Announce multi-account support

Show a one-time bottom sheet on the home screen to announce that several
accounts can now be added (element-hq/element-meta#3349).

- Add `Announcement.MultiAccount`, which is never shown by default.
- AppMigration11 queues the announcement on application upgrade only,
  and marks it as shown if the user already has several accounts.
- HomePresenter shows the bottom sheet only when the announcement is
  pending, the MultiAccount feature flag is enabled and the user has a
  single account.
- The "Add account" button hides the sheet, marks the announcement as
  dismissed and starts the add account flow through the new
  `HomeEntryPoint.Callback.navigateToAddAccount()`.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

features/announcement/impl/src/main/kotlin/io/element/android/features/announcement/impl/DefaultAnnouncementService.kt

@@ -29,10 +29,11 @@ class DefaultAnnouncementService(
 ) : AnnouncementService {
     override suspend fun showAnnouncement(announcement: Announcement) {
         when (announcement) {
-            is Announcement.Fullscreen -> showFullscreenAnnouncement(announcement)
+            is Announcement.Fullscreen -> showAnnouncementIfNeverShown(announcement)
             Announcement.NewNotificationSound -> {
                 announcementStore.setAnnouncementStatus(Announcement.NewNotificationSound, AnnouncementStatus.Show)
             }
+            Announcement.MultiAccount -> showAnnouncementIfNeverShown(announcement)
         }
     }
 
@@ -44,16 +45,20 @@ class DefaultAnnouncementService(
         return combine(
             flowOf(Unit),
             announcementStore.announcementStatusFlow(Announcement.NewNotificationSound),
-        ) { _, newNotificationSoundStatus ->
+            announcementStore.announcementStatusFlow(Announcement.MultiAccount),
+        ) { _, newNotificationSoundStatus, multiAccountStatus ->
             buildList {
                 if (newNotificationSoundStatus == AnnouncementStatus.Show) {
                     add(Announcement.NewNotificationSound)
                 }
+                if (multiAccountStatus == AnnouncementStatus.Show) {
+                    add(Announcement.MultiAccount)
+                }
             }
         }
     }
 
-    private suspend fun showFullscreenAnnouncement(announcement: Announcement.Fullscreen) {
+    private suspend fun showAnnouncementIfNeverShown(announcement: Announcement) {
         val currentValue = announcementStore.announcementStatusFlow(announcement).first()
         if (currentValue == AnnouncementStatus.NeverShown) {
             announcementStore.setAnnouncementStatus(announcement, AnnouncementStatus.Show)

features/announcement/impl/src/main/kotlin/io/element/android/features/announcement/impl/store/DefaultAnnouncementStore.kt

@@ -19,6 +19,7 @@ import kotlinx.coroutines.flow.map
 
 private val spaceAnnouncementKey = intPreferencesKey("spaceAnnouncement")
 private val newNotificationSoundKey = intPreferencesKey("newNotificationSound")
+private val multiAccountKey = intPreferencesKey("multiAccountAnnouncement")
 
 @ContributesBinding(AppScope::class)
 class DefaultAnnouncementStore(
@@ -36,11 +37,14 @@ class DefaultAnnouncementStore(
     override fun announcementStatusFlow(announcement: Announcement): Flow<AnnouncementStatus> {
         val key = announcement.toKey()
         // Default-status convention: Shown for one-shot intro/feature announcements that should
-        // NOT replay on first launch (Fullscreen.Space is disabled; NewNotificationSound is opted
-        // in by AppMigration08).
+        // NOT replay on first launch.
+        // - Fullscreen.Space is disabled
+        // - NewNotificationSound is opted in by AppMigration08
+        // - MultiAccount is opted in by AppMigration11
         val defaultStatus = when (announcement) {
             Announcement.Fullscreen.Space -> AnnouncementStatus.Shown
             Announcement.NewNotificationSound -> AnnouncementStatus.Shown
+            Announcement.MultiAccount -> AnnouncementStatus.Shown
         }
         return store.data.map { prefs ->
             val ordinal = prefs[key] ?: defaultStatus.ordinal
@@ -56,4 +60,5 @@ class DefaultAnnouncementStore(
 private fun Announcement.toKey() = when (this) {
     Announcement.Fullscreen.Space -> spaceAnnouncementKey
     Announcement.NewNotificationSound -> newNotificationSoundKey
+    Announcement.MultiAccount -> multiAccountKey
 }

features/announcement/impl/src/test/kotlin/io/element/android/features/announcement/impl/DefaultAnnouncementServiceTest.kt

@@ -51,6 +51,22 @@ class DefaultAnnouncementServiceTest {
         assertThat(announcementStore.announcementStatusFlow(Announcement.NewNotificationSound).first()).isEqualTo(AnnouncementStatus.Show)
     }
 
+    @Test
+    fun `when showing MultiAccount announcement, announcement is set to show only if it was never shown`() = runTest {
+        val announcementStore = InMemoryAnnouncementStore()
+        val sut = createDefaultAnnouncementService(
+            announcementStore = announcementStore,
+        )
+        assertThat(announcementStore.announcementStatusFlow(Announcement.MultiAccount).first()).isEqualTo(AnnouncementStatus.NeverShown)
+        sut.showAnnouncement(Announcement.MultiAccount)
+        assertThat(announcementStore.announcementStatusFlow(Announcement.MultiAccount).first()).isEqualTo(AnnouncementStatus.Show)
+        // Simulate user close the announcement
+        sut.onAnnouncementDismissed(Announcement.MultiAccount)
+        // Calling again showAnnouncement should not change the value
+        sut.showAnnouncement(Announcement.MultiAccount)
+        assertThat(announcementStore.announcementStatusFlow(Announcement.MultiAccount).first()).isEqualTo(AnnouncementStatus.Shown)
+    }
+
     @Test
     fun `test announcementsToShowFlow`() = runTest {
         val announcementStore = InMemoryAnnouncementStore()
@@ -61,7 +77,11 @@ class DefaultAnnouncementServiceTest {
             assertThat(awaitItem()).isEmpty()
             announcementStore.setAnnouncementStatus(Announcement.NewNotificationSound, AnnouncementStatus.Show)
             assertThat(awaitItem()).containsExactly(Announcement.NewNotificationSound)
+            announcementStore.setAnnouncementStatus(Announcement.MultiAccount, AnnouncementStatus.Show)
+            assertThat(awaitItem()).containsExactly(Announcement.NewNotificationSound, Announcement.MultiAccount)
             announcementStore.setAnnouncementStatus(Announcement.NewNotificationSound, AnnouncementStatus.Shown)
+            assertThat(awaitItem()).containsExactly(Announcement.MultiAccount)
+            announcementStore.setAnnouncementStatus(Announcement.MultiAccount, AnnouncementStatus.Shown)
             assertThat(awaitItem()).isEmpty()
         }
     }

features/announcement/impl/src/test/kotlin/io/element/android/features/announcement/impl/store/InMemoryAnnouncementStore.kt

@@ -16,9 +16,11 @@ import kotlinx.coroutines.flow.asStateFlow
 class InMemoryAnnouncementStore(
     initialFullscreenAnnouncementStatus: AnnouncementStatus = AnnouncementStatus.NeverShown,
     initialNewNotificationSoundAnnouncementStatus: AnnouncementStatus = AnnouncementStatus.NeverShown,
+    initialMultiAccountAnnouncementStatus: AnnouncementStatus = AnnouncementStatus.NeverShown,
 ) : AnnouncementStore {
     private val fullScreenAnnouncement = MutableStateFlow(initialFullscreenAnnouncementStatus)
     private val newNotificationSoundAnnouncement = MutableStateFlow(initialNewNotificationSoundAnnouncementStatus)
+    private val multiAccountAnnouncement = MutableStateFlow(initialMultiAccountAnnouncementStatus)
 
     override suspend fun setAnnouncementStatus(announcement: Announcement, status: AnnouncementStatus) {
         announcement.toMutableStateFlow().value = status
@@ -31,10 +33,12 @@ class InMemoryAnnouncementStore(
     override suspend fun reset() {
         fullScreenAnnouncement.value = AnnouncementStatus.NeverShown
         newNotificationSoundAnnouncement.value = AnnouncementStatus.NeverShown
+        multiAccountAnnouncement.value = AnnouncementStatus.NeverShown
     }
 
     private fun Announcement.toMutableStateFlow() = when (this) {
         is Announcement.Fullscreen -> fullScreenAnnouncement
         Announcement.NewNotificationSound -> newNotificationSoundAnnouncement
+        Announcement.MultiAccount -> multiAccountAnnouncement
     }
 }