feat(android): download notifications everywhere + swipe tabs (NowPlaying, Library)

- Downloads started from global search / Bibliothek now poll via the
  app-lifetime NotificationStore, so they show success/failure like the
  importer and artist page did (was a silent toast only).
- Swipe between tabs, synced with the tab bar, matching Erkunden:
  * Now Playing: Player <-> Lyrics <-> Queue (cover's skip-track swipe
    still wins as a child gesture).
  * Bibliothek: Playlists <-> Alben <-> Künstler <-> Offline.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -76,6 +76,10 @@ like Android), concert events become **reliable across web/Android**, and severa
 - **30s preview in the importer (Android)** — each resolved track now has a ▶/⏹ button that plays its
   Deezer/Spotify preview clip through the same app-level preview bar as Explore (library playback
   pauses; the row highlights while playing). Parity with the web importer.
+- **Swipe between tabs (Android)** — a left/right swipe now switches tabs in **Now Playing**
+  (Player ↔ Lyrics ↔ Queue) and in the **Bibliothek** (Playlists ↔ Alben ↔ Künstler ↔ Offline),
+  two-way synced with the tab bar, matching the existing Erkunden swipe. On Now Playing the cover's
+  own swipe (skip track) still wins, since it's a child gesture.
 
 ### Fixed
 - **Concert events reliability (Web + Android)** — Ticketmaster's free `keyword` search intermittently
@@ -105,6 +109,10 @@ like Android), concert events become **reliable across web/Android**, and severa
   the library and Deezer artist pages.
 - **"Falscher Künstler?" pin button minimised (Web + Android)** — reduced to a small ⚙ icon-only pill
   in the artist hero's corner instead of a full-width labelled button.
+- **Downloads from search/Bibliothek were silent (Android)** — a download started from the global
+  search / Bibliothek-Global tab fired only a transient toast and then registered no
+  success/failure notification (only the importer and artist page did). It now goes through the same
+  app-lifetime `NotificationStore` poll, so it notifies on completion even after you leave the screen.
 
 ---
 

android/app/src/main/kotlin/com/novasonic/app/ui/screen/LibraryScreen.kt

@@ -10,6 +10,8 @@ import androidx.compose.foundation.lazy.grid.items
 import androidx.compose.foundation.lazy.grid.rememberLazyGridState
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.lazy.rememberLazyListState
+import androidx.compose.foundation.pager.HorizontalPager
+import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.border
@@ -79,16 +81,28 @@ fun LibraryScreen(
     var showCreateDialog by remember { mutableStateOf(false) }
     var groupToDelete by remember { mutableStateOf<DownloadGroupEntity?>(null) }
 
+    // Swipe left/right to switch library tabs, kept in sync with the TabRow (like Erkunden): a chip
+    // tap animates the pager; a settled swipe updates the selected tab. Indicator is driven off the
+    // pager's current page so it moves WITH the swipe.
+    val pagerState = rememberPagerState(initialPage = state.tab.ordinal) { LibraryTab.entries.size }
+    LaunchedEffect(state.tab) {
+        if (pagerState.currentPage != state.tab.ordinal) pagerState.animateScrollToPage(state.tab.ordinal)
+    }
+    LaunchedEffect(pagerState.settledPage) {
+        val t = LibraryTab.entries[pagerState.settledPage]
+        if (t != state.tab) vm.selectTab(t)
+    }
+
     Box(Modifier.fillMaxSize()) {
     Column(Modifier.fillMaxSize()) {
         TabRow(
-            selectedTabIndex = state.tab.ordinal,
+            selectedTabIndex = pagerState.currentPage,
             containerColor   = MaterialTheme.colorScheme.background,
             contentColor     = NsAccent,
         ) {
             LibraryTab.entries.forEach { tab ->
                 Tab(
-                    selected = state.tab == tab,
+                    selected = pagerState.currentPage == tab.ordinal,
                     onClick  = { vm.selectTab(tab) },
                     text = {
                         Text(
@@ -108,16 +122,15 @@ fun LibraryScreen(
             }
         }
 
+        HorizontalPager(state = pagerState, modifier = Modifier.fillMaxSize()) { page ->
+        val pageTab = LibraryTab.entries[page]
         // The Offline tab is fed by the local Room DB (offlineGroups) and must stay usable even while
         // the online library is still loading or unreachable — only gate the network-backed tabs.
-        if (state.isLoading && state.tab != LibraryTab.OFFLINE) {
+        if (state.isLoading && pageTab != LibraryTab.OFFLINE) {
             Box(Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
                 CircularProgressIndicator(color = NsAccent)
             }
-            return@Column
+        } else when (pageTab) {
-        }
-
-        when (state.tab) {
             LibraryTab.ALBUMS -> Column(Modifier.fillMaxSize()) {
                 // Sort chips
                 androidx.compose.foundation.lazy.LazyRow(
@@ -388,9 +401,10 @@ fun LibraryScreen(
                 }
             }
         }
+        } // end HorizontalPager
     } // end Column
 
-    if (state.tab == LibraryTab.PLAYLISTS) {
+    if (pagerState.currentPage == LibraryTab.PLAYLISTS.ordinal) {
         FloatingActionButton(
             onClick = { showCreateDialog = true },
             modifier = Modifier

android/app/src/main/kotlin/com/novasonic/app/ui/screen/NowPlayingScreen.kt

@@ -13,6 +13,8 @@ import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.lazy.rememberLazyListState
+import androidx.compose.foundation.pager.HorizontalPager
+import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -76,6 +78,18 @@ fun NowPlayingScreen(
     val song = state.currentSong
     var tab by remember { mutableStateOf(NpTab.PLAYER) }
 
+    // Swipe left/right between Player / Lyrics / Queue, kept in sync with the tab pills (like
+    // Erkunden). A horizontal drag that starts on the cover still skips tracks — that gesture is a
+    // child pointerInput and consumes the drag before the pager sees it.
+    val pagerState = rememberPagerState(initialPage = tab.ordinal) { NpTab.entries.size }
+    LaunchedEffect(tab) {
+        if (pagerState.currentPage != tab.ordinal) pagerState.animateScrollToPage(tab.ordinal)
+    }
+    LaunchedEffect(pagerState.settledPage) {
+        val t = NpTab.entries[pagerState.settledPage]
+        if (t != tab) tab = t
+    }
+
     // Preload lyrics as soon as NowPlaying opens — so the Lyrics tab shows instantly
     val lyricsVm: LyricsViewModel = viewModel()
     LaunchedEffect(song?.id) {
@@ -178,7 +192,7 @@ fun NowPlayingScreen(
                         .padding(3.dp),
                 ) {
                     NpTab.entries.forEach { t ->
-                        val sel = tab == t
+                        val sel = pagerState.currentPage == t.ordinal
                         Box(
                             contentAlignment = Alignment.Center,
                             modifier = Modifier
@@ -210,8 +224,18 @@ fun NowPlayingScreen(
                 }
             }
 
+            // ── Swipeable tab content (Player / Lyrics / Queue) ────────────
+            HorizontalPager(
+                state    = pagerState,
+                modifier = Modifier.weight(1f).fillMaxWidth(),
+            ) { page ->
+            Column(
+                horizontalAlignment = Alignment.CenterHorizontally,
+                modifier = Modifier.fillMaxSize(),
+            ) {
+            when (NpTab.entries[page]) {
             // ── PLAYER TAB ─────────────────────────────────────────────────
-            if (tab == NpTab.PLAYER) {
+            NpTab.PLAYER -> {
                 var dragX by remember { mutableStateOf(0f) }
 
                 Spacer(Modifier.height(28.dp))
@@ -401,7 +425,7 @@ fun NowPlayingScreen(
             }
 
             // ── LYRICS TAB ─────────────────────────────────────────────────
-            if (tab == NpTab.LYRICS && song != null) {
+            NpTab.LYRICS -> if (song != null) {
                 val lyricsState by lyricsVm.state.collectAsStateWithLifecycle()
                 val lyricsListState = rememberLazyListState()
                 val density = LocalDensity.current
@@ -495,7 +519,7 @@ fun NowPlayingScreen(
             }
 
             // ── QUEUE TAB ──────────────────────────────────────────────────
-            if (tab == NpTab.QUEUE) {
+            NpTab.QUEUE -> {
                 // Radio mode toggle
                 if (onToggleRadio != null) {
                     Row(
@@ -593,6 +617,9 @@ fun NowPlayingScreen(
                     }
                 }
             }
+            } // end when
+            } // end inner Column
+            } // end HorizontalPager
         }
     }
 }

android/app/src/main/kotlin/com/novasonic/app/viewmodel/ExploreViewModel.kt

@@ -12,6 +12,7 @@ import com.novasonic.app.api.model.ItunesRssEntry
 import com.novasonic.app.api.model.Song
 import com.novasonic.app.api.model.artworkHd
 import com.novasonic.app.app
+import com.novasonic.app.data.NotificationStore
 import kotlinx.coroutines.*
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -315,7 +316,15 @@ class ExploreViewModel(app: Application) : AndroidViewModel(app) {
             }
             val client = ImporterClient(backendUrl)
             runCatching { client.download(request) }
-                .onSuccess { onDone(true, "✓ Download gestartet") }
+                .onSuccess {
+                    // App-lifetime poll → success/failure notification even after leaving the screen
+                    // (previously only the artist page + importer notified; search/Bibliothek was silent).
+                    NotificationStore.startPoll(
+                        backendUrl, request.jobId, request.title, request.artist ?: "",
+                        navType = type, navAlbum = item.collectionName ?: "", navArtist = item.artistName ?: "",
+                    )
+                    onDone(true, "✓ Download gestartet")
+                }
                 .onFailure { onDone(false, "Backend nicht erreichbar: ${it.message}") }
             client.close()
         }