Material3Components

The A2UI basic catalog drawn with Material 3.

A registry to hand to A2uiSurface. The composition it draws into must have a MaterialTheme above it: every renderer here reads the theme's typography and colour scheme, which is the point of a design-system adapter rather than an accident of how they are written.

All eighteen of the catalog's components, which is every component the specification's forty-three examples name. A component this registry does not know -- one from another catalog -- draws as an UnknownType placeholder rather than as nothing, so a surface using one is visibly incomplete instead of quietly wrong, and a host that has written its own can pass them to ComponentRegistry.with.

Video and AudioPlayer draw a media component's frame but play nothing. There is no player in Compose Multiplatform to draw, and shipping one means a media stack per target; a host that has one registers its own renderer for the two. See VideoRenderer, which says what that does and does not promise.

Image draws whatever LocalA2uiImageLoader is set to, and a described placeholder when the host has set none -- this module fetches nothing itself. See A2uiImageLoader.

Five words come from the host rather than from the payload. A picker dialog's confirm and cancel buttons, a filterable ChoicePicker's search field, a Modal's close button and a Video's frame have no text in the catalog to borrow, and leaving them unnamed makes them unusable with -- or invisible to -- a screen reader, so they are named through LocalA2uiStrings, English until a host provides otherwise. Everything else on a surface is the agent's own words.

Tabs and Modal hold state the agent cannot see. A tab strip's selected index and a modal's open-ness are the renderer's, because the catalog gives neither component a property to bind them to -- the guide says as much for Tabs. A Modal also intercepts its trigger's taps, so a trigger carrying an action does not dispatch it; see ModalRenderer.

checks -- the catalog's Checkable mixin -- is honoured by every component that carries it. A Button whose check fails is disabled, which is what the protocol asks for by name; a failing input is captioned with the message. See checkFailures, where the rules are evaluated, which a host writing its own input renderer can call for the same behaviour.