Fix NSFW sheet scroll on iOS/iPad, clean up audio pin

- WerkoutNSFWSheet: wrap content in ScrollView + ViewThatFits(in: .horizontal)
  so iPad's narrow sheet width falls back to VStack and content scrolls.
- Tighten padding on compact layouts (38→24).
- Revert AAC-preference in pinAudioSelection (stream is all AAC, no Dolby).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mlbTVOS/Views/DashboardView.swift

@@ -623,22 +623,24 @@ struct WerkoutNSFWSheet: View {
             sheetBackground
                 .ignoresSafeArea()
 
-            ViewThatFits {
-                HStack(alignment: .top, spacing: 32) {
-                    overviewColumn
-                        .frame(maxWidth: .infinity, alignment: .leading)
+            ScrollView(.vertical, showsIndicators: false) {
+                ViewThatFits(in: .horizontal) {
+                    HStack(alignment: .top, spacing: 32) {
+                        overviewColumn
+                            .frame(maxWidth: .infinity, alignment: .leading)
 
-                    actionColumn
-                        .frame(width: 360, alignment: .leading)
-                }
+                        actionColumn
+                            .frame(width: 360, alignment: .leading)
+                    }
 
-                VStack(alignment: .leading, spacing: 24) {
-                    overviewColumn
-                    actionColumn
-                        .frame(maxWidth: .infinity, alignment: .leading)
+                    VStack(alignment: .leading, spacing: 24) {
+                        overviewColumn
+                        actionColumn
+                            .frame(maxWidth: .infinity, alignment: .leading)
+                    }
                 }
             }
-            .padding(38)
+            .padding(usesStackedLayout ? 24 : 38)
             .background(
                 RoundedRectangle(cornerRadius: 34, style: .continuous)
                     .fill(.black.opacity(0.46))

mlbTVOS/Views/MultiStreamView.swift

@@ -352,11 +352,11 @@ private struct MultiStreamTile: View {
     @State private var player: AVPlayer?
     @State private var hasError = false
     @State private var startupPlaybackTask: Task<Void, Never>?
-    @State private var qualityUpgradeTask: Task<Void, Never>?
     @State private var werkoutMonitorTask: Task<Void, Never>?
     @State private var clipTimeLimitObserver: Any?
     @State private var isAdvancingClip = false
     @StateObject private var playbackDiagnostics = MultiStreamPlaybackDiagnostics()
+    @State private var audioDiagnostics: AudioDiagnostics?
 
     private static let maxClipDuration: Double = 15.0
     private static var audioSessionConfigured = false
@@ -446,8 +446,6 @@ private struct MultiStreamTile: View {
             logMultiView("tile disappeared id=\(stream.id) label=\(stream.label)")
             startupPlaybackTask?.cancel()
             startupPlaybackTask = nil
-            qualityUpgradeTask?.cancel()
-            qualityUpgradeTask = nil
             werkoutMonitorTask?.cancel()
             werkoutMonitorTask = nil
             if let player {
@@ -456,6 +454,8 @@ private struct MultiStreamTile: View {
             }
             player = nil
             playbackDiagnostics.clear(streamID: stream.id, reason: "tile disappeared")
+            audioDiagnostics?.detach()
+            audioDiagnostics = nil
         }
         #if os(tvOS)
         .focusEffectDisabled()
@@ -536,11 +536,8 @@ private struct MultiStreamTile: View {
             .clipShape(Capsule())
     }
 
-    private var multiViewStartupResolution: String { "504p" }
-
-    private var multiViewUpgradeTargetResolution: String? {
-        let desiredResolution = viewModel.defaultResolution
-        return desiredResolution == multiViewStartupResolution ? nil : desiredResolution
+    private var multiViewStartupResolution: String {
+        viewModel.defaultResolution
     }
 
     private func startStream() async {
@@ -556,18 +553,18 @@ private struct MultiStreamTile: View {
                 onPlaybackEnded: playbackEndedHandler(for: player)
             )
             scheduleStartupPlaybackRecovery(for: player)
-            scheduleQualityUpgrade(for: player)
             installClipTimeLimit(on: player)
+            attachAudioDiagnostics(to: player)
             logMultiView("startStream reused inline player id=\(stream.id) muted=\(player.isMuted)")
             return
         }
 
         if !Self.audioSessionConfigured {
             do {
-                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .moviePlayback)
+                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                 try AVAudioSession.sharedInstance().setActive(true)
                 Self.audioSessionConfigured = true
-                logMultiView("startStream audio session configured id=\(stream.id)")
+                logMultiView("startStream audio session configured id=\(stream.id) mode=default")
             } catch {
                 logMultiView("startStream audio session failed id=\(stream.id) error=\(error.localizedDescription)")
             }
@@ -583,8 +580,8 @@ private struct MultiStreamTile: View {
                 onPlaybackEnded: playbackEndedHandler(for: existingPlayer)
             )
             scheduleStartupPlaybackRecovery(for: existingPlayer)
-            scheduleQualityUpgrade(for: existingPlayer)
             installClipTimeLimit(on: existingPlayer)
+            attachAudioDiagnostics(to: existingPlayer)
             logMultiView("startStream reused shared player id=\(stream.id) muted=\(existingPlayer.isMuted)")
             return
         }
@@ -620,7 +617,7 @@ private struct MultiStreamTile: View {
             onPlaybackEnded: playbackEndedHandler(for: avPlayer)
         )
         scheduleStartupPlaybackRecovery(for: avPlayer)
-        scheduleQualityUpgrade(for: avPlayer)
+        attachAudioDiagnostics(to: avPlayer)
         logMultiView("startStream attached player id=\(stream.id) muted=\(avPlayer.isMuted) startupResolution=\(multiViewStartupResolution) fastStart=true calling playImmediately(atRate: 1.0)")
         avPlayer.playImmediately(atRate: 1.0)
         installClipTimeLimit(on: avPlayer)
@@ -633,19 +630,35 @@ private struct MultiStreamTile: View {
         )
 
         let item = makePlayerItem(url: url, headers: headers)
-        return AVPlayer(playerItem: item)
+        let player = AVPlayer(playerItem: item)
+        player.appliesMediaSelectionCriteriaAutomatically = false
+        logMultiView("startStream configured AVPlayer id=\(stream.id) appliesMediaSelectionCriteriaAutomatically=false")
+        return player
     }
 
     private func makePlayerItem(url: URL, headers: [String: String]) -> AVPlayerItem {
+        let item: AVPlayerItem
         if headers.isEmpty {
-            return AVPlayerItem(url: url)
+            item = AVPlayerItem(url: url)
+        } else {
+            let assetOptions: [String: Any] = [
+                "AVURLAssetHTTPHeaderFieldsKey": headers,
+            ]
+            let asset = AVURLAsset(url: url, options: assetOptions)
+            item = AVPlayerItem(asset: asset)
         }
+        item.allowedAudioSpatializationFormats = []
+        logMultiView("startStream configured player item id=\(stream.id) allowedAudioSpatializationFormats=[]")
+        pinAudioSelection(on: item)
+        return item
+    }
 
-        let assetOptions: [String: Any] = [
-            "AVURLAssetHTTPHeaderFieldsKey": headers,
-        ]
-        let asset = AVURLAsset(url: url, options: assetOptions)
-        return AVPlayerItem(asset: asset)
+    /// Pin the HLS audio rendition so ABR can't swap channel layouts mid-stream.
+    private func pinAudioSelection(on item: AVPlayerItem) {
+        let streamID = stream.id
+        Task { @MainActor in
+            await enforcePinnedMultiStreamAudioSelection(on: item, streamID: streamID)
+        }
     }
 
     private func scheduleStartupPlaybackRecovery(for player: AVPlayer) {
@@ -686,79 +699,17 @@ private struct MultiStreamTile: View {
         }
     }
 
-    private func scheduleQualityUpgrade(for player: AVPlayer) {
-        qualityUpgradeTask?.cancel()
-
-        guard stream.overrideURL == nil else {
-            logMultiView("qualityUpgrade skip id=\(stream.id) reason=override-url")
-            return
-        }
-
-        guard let targetResolution = multiViewUpgradeTargetResolution else {
-            logMultiView("qualityUpgrade skip id=\(stream.id) reason=target-already-\(multiViewStartupResolution)")
-            return
-        }
-
-        let streamID = stream.id
-        let label = stream.label
-        qualityUpgradeTask = Task { @MainActor in
-            let checkDelays: [Double] = [2.0, 4.0, 7.0, 15.0, 30.0]
-
-            for delay in checkDelays {
-                try? await Task.sleep(for: .seconds(delay))
-                guard !Task.isCancelled else { return }
-                guard let currentPlayer = self.player, currentPlayer === player else {
-                    logMultiView("qualityUpgrade abort id=\(streamID) label=\(label) reason=player-changed")
-                    return
-                }
-
-                let itemStatus = multiViewItemStatusDescription(player.currentItem?.status ?? .unknown)
-                let likelyToKeepUp = player.currentItem?.isPlaybackLikelyToKeepUp ?? false
-                let bufferEmpty = player.currentItem?.isPlaybackBufferEmpty ?? false
-                let indicatedBitrate = player.currentItem?.accessLog()?.events.last?.indicatedBitrate ?? 0
-                let stable = (itemStatus == "readyToPlay" || likelyToKeepUp) && !bufferEmpty
-
-                logMultiView(
-                    "qualityUpgrade check id=\(streamID) delay=\(delay)s targetResolution=\(targetResolution) stable=\(stable) rate=\(player.rate) indicatedBitrate=\(Int(indicatedBitrate))"
-                )
-
-                guard stable else { continue }
-
-                guard let upgradedURL = await viewModel.resolveStreamURL(
-                    for: stream,
-                    resolutionOverride: targetResolution,
-                    preserveServerResolutionWhenBest: false
-                ) else {
-                    logMultiView("qualityUpgrade failed id=\(streamID) targetResolution=\(targetResolution) reason=resolve-nil")
-                    return
-                }
-
-                if let currentURL = currentStreamURL(for: player), currentURL == upgradedURL {
-                    logMultiView("qualityUpgrade skip id=\(streamID) reason=same-url targetResolution=\(targetResolution)")
-                    return
-                }
-
-                logMultiView("qualityUpgrade begin id=\(streamID) targetResolution=\(targetResolution) url=\(upgradedURL.absoluteString)")
-                let upgradedItem = AVPlayerItem(url: upgradedURL)
-                upgradedItem.preferredForwardBufferDuration = 4
-                player.replaceCurrentItem(with: upgradedItem)
-                player.automaticallyWaitsToMinimizeStalling = false
-                playbackDiagnostics.attach(to: player, streamID: streamID, label: label)
-                viewModel.attachPlayer(player, to: streamID)
-                scheduleStartupPlaybackRecovery(for: player)
-                logMultiView("qualityUpgrade replay id=\(streamID) targetResolution=\(targetResolution)")
-                player.playImmediately(atRate: 1.0)
-                return
-            }
-
-            logMultiView("qualityUpgrade timeout id=\(streamID) targetResolution=\(targetResolution)")
-        }
-    }
-
     private func currentStreamURL(for player: AVPlayer) -> URL? {
         (player.currentItem?.asset as? AVURLAsset)?.url
     }
 
+    private func attachAudioDiagnostics(to player: AVPlayer) {
+        if audioDiagnostics == nil {
+            audioDiagnostics = AudioDiagnostics(tag: "multi:\(stream.label)")
+        }
+        audioDiagnostics?.attach(to: player)
+    }
+
 
     private func installClipTimeLimit(on player: AVPlayer) {
         removeClipTimeLimit(from: player)
@@ -867,6 +818,45 @@ private struct MultiStreamTile: View {
     }
 }
 
+@MainActor
+private func enforcePinnedMultiStreamAudioSelection(on item: AVPlayerItem, streamID: String) async {
+    let asset = item.asset
+    guard let group = try? await asset.loadMediaSelectionGroup(for: .audible),
+          let option = preferredMultiStreamAudioOption(in: group) else { return }
+    let current = item.currentMediaSelection.selectedMediaOption(in: group)
+    if current != option {
+        item.select(option, in: group)
+    }
+    logMultiView(
+        "pinAudioSelection id=\(streamID) selected=\(option.displayName) current=\(current?.displayName ?? "nil") options=\(group.options.count)"
+    )
+}
+
+private func preferredMultiStreamAudioOption(in group: AVMediaSelectionGroup) -> AVMediaSelectionOption? {
+    let defaultOption = group.defaultOption
+    return group.options.max { lhs, rhs in
+        multiStreamAudioPreferenceScore(for: lhs, defaultOption: defaultOption) < multiStreamAudioPreferenceScore(for: rhs, defaultOption: defaultOption)
+    } ?? defaultOption ?? group.options.first
+}
+
+private func multiStreamAudioPreferenceScore(for option: AVMediaSelectionOption, defaultOption: AVMediaSelectionOption?) -> Int {
+    let name = option.displayName.lowercased()
+    var score = 0
+
+    if option == defaultOption { score += 40 }
+    if name.contains("stereo") || name.contains("2.0") || name.contains("main") { score += 30 }
+    if name.contains("english") || name.contains("eng") { score += 20 }
+    if name.contains("surround") || name.contains("5.1") || name.contains("atmos") { score -= 30 }
+    if name.contains("spanish") || name.contains("sap") || name.contains("descriptive") || name.contains("alternate") {
+        score -= 25
+    }
+    if option.hasMediaCharacteristic(.describesVideoForAccessibility) {
+        score -= 40
+    }
+
+    return score
+}
+
 private struct MultiStreamPlayerLayerView: UIViewRepresentable {
     let player: AVPlayer
     let streamID: String
@@ -1481,3 +1471,245 @@ private func nextMultiViewFocusID(
         .streamID
 }
 #endif
+
+// MARK: - AudioDiagnostics
+//
+// Audio-specific diagnostic logging. Attach one `AudioDiagnostics` per AVPlayer
+// you want to track. Emits a `[AUDIO]`-prefixed 1 Hz heartbeat with rate,
+// mute, time, bitrate, and route info — plus immediate logs on route changes,
+// interruptions, access-log events, and media-selection changes.
+//
+// Grep Xcode console with `[AUDIO]` to isolate these lines.
+
+@MainActor
+final class AudioDiagnostics {
+    private let tag: String
+    private weak var player: AVPlayer?
+    private var heartbeatTask: Task<Void, Never>?
+    private var observations: [NSKeyValueObservation] = []
+    private var tokens: [NSObjectProtocol] = []
+
+    private static var processWideInstalled = false
+
+    init(tag: String) {
+        self.tag = tag
+        AudioDiagnostics.installProcessWideObservers()
+    }
+
+    deinit {
+        heartbeatTask?.cancel()
+    }
+
+    func attach(to player: AVPlayer) {
+        detach()
+        self.player = player
+        log("attach rate=\(player.rate) isMuted=\(player.isMuted) volume=\(player.volume)")
+
+        observations.append(
+            player.observe(\.rate, options: [.new]) { [weak self] p, _ in
+                Task { @MainActor in self?.log("rate-change rate=\(p.rate) tc=\(p.timeControlStatus.rawValue)") }
+            }
+        )
+        observations.append(
+            player.observe(\.isMuted, options: [.new]) { [weak self] p, _ in
+                Task { @MainActor in self?.log("isMuted-change value=\(p.isMuted)") }
+            }
+        )
+        observations.append(
+            player.observe(\.volume, options: [.new]) { [weak self] p, _ in
+                Task { @MainActor in self?.log("volume-change value=\(p.volume)") }
+            }
+        )
+
+        if let item = player.currentItem {
+            attachItemObservers(item)
+        }
+        observations.append(
+            player.observe(\.currentItem, options: [.new]) { [weak self] p, _ in
+                Task { @MainActor in
+                    guard let self else { return }
+                    self.log("currentItem-change newItem=\(p.currentItem != nil)")
+                    if let item = p.currentItem {
+                        self.attachItemObservers(item)
+                    }
+                }
+            }
+        )
+
+        startHeartbeat()
+    }
+
+    func detach() {
+        heartbeatTask?.cancel()
+        heartbeatTask = nil
+        observations.removeAll()
+        for t in tokens {
+            NotificationCenter.default.removeObserver(t)
+        }
+        tokens.removeAll()
+        player = nil
+    }
+
+    private func attachItemObservers(_ item: AVPlayerItem) {
+        tokens.append(
+            NotificationCenter.default.addObserver(
+                forName: .AVPlayerItemNewAccessLogEntry,
+                object: item,
+                queue: .main
+            ) { [weak self, weak item] _ in
+                guard let self, let event = item?.accessLog()?.events.last else { return }
+                Task { @MainActor in
+                    self.log(
+                        "accessLog indicated=\(Int(event.indicatedBitrate)) observed=\(Int(event.observedBitrate)) switches=\(event.numberOfMediaRequests) stalls=\(event.numberOfStalls) avgVideo=\(Int(event.averageVideoBitrate)) avgAudio=\(Int(event.averageAudioBitrate))"
+                    )
+                }
+            }
+        )
+
+        tokens.append(
+            NotificationCenter.default.addObserver(
+                forName: .AVPlayerItemNewErrorLogEntry,
+                object: item,
+                queue: .main
+            ) { [weak self, weak item] _ in
+                guard let self, let event = item?.errorLog()?.events.last else { return }
+                Task { @MainActor in
+                    self.log("errorLog domain=\(event.errorDomain) statusCode=\(event.errorStatusCode) comment=\(event.errorComment ?? "nil")")
+                }
+            }
+        )
+
+        tokens.append(
+            NotificationCenter.default.addObserver(
+                forName: AVPlayerItem.mediaSelectionDidChangeNotification,
+                object: item,
+                queue: .main
+            ) { [weak self, weak item] _ in
+                guard let self, let item else { return }
+                Task { @MainActor in
+                    await enforcePinnedMultiStreamAudioSelection(on: item, streamID: self.tag)
+                    let asset = item.asset
+                    guard let group = try? await asset.loadMediaSelectionGroup(for: .audible),
+                          let selected = item.currentMediaSelection.selectedMediaOption(in: group) else {
+                        self.log("mediaSelection-change selected=nil")
+                        return
+                    }
+                    let codec = (selected.mediaSubTypes as [NSNumber]).map { audioDiagFourCC($0.uint32Value) }.joined(separator: ",")
+                    self.log("mediaSelection-change audio=\"\(selected.displayName)\" codec=\(codec)")
+                }
+            }
+        )
+    }
+
+    private func startHeartbeat() {
+        heartbeatTask?.cancel()
+        heartbeatTask = Task { @MainActor [weak self] in
+            while !Task.isCancelled {
+                self?.emitHeartbeat()
+                try? await Task.sleep(for: .seconds(1))
+            }
+        }
+    }
+
+    private func emitHeartbeat() {
+        guard let player, let item = player.currentItem else { return }
+        let currentTime = CMTimeGetSeconds(player.currentTime())
+        let event = item.accessLog()?.events.last
+        let indicated = event.map { Int($0.indicatedBitrate) } ?? 0
+        let observed = event.map { Int($0.observedBitrate) } ?? 0
+        log(
+            "hb t=\(String(format: "%.1f", currentTime))s rate=\(player.rate) tc=\(player.timeControlStatus.rawValue) muted=\(player.isMuted) vol=\(String(format: "%.2f", player.volume)) indicated=\(indicated) observed=\(observed) ltku=\(item.isPlaybackLikelyToKeepUp) route=\(AudioDiagnostics.currentRouteDescription())"
+        )
+    }
+
+    private func log(_ message: String) {
+        let ts = AudioDiagnostics.timestamp()
+        print("[AUDIO \(tag) \(ts)] \(message)")
+    }
+
+    // MARK: Process-wide
+
+    private static func installProcessWideObservers() {
+        guard !processWideInstalled else { return }
+        processWideInstalled = true
+
+        let session = AVAudioSession.sharedInstance()
+        print("[AUDIO SYSTEM \(timestamp())] initial category=\(session.category.rawValue) mode=\(session.mode.rawValue) sampleRate=\(session.sampleRate) route=\(currentRouteDescription())")
+
+        NotificationCenter.default.addObserver(
+            forName: AVAudioSession.routeChangeNotification,
+            object: nil,
+            queue: .main
+        ) { notification in
+            let reasonValue = notification.userInfo?[AVAudioSessionRouteChangeReasonKey] as? UInt ?? 0
+            let reason = AVAudioSession.RouteChangeReason(rawValue: reasonValue).map(audioDiagReasonDescription) ?? "unknown(\(reasonValue))"
+            let prev = (notification.userInfo?[AVAudioSessionRouteChangePreviousRouteKey] as? AVAudioSessionRouteDescription).map(routeDescription) ?? "nil"
+            print("[AUDIO SYSTEM \(timestamp())] routeChange reason=\(reason) previous=\(prev) current=\(currentRouteDescription())")
+        }
+
+        NotificationCenter.default.addObserver(
+            forName: AVAudioSession.interruptionNotification,
+            object: nil,
+            queue: .main
+        ) { notification in
+            let typeValue = notification.userInfo?[AVAudioSessionInterruptionTypeKey] as? UInt ?? 0
+            let type = AVAudioSession.InterruptionType(rawValue: typeValue).map(audioDiagInterruptionDescription) ?? "unknown(\(typeValue))"
+            print("[AUDIO SYSTEM \(timestamp())] interruption type=\(type)")
+        }
+    }
+
+    nonisolated static func currentRouteDescription() -> String {
+        routeDescription(AVAudioSession.sharedInstance().currentRoute)
+    }
+
+    nonisolated static func routeDescription(_ route: AVAudioSessionRouteDescription) -> String {
+        let outs = route.outputs.map { "\($0.portType.rawValue):\($0.portName)" }.joined(separator: ",")
+        return outs.isEmpty ? "none" : outs
+    }
+
+    nonisolated static func timestamp() -> String {
+        audioDiagTSFormatter.string(from: Date())
+    }
+}
+
+private let audioDiagTSFormatter: DateFormatter = {
+    let f = DateFormatter()
+    f.dateFormat = "HH:mm:ss.SSS"
+    return f
+}()
+
+private func audioDiagFourCC(_ raw: UInt32) -> String {
+    let bytes: [UInt8] = [
+        UInt8((raw >> 24) & 0xFF),
+        UInt8((raw >> 16) & 0xFF),
+        UInt8((raw >> 8) & 0xFF),
+        UInt8(raw & 0xFF),
+    ]
+    let chars = bytes.map { b -> Character in
+        let scalar = UnicodeScalar(b)
+        return (0x20...0x7E).contains(b) ? Character(scalar) : "?"
+    }
+    return String(chars)
+}
+
+private func audioDiagReasonDescription(_ reason: AVAudioSession.RouteChangeReason) -> String {
+    switch reason {
+    case .unknown: "unknown"
+    case .newDeviceAvailable: "newDeviceAvailable"
+    case .oldDeviceUnavailable: "oldDeviceUnavailable"
+    case .categoryChange: "categoryChange"
+    case .override: "override"
+    case .wakeFromSleep: "wakeFromSleep"
+    case .noSuitableRouteForCategory: "noSuitableRouteForCategory"
+    case .routeConfigurationChange: "routeConfigurationChange"
+    @unknown default: "unknown-future"
+    }
+}
+
+private func audioDiagInterruptionDescription(_ type: AVAudioSession.InterruptionType) -> String {
+    switch type {
+    case .began: "began"
+    case .ended: "ended"
+    @unknown default: "unknown-future"
+    }
+}

mlbTVOS/Views/SingleStreamPlayerView.swift

@@ -57,22 +57,70 @@ private func singleStreamTimeControlDescription(_ status: AVPlayer.TimeControlSt
 }
 
 private func makeSingleStreamPlayerItem(from source: SingleStreamPlaybackSource) -> AVPlayerItem {
+    let item: AVPlayerItem
     if source.httpHeaders.isEmpty {
-        let item = AVPlayerItem(url: source.url)
-        item.preferredForwardBufferDuration = 8
-        return item
+        item = AVPlayerItem(url: source.url)
+    } else {
+        let assetOptions: [String: Any] = [
+            "AVURLAssetHTTPHeaderFieldsKey": source.httpHeaders,
+        ]
+        let asset = AVURLAsset(url: source.url, options: assetOptions)
+        item = AVPlayerItem(asset: asset)
+        logSingleStream(
+            "Configured authenticated AVURLAsset headerKeys=\(singleStreamHeaderKeysDescription(source.httpHeaders))"
+        )
+    }
+    item.preferredForwardBufferDuration = 8
+    item.allowedAudioSpatializationFormats = []
+    logSingleStream("Configured player item preferredForwardBufferDuration=8 allowedAudioSpatializationFormats=[]")
+    pinSingleStreamAudioSelection(on: item)
+    return item
+}
+
+/// Pin the HLS audio rendition so ABR can't swap channel layouts mid-stream.
+private func pinSingleStreamAudioSelection(on item: AVPlayerItem) {
+    Task { @MainActor in
+        await enforcePinnedSingleStreamAudioSelection(on: item)
+    }
+}
+
+@MainActor
+private func enforcePinnedSingleStreamAudioSelection(on item: AVPlayerItem) async {
+    let asset = item.asset
+    guard let group = try? await asset.loadMediaSelectionGroup(for: .audible),
+          let option = preferredSingleStreamAudioOption(in: group) else { return }
+    let current = item.currentMediaSelection.selectedMediaOption(in: group)
+    if current != option {
+        item.select(option, in: group)
+    }
+    logSingleStream(
+        "pinAudioSelection selected=\(option.displayName) current=\(current?.displayName ?? "nil") options=\(group.options.count)"
+    )
+}
+
+private func preferredSingleStreamAudioOption(in group: AVMediaSelectionGroup) -> AVMediaSelectionOption? {
+    let defaultOption = group.defaultOption
+    return group.options.max { lhs, rhs in
+        audioPreferenceScore(for: lhs, defaultOption: defaultOption) < audioPreferenceScore(for: rhs, defaultOption: defaultOption)
+    } ?? defaultOption ?? group.options.first
+}
+
+private func audioPreferenceScore(for option: AVMediaSelectionOption, defaultOption: AVMediaSelectionOption?) -> Int {
+    let name = option.displayName.lowercased()
+    var score = 0
+
+    if option == defaultOption { score += 40 }
+    if name.contains("stereo") || name.contains("2.0") || name.contains("main") { score += 30 }
+    if name.contains("english") || name.contains("eng") { score += 20 }
+    if name.contains("surround") || name.contains("5.1") || name.contains("atmos") { score -= 30 }
+    if name.contains("spanish") || name.contains("sap") || name.contains("descriptive") || name.contains("alternate") {
+        score -= 25
+    }
+    if option.hasMediaCharacteristic(.describesVideoForAccessibility) {
+        score -= 40
     }
 
-    let assetOptions: [String: Any] = [
-        "AVURLAssetHTTPHeaderFieldsKey": source.httpHeaders,
-    ]
-    let asset = AVURLAsset(url: source.url, options: assetOptions)
-    let item = AVPlayerItem(asset: asset)
-    item.preferredForwardBufferDuration = 8
-    logSingleStream(
-        "Configured authenticated AVURLAsset headerKeys=\(singleStreamHeaderKeysDescription(source.httpHeaders))"
-    )
-    return item
+    return score
 }
 
 struct SingleStreamPlaybackScreen: View {
@@ -544,20 +592,27 @@ struct SingleStreamPlayerView: UIViewControllerRepresentable {
             )
 
             do {
-                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .moviePlayback)
+                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                 try AVAudioSession.sharedInstance().setActive(true)
-                logSingleStream("AVAudioSession configured for playback")
+                logSingleStream("AVAudioSession configured for playback mode=default")
             } catch {
                 logSingleStream("AVAudioSession configuration failed error=\(error.localizedDescription)")
             }
 
             let playerItem = makeSingleStreamPlayerItem(from: source)
             let player = AVPlayer(playerItem: playerItem)
+            player.appliesMediaSelectionCriteriaAutomatically = false
             player.automaticallyWaitsToMinimizeStalling = true
             player.isMuted = source.forceMuteAudio
-            logSingleStream("Configured player for quality ramp preferredForwardBufferDuration=8 automaticallyWaitsToMinimizeStalling=true")
+            logSingleStream(
+                "Configured player for quality ramp preferredForwardBufferDuration=8 automaticallyWaitsToMinimizeStalling=true appliesMediaSelectionCriteriaAutomatically=false"
+            )
             context.coordinator.attachDebugObservers(to: player, url: url, resolveNextSource: resolveNextSource)
             controller.player = player
+            if context.coordinator.audioDiagnostics == nil {
+                context.coordinator.audioDiagnostics = AudioDiagnostics(tag: "single")
+            }
+            context.coordinator.audioDiagnostics?.attach(to: player)
             logSingleStream("AVPlayer assigned to controller; calling playImmediately(atRate: 1.0)")
             player.playImmediately(atRate: 1.0)
             context.coordinator.installClipTimeLimit(on: player, resolveNextSource: resolveNextSource)
@@ -589,6 +644,10 @@ struct SingleStreamPlayerView: UIViewControllerRepresentable {
             logSingleStream("dismantleUIViewController — PiP active, observers cleared but keeping player")
             return
         }
+        Task { @MainActor in
+            coordinator.audioDiagnostics?.detach()
+            coordinator.audioDiagnostics = nil
+        }
         uiViewController.player?.pause()
         uiViewController.player = nil
         logSingleStream("dismantleUIViewController complete")
@@ -600,6 +659,7 @@ struct SingleStreamPlayerView: UIViewControllerRepresentable {
         private var startupRecoveryTask: Task<Void, Never>?
         private var qualityMonitorTask: Task<Void, Never>?
         private var clipTimeLimitObserver: Any?
+        var audioDiagnostics: AudioDiagnostics?
         private static let maxClipDuration: Double = 15.0
         var onTogglePitchInfo: (() -> Void)?
         var onToggleGameCenter: (() -> Void)?
@@ -791,6 +851,19 @@ struct SingleStreamPlayerView: UIViewControllerRepresentable {
                     }
                 }
             )
+
+            notificationTokens.append(
+                NotificationCenter.default.addObserver(
+                    forName: AVPlayerItem.mediaSelectionDidChangeNotification,
+                    object: item,
+                    queue: .main
+                ) { _ in
+                    logSingleStream("Notification mediaSelectionDidChange")
+                    Task { @MainActor in
+                        await enforcePinnedSingleStreamAudioSelection(on: item)
+                    }
+                }
+            )
         }
 
         func scheduleStartupRecovery(for player: AVPlayer) {