fix(alarms): keep a ringing card out of the swipe, and Undo off the ViewModel scope

A ringing alarm's card no longer swipes or offers Delete: it leads to
the ring screen, and a swipe must not get round the dismiss challenge.
A drag cancelled before release (a ring screen opening on top) never
deletes. Undo restores on the application scope, since a claimed Undo
has no second chance. Closing a cycle and deleting share one teardown.

app/src/main/java/de/jeanlucmakiola/clockula/alarm/AlarmEngine.kt

@@ -153,11 +153,7 @@ class AlarmEngine @Inject constructor(
     private suspend fun deleteLocked(alarmId: Long): DeletedAlarm? {
         val alarm = alarms.find(alarmId) ?: return null
         val state = states.state(alarmId)
-        if (state.ringingSince != null) {
-            ring.stopRinging(alarmId)
-            scheduler.cancelAutoSilence()
-        }
-        notifier.clearSnoozed(alarmId)
+        silenceLocked(alarmId, state)
         alarms.delete(alarmId)
         rescheduleLocked()
         return AlarmDeletion.snapshot(alarm, state)
@@ -406,11 +402,7 @@ class AlarmEngine @Inject constructor(
      * with its backstop intact.
      */
     private suspend fun closeCycleLocked(alarmId: Long, state: AlarmRingState) {
-        if (state.ringingSince != null) {
-            ring.stopRinging(alarmId)
-            scheduler.cancelAutoSilence()
-        }
-        notifier.clearSnoozed(alarmId)
+        silenceLocked(alarmId, state)
 
         val closed = state.copy(ringingSince = null, snoozedUntil = null, snoozeCount = 0)
         if (closed != state) states.save(closed)
@@ -419,4 +411,17 @@ class AlarmEngine @Inject constructor(
         if (alarm != null && !alarm.repeatDays.isRepeating) disableOrDeleteLocked(alarm)
         rescheduleLocked()
     }
+
+    /**
+     * Everything audible or visible an alarm's cycle holds: the ring service and
+     * its backstop if it is the one ringing, and its snooze notification. The
+     * one teardown, for closing a cycle and for deleting the alarm.
+     */
+    private fun silenceLocked(alarmId: Long, state: AlarmRingState) {
+        if (state.ringingSince != null) {
+            ring.stopRinging(alarmId)
+            scheduler.cancelAutoSilence()
+        }
+        notifier.clearSnoozed(alarmId)
+    }
 }

app/src/main/java/de/jeanlucmakiola/clockula/ui/alarms/AlarmRow.kt

@@ -48,7 +48,9 @@ import java.util.Locale
  *
  * Swiping it towards the end edge deletes it, and so does the card's "Delete"
  * custom action, which is the same verb for a screen reader or switch access,
- * where a swipe is not to be had. The list's snackbar offers the Undo.
+ * where a swipe is not to be had. The list's snackbar offers the Undo. Neither
+ * is offered while the alarm rings: the card leads to the ring screen then, and
+ * a swipe must not become a way round its dismiss challenge.
  */
 @Composable
 internal fun AlarmRow(
@@ -76,16 +78,19 @@ internal fun AlarmRow(
         onDelete = onDelete,
         shape = RoundedCornerShape(SwipeBackgroundCorner),
         modifier = modifier.padding(horizontal = GroupedListInset),
+        enabled = !row.ringing,
     ) {
         GroupedSurface(
             position = Position.Alone,
             modifier = Modifier.semantics {
-                customActions = listOf(
-                    CustomAccessibilityAction(deleteAction) {
-                        onDelete()
-                        true
-                    },
-                )
+                if (!row.ringing) {
+                    customActions = listOf(
+                        CustomAccessibilityAction(deleteAction) {
+                            onDelete()
+                            true
+                        },
+                    )
+                }
             },
             onClick = onClick,
             color = if (row.enabled) {

app/src/main/java/de/jeanlucmakiola/clockula/ui/alarms/AlarmsViewModel.kt

@@ -10,6 +10,8 @@ import de.jeanlucmakiola.clockula.domain.AlarmDraft
 import de.jeanlucmakiola.clockula.domain.alarm.DeletedAlarm
 import de.jeanlucmakiola.clockula.domain.time.WallClock
 import de.jeanlucmakiola.clockula.domain.time.ZoneProvider
+import de.jeanlucmakiola.floret.di.ApplicationScope
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.SharingStarted
@@ -30,6 +32,8 @@ class AlarmsViewModel @Inject internal constructor(
     private val zones: ZoneProvider,
     private val source: AlarmListSource,
     private val undo: AlarmUndo,
+    // `@param:` — see AlarmEditorViewModel.
+    @param:ApplicationScope private val appScope: CoroutineScope,
 ) : ViewModel() {
 
     val state: StateFlow<AlarmsUiState> = source.rows()
@@ -90,10 +94,14 @@ class AlarmsViewModel @Inject internal constructor(
         viewModelScope.launch { engine.delete(alarmId)?.let(undo::offer) }
     }
 
-    /** The snackbar's Undo. Claimed first, so a double tap restores once. */
+    /**
+     * The snackbar's Undo. Claimed first, so a double tap restores once, and
+     * restored on the application scope: once claimed there is no second
+     * chance, so a back press that clears this ViewModel must not drop it.
+     */
     fun onUndoDelete(deleted: DeletedAlarm) {
         if (!undo.take(deleted)) return
-        viewModelScope.launch { engine.restore(deleted) }
+        appScope.launch { engine.restore(deleted) }
     }
 
     /** The snackbar timed out or was swiped away: the delete stands. */

app/src/main/java/de/jeanlucmakiola/clockula/ui/common/SwipeToDelete.kt

@@ -61,6 +61,7 @@ internal fun SwipeToDelete(
     onDelete: () -> Unit,
     shape: Shape,
     modifier: Modifier = Modifier,
+    enabled: Boolean = true,
     content: @Composable () -> Unit,
 ) {
     val currentOnDelete by rememberUpdatedState(onDelete)
@@ -80,7 +81,8 @@ internal fun SwipeToDelete(
     Box(
         modifier = modifier
             .onSizeChanged { width = it.width }
-            .pointerInput(direction, flingVelocity) {
+            .pointerInput(direction, flingVelocity, enabled) {
+                if (!enabled) return@pointerInput
                 awaitEachGesture {
                     val down = awaitFirstDown(requireUnconsumed = false)
                     val velocity = VelocityTracker()
@@ -100,7 +102,7 @@ internal fun SwipeToDelete(
                     // launched, so the next delta can arrive before it lands.
                     var position = (travel.value + slopOvershoot).coerceIn(0f, width.toFloat())
                     var armed = position >= width * DeleteFraction
-                    horizontalDrag(start.id) { change ->
+                    val released = horizontalDrag(start.id) { change ->
                         velocity.addPointerInputChange(change)
                         position = (position + change.positionChange().x * direction)
                             .coerceIn(0f, width.toFloat())
@@ -118,6 +120,9 @@ internal fun SwipeToDelete(
                     // towards the start is kept however far it had gone.
                     val towardsEnd = velocity.calculateVelocity().x * direction
                     val delete = when {
+                        // Cancelled rather than let go (a ring screen opening
+                        // on top, the shade pulled): nothing was decided.
+                        !released -> false
                         towardsEnd >= flingVelocity -> position > 0f
                         towardsEnd <= -flingVelocity -> false
                         else -> armed

app/src/main/java/de/jeanlucmakiola/clockula/ui/timers/TimersViewModel.kt

@@ -9,6 +9,8 @@ import de.jeanlucmakiola.clockula.domain.Timer
 import de.jeanlucmakiola.clockula.domain.TimerDraft
 import de.jeanlucmakiola.clockula.domain.timer.TimerPresets
 import de.jeanlucmakiola.clockula.timer.TimerEngine
+import de.jeanlucmakiola.floret.di.ApplicationScope
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
@@ -31,6 +33,9 @@ class TimersViewModel @Inject internal constructor(
     private val engine: TimerEngine,
     private val settings: SettingsPrefs,
     source: TimerListSource,
+    // `@param:` — the qualifier has no explicit @Target, and K2 resolves a bare
+    // annotation on a constructor `val` to the property instead.
+    @param:ApplicationScope private val appScope: CoroutineScope,
 ) : ViewModel() {
 
     /** `WhileSubscribed(5_000)`, seeded [TimersUiState.Loading]. */
@@ -98,10 +103,14 @@ class TimersViewModel @Inject internal constructor(
         engine.delete(timerId)?.let { undoSlot.value = it }
     }
 
-    /** The snackbar's Undo. Claimed first, so a double tap restores once. */
+    /**
+     * The snackbar's Undo. Claimed first, so a double tap restores once, and
+     * restored on the application scope: once claimed there is no second
+     * chance, so a back press that clears this ViewModel must not drop it.
+     */
     fun onUndoDelete(timer: Timer) {
         if (!undoSlot.compareAndSet(timer, null)) return
-        launchOnEngine { engine.restore(timer) }
+        appScope.launch { engine.restore(timer) }
     }
 
     /** The snackbar timed out or was swiped away: the delete stands. */

app/src/test/java/de/jeanlucmakiola/clockula/ui/alarms/AlarmsViewModelTest.kt

@@ -53,6 +53,7 @@ class AlarmsViewModelTest {
         zones = harness.zones,
         source = AlarmListSource(harness.engine, harness.wallClock, harness.ticker),
         undo = undo,
+        appScope = this,
     ).also { viewModel -> backgroundScope.launch { viewModel.state.collect {} } }
 
     private fun AlarmsUiState.rows(): List<AlarmRowState> = (this as AlarmsUiState.Loaded).rows

app/src/test/java/de/jeanlucmakiola/clockula/ui/timers/TimersViewModelTest.kt

@@ -50,6 +50,7 @@ class TimersViewModelTest {
         engine = harness.engine,
         settings = harness.settings,
         source = TimerListSource(harness.timers, harness.elapsed, harness.wallClock, harness.ticker),
+        appScope = this,
     ).also { viewModel -> backgroundScope.launch { viewModel.state.collect {} } }
 
     private fun TimersUiState.loaded(): TimersUiState.Loaded = this as TimersUiState.Loaded

docs/ARCHITECTURE.md

@@ -1718,7 +1718,9 @@ be a lie; the user who wants that has the enable switch.
 An alarm is deleted by swiping its card towards the end edge, by the card's
 **Delete** custom accessibility action (the same verb for TalkBack and switch
 access, where there is no swipe), or from the editor's top bar. None of them
-asks first. Each is followed by a snackbar on the list ("07:00 alarm deleted",
+asks first. A *ringing* card offers neither the swipe nor the action: it leads
+to the ring screen, and a swipe must not become a way round its dismiss
+challenge. Each is followed by a snackbar on the list ("07:00 alarm deleted",
 **Undo**), as in Google Clock. v1 asked before instead, on the argument that a
 mistaken delete is found at 07:00 rather than now. But a dialog catches no more
 than the snackbar does: both only catch the slip noticed in the moment, and a