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Spectacular

Slot Content

A SlotContent is the anonymous structural triplet — anatomy, elements, and layout — used as a named fill for a slot. It carries no metadata of its own; its identity lives at the key under which it is stored.

interface SlotContent {
  anatomy: Anatomy;
  elements: Elements;
  layout: Layout;
}

Properties

PropertyTypeRequiredDescription
anatomyAnatomyYesElement type map for this fill
elementsElementsYesElement-level content, styles, and prop configurations
layoutLayoutYesTree ordering of the elements

Where it lives

SlotContent entries are stored in named registries and referenced — never inlined — by a SlotContentRef ($slotContent pointer):

  • Component.slotContentExamples — component-scoped fills, e.g. "#/components/pill/slotContentExamples/composedLabel". Emitted when settings.spec.defaultSlotContent is on.
  • Composition.slotContent — fills bundled alongside a Composition’s primary content, e.g. "#/compositions/filterResultsPage/slotContent/pageHeader".

specs-from-figma de-duplicates entries by structural equality across variants and slots — identical fills share a single registry entry.

When no entry exists

A registry entry is how a non-default slot is filled. A fill into a slot marked defaultSlot: true produces no entry at all: the filling instance is nested as a plain child of the element it fills, in whatever anatomy, elements and layout that element already lives in.

So the registry holds what the structure cannot say on its own, and nothing more. A screen built from four nested layout components used to contribute an entry per level, each pointed at once from the level above; it now contributes none, and the entries that remain are its genuinely multi-slot fills.

The same collapse applies inside an entry. A non-default slot’s fill is still an entry, but a default-slot chain beneath it nests within that one entry rather than spawning another per level.

Further Reading