On a device, the folded Duo list kept Search and New chat in the
accessibility tree but never drew them. A collapsed split's primary
column reaches the vertical bar only through its navigation items, not
its toolbar. Unfolded, the search slot added to the sidebar toolbar
moved into the detail rail and drew a glass backdrop over the whole
detail column.

- A collapsed split's primary column merges its toolbar items into its
  trailing navigation items again. Detail columns and the unfolded
  sidebar keep real toolbar groups.
- The workspace toolbar drops the Duo search slot, so UIKit places the
  list's search automatically again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>