Fix coroutine scoping of Redwood Treehouse UI

Ensure that Zipline resources aren't closed until the UI's coroutine scope job completes

CHANGELOG.md

@@ -35,6 +35,7 @@ Fixed:
 - Fix `TreehouseUIView` to size itself according to the size of its subview.
 - In `UIViewLazyList`, adding `beginUpdates`/`endUpdates` calls to `insertRows`/`deleteRows`, and wrapping changes in `UIView.performWithoutAnimation` blocks.
 - Fix memory leak in 'protocol-guest' and 'protocol-host' where child nodes beneath a removed node were incorrectly retained in an internal map indefinitely.
+- Ensure that Zipline services are not closed prematurely when disposing a Treehouse UI.
 
 
 ## [0.9.0] - 2024-02-28

redwood-treehouse-guest/src/commonMain/kotlin/app/cash/redwood/treehouse/treehouseCompose.kt

@@ -27,8 +27,12 @@ import app.cash.redwood.ui.OnBackPressedDispatcher
 import app.cash.redwood.ui.UiConfiguration
 import app.cash.zipline.ZiplineScope
 import app.cash.zipline.ZiplineScoped
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.job
 import kotlinx.coroutines.plus
 
 /**
@@ -55,6 +59,11 @@ private class RedwoodZiplineTreehouseUi(
    */
   override val scope = (treehouseUi as? ZiplineScoped)?.scope ?: ZiplineScope()
 
+  private val coroutineScope = CoroutineScope(
+    appLifecycle.coroutineScope.coroutineContext +
+      Job(appLifecycle.coroutineScope.coroutineContext.job),
+  )
+
   private lateinit var composition: RedwoodComposition
 
   private lateinit var saveableStateRegistry: SaveableStateRegistry
@@ -102,7 +111,7 @@ private class RedwoodZiplineTreehouseUi(
     )
 
     val composition = ProtocolRedwoodComposition(
-      scope = appLifecycle.coroutineScope + appLifecycle.frameClock,
+      scope = coroutineScope + appLifecycle.frameClock,
       bridge = bridge,
       widgetVersion = appLifecycle.widgetVersion,
       changesSink = host,
@@ -121,9 +130,12 @@ private class RedwoodZiplineTreehouseUi(
   }
 
   override fun close() {
+    coroutineScope.coroutineContext.job.invokeOnCompletion {
+      scope.close()
+    }
+    coroutineScope.cancel()
     composition.cancel()
     treehouseUi.close()
-    scope.close()
   }
 }