Agent skill

compose-multiplatform-patterns

Compose Multiplatform and Jetpack Compose patterns for KMP projects — state management, navigation, theming, performance, and platform-specific UI.

View SKILL.md on GitHub Repository
Stars 132,726
Forks 19,206

Install this agent skill to your Project

npx add-skill https://github.com/affaan-m/everything-claude-code/tree/main/skills/compose-multiplatform-patterns

SKILL.md

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 mutableStateOf in ViewModels when MutableStateFlow with collectAsStateWithLifecycle is safer for lifecycle
  • Passing NavController deep into composables — pass lambda callbacks instead
  • Heavy computation inside @Composable functions — move to ViewModel or remember {}
  • 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.

Recommended Agent Skills

Expand your agent's capabilities with these related and highly-rated skills.

affaan-m/everything-claude-code

python-testing

Python testing best practices using pytest including fixtures, parametrization, mocking, coverage analysis, async testing, and test organization. Use when writing or improving Python tests.

132,726 19,206
Explore
affaan-m/everything-claude-code

golang-patterns

Go-specific design patterns and best practices including functional options, small interfaces, dependency injection, concurrency patterns, error handling, and package organization. Use when working with Go code to apply idiomatic Go patterns.

132,726 19,206
Explore
affaan-m/everything-claude-code

e2e-testing

Playwright E2E testing patterns, Page Object Model, configuration, CI/CD integration, artifact management, and flaky test strategies.

132,726 19,206
Explore
affaan-m/everything-claude-code

agentic-engineering

Operate as an agentic engineer using eval-first execution, decomposition, and cost-aware model routing. Use when AI agents perform most implementation work and humans enforce quality and risk controls.

132,726 19,206
Explore
affaan-m/everything-claude-code

api-design

REST API design patterns including resource naming, status codes, pagination, filtering, error responses, versioning, and rate limiting for production APIs.

132,726 19,206
Explore
affaan-m/everything-claude-code

python-patterns

Python-specific design patterns and best practices including protocols, dataclasses, context managers, decorators, async/await, type hints, and package organization. Use when working with Python code to apply Pythonic patterns.

132,726 19,206
Explore

Didn't find tool you were looking for?

Be as detailed as possible for better results