Template part focus mode, and the header nobody could find

Editing a header meant opening a template, finding the part inside it, and editing in place with the rest of the page as context — which sounds helpful and is not.

the old path:
  Appearance → Editor → Templates → Index →
  click into the header → edit, with 40 blocks of
  page content surrounding it

the new one:
  Appearance → Editor → Patterns → Template parts →
  Header → edit, alone

and the change that mattered: the header is now a thing
with a name in a list, rather than a region inside a
template.

Making template parts navigable as objects rather than as regions is a small information architecture change with a large effect on whether a non-developer can find anything. Three of four editors we watched had never successfully edited a header before this; all four could after a two-minute explanation.