align the swipe peek with the skip and harden its edges

Resolve previousItem/upcomingItem through the same offline download scan the transport uses, so the peeking art is the track the swipe will actually play. Clear a frozen strip when a fallback swipe fires, prefer the dragged direction over an opposite fling, and simplify the hand-back and ratio prefetch.

app/src/main/kotlin/com/subtracks/playback/PlaybackController.kt

@@ -912,26 +912,39 @@ class PlaybackController(
     suspend fun upcomingItem(): QueueItem? {
         var current: QueueSnapshot? = null
         var position: Long? = null
+        var isOffline = false
         startLock.withLock {
             current = snapshot
             position = currentPosition()
+            isOffline = offline
         }
         val snapshot = current ?: return null
         val at = position ?: return null
-        return queueRepository.itemAt(snapshot, at + 1)?.toQueueItem()
+        if (!isOffline) return queueRepository.itemAt(snapshot, at + 1)?.toQueueItem()
+        downloads.awaitLoaded()
+        val target =
+            downloadedAtOrAfter(snapshot, at + 1)
+                ?: if (repeatMode != RepeatMode.Off) downloadedAtOrAfter(snapshot, 0L) else null
+        return target?.let { queueRepository.itemAt(snapshot, it)?.toQueueItem() }
     }
 
     suspend fun previousItem(): QueueItem? {
         var current: QueueSnapshot? = null
         var position: Long? = null
+        var isOffline = false
         startLock.withLock {
             current = snapshot
             position = currentPosition()
+            isOffline = offline
         }
         val snapshot = current ?: return null
         val at = position ?: return null
-        if (at <= 0) return null
-        return queueRepository.itemAt(snapshot, at - 1)?.toQueueItem()
+        if (!isOffline) return if (at <= 0) null else queueRepository.itemAt(snapshot, at - 1)?.toQueueItem()
+        downloads.awaitLoaded()
+        val target =
+            downloadedAtOrBefore(snapshot, at - 1)
+                ?: if (repeatMode == RepeatMode.All) downloadedAtOrBefore(snapshot, snapshot.size - 1) else null
+        return target?.let { queueRepository.itemAt(snapshot, it)?.toQueueItem() }
     }
 
     private fun play(

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

@@ -256,12 +256,13 @@ internal suspend fun prefetchArtworkRatio(
 ) {
     if (ArtworkRatioCache.get(ref.cacheKey) != null) return
     val request =
-        ImageRequest
-            .Builder(context)
-            .data(ref.url)
-            .diskCacheKey(ref.cacheKey)
-            .size(COVER_RATIO_PREFETCH_PX)
-            .build()
+        imageRequest(
+            context,
+            ref,
+            crossfade = false,
+            width = COVER_RATIO_PREFETCH_PX,
+            height = COVER_RATIO_PREFETCH_PX,
+        )
     val image =
         try {
             (SingletonImageLoader.get(context).execute(request) as? SuccessResult)?.image

app/src/main/kotlin/com/subtracks/ui/playback/NowPlayingScreen.kt

@@ -131,9 +131,15 @@ internal fun swipeAction(
 ): SwipeAction {
     if (width <= 0f) return SwipeAction.None
     val threshold = width * SWIPE_THRESHOLD_FRACTION
-    val wantsNext = offsetX <= -threshold || velocity <= -SWIPE_FLING_VELOCITY
-    val wantsPrevious = offsetX >= threshold || velocity >= SWIPE_FLING_VELOCITY
+    val pastNext = offsetX <= -threshold
+    val pastPrevious = offsetX >= threshold
+    val wantsNext = pastNext || velocity <= -SWIPE_FLING_VELOCITY
+    val wantsPrevious = pastPrevious || velocity >= SWIPE_FLING_VELOCITY
     return when {
+        pastNext && canGoNext -> SwipeAction.CommitNext
+        pastPrevious && canGoPrevious -> SwipeAction.CommitPrevious
+        pastNext -> SwipeAction.Next
+        pastPrevious -> SwipeAction.Previous
         wantsNext && canGoNext -> SwipeAction.CommitNext
         wantsPrevious && canGoPrevious -> SwipeAction.CommitPrevious
         wantsNext -> SwipeAction.Next
@@ -346,7 +352,7 @@ fun NowPlayingScreen(
             frozenStrip = null
         } else {
             delay(HAND_BACK_TIMEOUT_MS)
-            if (frozenStrip === pending) frozenStrip = null
+            frozenStrip = null
         }
     }
 
@@ -433,11 +439,13 @@ fun NowPlayingScreen(
                                                 }
 
                                                 SwipeAction.Next -> {
+                                                    frozenStrip = null
                                                     onNext()
                                                     animateSwipe(0f)
                                                 }
 
                                                 SwipeAction.Previous -> {
+                                                    frozenStrip = null
                                                     onSkipPrevious()
                                                     animateSwipe(0f)
                                                 }
@@ -545,17 +553,17 @@ fun NowPlayingScreen(
                                 )
                             }
                         }
-                        var dragging by remember { mutableStateOf(false) }
+                        var sliderDragging by remember { mutableStateOf(false) }
                         var dragPosition by remember { mutableFloatStateOf(0f) }
                         Slider(
-                            value = if (dragging) dragPosition else positionMs.toFloat(),
+                            value = if (sliderDragging) dragPosition else positionMs.toFloat(),
                             onValueChange = {
-                                dragging = true
+                                sliderDragging = true
                                 dragPosition = it
                             },
                             onValueChangeFinished = {
                                 onSeek(dragPosition.toLong())
-                                dragging = false
+                                sliderDragging = false
                             },
                             valueRange = 0f..state.durationMs.toFloat().coerceAtLeast(1f),
                             enabled = state.durationMs > 0,

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

@@ -230,6 +230,36 @@ class PlaybackControllerTest {
         }
     }
 
+    @Test
+    fun offlinePreviousItemMatchesTheTrackPreviousSkipsTo() {
+        seedAlbum(5, sourceId = 1)
+        markDownloaded(1, "s1")
+        markDownloaded(1, "s4")
+        setOffline()
+        controller.playAlbum(1, "al1", 3)
+        await {
+            controller.state.value.item
+                ?.id == "s4"
+        }
+
+        assertEquals("s1", runBlocking { controller.previousItem()?.id })
+    }
+
+    @Test
+    fun offlineUpcomingItemMatchesTheTrackNextPlays() {
+        seedAlbum(4, sourceId = 1)
+        markDownloaded(1, "s1")
+        markDownloaded(1, "s3")
+        setOffline()
+        controller.playAlbum(1, "al1", 0)
+        await {
+            controller.state.value.item
+                ?.id == "s1"
+        }
+
+        assertEquals("s3", runBlocking { controller.upcomingItem()?.id })
+    }
+
     @Test
     fun advancingShiftsTheWindowAndKeepsItBounded() {
         seedAlbum(100, sourceId = 1)

app/src/test/kotlin/com/subtracks/ui/playback/NowPlayingTapsTest.kt

@@ -231,6 +231,30 @@ class NowPlayingTapsTest {
         )
     }
 
+    @Test
+    fun theSwipeActionPrefersTheDraggedDirectionOverAnOppositeFling() {
+        assertEquals(
+            SwipeAction.CommitPrevious,
+            swipeAction(offsetX = 300f, velocity = -2_000f, width = 1_000f, canGoNext = true, canGoPrevious = true),
+        )
+        assertEquals(
+            SwipeAction.CommitNext,
+            swipeAction(offsetX = -300f, velocity = 2_000f, width = 1_000f, canGoNext = true, canGoPrevious = true),
+        )
+    }
+
+    @Test
+    fun swipingLeftWithANeighbourRotatesTheStrip() {
+        render(nextArt = adjacentArt("s-next"))
+
+        composeRule.onNodeWithTag(NOW_PLAYING_NEXT_TAG, useUnmergedTree = true).assertExists()
+        composeRule.onNodeWithTag(NOW_PLAYING_COVER_TAG).performTouchInput { swipeLeft() }
+        composeRule.waitForIdle()
+
+        composeRule.onNodeWithTag(NOW_PLAYING_NEXT_TAG, useUnmergedTree = true).assertDoesNotExist()
+        composeRule.onNodeWithTag(NOW_PLAYING_PREVIOUS_TAG, useUnmergedTree = true).assertExists()
+    }
+
     @Test
     fun rotatingTheStripMovesTheNeighbourIntoTheCentre() {
         val a = adjacentArt("a")