diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 4b57441..6a8a27d 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -20,8 +20,8 @@ android {
         applicationId = "solutions.tretter.githugandroid"
         minSdk = 26
         targetSdk = 35
-        versionCode = 175
-        versionName = "0.1.174"
+        versionCode = 176
+        versionName = "0.1.175"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
diff --git a/app/src/androidTest/java/solutions/tretter/githugandroid/GitRepositoryRuntimeInstrumentedTest.kt b/app/src/androidTest/java/solutions/tretter/githugandroid/GitRepositoryRuntimeInstrumentedTest.kt
index 9e14481..5ffebc7 100644
--- a/app/src/androidTest/java/solutions/tretter/githugandroid/GitRepositoryRuntimeInstrumentedTest.kt
+++ b/app/src/androidTest/java/solutions/tretter/githugandroid/GitRepositoryRuntimeInstrumentedTest.kt
@@ -6,6 +6,7 @@ import androidx.compose.ui.test.junit4.createEmptyComposeRule
 import androidx.compose.ui.test.onNodeWithTag
 import androidx.compose.ui.test.performClick
 import androidx.compose.ui.test.performImeAction
+import androidx.compose.ui.test.performScrollTo
 import androidx.compose.ui.test.performTextClearance
 import androidx.compose.ui.test.performTextInput
 import androidx.test.core.app.ActivityScenario
@@ -62,6 +63,21 @@ class GitRepositoryRuntimeInstrumentedTest {
         }
     }
 
+    @Test
+    fun selectingLevelFromLevelsPaneUpdatesExerciseImmediately() {
+        launchFreshApp().use {
+            composeRule.onNodeWithTag("level-submodule")
+                .performScrollTo()
+                .performClick()
+
+            composeRule.waitUntil(timeoutMillis = 1_500) {
+                composeRule.onAllNodes(hasText(submoduleLevel().title, substring = true))
+                    .fetchSemanticsNodes()
+                    .isNotEmpty()
+            }
+        }
+    }
+
     private fun launchFreshApp(): ActivityScenario<MainActivity> {
         val context = InstrumentationRegistry.getInstrumentation().targetContext
         File(context.filesDir, "githug-sandboxes").deleteRecursively()
diff --git a/app/src/main/java/solutions/tretter/githugandroid/GitHugApp.kt b/app/src/main/java/solutions/tretter/githugandroid/GitHugApp.kt
index 34f1d41..ceabecb 100644
--- a/app/src/main/java/solutions/tretter/githugandroid/GitHugApp.kt
+++ b/app/src/main/java/solutions/tretter/githugandroid/GitHugApp.kt
@@ -34,8 +34,10 @@ import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.TextRange
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.unit.dp
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 @Composable
 fun GitHugApp() {
@@ -73,6 +75,8 @@ fun GitHugApp() {
         var historyIndex by remember { mutableStateOf(-1) }
         var historyDraft by remember { mutableStateOf("") }
         var hasRestoredProgress by remember { mutableStateOf(false) }
+        var isPreparingLevel by remember { mutableStateOf(false) }
+        var levelLoadRequestId by remember { mutableStateOf(0) }
         var editorState by remember { mutableStateOf<TextEditorState?>(null) }
         var gitMessageEditorState by remember { mutableStateOf<GitMessageEditorState?>(null) }
         var manPageState by remember { mutableStateOf<ManPageState?>(null) }
@@ -233,11 +237,14 @@ fun GitHugApp() {
             index: Int,
             message: List<String> = listOf("Loaded level: ${levels[index].title}"),
             keepSuppressedImeEcho: Boolean = false,
+            prepareInBackground: Boolean = false,
         ) {
-            AppLog.d("GitHugApp", "Loading level index=$index id=${levels[index].id} title=${levels[index].title}")
+            val level = levels[index]
+            val requestId = levelLoadRequestId + 1
+            levelLoadRequestId = requestId
+            AppLog.d("GitHugApp", "Loading level index=$index id=${level.id} title=${level.title} background=$prepareInBackground")
             currentLevelIndex = index
-            repo = runtime.prepareLevel(levels[index])
-            output = message
+            output = if (prepareInBackground) listOf("Preparing level: ${level.title}") else message
             clearCommandInput(recreateField = true)
             if (!keepSuppressedImeEcho) {
                 suppressedImeEcho = null
@@ -250,10 +257,29 @@ fun GitHugApp() {
             editorState = null
             gitMessageEditorState = null
             manPageState = null
+            if (prepareInBackground) {
+                isPreparingLevel = true
+                repo = RepoState()
+                scope.launch {
+                    val preparedRepo = withContext(Dispatchers.Default) {
+                        runtime.prepareLevel(level)
+                    }
+                    if (levelLoadRequestId == requestId) {
+                        AppLog.d("GitHugApp", "Prepared level index=$index id=${level.id}")
+                        repo = preparedRepo
+                        output = message
+                        isPreparingLevel = false
+                        clearCommandInput(recreateField = true)
+                    }
+                }
+            } else {
+                isPreparingLevel = false
+                repo = runtime.prepareLevel(level)
+            }
             paneLayout = paneLayout.copy(
                 weights = paneLayout.weights + recommendedPaneWeights(
                     heights = recommendedPaneHeights(
-                        level = levels[index],
+                        level = level,
                         levelCount = levels.size,
                         outputLineCount = 1,
                         screenHeightDp = screenHeightDp,
@@ -457,6 +483,12 @@ fun GitHugApp() {
             val submittedText = commandInput.text
             val raw = submittedText.trim()
             if (raw.isBlank()) return
+            if (isPreparingLevel) {
+                output = output + "Still preparing ${currentLevel.title}. Try again in a moment."
+                clearCommandInput(recreateField = true)
+                applyRecommendedPaneWeights(persist = false, outputLineCount = terminalOutputLineCount(output))
+                return
+            }
             val isInteractiveInput = repo.interactiveAddSession != null
 
             showHelpOverlay = false
@@ -560,7 +592,9 @@ fun GitHugApp() {
                                     })
                                 },
                                 levelsContent = {
-                                    LevelsPane(levels, currentLevelIndex, completedLevels) { index -> loadLevel(index) }
+                                    LevelsPane(levels, currentLevelIndex, completedLevels) { index ->
+                                        loadLevel(index, prepareInBackground = true)
+                                    }
                                 },
                                 visualContent = { VisualPane(repo) },
                                 exerciseContent = {