fix: tie back arrow to pipeline idle state

Computed from operation states in SettingsViewModel instead of a fixed
delay; cancel and error release the arrow immediately.

app/src/main/java/com/example/research/feature/download/model/DownloadState.kt

@@ -11,3 +11,6 @@ sealed class DownloadState {
     data class Error(val message: String) : DownloadState()
     data object Cancelled : DownloadState()
 }
+
+val DownloadState.isActive: Boolean
+    get() = this is DownloadState.Loading || this is DownloadState.Extracting || this is DownloadState.Success

app/src/main/java/com/example/research/ui/navigation/AppNavigation.kt

@@ -9,15 +9,11 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.window.core.layout.WindowSizeClass.Companion.WIDTH_DP_MEDIUM_LOWER_BOUND
 import com.example.research.feature.search.SearchAction
 import com.example.research.feature.search.SearchViewModel
-import com.example.research.feature.download.model.DownloadState
 import com.example.research.ui.about.AboutScreen
 import com.example.research.ui.article.ArticleRoute
 import com.example.research.ui.main.MainRoute
-import com.example.research.ui.settings.ImportState
 import com.example.research.ui.settings.SettingsRoute
 import com.example.research.ui.settings.SettingsViewModel
-import kotlinx.coroutines.delay
-import kotlin.time.Duration.Companion.milliseconds
 
 private data class NavigationState(
     val shouldShowSettings: Boolean,
@@ -54,35 +50,10 @@ fun AppNavigation(
     val currentScreen = screenStack.lastOrNull() ?: Screen.Home
 
     val settingsState by settingsViewModel.uiState.collectAsStateWithLifecycle()
-    val progressSnapshot by settingsViewModel.progressSnapshot.collectAsStateWithLifecycle()
-    val isPipelineActiveByState = remember(
-        progressSnapshot,
-        settingsState.indexingProgress.isIndexing,
-        settingsState.downloadState,
-        settingsState.importState,
-    ) {
-        progressSnapshot != null ||
-            settingsState.indexingProgress.isIndexing ||
-            settingsState.downloadState is DownloadState.Loading ||
-            settingsState.downloadState is DownloadState.Extracting ||
-            settingsState.downloadState is DownloadState.Success ||
-            settingsState.importState is ImportState.Importing ||
-            settingsState.importState is ImportState.Extracting ||
-            settingsState.importState is ImportState.Success
-    }
-    var stickyPipelineActive by rememberSaveable { mutableStateOf(false) }
-    LaunchedEffect(isPipelineActiveByState) {
-        if (isPipelineActiveByState) {
-            stickyPipelineActive = true
-        } else {
-            delay(1500.milliseconds)
-            stickyPipelineActive = false
-        }
-    }
 
     val navState by remember {
         derivedStateOf {
-            val isOperationActive = stickyPipelineActive
+            val isOperationActive = !settingsState.pipelineIdle
             val hasConfirmedNoDictionaries =
                 settingsState.hasCompletedStartupScan && settingsState.dictionaries.isEmpty()
             val hasSeededNoDictionaries = seedNoDictionaries && !settingsState.hasCompletedStartupScan

app/src/main/java/com/example/research/ui/settings/ImportState.kt

@@ -10,3 +10,6 @@ sealed interface ImportState {
     data object Success : ImportState
     data class Error(val message: String) : ImportState
 }
+
+val ImportState.isActive: Boolean
+    get() = this is ImportState.Importing || this is ImportState.Extracting || this is ImportState.Success

app/src/main/java/com/example/research/ui/settings/SettingsUiState.kt

@@ -23,6 +23,7 @@ data class SettingsUiState(
     val importState: ImportState = ImportState.Idle,
     val dictionarySources: List<DictionarySource> = emptyList(),
     val hasCompletedStartupScan: Boolean = false,
+    val pipelineIdle: Boolean = true,
     val appVersion: String = "1.0",
 )
 

app/src/main/java/com/example/research/ui/settings/SettingsViewModel.kt

@@ -19,6 +19,7 @@ import com.example.research.data.local.preferences.PreferencesManager
 import com.example.research.data.repository.LocalDictionaryRepository
 import com.example.research.feature.download.DownloadManager
 import com.example.research.feature.download.model.DownloadState
+import com.example.research.feature.download.model.isActive
 import com.example.research.feature.download.repository.DictionaryRepository
 import com.example.research.feature.import.DictionaryImportManager
 import kotlinx.coroutines.Dispatchers
@@ -225,6 +226,9 @@ class SettingsViewModel(
                     importState = operationState.importState,
                     dictionaryStatus = operationState.dictionaryStatus,
                     hasCompletedStartupScan = operationState.hasCompletedStartupScan,
+                    pipelineIdle = !isIndexing &&
+                        !operationState.downloadState.isActive &&
+                        !operationState.importState.isActive,
                     isThemeExpanded = operationState.isThemeExpanded,
                     isLanguageExpanded = operationState.isLanguageExpanded,
                     isDictionariesExpanded = operationState.isDictionariesExpanded,