TabUi

Marks a @Composable function as the Android renderer for a tab-root presenter.

Tab roots are wrapped in TabChild<*> rather than ScreenDestination<*> (per the codegen for @NavDestination(kind = TAB_ROOT)), so the matcher emitted for @ScreenUi does not fire on them. @TabUi emits a parallel renderer that downcasts to TabChild so the same Set<ScreenContent> multibinding can dispatch tab roots and stack screens uniformly. The host Children body becomes a single firstOrNull { it.matches(child) } lookup rather than a hand-written when over tab presenter types.

Example

@Composable
@TabUi(presenter = DiscoverShowsPresenter::class, parentScope = ActivityScope::class)
fun DiscoverScreen(
    presenter: DiscoverShowsPresenter,
    modifier: Modifier = Modifier,
) {
    // ... compose UI here
}

The processor emits one file (DiscoverScreenUiBinding.kt) into the same module's <package>.di sub-package. The file contains a @BindingContainer @ContributesTo(parentScope) object whose single @Provides @IntoSet function returns a ScreenContent that:

• tests whether the active navigation child is a TabChild<*> whose presenter is an instance of presenter;

• invokes the annotated composable with the cast presenter and the incoming Modifier.

Composable signature requirement

The annotated function must match the signature @Composable fun <Name>(presenter: <PresenterType>, modifier: Modifier = Modifier). The processor does not enforce parameter names at parse time, but the generated code calls the composable with presenter = ..., modifier = modifier.

When to use it

Pair this with @NavDestination(kind = TAB_ROOT) on the matching tab presenter. The presenter lives in the shared Kotlin Multiplatform layer; the composable lives in an Android-only ui module. The processor emits one binding for each so they wire together at runtime through the Set<ScreenContent> multibinding the navigation host iterates.