fix(alarms): word the alarm-set snackbar once per announcement

Every write re-read the engine and re-worded a standing announcement,
so tapping Mon-Fri while the snackbar showed restarted it on each tap,
as did a label keystroke across a minute. The words now come from the
first read; later writes can only take the snackbar down, when the
alarm stops ringing. The settled announcement still replaces it once.

Deleting no longer retracts by hand: a deleted alarm already reads as
nothing to say.

Refs #19

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

@@ -248,8 +248,6 @@ class AlarmEditorViewModel @Inject internal constructor(
             if (engine.ringSession()?.alarm?.id == alarmId) engine.dismiss(alarmId)
             alarms.delete(alarmId)
             engine.reschedule()
-            // "Set for 2 hours from now" must not outlive the alarm on the list.
-            announcer.retract(alarmId)
             _state.value = AlarmEditorUiState.Gone
         }
     }

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

@@ -99,14 +99,24 @@ internal class AlarmSetAnnouncer @Inject constructor(
             if (announcement == null || elapsed.elapsedRealtime() - announcement.at >= FRESH_FOR) {
                 flowOf(null)
             } else {
+                // Worded once, from the first read: later writes — the next
+                // repeat-day tap, a label keystroke across a minute — must not
+                // restart a snackbar already showing. They can only take it
+                // down, when the alarm stops ringing at all.
+                var worded: AlarmSetNotice? = null
                 engine.upcoming().map { upcoming ->
                     val entry = upcoming.firstOrNull { it.alarm.id == announcement.alarmId }
                     val countdown = AlarmSetCountdown.of(entry, wall.now())
-                    // Nothing to say is the answer for good: an announcement
-                    // left standing would speak up later, long after the
-                    // action, should something else switch the alarm back on.
-                    if (countdown == null) dropIfCurrent(announcement)
-                    countdown?.let { AlarmSetNotice(announcement.alarmId, it, announcement.sequence) }
+                    if (countdown == null) {
+                        // Nothing to say is the answer for good: left standing,
+                        // it would speak up long after the action, should
+                        // something else switch the alarm back on.
+                        clear(announcement.sequence)
+                        null
+                    } else {
+                        worded ?: AlarmSetNotice(announcement.alarmId, countdown, announcement.sequence)
+                            .also { worded = it }
+                    }
                 }
             }
         }
@@ -150,12 +160,10 @@ internal class AlarmSetAnnouncer @Inject constructor(
     }
 
     /** [notice] was shown until it timed out or was swiped away. */
-    fun consumed(notice: AlarmSetNotice) {
-        current.update { standing -> standing?.takeUnless { it.sequence == notice.sequence } }
-    }
+    fun consumed(notice: AlarmSetNotice) = clear(notice.sequence)
 
-    private fun dropIfCurrent(announcement: Announcement) {
-        current.update { standing -> standing?.takeUnless { it.sequence == announcement.sequence } }
+    private fun clear(sequence: Long) {
+        current.update { standing -> standing?.takeUnless { it.sequence == sequence } }
     }
 
     private companion object {

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

@@ -343,6 +343,31 @@ class AlarmEditorViewModelTest {
             }
         }
 
+    @Test
+    fun `day taps while a notice shows do not restart it before they settle`(@TempDir tempDir: Path) =
+        runTest(main.dispatcher) {
+            val harness = alarmEngineHarness(tempDir, now = fiveToday)
+            harness.givenAlarmWith(hour = 7)
+            val viewModel = editor(harness)
+            advanceUntilIdle()
+            viewModel.onTimePicked(9, 0)
+            advanceUntilIdle()
+
+            viewModel.alarmSetNotice.test {
+                assertThat(awaitItem()?.countdown).isEqualTo(NextFireLabel.InHoursMinutes(4, 0))
+                viewModel.onDayToggled(DayOfWeek.MONDAY)
+                advanceTimeBy(300)
+                viewModel.onDayToggled(DayOfWeek.TUESDAY)
+                advanceTimeBy(300)
+                expectNoEvents()
+                advanceUntilIdle()
+
+                // One more snackbar, once settled: Wednesday 05:00 to Monday 09:00.
+                assertThat(awaitItem()?.countdown).isEqualTo(NextFireLabel.InDaysHours(5, 4))
+                expectNoEvents()
+            }
+        }
+
     @Test
     fun `leaving while the days settle still announces them, for the list`(@TempDir tempDir: Path) =
         runTest(main.dispatcher) {