rememberRetained state lost on pop() in KMP since v0.28.1

[kei-1111]

Note

I'm not a native English speaker, so I used AI assistance to write this discussion. I apologize if there are any unclear expressions.
Also, I'm not entirely sure if this is a bug or intended behavior change. If this is the expected behavior in v0.28.1+, I would appreciate guidance on the correct way to retain state across backstack navigation.

Summary

When using NavigableCircuitContent in a Kotlin Multiplatform project (commonMain), rememberRetained state is lost when navigating back via navigator.pop(). This issue does not occur in v0.28.0 but appears in v0.28.1 and later versions (tested up to v0.31.0).

Environment

• Circuit version: 0.31.0 (issue appears from 0.28.1+)
• Kotlin version: 2.2.21
• Compose Multiplatform version: 1.10.0-rc02
• Platform: Android (commonMain code)
• Working version: 0.28.0

Reproduction Steps

1. Create a simple two-screen app with NavigableCircuitContent
2. Use rememberRetained in the first screen's presenter to hold state (e.g., a counter)
3. Navigate to the second screen using navigator.goTo()
4. Navigate back using navigator.pop()
5. Expected: The state in the first screen is preserved
6. Actual: The state is reset to its initial value

Video

v0.28.0 (Working)	v0.31.0 (Not Working)
Screen_recording_20251211_141318.mp4	Screen_recording_20251211_140147.mp4

Minimal Reproduction Code

App.kt (commonMain)

@Composable
fun App() {
    val circuit = Circuit.Builder()
        .addPresenterFactory(PresenterFactory())
        .addUiFactory(UiFactory())
        .build()
    val backStack = rememberSaveableBackStack(HomeScreen)
    val navigator = rememberCircuitNavigator(backStack) {}

    CircuitCompositionLocals(circuit) {
        NavigableCircuitContent(navigator, backStack)
    }
}

PresenterFactory.kt (commonMain)

class PresenterFactory : Presenter.Factory {
    override fun create(
        screen: Screen,
        navigator: Navigator,
        context: CircuitContext
    ): Presenter<*>? {
        return when (screen) {
            is HomeScreen -> HomePresenter(navigator)
            is SettingsScreen -> SettingsPresenter(navigator)
            else -> null
        }
    }
}

UiFactory.kt (commonMain)

class UiFactory : Ui.Factory {
    override fun create(
        screen: Screen,
        context: CircuitContext
    ): Ui<*>? {
        return when(screen) {
            is HomeScreen -> ui<HomeState> { state, modifier -> Home(state, modifier) }
            is SettingsScreen -> ui<SettingsState> { state, modifier -> Settings(state, modifier) }
            else -> null
        }
    }
}

HomePresenter.kt (commonMain)

@CommonParcelize
object HomeScreen : Screen

data class HomeState(
    val count: Int,
    val eventSink: (HomeEvent) -> Unit
) : CircuitUiState

sealed interface HomeEvent : CircuitUiEvent {
    data object Increase : HomeEvent
    data object Decrease : HomeEvent
    data object NavigateSettings : HomeEvent
}

class HomePresenter(
    val navigator: Navigator,
) : Presenter<HomeState> {
    @Composable
    override fun present(): HomeState {
        // This state is lost after pop() from SettingsScreen
        var count by rememberRetained { mutableStateOf(0) }

        return HomeState(
            count = count,
            eventSink = { event ->
                when (event) {
                    HomeEvent.Decrease -> count--
                    HomeEvent.Increase -> count++
                    HomeEvent.NavigateSettings -> navigator.goTo(SettingsScreen)
                }
            }
        )
    }
}

SettingsPresenter.kt (commonMain)

@CommonParcelize
object SettingsScreen : Screen

data class SettingsState(
    val eventSink: (SettingsEvent) -> Unit,
) : CircuitUiState

sealed interface SettingsEvent : CircuitUiEvent {
    data object NavigateBack : SettingsEvent
}

class SettingsPresenter(
    val navigator: Navigator
) : Presenter<SettingsState> {
    @Composable
    override fun present(): SettingsState {
        return SettingsState(
            eventSink = { event ->
                when(event) {
                    SettingsEvent.NavigateBack -> navigator.pop()
                }
            }
        )
    }
}

[bodoss]

I have the same issue. Can't upgrade the lib.

[stagg]

This is a known bug with some of the underlying runtime changes and will be fixed once we support Compose 1.10. We're not quite at compose 1.10 support yet, just waiting on the stable release of compose-multiplatform.
There is a preview alpha based on changes in this PR #2379 which should include the fix for this issue.

[bodoss]

This is a known bug with some of the underlying runtime changes and will be fixed once we support Compose 1.10. We're not quite at compose 1.10 support yet, just waiting on the stable release of compose-multiplatform. There is a preview alpha based on changes in this PR #2379 which should include the fix for this issue.

For me, the bug is reproducible with Compose Multiplatform 1.9.3 as well, if circuit is >0.28.0

[kei-1111]

Thank you for your response! I look forward to the correction.