Como usar
- Copie o comando e verifique o pacote antes de instalar no seu ambiente de agente.
- Consulte no original as ferramentas, credenciais e ambientes necessários.
- Descreva os dados de entrada e a entrega esperada; confira a saída com as fontes.
npx skills add https://github.com/affaan-m/ecc --skill compose-multiplatform-patternsAntes de começar
- A instalação não inclui assinatura de modelo, franquia API ou acesso aos seus arquivos.
- Estrelas e instalações indicam atividade, não um teste independente de qualidade ou segurança.
Documento original do Skill
Renderizado do repositório de origem, preservando títulos, exemplos, código, tabelas, links e imagens.
Compose Multiplatform Patterns
Patterns for building shared UI across Android, iOS, Desktop, and Web using Compose Multiplatform and Jetpack Compose. Covers state management, navigation, theming, and performance.
When to Activate
- Building Compose UI (Jetpack Compose or Compose Multiplatform)
- Managing UI state with ViewModels and Compose state
- Implementing navigation in KMP or Android projects
- Designing reusable composables and design systems
- Optimizing recomposition and rendering performance
State Management
ViewModel + Single State Object
Use a single data class for screen state. Expose it as StateFlow and collect in Compose:
kotlin
data class ItemListState(
val items: List<Item> = emptyList(),
val isLoading: Boolean = false,
val error: String? = null,
val searchQuery: String = ""
)
class ItemListViewModel(
private val getItems: GetItemsUseCase
) : ViewModel() {
private val _state = MutableStateFlow(ItemListState())
val state: StateFlow<ItemListState> = _state.asStateFlow()
fun onSearch(query: String) {
_state.update { it.copy(searchQuery = query) }
loadItems(query)
}
private fun loadItems(query: String) {
viewModelScope.launch {
_state.update { it.copy(isLoading = true) }
getItems(query).fold(
onSuccess = { items -> _state.update { it.copy(items = items, isLoading = false) } },
onFailure = { e -> _state.update { it.copy(error = e.message, isLoading = false) } }
)
}
}
}Collecting State in Compose
kotlin
@Composable
fun ItemListScreen(viewModel: ItemListViewModel = koinViewModel()) {
val state by viewModel.state.collectAsStateWithLifecycle()
ItemListContent(
state = state,
onSearch = viewModel::onSearch
)
}
@Composable
private fun ItemListContent(
state: ItemListState,
onSearch: (String) -> Unit
) {
// Stateless composable — easy to preview and test
}Event Sink Pattern
For complex screens, use a sealed interface for events instead of multiple callback lambdas:
kotlin
sealed interface ItemListEvent {
data class Search(val query: String) : ItemListEvent
data class Delete(val itemId: String) : ItemListEvent
data object Refresh : ItemListEvent
}
// In ViewModel
fun onEvent(event: ItemListEvent) {
when (event) {
is ItemListEvent.Search -> onSearch(event.query)
is ItemListEvent.Delete -> deleteItem(event.itemId)
is ItemListEvent.Refresh -> loadItems(_state.value.searchQuery)
}
}
// In Composable — single lambda instead of many
ItemListContent(
state = state,
onEvent = viewModel::onEvent
)Navigation
Type-Safe Navigation (Compose Navigation 2.8+)
Define routes as @Serializable objects:
kotlin
@Serializable data object HomeRoute
@Serializable data class DetailRoute(val id: String)
@Serializable data object SettingsRoute
@Composable
fun AppNavHost(navController: NavHostController = rememberNavController()) {
NavHost(navController, startDestination = HomeRoute) {
composable<HomeRoute> {
HomeScreen(onNavigateToDetail = { id -> navController.navigate(DetailRoute(id)) })
}
composable<DetailRoute> { backStackEntry ->
val route = backStackEntry.toRoute<DetailRoute>()
DetailScreen(id = route.id)
}
composable<SettingsRoute> { SettingsScreen() }
}
}Dialog and Bottom Sheet Navigation
Use dialog() and overlay patterns instead of imperative show/hide:
kotlin
NavHost(navController, startDestination = HomeRoute) {
composable<HomeRoute> { /* ... */ }
dialog<ConfirmDeleteRoute> { backStackEntry ->
val route = backStackEntry.toRoute<ConfirmDeleteRoute>()
ConfirmDeleteDialog(
itemId = route.itemId,
onConfirm = { navController.popBackStack() },
onDismiss = { navController.popBackStack() }
)
}
}Composable Design
Slot-Based APIs
Design composables with slot parameters for flexibility:
kotlin
@Composable
fun AppCard(
modifier: Modifier = Modifier,
header: @Composable () -> Unit = {},
content: @Composable ColumnScope.() -> Unit,
actions: @Composable RowScope.() -> Unit = {}
) {
Card(modifier = modifier) {
Column {
header()
Column(content = content)
Row(horizontalArrangement = Arrangement.End, content = actions)
}
}
}Modifier Ordering
Modifier order matters — apply in this sequence:
kotlin
Text(
text = "Hello",
modifier = Modifier
.padding(16.dp) // 1. Layout (padding, size)
.clip(RoundedCornerShape(8.dp)) // 2. Shape
.background(Color.White) // 3. Drawing (background, border)
.clickable { } // 4. Interaction
)KMP Platform-Specific UI
expect/actual for Platform Composables
kotlin
// commonMain
@Composable
expect fun PlatformStatusBar(darkIcons: Boolean)
// androidMain
@Composable
actual fun PlatformStatusBar(darkIcons: Boolean) {
val systemUiController = rememberSystemUiController()
SideEffect { systemUiController.setStatusBarColor(Color.Transparent, darkIcons) }
}
// iosMain
@Composable
actual fun PlatformStatusBar(darkIcons: Boolean) {
// iOS handles this via UIKit interop or Info.plist
}Performance
Stable Types for Skippable Recomposition
Mark classes as @Stable or @Immutable when all properties are stable:
kotlin
@Immutable
data class ItemUiModel(
val id: String,
val title: String,
val description: String,
val progress: Float
)Use key() and Lazy Lists Correctly
kotlin
LazyColumn {
items(
items = items,
key = { it.id } // Stable keys enable item reuse and animations
) { item ->
ItemRow(item = item)
}
}Defer Reads with derivedStateOf
kotlin
val listState = rememberLazyListState()
val showScrollToTop by remember {
derivedStateOf { listState.firstVisibleItemIndex > 5 }
}Avoid Allocations in Recomposition
kotlin
// BAD — new lambda and list every recomposition
items.filter { it.isActive }.forEach { ActiveItem(it, onClick = { handle(it) }) }
// GOOD — key each item so callbacks stay attached to the right row
val activeItems = remember(items) { items.filter { it.isActive } }
activeItems.forEach { item ->
key(item.id) {
ActiveItem(item, onClick = { handle(item) })
}
}Theming
Material 3 Dynamic Theming
kotlin
@Composable
fun AppTheme(
darkTheme: Boolean = isSystemInDarkTheme(),
dynamicColor: Boolean = true,
content: @Composable () -> Unit
) {
val colorScheme = when {
dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
if (darkTheme) dynamicDarkColorScheme(LocalContext.current)
else dynamicLightColorScheme(LocalContext.current)
}
darkTheme -> darkColorScheme()
else -> lightColorScheme()
}
MaterialTheme(colorScheme = colorScheme, content = content)
}Anti-Patterns to Avoid
- Using
mutableStateOfin ViewModels whenMutableStateFlowwithcollectAsStateWithLifecycleis safer for lifecycle - Passing
NavControllerdeep into composables — pass lambda callbacks instead - Heavy computation inside
@Composablefunctions — move to ViewModel orremember {} - Using
LaunchedEffect(Unit)as a substitute for ViewModel init — it re-runs on configuration change in some setups - Creating new object instances in composable parameters — causes unnecessary recomposition
References
See skill: android-clean-architecture for module structure and layering. See skill: kotlin-coroutines-flows for coroutine and Flow patterns.
