library: cover starred/downloaded shuffle in tests, dedupe list predicate

app/src/main/kotlin/com/subtracks/ui/components/ViewportFill.kt

@@ -101,8 +101,9 @@ fun ScrollToTopOnRequest(
 ) {
     var previous by remember { mutableStateOf(request) }
     LaunchedEffect(request) {
-        if (request != null && previous != null && request != previous) state.animateScrollToItem(0)
+        val stale = previous
         previous = request
+        if (request != null && stale != null && request != stale) state.animateScrollToItem(0)
     }
 }
 
@@ -113,7 +114,8 @@ fun ScrollToTopOnRequest(
 ) {
     var previous by remember { mutableStateOf(request) }
     LaunchedEffect(request) {
-        if (request != null && previous != null && request != previous) state.animateScrollToItem(0)
+        val stale = previous
         previous = request
+        if (request != null && stale != null && request != stale) state.animateScrollToItem(0)
     }
 }

app/src/main/kotlin/com/subtracks/ui/home/HomeListScreen.kt

@@ -148,10 +148,6 @@ fun HomeListScreen(
     val resources = LocalResources.current
     val scope = rememberCoroutineScope()
     val songListState = rememberLazyListState()
-    val isSongList =
-        request.downloaded == OfflineListKind.Songs ||
-            request.section == HomeSection.RecentlyStarredSongs ||
-            request.genre != null
     Scaffold(
         modifier = modifier,
         topBar = {
@@ -163,7 +159,7 @@ fun HomeListScreen(
                     }
                 },
                 modifier =
-                    if (isSongList) {
+                    if (onShuffle != null) {
                         Modifier.clickable(onClickLabel = stringResource(R.string.scroll_to_top)) {
                             scope.launch { songListState.animateScrollToItem(0) }
                         }

app/src/test/kotlin/com/subtracks/playback/PlaybackControllerTest.kt

@@ -2413,6 +2413,40 @@ class PlaybackControllerTest {
         assertEquals(setOf("r1", "r2"), handle.items.map { it.id }.toSet())
     }
 
+    @Test
+    fun shuffleStarredPlaysOnlyStarredSongs() {
+        seedStarred()
+
+        controller.shuffleStarred(1)
+        await { controller.state.value.item != null && controller.state.value.shuffle }
+
+        assertTrue(controller.state.value.shuffle)
+        assertEquals(
+            QueueKind.Starred,
+            controller.state.value.context
+                ?.kind,
+        )
+        assertEquals(setOf("t1", "t2"), handle.items.map { it.id }.toSet())
+    }
+
+    @Test
+    fun shuffleDownloadedPlaysOnlyDownloadedSongs() {
+        seedAlbum(3, sourceId = 1)
+        markDownloaded(1, "s1")
+        markDownloaded(1, "s3")
+
+        controller.shuffleDownloaded(1)
+        await { controller.state.value.item != null && controller.state.value.shuffle }
+
+        assertTrue(controller.state.value.shuffle)
+        assertEquals(
+            QueueKind.Downloaded,
+            controller.state.value.context
+                ?.kind,
+        )
+        assertEquals(setOf("s1", "s3"), handle.items.map { it.id }.toSet())
+    }
+
     @Test
     fun artistQueueRowsFollowTheFlatShuffleIdOrder() {
         seedArtist()
@@ -3142,6 +3176,19 @@ class PlaybackControllerTest {
         }
     }
 
+    private fun seedStarred() {
+        runBlocking {
+            db.sourcesDao().upsertSource(Source(1, "source 1", "http://localhost:1", true, 1))
+            db.libraryDao().upsertSongs(
+                listOf(
+                    Song(1, "t1", "al1", "ar1", "Star 1", "Album", "Artist", 100, 1, 1, 1_700_000_000L, null),
+                    Song(1, "t2", "al1", "ar1", "Star 2", "Album", "Artist", 100, 2, 1, 1_700_000_000L, null),
+                    Song(1, "n1", "al1", "ar1", "Plain 1", "Album", "Artist", 100, 3, 1, null, null),
+                ),
+            )
+        }
+    }
+
     private fun seedAlbumTracks(
         albumId: String,
         count: Int,