at boards.
• Run the same logic, then do writes only when moving cards.

I'm going to hold this for now and maybe pursue some adjacent changes to see if that clarifies the direction.