android/architecture-samples

val remoteTasks = networkDataSource.loadTasks()
localDataSource.deleteAll()
localDataSource.upsertAll(remoteTasks.toLocal())

Every local write pushes the whole table to the network in a background job that returns immediately. refresh() then replaces the local table with whatever the network holds. clearCompletedTasks() calls refresh() straight after the local delete (TasksViewModel.kt:108-110), and a pull-to-refresh right after an edit has the same race. If the read reaches the network before the push, cleared tasks come back, and new or edited tasks revert or disappear.

Do not replace local rows that have unsynced changes. Track a pending-sync flag or version per task and merge by row, or wait for any outstanding push to finish before pulling. Do not refresh immediately after a local mutation.

Scaffold(
    modifier = modifier.fillMaxSize(),

The activity calls enableEdgeToEdge() (TodoActivity.kt:33), so the manifest's adjustResize no longer shrinks the window. Nothing in app/src/main applies IME insets (searched for imePadding and WindowInsets: none found). With the keyboard open, the lower part of the 350dp description field and the save button sit under the keyboard. Users have to dismiss the keyboard to reach the save button.

Add Modifier.imePadding() to the form column, or include IME insets in the Scaffold's content insets.

# Some methods are only called from tests, so make sure the shrinker keeps them.
-keep class com.example.android.architecture.blueprints.** { *; }

The release build type enables minification with this file. The blanket keep rule, added only so tests can reach some methods, turns off shrinking and obfuscation for the whole app in production. -ignorewarnings (line 19) hides real missing-class problems, and the Espresso keep rules ship in the release APK. The result is a larger, easier-to-reverse-engineer release, and build warnings that could flag broken code are silenced.

Move the test-only keep rules to proguardTest-rules.pro, or to a debug-only rules file. Keep only what release actually needs (Room and Hilt entry points) and remove -ignorewarnings.

implementation(libs.androidx.test.espresso.idling.resources)

The Espresso idling-resource library is on the production classpath. The helper util/SimpleCountingIdlingResource.kt lives in the main source set although no production code uses it.

Move the helper to a debug or test source set (or :shared-test). Change the dependency to debugImplementation or androidTestImplementation.

// TODO: Show error message?
StatisticsUiState(isEmpty = true, isLoading = false)

When loading fails, the screen shows the empty state with no explanation. The user cannot tell a failure from having no tasks.

Add a userMessage to StatisticsUiState, as the other screens have, and show the existing "error while loading tasks" string in a snackbar.

} catch (e: Exception) {
    // In a real app you'd handle the exception e.g. by exposing a `networkStatus` flow

If the backup to the network fails, the user is never told their data is not backed up, and a later refresh can replace the unsaved local data (see finding 14). Catching Exception also swallows coroutine cancellation.

Rethrow CancellationException. Expose a sync-status or error state that the UI can show, and retry, for example with WorkManager.

focusedBorderColor = Color.Transparent,
unfocusedBorderColor = Color.Transparent,
cursorColor = MaterialTheme.colorScheme.onSecondary

The app theme does not override onSecondary, so it stays white in the light colour scheme, and the caret is drawn white on a near-white surface. Both fields also have transparent borders in every state. Users get no sign of where to tap or where they are typing.

Use a contrasting cursor colour such as colorScheme.primary. Give the fields a visible focused border or a filled container.

<color name="colorPrimary">#FFFFF0</color>

Several colour and drawable tokens, and the drawables built on them, are no longer referenced by any code. attrs.xml still declares an unused styleable. colorPrimary here also contradicts the Compose primary colour. This makes it unclear which colour source is authoritative.

Delete the unused resources and keep one source of colour tokens.

Icon(Icons.Filled.ArrowBack, stringResource(id = R.string.menu_back))

The app declares RTL support, and the add/edit bar uses the auto-mirrored icon. The detail bar uses the deprecated non-mirrored one, so its arrow points the wrong way in RTL languages.

Use Icons.AutoMirrored.Filled.ArrowBack in both places.

items(tasks) { task ->

After a refresh, a filter change or a completion toggle, item identity and scroll position follow the list index rather than the task, so the view can jump or animate the wrong row.

Use items(tasks, key = { it.id }).

SwipeRefresh(

The shared loading container uses the deprecated Accompanist SwipeRefresh, while the add/edit screen uses Material 3 PullToRefreshBox. In the add/edit screen, isRefreshing is never set to true, onRefresh does nothing and the content is empty, so the loading state is a blank screen. An Accompanist theme dependency is also carried that no code uses.

Move to Material 3 PullToRefreshBox throughout. Show a progress indicator while the edit form loads, and drop the unused Accompanist dependencies.

private fun saveTasksToNetwork() {
    scope.launch {
        val localTasks = localDataSource.getAll()

Each mutation launches an independent job that reads a snapshot and then waits for the network. With quick successive edits, the jobs can reach the network in a different order from the one in which they took their snapshots. The last write then carries stale data, and the next refresh brings the stale data back into the app.

Keep a single sync job. If one is in flight, mark it dirty and run it once more when it finishes, or use a conflated channel or WorkManager unique work, so the final push always carries the latest snapshot.

private fun createNewTask() = viewModelScope.launch {
    taskRepository.createTask(uiState.value.title, uiState.value.description)

The save button (AddEditTaskScreen.kt:74) stays active while a save runs, and each call generates a new random id. A second tap before navigation completes creates a second, identical task.

Ignore saveTask() while a save is in progress (an isSaving flag or a held job), or generate the id once per screen so repeated calls update the same row.

localDataSource.deleteAll()
localDataSource.upsertAll(remoteTasks.toLocal())

The two statements run as separate database operations. List observers can briefly receive an empty table, so the "no tasks" state flickers. If the process dies or the insert fails between the two calls, every local task is gone, including any not yet pushed.

Do both in one Room transaction (a @Transaction DAO method such as replaceAll, or withTransaction {}), or upsert the remote rows and delete only the rows missing from the remote list.

) ?: throw Exception("Task (id $taskId) not found")

When the task is missing, AddEditTaskViewModel.loadTask silently shows an empty form (lines 140-143). The task can vanish this way after a refresh (finding 14). If the user fills the form and taps save, updateTask throws inside viewModelScope.launch with no handler, and the app crashes.

When the task is null, show a "task not found" message and close the screen. Catch the failure in the ViewModel, or have updateTask return a result instead of throwing.

fun observeById(taskId: String): Flow<LocalTask>

The repository exposes Flow<Task?> and the detail ViewModel has a dedicated "task not found" branch. Because the DAO promises a non-null row, a missing or just-deleted task fails inside the stream instead of emitting null. The user sees the generic "error while loading" message and the stream stops. The in-memory test fakes emit null, so the tests hide the difference.

Declare Flow<LocalTask?>, map with it?.toExternal(), and add a test that deletes the observed task.

modifier = modifier.padding(paddingValues)

The padded modifier goes to the refresh container (line 85) and is also the base of commonModifier (line 77), which the inner column uses. The top-bar and system-bar insets are therefore added twice, and the statistics text sits visibly lower than on the other screens. The screen's own modifier parameter is also reused on both the Scaffold and the content.

Pass Modifier.padding(paddingValues) to the content. Apply the insets once on the outer container, and build the inner modifier from a fresh Modifier.

android.enableJetifier=true

Jetifier rewrites every dependency at build time. On an AndroidX-only project it only adds build time.

Set android.enableJetifier=false and confirm the build still passes.

val primaryDarkColor: Color = Color(0xFF263238)

The same value is declared in TodoTheme, here, and in colors.xml. The drawer header paints this constant but takes its text colour from the theme, so any theme change (such as a future dark scheme) breaks the pairing.

Use MaterialTheme.colorScheme.primary and onPrimary in the drawer header, and delete the constant.

private fun TasksContentPreview() {
    MaterialTheme {
        Surface {

The previews show a different colour scheme from the one the app renders, so visual reviews are misleading.

Wrap every preview in TodoTheme.

androidxCompose = "1.2.0"

The entry is unused, but it suggests a Compose version far older than the APIs the code relies on. That misleads readers and tooling.

Remove it so the Compose BOM is the only version source.

fun LocalTask.toNetwork() = NetworkTask(
    id = id,
    title = title,

NetworkTask has a priority field that the local and external models do not store. Each push would write it back as null. Nothing in this codebase sets a priority today, but it would be silently erased once a real backend supplies one.

Carry priority through the local model (with a Room migration), or remove it from the network model until it is supported.

localDataSource.updateCompleted(taskId = taskId, completed = true)
saveTasksToNetwork()

Seven methods repeat the same pair of calls. Every current path does call the push, but a future write method that forgets it would silently leave the network copy out of date.

Route all mutations through one private helper that performs the local write and schedules the sync.

val isEmpty
    get() = title.isEmpty() || description.isEmpty()

Only the add/edit ViewModel checks this. Repository create and update calls, and data imported from the network, can write rows that break it.

Validate in createTask and updateTask, and filter or normalise imported rows.

_isLoading.value = true
viewModelScope.launch {
    taskRepository.refresh()

A pull-to-refresh and a menu refresh can run at the same time. The first to finish clears the loading flag while the other is still running. The same pattern appears in the detail and statistics ViewModels.

Keep a refreshJob and return early while it is active.

// TODO: Show error message?

Unresolved questions, such as error display on statistics and the sync-failure strategy in the repository, are not recorded anywhere a maintainer would look. The only documents in the repository are README.md and CONTRIBUTING.md (searched **/*.md).

Keep a short "open decisions" section in a design document and link the TODOs to it.

For more information, see the [app's specification](https://github.com/googlesamples/android-architecture/wiki/To-do-app-specification).

The repository itself contains no worked example of the main flow (create, complete, filter, clear, refresh). The external link can drift from the code.

Add a short written walk-through of the main flow to the repository docs.

private fun filterTasks(tasks: List<Task>, filteringType: TasksFilterType): List<Task> {

filterTasks and getFilterUiInfo hold no state but can only be tested through the ViewModel. The statistics feature already keeps its pure logic in a separate utility file.

Move both to top-level functions next to TasksFilterType and unit-test them directly.

private val _userMessage: MutableStateFlow<Int?> = MutableStateFlow(null)

The same message state, the show/clear functions and the LaunchedEffect snackbar block are repeated in the tasks, task-detail and add/edit ViewModel/screen pairs (TaskDetailScreen.kt:84, TasksScreen.kt:112, AddEditTaskScreen.kt:98). Fixes such as message de-duplication have to be made three times.

Extract one small message holder and one SnackbarMessageEffect composable into util/, and use them in all three places.