Blocks

A block is an arrangement two showcases build, and the library does not.

That is a real third category and it existed here for months without a name. field-notes and metadata-form are the same arrangement seen from two sides: a workspace with a header, an activity rail, one <main>, and panels that open beside it. Everything specific to either one stays in its own directory — but the furniture between them was being written twice, and drifting apart while it was:

• the panel headers were h-9 in one showcase and h-12 in the other;
• the tally badge was a HoverCard with a reveal in one and a plain Badge in the other;
• the activity rail existed in only one of them, as a ToggleGroup standing in for a region.

None of that is a library defect. It is what specificity is allowed to produce once there is more than one specific screen, and the answer is to name the shared half rather than to promote it.

Why these are not components

A part here earns its place by having two call sites in showcases/ — which is an-export-needs-a-second-call-site applied one layer down. Two showcases is not two products. Every one of these knows something the library must not: PaneHeader knows a panel has a document and a health, FindingsBadge knows a finding has a where, PanelRail knows the edge is where panels are switched. The library ships regions, toggles, badges and splitters; a block is one opinion about how to put four of them together.

So they are not exported, not versioned and not on their way to being. They live in docs/showcases/shared/index.tsx, and anything with one call site belongs in that showcase's own directory instead.