The catalog page was one undifferentiated grid filtered only by tier, so a
memory provider sat between two Desktop panes. Entries now carry an optional
``category`` (memory | desktop | platform | web | tools | voice | automation |
models | other, default other) that the loader, the admission validator and
the site extractor all understand.
/docs/plugins renders one shelf per category in browse mode, a category pill
row under the tier pills, a clickable category chip on every card, and a
results bar (active category, count, clear) when a filter or search flattens
the view. ``hermes plugins catalog`` gains a Category column and groups by it.
All 18 shipped entries are categorised. Unknown categories fail admission
(same contract as tier) so a typo cannot create a phantom shelf.
