Change animation on cold start by a fader animation.

appnav/src/main/kotlin/io/element/android/appnav/LoggedInFlowNode.kt

@@ -64,6 +64,9 @@ import io.element.android.features.userprofile.api.UserProfileEntryPoint
 import io.element.android.features.verifysession.api.IncomingVerificationEntryPoint
 import io.element.android.libraries.architecture.BackstackView
 import io.element.android.libraries.architecture.BaseFlowNode
+import io.element.android.libraries.architecture.animation.rememberDefaultTransitionHandler
+import io.element.android.libraries.architecture.animation.rememberFaderTransitionHandler
+import io.element.android.libraries.architecture.appyx.rememberDelegateTransitionHandler
 import io.element.android.libraries.architecture.createNode
 import io.element.android.libraries.architecture.waitForNavTargetAttached
 import io.element.android.libraries.designsystem.utils.snackbar.SnackbarDispatcher
@@ -540,7 +543,16 @@ class LoggedInFlowNode(
     override fun View(modifier: Modifier) {
         Box(modifier = modifier) {
             val ftueState by ftueService.state.collectAsState()
-            BackstackView()
+            val backstackSlider = rememberDefaultTransitionHandler<NavTarget>()
+            val backstackFader = rememberFaderTransitionHandler<NavTarget>()
+            val transitionHandler = rememberDelegateTransitionHandler<NavTarget, BackStack.State> { navTarget ->
+                when (navTarget) {
+                    NavTarget.Home,
+                    NavTarget.Ftue -> backstackFader
+                    else -> backstackSlider
+                }
+            }
+            BackstackView(transitionHandler = transitionHandler)
             if (ftueState is FtueState.Complete) {
                 PermanentChild(permanentNavModel = permanentNavModel, navTarget = NavTarget.LoggedInPermanent)
             }

appnav/src/main/kotlin/io/element/android/appnav/RootFlowNode.kt

@@ -9,8 +9,6 @@ package io.element.android.appnav
 
 import android.content.Intent
 import android.os.Parcelable
-import androidx.compose.animation.core.Spring
-import androidx.compose.animation.core.spring
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.lifecycle.lifecycleScope
@@ -21,8 +19,6 @@ import com.bumble.appyx.core.state.MutableSavedStateMap
 import com.bumble.appyx.navmodel.backstack.BackStack
 import com.bumble.appyx.navmodel.backstack.operation.pop
 import com.bumble.appyx.navmodel.backstack.operation.push
-import com.bumble.appyx.navmodel.backstack.transitionhandler.rememberBackstackFader
-import com.bumble.appyx.navmodel.backstack.transitionhandler.rememberBackstackSlider
 import dev.zacsweers.metro.AppScope
 import dev.zacsweers.metro.Assisted
 import dev.zacsweers.metro.AssistedInject
@@ -42,6 +38,8 @@ import io.element.android.features.signedout.api.SignedOutEntryPoint
 import io.element.android.libraries.accountselect.api.AccountSelectEntryPoint
 import io.element.android.libraries.architecture.BackstackView
 import io.element.android.libraries.architecture.BaseFlowNode
+import io.element.android.libraries.architecture.animation.rememberDefaultTransitionHandler
+import io.element.android.libraries.architecture.animation.rememberFaderTransitionHandler
 import io.element.android.libraries.architecture.appyx.rememberDelegateTransitionHandler
 import io.element.android.libraries.architecture.createNode
 import io.element.android.libraries.architecture.waitForChildAttached
@@ -171,15 +169,12 @@ import timber.log.Timber
             modifier = modifier,
             onOpenBugReport = this::onOpenBugReport,
         ) {
-            val backstackSlider = rememberBackstackSlider<NavTarget>(
-                transitionSpec = { spring(stiffness = Spring.StiffnessMediumLow) },
-            )
-            val backstackFader = rememberBackstackFader<NavTarget>(
-                transitionSpec = { spring(stiffness = Spring.StiffnessMediumLow) },
-            )
+            val backstackSlider = rememberDefaultTransitionHandler<NavTarget>()
+            val backstackFader = rememberFaderTransitionHandler<NavTarget>()
             val transitionHandler = rememberDelegateTransitionHandler<NavTarget, BackStack.State> { navTarget ->
                 when (navTarget) {
                     is NavTarget.SplashScreen,
+                    is NavTarget.NotLoggedInFlow,
                     is NavTarget.LoggedInFlow -> backstackFader
                     else -> backstackSlider
                 }

libraries/architecture/src/main/kotlin/io/element/android/libraries/architecture/BaseFlowNode.kt

@@ -7,8 +7,6 @@
 
 package io.element.android.libraries.architecture
 
-import androidx.compose.animation.core.Spring
-import androidx.compose.animation.core.spring
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.BoxScope
 import androidx.compose.runtime.Composable
@@ -25,7 +23,7 @@ import com.bumble.appyx.core.node.ParentNode
 import com.bumble.appyx.core.plugin.Plugin
 import com.bumble.appyx.navmodel.backstack.BackStack
 import com.bumble.appyx.navmodel.backstack.transitionhandler.rememberBackstackFader
-import com.bumble.appyx.navmodel.backstack.transitionhandler.rememberBackstackSlider
+import io.element.android.libraries.architecture.animation.rememberDefaultTransitionHandler
 import io.element.android.libraries.architecture.overlay.Overlay
 
 /**
@@ -61,9 +59,7 @@ abstract class BaseFlowNode<NavTarget : Any>(
 @Composable
 inline fun <reified NavTarget : Any> BaseFlowNode<NavTarget>.BackstackView(
     modifier: Modifier = Modifier,
-    transitionHandler: TransitionHandler<NavTarget, BackStack.State> = rememberBackstackSlider(
-        transitionSpec = { spring(stiffness = Spring.StiffnessMediumLow) },
-    ),
+    transitionHandler: TransitionHandler<NavTarget, BackStack.State> = rememberDefaultTransitionHandler(),
 ) {
     Children(
         modifier = modifier,

libraries/architecture/src/main/kotlin/io/element/android/libraries/architecture/animation/ScreenTransition.kt

@@ -12,6 +12,7 @@ import androidx.compose.animation.core.spring
 import androidx.compose.runtime.Composable
 import com.bumble.appyx.core.navigation.transition.ModifierTransitionHandler
 import com.bumble.appyx.navmodel.backstack.BackStack
+import com.bumble.appyx.navmodel.backstack.transitionhandler.rememberBackstackFader
 import com.bumble.appyx.navmodel.backstack.transitionhandler.rememberBackstackSlider
 
 @Composable
@@ -20,3 +21,10 @@ fun <NavTarget> rememberDefaultTransitionHandler(): ModifierTransitionHandler<Na
         transitionSpec = { spring(stiffness = Spring.StiffnessMediumLow) },
     )
 }
+
+@Composable
+fun <NavTarget> rememberFaderTransitionHandler(): ModifierTransitionHandler<NavTarget, BackStack.State> {
+    return rememberBackstackFader(
+        transitionSpec = { spring(stiffness = Spring.StiffnessMediumLow) },
+    )
+}