WIP persist tab state

build.gradle.kts

@@ -100,6 +100,8 @@ allprojects {
         "**/FilterList.kt",
         "**/Remove.kt",
         "**/Pets.kt",
+        "**/RetainedStateHolder*.kt",
+        "**/RetainedStateRestorationTester.kt",
       )
     }
   }

circuit-foundation/src/commonMain/kotlin/com/slack/circuit/foundation/CircuitContent.kt

@@ -37,32 +37,7 @@ public fun CircuitContent(
   unavailableContent: (@Composable (screen: Screen, modifier: Modifier) -> Unit) =
     circuit.onUnavailableContent,
 ) {
-  val navigator =
-    remember(onNavEvent) {
-      object : Navigator {
-        override fun goTo(screen: Screen) {
-          onNavEvent(NavEvent.GoTo(screen))
-        }
-
-        override fun resetRoot(
-          newRoot: Screen,
-          saveState: Boolean,
-          restoreState: Boolean,
-        ): List<Screen> {
-          onNavEvent(NavEvent.ResetRoot(newRoot, saveState, restoreState))
-          return emptyList()
-        }
-
-        override fun pop(): Screen? {
-          onNavEvent(NavEvent.Pop)
-          return null
-        }
-
-        override fun peek(): Screen = screen
-
-        override fun peekBackStack(): List<Screen> = listOf(screen)
-      }
-    }
+  val navigator = remember(onNavEvent) { Navigator.navEventNavigator(screen, onNavEvent) }
   CircuitContent(screen, navigator, modifier, circuit, unavailableContent)
 }
 

circuit-foundation/src/commonMain/kotlin/com/slack/circuit/foundation/NavEvent.kt

@@ -19,6 +19,35 @@ public fun Navigator.onNavEvent(event: NavEvent) {
   }
 }
 
+public fun Navigator.Companion.navEventNavigator(
+  screen: Screen,
+  onNavEvent: (event: NavEvent) -> Unit,
+): Navigator {
+  return object : Navigator {
+    override fun goTo(screen: Screen) {
+      onNavEvent(NavEvent.GoTo(screen))
+    }
+
+    override fun resetRoot(
+      newRoot: Screen,
+      saveState: Boolean,
+      restoreState: Boolean,
+    ): List<Screen> {
+      onNavEvent(NavEvent.ResetRoot(newRoot, saveState, restoreState))
+      return emptyList()
+    }
+
+    override fun pop(): Screen? {
+      onNavEvent(NavEvent.Pop)
+      return null
+    }
+
+    override fun peek(): Screen = screen
+
+    override fun peekBackStack(): List<Screen> = listOf(screen)
+  }
+}
+
 /** A sealed navigation interface intended to be used when making a navigation callback. */
 public sealed interface NavEvent : CircuitUiEvent {
   /** Corresponds to [Navigator.pop]. */