From 061d0c1f47270d22a13f417b167395274551fa81 Mon Sep 17 00:00:00 2001
From: sqz <sqz@sqzdeMac-mini.local>
Date: Thu, 1 Oct 2026 12:23:45 +0800
Subject: [PATCH] fix: restore iOS sliders and background artwork updates

Complete history and lyric diagnostic request cleanup, preserve Android volume drags, and resolve Sony API compatibility and lint errors.
---
 .../controllerapp/ui/ControllerAppUi.kt       |  23 +-
 .../controllerapp/ui/VolumeSliderState.kt     |  24 ++
 .../controllerapp/ui/VolumeSliderStateTest.kt |  33 ++
 .../IOSBleFeasibility/BLETestManager.swift    | 342 ++++++++++++++---
 .../IOSBleFeasibility/ContentView.swift       | 216 +++++++----
 .../IOSBleFeasibility/FullLyricsView.swift    |  12 +-
 .../LiveActivityArtworkStore.swift            |  61 ++-
 .../LiveActivityManager.swift                 |   9 +-
 .../IOSBleFeasibility/Localizable.xcstrings   |   2 +
 .../LyricDiagnosticView.swift                 |  12 +-
 .../PerformanceStabilityTests.swift           | 347 +++++++++++++++++-
 PlayerAgentApp/build.gradle                   |   1 +
 PlayerAgentApp/src/main/AndroidManifest.xml   |   3 +
 .../com/example/playeragent/MainActivity.kt   |   8 +-
 .../example/playeragent/ble/BleNotifyQueue.kt |   3 +-
 .../ble/ControllerGattClientManager.kt        |   5 +-
 .../playeragent/media/CurrentLyricProbe.kt    |  10 +-
 .../playeragent/media/QrcLyricCacheManager.kt |   9 +-
 .../media/QrcParsedCacheIndexStore.kt         |  28 +-
 .../media/CurrentLyricProbeTest.kt            |  18 +
 .../media/QrcParsedCacheIndexStoreTest.kt     |  28 ++
 docs/ALBUM_ART_ARCHITECTURE.md                |   1 +
 docs/CONTROL_INTERACTION_AUDIT.md             | 123 +++++++
 docs/IOS_ARCHITECTURE.md                      |   4 +
 24 files changed, 1120 insertions(+), 202 deletions(-)
 create mode 100644 ControllerApp/src/main/java/com/example/controllerapp/ui/VolumeSliderState.kt
 create mode 100644 ControllerApp/src/test/java/com/example/controllerapp/ui/VolumeSliderStateTest.kt
 create mode 100644 PlayerAgentApp/src/test/java/com/example/playeragent/media/CurrentLyricProbeTest.kt
 create mode 100644 docs/CONTROL_INTERACTION_AUDIT.md

diff --git a/ControllerApp/src/main/java/com/example/controllerapp/ui/ControllerAppUi.kt b/ControllerApp/src/main/java/com/example/controllerapp/ui/ControllerAppUi.kt
index 892b57d..db3e551 100644
--- a/ControllerApp/src/main/java/com/example/controllerapp/ui/ControllerAppUi.kt
+++ b/ControllerApp/src/main/java/com/example/controllerapp/ui/ControllerAppUi.kt
@@ -825,14 +825,15 @@ private fun VolumeControl(
     enabled: Boolean,
     onVolume: (Int) -> Unit
 ) {
-    var value by remember(playback.volumeCurrent, playback.volumeMax) {
-        mutableFloatStateOf(playback.volumeCurrent.toFloat())
+    val sliderState = remember { VolumeSliderState() }
+    val value = sliderState.displayedValue(playback.volumeCurrent, playback.volumeMax)
+    LaunchedEffect(enabled, playback.volumeMax) {
+        if (!enabled || playback.volumeMax <= 0) sliderState.cancel()
     }
-    var dragging by remember { mutableStateOf(false) }
-    LaunchedEffect(value, dragging) {
-        if (dragging) {
+    LaunchedEffect(sliderState.draggedValue, enabled, playback.volumeMax) {
+        if (sliderState.draggedValue != null && enabled && playback.volumeMax > 0) {
             delay(90L)
-            onVolume(value.toInt())
+            onVolume(sliderState.displayedValue(playback.volumeCurrent, playback.volumeMax).toInt())
         }
     }
     Row(
@@ -845,12 +846,14 @@ private fun VolumeControl(
             valueRange = 0f..playback.volumeMax.coerceAtLeast(1).toFloat(),
             enabled = enabled && playback.volumeMax > 0,
             onValueChange = {
-                dragging = true
-                value = it
+                sliderState.drag(it)
             },
             onValueChangeFinished = {
-                onVolume(value.toInt())
-                dragging = false
+                if (enabled && playback.volumeMax > 0) {
+                    sliderState.finish(playback.volumeCurrent, playback.volumeMax)?.let(onVolume)
+                } else {
+                    sliderState.cancel()
+                }
             },
             modifier = Modifier.weight(1f)
         )
diff --git a/ControllerApp/src/main/java/com/example/controllerapp/ui/VolumeSliderState.kt b/ControllerApp/src/main/java/com/example/controllerapp/ui/VolumeSliderState.kt
new file mode 100644
index 0000000..ed48a86
--- /dev/null
+++ b/ControllerApp/src/main/java/com/example/controllerapp/ui/VolumeSliderState.kt
@@ -0,0 +1,24 @@
+package com.example.controllerapp.ui
+
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+
+/** Remote acknowledgements may update playback while the local edit stays authoritative. */
+internal class VolumeSliderState {
+    var draggedValue by mutableStateOf<Float?>(null)
+        private set
+
+    fun displayedValue(current: Int, maximum: Int): Float =
+        (draggedValue ?: current.toFloat()).coerceIn(0f, maximum.coerceAtLeast(0).toFloat())
+
+    fun drag(value: Float) { draggedValue = value }
+
+    fun finish(current: Int, maximum: Int): Int? {
+        val finalValue = draggedValue?.let { displayedValue(current, maximum).toInt() }
+        cancel()
+        return finalValue
+    }
+
+    fun cancel() { draggedValue = null }
+}
diff --git a/ControllerApp/src/test/java/com/example/controllerapp/ui/VolumeSliderStateTest.kt b/ControllerApp/src/test/java/com/example/controllerapp/ui/VolumeSliderStateTest.kt
new file mode 100644
index 0000000..3bd6adc
--- /dev/null
+++ b/ControllerApp/src/test/java/com/example/controllerapp/ui/VolumeSliderStateTest.kt
@@ -0,0 +1,33 @@
+package com.example.controllerapp.ui
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class VolumeSliderStateTest {
+    @Test
+    fun delayedRemoteAckDoesNotOverwriteDragOrFinalCommand() {
+        val state = VolumeSliderState()
+        assertEquals(5f, state.displayedValue(5, 15), 0.001f)
+        state.drag(8f)
+        state.drag(12f)
+        assertEquals(12f, state.displayedValue(8, 15), 0.001f)
+        assertEquals(12, state.finish(8, 15))
+        assertNull(state.draggedValue)
+        assertEquals(12f, state.displayedValue(12, 15), 0.001f)
+        assertNull(state.finish(12, 15))
+    }
+
+    @Test
+    fun changedMaximumClampsFinalValueAndDisconnectCancelsEdit() {
+        val state = VolumeSliderState()
+        state.drag(14f)
+        assertEquals(7f, state.displayedValue(3, 7), 0.001f)
+        assertEquals(7, state.finish(3, 7))
+        state.drag(9f)
+        state.cancel()
+        assertEquals(3f, state.displayedValue(3, 15), 0.001f)
+        assertNull(state.finish(3, 15))
+        assertEquals(0f, state.displayedValue(3, 0), 0.001f)
+    }
+}
diff --git a/IOSBleFeasibility/IOSBleFeasibility/BLETestManager.swift b/IOSBleFeasibility/IOSBleFeasibility/BLETestManager.swift
index b8457d4..94a26d2 100644
--- a/IOSBleFeasibility/IOSBleFeasibility/BLETestManager.swift
+++ b/IOSBleFeasibility/IOSBleFeasibility/BLETestManager.swift
@@ -76,6 +76,19 @@ enum CommandWriteTimeoutPolicy {
 }
 
 enum CommandWriteQueuePolicy {
+    static func canRun(
+        appIsActive: Bool,
+        isControl: Bool,
+        command: String,
+        artworkID: String?,
+        artworkQuality: String?,
+        currentArtworkID: String
+    ) -> Bool {
+        if appIsActive || isControl { return true }
+        return command == "ALBUM_ART_REQUEST" && artworkQuality == "preview" &&
+            !currentArtworkID.isEmpty && artworkID == currentArtworkID
+    }
+
     static func shouldDropPending(
         existingCommand: String,
         existingIsProtected: Bool,
@@ -301,6 +314,7 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         didSet { syncDiagnosticsStore() }
     }
     @Published private(set) var lyricDiagnosticLastUpdatedAt: Date?
+    @Published private(set) var lyricDiagnosticRequestError: String?
     @Published private(set) var isPlaying = false {
         didSet { syncPlaybackTimelineStore() }
     }
@@ -596,6 +610,33 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
     private var mediaFieldDumpChunks: [Int: Data] = [:]
     private var historyPayloads: [String: HistoryPayloadAssembly] = [:]
     private var pendingHistoryRequests: [String: HistoryRequestKind] = [:]
+    private var historyRequestTimeouts: [String: DispatchWorkItem] = [:]
+    private var historyRequestSequences: [String: UInt64] = [:]
+    private var historyTransferToken = UUID()
+    private var lyricDiagnosticRequestToken = UUID()
+    private var lyricDiagnosticTimeout: DispatchWorkItem?
+    private var lyricDiagnosticRequestSequence: UInt64?
+    private var backgroundArtworkTask: BoundedBackgroundTask?
+    private var backgroundArtworkID = ""
+    #if DEBUG
+    var commandSenderForTesting: ((String, [String: Any]) -> Bool)?
+    var responseTimeoutForTesting: TimeInterval?
+
+    func configureResponseTests(trackID: String = "fixture-track") {
+        currentTrackID = trackID
+        connectionStatus = "已连接"
+        appLifecycleState = "active"
+    }
+
+    func receiveStatusForTesting(_ object: [String: Any]) {
+        parseStatus(object, type: object["type"] as? String ?? "", recordTransportActivity: false)
+    }
+
+    func disconnectResponseTests() {
+        clearConnectionTransports(reason: "test disconnect")
+        connectionStatus = "未连接"
+    }
+    #endif
     private var pendingPlaybackStatsRanges: [String] = []
     private var refreshStatsAfterHistorySync = false
     private var lastSyncedHistorySessionId: Int64 = 0
@@ -705,6 +746,8 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         let isControl: Bool
         let volumeValue: Int?
         let volumeReason: String?
+        var artworkID: String? = nil
+        var artworkQuality: String? = nil
     }
 
     private struct TrackInfoTransferPayload: Decodable, Sendable {
@@ -754,10 +797,15 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         var chunks: [Int: LyricLine] = [:]
     }
 
-    override init() {
+    override convenience init() {
+        self.init(automaticallyStartBluetooth: true)
+    }
+
+    init(automaticallyStartBluetooth: Bool) {
         super.init()
         syncAllStores()
         syncPreferencesStateFromStore()
+        guard automaticallyStartBluetooth else { return }
         logAppExperienceModeLoaded()
         log("[BLE-iOS] app log store ready")
         LiveActivityCommandBridge.shared.register(self, logger: { [weak self] message in
@@ -1745,6 +1793,9 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         subscribeNotifyTimeoutWorkItem?.cancel()
         foregroundValidationTimeoutWorkItem?.cancel()
         foregroundInflightSettleWorkItem?.cancel()
+        historyRequestTimeouts.values.forEach { $0.cancel() }
+        lyricDiagnosticTimeout?.cancel()
+        backgroundArtworkTask?.end()
         NotificationCenter.default.removeObserver(self)
     }
 
@@ -1927,8 +1978,9 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
 
     func requestLyricDiagnostic(manual: Bool = false) {
         let trackID = currentTrackID
-        guard !trackID.isEmpty else {
-            log("[LyricsDiag-iOS] request skipped reason=no track")
+        guard !trackID.isEmpty, connectionStatus == "已连接", appLifecycleState == "active" else {
+            finishLyricDiagnosticRequest(error: "诊断暂不可用，请确认连接后重试")
+            log("[LyricsDiag-iOS] request skipped reason=not ready")
             return
         }
         if !manual,
@@ -1940,15 +1992,53 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         if !manual {
             lastAutomaticLyricDiagnosticRequestAt[trackID] = Date()
         }
+        finishLyricDiagnosticRequest()
         lyricDiagnosticLoading = true
+        let token = UUID()
+        lyricDiagnosticRequestToken = token
+        let sequence = nextCommandSeq()
+        lyricDiagnosticRequestSequence = sequence
         log("[LyricsDiag-iOS] request trackId=\(trackID) manual=\(manual)")
-        sendCommand(
+        guard sendCommand(
             cmd: "GET_LYRIC_DIAGNOSTIC",
             extra: [
                 "trackId": trackID,
                 "time": Int64(Date().timeIntervalSince1970 * 1_000)
-            ]
-        )
+            ],
+            seq: sequence
+        ) else {
+            finishLyricDiagnosticRequest(error: "诊断暂不可用，请确认连接后重试")
+            return
+        }
+        let timeout = DispatchWorkItem { [weak self] in
+            guard let self, self.lyricDiagnosticRequestToken == token else { return }
+            self.finishLyricDiagnosticRequest(error: "诊断请求超时，请重试")
+        }
+        lyricDiagnosticTimeout = timeout
+        DispatchQueue.main.asyncAfter(deadline: .now() + responseTimeout(default: 10), execute: timeout)
+    }
+
+    private func responseTimeout(default seconds: TimeInterval) -> TimeInterval {
+        #if DEBUG
+        return responseTimeoutForTesting ?? seconds
+        #else
+        return seconds
+        #endif
+    }
+
+    private func finishLyricDiagnosticRequest(error: String? = nil) {
+        lyricDiagnosticTimeout?.cancel()
+        lyricDiagnosticTimeout = nil
+        lyricDiagnosticRequestToken = UUID()
+        if let sequence = lyricDiagnosticRequestSequence {
+            pendingCommandWrites.removeAll { $0.seq == sequence }
+        }
+        lyricDiagnosticRequestSequence = nil
+        lyricDiagnosticLoading = false
+        lyricDiagnosticRequestError = error
+        if error != nil {
+            lastAutomaticLyricDiagnosticRequestAt.removeValue(forKey: currentTrackID)
+        }
     }
 
     func refreshNowPlayingDiagnostics() {
@@ -2457,7 +2547,6 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
             playbackHistoryStatus = "同步中..."
             return
         }
-        isPlaybackHistorySyncing = true
         refreshStatsAfterHistorySync = true
         playbackHistoryStatus = "同步播放历史..."
         requestPlaybackHistorySince(afterSessionId: lastSyncedHistorySessionId)
@@ -2474,11 +2563,11 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
             syncPlaybackHistory()
             return
         }
-        isLoadingMoreHistory = true
-        let requestId = "history-page-\(currentTimeMs())"
-        pendingHistoryRequests[requestId] = .page
+        let requestId = "history-page-\(UUID().uuidString.prefix(8))"
         log("[HistorySync] request page requestId=\(requestId) before=\(beforeSessionId)")
-        sendCommand(
+        sendHistoryRequest(
+            requestId: requestId,
+            kind: .page,
             cmd: "GET_PLAY_HISTORY_PAGE",
             extra: [
                 "requestId": requestId,
@@ -2503,10 +2592,11 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         guard connectionStatus == "已连接",
               !pendingPlaybackStatsRanges.isEmpty else { return }
         let range = pendingPlaybackStatsRanges.removeFirst()
-        let requestId = "stats-\(range)-\(currentTimeMs())"
-        pendingHistoryRequests[requestId] = .stats(range)
+        let requestId = "stats-\(range)-\(UUID().uuidString.prefix(8))"
         log("[HistorySync] request stats requestId=\(requestId) range=\(range)")
-        sendCommand(
+        sendHistoryRequest(
+            requestId: requestId,
+            kind: .stats(range),
             cmd: "GET_PLAY_STATS",
             extra: [
                 "requestId": requestId,
@@ -2516,6 +2606,7 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
     }
 
     func clearLocalPlaybackHistory() {
+        resetHistoryRequests(reason: "local cache cleared")
         PlaybackHistoryStore.shared.clear { [weak self] in
             DispatchQueue.main.async {
                 guard let self else { return }
@@ -2529,10 +2620,11 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
     }
 
     private func requestPlaybackHistorySince(afterSessionId: Int64) {
-        let requestId = "history-since-\(currentTimeMs())"
-        pendingHistoryRequests[requestId] = .since
+        let requestId = "history-since-\(UUID().uuidString.prefix(8))"
         log("[HistorySync] request since requestId=\(requestId) after=\(afterSessionId)")
-        sendCommand(
+        sendHistoryRequest(
+            requestId: requestId,
+            kind: .since,
             cmd: "GET_PLAY_HISTORY_SINCE",
             extra: [
                 "requestId": requestId,
@@ -2542,6 +2634,70 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         )
     }
 
+    private func sendHistoryRequest(
+        requestId: String,
+        kind: HistoryRequestKind,
+        cmd: String,
+        extra: [String: Any]
+    ) {
+        pendingHistoryRequests[requestId] = kind
+        switch kind {
+        case .since: isPlaybackHistorySyncing = true
+        case .page: isLoadingMoreHistory = true
+        case .stats: break
+        }
+        let sequence = nextCommandSeq()
+        historyRequestSequences[requestId] = sequence
+        guard appLifecycleState == "active", sendCommand(cmd: cmd, extra: extra, seq: sequence) else {
+            failHistoryRequest(requestId, reason: "请求未发送，请确认 Sony 连接")
+            return
+        }
+        let token = historyTransferToken
+        let timeout = DispatchWorkItem { [weak self] in
+            guard let self, self.historyTransferToken == token else { return }
+            self.failHistoryRequest(requestId, reason: "请求超时，请重试")
+        }
+        historyRequestTimeouts[requestId] = timeout
+        DispatchQueue.main.asyncAfter(deadline: .now() + responseTimeout(default: 30), execute: timeout)
+    }
+
+    private func removeHistoryRequest(_ requestId: String) -> HistoryRequestKind? {
+        historyRequestTimeouts.removeValue(forKey: requestId)?.cancel()
+        historyPayloads.removeValue(forKey: requestId)
+        if let sequence = historyRequestSequences.removeValue(forKey: requestId) {
+            pendingCommandWrites.removeAll { $0.seq == sequence }
+        }
+        return pendingHistoryRequests.removeValue(forKey: requestId)
+    }
+
+    private func failHistoryRequest(_ requestId: String, reason: String) {
+        guard let kind = removeHistoryRequest(requestId) else { return }
+        playbackHistoryStatus = "同步失败：\(reason)"
+        log("[HistorySync] failed requestId=\(requestId) reason=\(reason)")
+        switch kind {
+        case .since:
+            isPlaybackHistorySyncing = false
+            refreshStatsAfterHistorySync = false
+        case .page:
+            isLoadingMoreHistory = false
+        case .stats:
+            requestNextPlaybackStats()
+        }
+    }
+
+    private func resetHistoryRequests(reason: String) {
+        historyTransferToken = UUID()
+        let hadRequests = !pendingHistoryRequests.isEmpty
+        for requestId in Array(pendingHistoryRequests.keys) { _ = removeHistoryRequest(requestId) }
+        historyPayloads.removeAll()
+        pendingPlaybackStatsRanges.removeAll()
+        isPlaybackHistorySyncing = false
+        isLoadingMoreHistory = false
+        refreshStatsAfterHistorySync = false
+        if hadRequests { playbackHistoryStatus = "同步已取消，请重试" }
+        log("[HistorySync] reset reason=\(reason)")
+    }
+
     private func sendUserCommand(cmd: String, extra: [String: Any] = [:]) {
         playbackStateRefreshWorkItem?.cancel()
         playbackStateRefreshWorkItem = nil
@@ -2565,11 +2721,13 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         sendCommand(cmd: cmd, extra: extra, seq: seq)
     }
 
-    func sendCommand(cmd: String, extra: [String: Any] = [:]) {
-        sendCommand(cmd: cmd, extra: extra, seq: nil)
+    @discardableResult
+    func sendCommand(cmd: String, extra: [String: Any] = [:]) -> Bool {
+        return sendCommand(cmd: cmd, extra: extra, seq: nil)
     }
 
-    private func sendCommand(cmd: String, extra: [String: Any] = [:], seq providedSeq: UInt64?) {
+    @discardableResult
+    private func sendCommand(cmd: String, extra: [String: Any] = [:], seq providedSeq: UInt64?) -> Bool {
         let seq = providedSeq ?? nextCommandSeq()
         let startMs = currentTimeMs()
         var payload = extra
@@ -2582,6 +2740,10 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
         }
         payload["seq"] = seq
 
+        #if DEBUG
+        if let sender = commandSenderForTesting { return sender(cmd, payload) }
+        #endif
+
         let connected = sonyPeripheral?.state == .connected
         let characteristicReady = sonyCommandCharacteristic != nil
         ctrlLog(
@@ -2599,7 +2761,7 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
                     "reason=unhealthy health=\(connectionHealthState)"
             )
             log("[Command] send failed \(cmd): unhealthy \(connectionHealthState)")
-            return
+            return false
         }
 
         guard JSONSerialization.isValidJSONObject(payload),
@@ -2607,7 +2769,7 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
               let text = String(data: data, encoding: .utf8) else {
             ctrlLog("[CTRL-iOS] write skipped seq=\(seq) cmd=\(cmd) reason=encode_failed")
             log("[Command] encode failed \(cmd)")
-            return
+            return false
         }
 
         guard let sonyPeripheral,
@@ -2619,7 +2781,7 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
             if connected, sonyCommandCharacteristic == nil {
                 performHardReconnect(reason: "command characteristic nil while connected", manual: false)
             }
-            return
+            return false
         }
 
         enqueueCommandWrite(
@@ -2632,9 +2794,12 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
                 enqueuedMonoMs: monotonicTimeMs(),
                 isControl: isControlCommand(cmd),
                 volumeValue: nil,
-                volumeReason: nil
+                volumeReason: nil,
+                artworkID: cmd == "ALBUM_ART_REQUEST" ? extra["id"] as? String : nil,
+                artworkQuality: cmd == "ALBUM_ART_REQUEST" ? extra["quality"] as? String : nil
             )
         )
+        return true
     }
 
     private func enqueueCommandWrite(_ request: PendingCommandWrite) {
@@ -2694,22 +2859,30 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
     }
 
     private func flushCommandWriteQueue() {
-        // Background execution is opportunistic. Keep queued synchronization
-        // work frozen until foreground, while still allowing a user initiated
-        // Live Activity control (which is ordered ahead of background work).
-        if appLifecycleState != "active",
-           pendingCommandWrites.first?.isControl != true {
-            return
+        let artworkID = albumArtReceiver.currentAlbumArtID
+        pendingCommandWrites.removeAll {
+            $0.cmd == "ALBUM_ART_REQUEST" && $0.artworkID != artworkID
         }
+        // A BLE wake-up may fetch the current preview for the Island. HQ,
+        // history, diagnostics and periodic synchronization wait for foreground.
         guard commandWriteInflight.isEmpty,
-              !pendingCommandWrites.isEmpty,
+              let requestIndex = pendingCommandWrites.firstIndex(where: {
+                  CommandWriteQueuePolicy.canRun(
+                      appIsActive: appLifecycleState == "active",
+                      isControl: $0.isControl,
+                      command: $0.cmd,
+                      artworkID: $0.artworkID,
+                      artworkQuality: $0.artworkQuality,
+                      currentArtworkID: artworkID
+                  )
+              }),
               let sonyPeripheral,
               sonyPeripheral.state == .connected,
               let sonyCommandCharacteristic else {
             return
         }
 
-        let request = pendingCommandWrites.removeFirst()
+        let request = pendingCommandWrites.remove(at: requestIndex)
         let writeBeginMs = currentTimeMs()
         let writeBeginMonoMs = monotonicTimeMs()
         commandWriteInflight.append(
@@ -4460,6 +4633,10 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
 
     private func clearConnectionTransports(reason: String) {
         log("[BLE-Reconnect] clear characteristics reason=\(reason)")
+        resetHistoryRequests(reason: reason)
+        finishLyricDiagnosticRequest(error: lyricDiagnosticLoading ? "诊断暂不可用，请确认连接后重试" : nil)
+        backgroundArtworkTask?.end()
+        backgroundArtworkTask = nil
         resetClockSync(reason: reason)
         coreBluetoothRestoreTimeoutWorkItem?.cancel()
         coreBluetoothRestoreTimeoutWorkItem = nil
@@ -4649,6 +4826,8 @@ final class BLETestManager: NSObject, ObservableObject, @unchecked Sendable {
 
     @objc private func appDidBecomeActive() {
         updateAppLifecycleState(.active, emitLog: true)
+        backgroundArtworkTask?.end()
+        backgroundArtworkTask = nil
         handleAppForegroundReconnectCheck()
     }
 
@@ -5922,9 +6101,9 @@ extension BLETestManager: CBPeripheralDelegate {
         }
     }
 
-    private func parseStatus(_ object: [String: Any], type: String) {
+    private func parseStatus(_ object: [String: Any], type: String, recordTransportActivity: Bool = true) {
         let apply: () -> Void = {
-            self.markStatusNotifyReceived(type: type)
+            if recordTransportActivity { self.markStatusNotifyReceived(type: type) }
             self.observeV3StatusMetadata(object, type: type)
             switch type {
             case "link":
@@ -6280,6 +6459,7 @@ extension BLETestManager: CBPeripheralDelegate {
 
             case "albumArtOffer":
                 let id = object["id"] as? String ?? ""
+                self.beginBackgroundArtworkTask(id: id)
                 self.albumArtReceiver.handleOffer(id: id)
 
             case "albumArtStart":
@@ -6445,15 +6625,7 @@ extension BLETestManager: CBPeripheralDelegate {
             case "playHistoryError":
                 let requestId = object["requestId"] as? String ?? ""
                 let message = object["message"] as? String ?? "unknown"
-                let failedKind = self.pendingHistoryRequests.removeValue(forKey: requestId)
-                if case .some(.stats) = failedKind {
-                    self.requestNextPlaybackStats()
-                } else {
-                    self.isPlaybackHistorySyncing = false
-                }
-                self.isLoadingMoreHistory = false
-                self.playbackHistoryStatus = "同步失败：\(message)"
-                self.log("[HistorySync] error requestId=\(requestId) message=\(message)")
+                self.failHistoryRequest(requestId, reason: message)
 
             default:
                 self.log("[Status] unsupported type=\(type)")
@@ -6533,6 +6705,14 @@ extension BLETestManager: CBPeripheralDelegate {
             ? "，可重试\(payload.retryAfterMs.map { "（\($0)ms 后）" } ?? "")"
             : ""
         lastCommandErrorSummary = "\(correlatedCommand)：\(payload.code)\(retryText)"
+        if let sequence = payload.sequence {
+            if let requestId = historyRequestSequences.first(where: { $0.value == sequence })?.key {
+                failHistoryRequest(requestId, reason: payload.code)
+            }
+            if lyricDiagnosticRequestSequence == sequence {
+                finishLyricDiagnosticRequest(error: "诊断暂不可用，请确认连接后重试")
+            }
+        }
         log(
             "[BLE-V3] commandError seq=\(payload.sequence.map { String($0) } ?? "-") " +
                 "cmd=\(correlatedCommand) domain=\(payload.domain.rawValue) " +
@@ -6631,8 +6811,10 @@ extension BLETestManager: CBPeripheralDelegate {
         let responseType = object["responseType"] as? String ?? ""
         let size = Self.intValue(object["size"])
         let chunks = Self.intValue(object["chunks"])
-        guard !requestId.isEmpty, !responseType.isEmpty, size > 0, chunks > 0 else {
+        guard pendingHistoryRequests[requestId] != nil else { return }
+        guard !responseType.isEmpty, size > 0, chunks > 0 else {
             log("[HistorySync] invalid payload start")
+            failHistoryRequest(requestId, reason: "无效的历史分包信息")
             return
         }
         historyPayloads[requestId] = HistoryPayloadAssembly(
@@ -6652,6 +6834,7 @@ extension BLETestManager: CBPeripheralDelegate {
               let base64 = object["data"] as? String,
               let chunk = Data(base64Encoded: base64) else {
             log("[HistorySync] invalid payload chunk requestId=\(requestId) index=\(index)")
+            failHistoryRequest(requestId, reason: "无效的历史分包")
             return
         }
         assembly.chunks[index] = chunk
@@ -6663,8 +6846,10 @@ extension BLETestManager: CBPeripheralDelegate {
         guard let assembly = historyPayloads.removeValue(forKey: requestId),
               assembly.chunks.count == assembly.expectedChunks else {
             log("[HistorySync] payload end missing chunks requestId=\(requestId)")
+            failHistoryRequest(requestId, reason: "历史分包不完整，请重试")
             return
         }
+        let token = historyTransferToken
         protocolDecodeQueue.async { [weak self] in
             guard let self else { return }
             let signpost = AppPerformanceLog.protocolSignposter.beginInterval("History Payload Decode")
@@ -6674,7 +6859,8 @@ extension BLETestManager: CBPeripheralDelegate {
                 guard let chunk = assembly.chunks[index] else {
                     AppPerformanceLog.protocolSignposter.endInterval("History Payload Decode", signpost)
                     DispatchQueue.main.async { [weak self] in
-                        self?.log("[HistorySync] payload missing chunk requestId=\(requestId) index=\(index)")
+                        guard let self, self.historyTransferToken == token else { return }
+                        self.failHistoryRequest(requestId, reason: "历史分包不完整，请重试")
                     }
                     return
                 }
@@ -6685,9 +6871,13 @@ extension BLETestManager: CBPeripheralDelegate {
                 : nil
             AppPerformanceLog.protocolSignposter.endInterval("History Payload Decode", signpost)
             DispatchQueue.main.async { [weak self] in
-                guard let self else { return }
-                guard let decoded else {
+                guard let self, self.historyTransferToken == token,
+                      self.pendingHistoryRequests[requestId] != nil else { return }
+                guard let decoded,
+                      decoded["requestId"] as? String == requestId,
+                      decoded["type"] as? String == assembly.responseType else {
                     self.log("[HistorySync] payload decode failed requestId=\(requestId)")
+                    self.failHistoryRequest(requestId, reason: "历史数据解析失败，请重试")
                     return
                 }
                 self.log("[HistorySync] payload decoded requestId=\(requestId) bytes=\(data.count)")
@@ -6699,12 +6889,25 @@ extension BLETestManager: CBPeripheralDelegate {
     private func handleHistoryPayload(_ object: [String: Any]) {
         let type = object["type"] as? String ?? ""
         let requestId = object["requestId"] as? String ?? ""
+        guard let kind = pendingHistoryRequests[requestId] else { return }
+        let expectedType: String
+        switch kind {
+        case .since: expectedType = "playHistorySince"
+        case .page: expectedType = "playHistoryPage"
+        case .stats: expectedType = "playStats"
+        }
+        guard type == expectedType else {
+            failHistoryRequest(requestId, reason: "历史响应类型不匹配")
+            return
+        }
+        let token = historyTransferToken
         switch type {
         case "playHistoryPage", "playHistorySince":
             let sessions = decodeHistorySessions(object["items"] as? [[String: Any]] ?? [])
             PlaybackHistoryStore.shared.mergeSessions(sessions) { [weak self] merged in
                 DispatchQueue.main.async {
-                    guard let self else { return }
+                    guard let self, self.historyTransferToken == token,
+                          self.pendingHistoryRequests[requestId] != nil else { return }
                     self.playbackHistorySessions = merged
                     self.handleHistoryRequestCompletion(
                         type: type,
@@ -6717,15 +6920,12 @@ extension BLETestManager: CBPeripheralDelegate {
 
         case "playStats":
             guard let stats = decodePlaybackStats(object) else {
-                pendingHistoryRequests.removeValue(forKey: requestId)
-                playbackHistoryStatus = "统计解析失败"
-                log("[HistorySync] stats decode failed requestId=\(requestId)")
-                requestNextPlaybackStats()
+                failHistoryRequest(requestId, reason: "统计解析失败")
                 return
             }
             playbackStats[stats.range] = stats
             PlaybackHistoryStore.shared.saveStats(stats)
-            pendingHistoryRequests.removeValue(forKey: requestId)
+            _ = removeHistoryRequest(requestId)
             playbackHistoryStatus = "统计已更新"
             log("[HistorySync] stats updated range=\(stats.range)")
             requestNextPlaybackStats()
@@ -6741,8 +6941,13 @@ extension BLETestManager: CBPeripheralDelegate {
         received: Int,
         response: [String: Any]
     ) {
-        let kind = pendingHistoryRequests.removeValue(forKey: requestId)
         let hasMore = response["hasMore"] as? Bool ?? false
+        if type == "playHistorySince", hasMore,
+           Self.int64Value(response["lastSessionId"]) <= lastSyncedHistorySessionId {
+            failHistoryRequest(requestId, reason: "历史同步游标未推进")
+            return
+        }
+        guard removeHistoryRequest(requestId) != nil else { return }
         if type == "playHistorySince" {
             let lastSessionId = Self.int64Value(response["lastSessionId"])
             if lastSessionId > lastSyncedHistorySessionId {
@@ -6769,8 +6974,6 @@ extension BLETestManager: CBPeripheralDelegate {
             isLoadingMoreHistory = false
             playbackHistoryStatus = received == 0 ? "没有更多历史" : "已加载更多"
             log("[HistorySync] page received=\(received) hasMore=\(hasMore)")
-        } else if kind == nil {
-            log("[HistorySync] response without pending requestId=\(requestId)")
         }
     }
 
@@ -6899,7 +7102,7 @@ extension BLETestManager: CBPeripheralDelegate {
             translationLyricsState = .idle
             romanizationLyricsState = .idle
             lyricDiagnostic = nil
-            lyricDiagnosticLoading = false
+            finishLyricDiagnosticRequest()
             lyricDiagnosticLastUpdatedAt = nil
             mediaLoadingState.lyric = .waitingQqQrc
             mediaLoadingState.artwork = .preview(received: 0, expected: 0)
@@ -7018,7 +7221,7 @@ extension BLETestManager: CBPeripheralDelegate {
         fullLyricsTrackId = ""
         isFullLyricsCurrent = false
         lyricDiagnostic = nil
-        lyricDiagnosticLoading = false
+        finishLyricDiagnosticRequest()
         lyricDiagnosticLastUpdatedAt = nil
         isPlaying = false
         updateProgressTimerState()
@@ -7074,8 +7277,10 @@ extension BLETestManager: CBPeripheralDelegate {
         )
         lastLiveActivityRequestAt = Date()
         lastLiveActivityRequestTrackID = snapshotTrackID
+        let backgroundTask = BoundedBackgroundTask(name: "Live Activity publication")
 
         Task { @MainActor in
+            defer { backgroundTask.end() }
             LiveActivityManager.shared.update(
                 title: snapshotTitle,
                 artist: snapshotArtist,
@@ -7958,7 +8163,7 @@ extension BLETestManager: CBPeripheralDelegate {
             return
         }
         lyricDiagnostic = parseLyricDiagnostic(object)
-        lyricDiagnosticLoading = false
+        finishLyricDiagnosticRequest()
         lyricDiagnosticLastUpdatedAt = Date()
         if let diagnostic = lyricDiagnostic {
             if diagnostic.status == "waiting_qqmusic_cache" ||
@@ -7977,7 +8182,7 @@ extension BLETestManager: CBPeripheralDelegate {
     }
 
     private func handleLyricDiagnosticUnavailable(_ object: [String: Any]) {
-        lyricDiagnosticLoading = false
+        finishLyricDiagnosticRequest(error: "诊断暂不可用，请确认连接后重试")
         let reason = object["reason"] as? String ?? "unavailable"
         log("[LyricsDiag-iOS] unavailable reason=\(reason)")
     }
@@ -9213,6 +9418,7 @@ extension BLETestManager: CBPeripheralDelegate {
         key: String,
         reason: String
     ) {
+        beginBackgroundArtworkTask(id: key)
         let trackAtStart = currentTrackID
         let revision = currentLiveArtworkRevision + 1
         let writeRequest = liveArtworkRevisionFence.begin()
@@ -9245,6 +9451,10 @@ extension BLETestManager: CBPeripheralDelegate {
                         "revision=\(revision) source=\(reason)"
                 )
                 self.updateLiveActivity(force: true, reason: "artworkReady")
+                if self.backgroundArtworkID == key {
+                    self.backgroundArtworkTask?.end()
+                    self.backgroundArtworkTask = nil
+                }
             }
         )
     }
@@ -9260,6 +9470,14 @@ extension BLETestManager: CBPeripheralDelegate {
         }
     }
 
+    private func beginBackgroundArtworkTask(id: String) {
+        guard appLifecycleState != "active", !id.isEmpty else { return }
+        if backgroundArtworkID == id, backgroundArtworkTask?.isActive == true { return }
+        backgroundArtworkTask?.end()
+        backgroundArtworkID = id
+        backgroundArtworkTask = BoundedBackgroundTask(name: "Current artwork preview")
+    }
+
     private func finishRemoteLogTransfer() {
         guard remoteLogExpectedChunks > 0,
               remoteLogChunks.count == remoteLogExpectedChunks else {
@@ -9466,6 +9684,10 @@ extension BLETestManager: AlbumArtReceiverDelegate {
     }
 
     func albumArtSendCommand(cmd: String, extra: [String: Any]) {
+        if cmd == "ALBUM_ART_REQUEST", extra["quality"] as? String == "preview",
+           let id = extra["id"] as? String {
+            beginBackgroundArtworkTask(id: id)
+        }
         sendCommand(cmd: cmd, extra: extra)
     }
 
diff --git a/IOSBleFeasibility/IOSBleFeasibility/ContentView.swift b/IOSBleFeasibility/IOSBleFeasibility/ContentView.swift
index d12c8bf..21ef830 100644
--- a/IOSBleFeasibility/IOSBleFeasibility/ContentView.swift
+++ b/IOSBleFeasibility/IOSBleFeasibility/ContentView.swift
@@ -1,4 +1,5 @@
 import SwiftUI
+import UIKit
 
 private final class BLETestManagerOwner: ObservableObject {
     let manager: BLETestManager
@@ -19,6 +20,7 @@ struct ContentView: View {
     @State private var showSystemHealthOverview = false
     @State private var showPreferences = false
     @State private var showDeviceDetails = false
+    @State private var deferredDiagnostic: DeferredPlayerDiagnostic?
 
     private var manager: BLETestManager { managerOwner.manager }
 
@@ -54,11 +56,12 @@ struct ContentView: View {
             .sheet(isPresented: $showPreferences) {
                 PreferencesView(bleManager: manager, onDismiss: { showPreferences = false })
             }
-            .sheet(isPresented: $showDeviceDetails) {
+            .sheet(isPresented: $showDeviceDetails, onDismiss: presentDeferredDiagnostic) {
                 DeviceDetailView(
                     manager: manager,
                     onShowAdvancedDiagnostics: {
-                        showNowPlayingDiagnostic = true
+                        deferredDiagnostic = .nowPlaying
+                        showDeviceDetails = false
                     }
                 )
             }
@@ -80,13 +83,13 @@ struct ContentView: View {
                     onDismiss: { showSystemHealthOverview = false }
                 )
             }
-            .fullScreenCover(isPresented: $showFullLyrics) {
+            .fullScreenCover(isPresented: $showFullLyrics, onDismiss: presentDeferredDiagnostic) {
                 FullLyricsStoreHost(
                     manager: manager,
                     onDismiss: { showFullLyrics = false },
                     onShowDiagnostic: {
+                        deferredDiagnostic = .lyrics
                         showFullLyrics = false
-                        showLyricDiagnostic = true
                     }
                 )
             }
@@ -102,6 +105,7 @@ struct ContentView: View {
             }
             .onChange(of: preferences.appExperienceMode) { _, mode in
                 if mode == .daily {
+                    deferredDiagnostic = nil
                     showDebugPage = false
                     showLyricDiagnostic = false
                     showNowPlayingDiagnostic = false
@@ -110,6 +114,21 @@ struct ContentView: View {
             }
         }
     }
+
+    private func presentDeferredDiagnostic() {
+        let diagnostic = deferredDiagnostic
+        deferredDiagnostic = nil
+        switch diagnostic {
+        case .nowPlaying: showNowPlayingDiagnostic = true
+        case .lyrics: showLyricDiagnostic = true
+        case nil: break
+        }
+    }
+}
+
+private enum DeferredPlayerDiagnostic {
+    case nowPlaying
+    case lyrics
 }
 
 private struct PlayerBackgroundHost: View {
@@ -340,7 +359,7 @@ private struct PlayerHeaderStoreView: View {
                 Image(systemName: "ellipsis")
                     .font(.system(size: 22, weight: .semibold))
                     .foregroundStyle(.white.opacity(0.86))
-                    .frame(width: 42, height: 42)
+                    .frame(width: 44, height: 44)
                     .background(.white.opacity(0.05), in: Circle())
                     .overlay { Circle().stroke(.white.opacity(0.08), lineWidth: 1) }
             }
@@ -858,7 +877,7 @@ private struct PlaybackProgressStoreView: View {
     }
 }
 
-private struct CompactPlayerSlider: View {
+struct CompactPlayerSlider: View {
     let value: Binding<Double>
     let range: ClosedRange<Double>
     let step: Double?
@@ -869,74 +888,137 @@ private struct CompactPlayerSlider: View {
     let onEditingChanged: (Bool) -> Void
 
     var body: some View {
-        GeometryReader { proxy in
-            let thumbDiameter = CompactSliderPresentation.thumbDiameter
-            let trackWidth = max(proxy.size.width - thumbDiameter, 0)
-            let progress = CGFloat(
-                CompactSliderPresentation.normalizedProgress(
-                    value: value.wrappedValue,
-                    lowerBound: range.lowerBound,
-                    upperBound: range.upperBound
-                )
-            )
-            let fillWidth = trackWidth * progress
-            let centerY = proxy.size.height / 2
-            let thumbX = thumbDiameter / 2 + fillWidth
-
-            ZStack(alignment: .topLeading) {
-                Capsule()
-                    .fill(.white.opacity(0.18))
-                    .frame(width: trackWidth, height: CompactSliderPresentation.trackHeight)
-                    .position(x: proxy.size.width / 2, y: centerY)
+        CompactNativePlayerSlider(configuration: self)
+            .disabled(!isEnabled)
+            .frame(height: CompactSliderPresentation.interactionHeight)
+    }
+}
 
-                Capsule()
-                    .fill(accentColor)
-                    .frame(width: fillWidth, height: CompactSliderPresentation.trackHeight)
-                    .position(x: thumbDiameter / 2 + fillWidth / 2, y: centerY)
+private struct CompactNativePlayerSlider: UIViewRepresentable {
+    let configuration: CompactPlayerSlider
 
-                Circle()
-                    .fill(.white)
-                    .frame(width: thumbDiameter, height: thumbDiameter)
-                    .overlay {
-                        Circle().strokeBorder(accentColor.opacity(0.72), lineWidth: 1)
-                    }
-                    .shadow(color: .black.opacity(0.24), radius: 2, y: 1)
-                    .position(x: thumbX, y: centerY)
-                    .allowsHitTesting(false)
+    func makeCoordinator() -> Coordinator { Coordinator(parent: configuration) }
 
-                interactiveSlider
-                    .frame(width: proxy.size.width, height: proxy.size.height)
-                    .opacity(0.001)
+    func makeUIView(context: Context) -> CompactSliderControl {
+        let slider = CompactSliderControl()
+        slider.addTarget(context.coordinator, action: #selector(Coordinator.beginEditing), for: .touchDown)
+        slider.addTarget(context.coordinator, action: #selector(Coordinator.valueChanged(_:)), for: .valueChanged)
+        slider.addTarget(
+            context.coordinator,
+            action: #selector(Coordinator.endEditing),
+            for: [.touchUpInside, .touchUpOutside, .touchCancel]
+        )
+        slider.onAccessibilityAdjustment = { [weak coordinator = context.coordinator] control, direction in
+            coordinator?.adjustAccessibility(control, direction: direction)
+        }
+        return slider
+    }
+
+    func updateUIView(_ slider: CompactSliderControl, context: Context) {
+        context.coordinator.parent = configuration
+        slider.minimumValue = Float(configuration.range.lowerBound)
+        slider.maximumValue = Float(configuration.range.upperBound)
+        slider.isEnabled = configuration.isEnabled
+        if !configuration.isEnabled, context.coordinator.isEditing {
+            let coordinator = context.coordinator
+            DispatchQueue.main.async { [weak coordinator] in
+                guard let coordinator, !coordinator.parent.isEnabled else { return }
+                coordinator.endEditing()
             }
         }
-        .frame(height: CompactSliderPresentation.interactionHeight)
-        .contentShape(Rectangle())
-        .opacity(isEnabled ? 1 : 0.45)
+        if !context.coordinator.isEditing {
+            slider.value = Float(min(
+                max(configuration.value.wrappedValue, configuration.range.lowerBound),
+                configuration.range.upperBound
+            ))
+        }
+        slider.applyTint(UIColor(configuration.accentColor))
+        slider.alpha = configuration.isEnabled ? 1 : 0.45
+        slider.accessibilityLabel = AppLocalization.string(configuration.accessibilityLabel)
+        slider.accessibilityValue = configuration.accessibilityValue
     }
 
-    @ViewBuilder
-    private var interactiveSlider: some View {
-        if let step {
-            Slider(
-                value: value,
-                in: range,
-                step: step,
-                onEditingChanged: onEditingChanged
-            )
-            .disabled(!isEnabled)
-            .accessibilityLabel(accessibilityLabel)
-            .accessibilityValue(accessibilityValue)
-        } else {
-            Slider(
-                value: value,
-                in: range,
-                onEditingChanged: onEditingChanged
+    func sizeThatFits(_ proposal: ProposedViewSize, uiView: CompactSliderControl, context: Context) -> CGSize? {
+        CGSize(width: proposal.width ?? 160, height: CompactSliderPresentation.interactionHeight)
+    }
+
+    final class Coordinator: NSObject {
+        var parent: CompactPlayerSlider
+        private(set) var isEditing = false
+
+        init(parent: CompactPlayerSlider) { self.parent = parent }
+
+        @objc func beginEditing() {
+            guard parent.isEnabled, !isEditing else { return }
+            isEditing = true
+            parent.onEditingChanged(true)
+        }
+
+        @objc func valueChanged(_ slider: UISlider) {
+            guard parent.isEnabled else { return }
+            // Non-touch changes must commit as one complete edit, too.
+            let completesImmediately = !isEditing
+            beginEditing()
+            var newValue = Double(slider.value)
+            if let step = parent.step, step > 0 {
+                newValue = parent.range.lowerBound +
+                    ((newValue - parent.range.lowerBound) / step).rounded() * step
+            }
+            newValue = min(max(newValue, parent.range.lowerBound), parent.range.upperBound)
+            slider.value = Float(newValue)
+            parent.value.wrappedValue = newValue
+            if completesImmediately { endEditing() }
+        }
+
+        @objc func endEditing() {
+            guard isEditing else { return }
+            isEditing = false
+            parent.onEditingChanged(false)
+        }
+
+        func adjustAccessibility(_ slider: UISlider, direction: Double) {
+            guard parent.isEnabled else { return }
+            let increment = parent.step ?? (parent.range.upperBound - parent.range.lowerBound) / 20
+            let newValue = min(
+                max(parent.value.wrappedValue + direction * increment, parent.range.lowerBound),
+                parent.range.upperBound
             )
-            .disabled(!isEnabled)
-            .accessibilityLabel(accessibilityLabel)
-            .accessibilityValue(accessibilityValue)
+            guard newValue != parent.value.wrappedValue else { return }
+            slider.value = Float(newValue)
+            valueChanged(slider)
+        }
+    }
+}
+
+final class CompactSliderControl: UISlider {
+    var onAccessibilityAdjustment: ((CompactSliderControl, Double) -> Void)?
+    private var appliedTint: UIColor?
+
+    override func trackRect(forBounds bounds: CGRect) -> CGRect {
+        let track = super.trackRect(forBounds: bounds)
+        return CGRect(x: track.minX, y: bounds.midY - 1.5, width: track.width, height: 3)
+    }
+
+    func applyTint(_ color: UIColor) {
+        guard appliedTint != color else { return }
+        appliedTint = color
+        minimumTrackTintColor = color
+        maximumTrackTintColor = UIColor.white.withAlphaComponent(0.18)
+        let image = UIGraphicsImageRenderer(size: CGSize(width: 11, height: 11)).image { _ in
+            let circle = UIBezierPath(ovalIn: CGRect(x: 0.5, y: 0.5, width: 10, height: 10))
+            UIColor.white.setFill()
+            circle.fill()
+            color.withAlphaComponent(0.72).setStroke()
+            circle.lineWidth = 1
+            circle.stroke()
         }
+        setThumbImage(image, for: .normal)
+        setThumbImage(image, for: .highlighted)
+        setThumbImage(image, for: .disabled)
     }
+
+    override func accessibilityIncrement() { onAccessibilityAdjustment?(self, 1) }
+    override func accessibilityDecrement() { onAccessibilityAdjustment?(self, -1) }
 }
 
 private struct PlaybackControlsStoreView: View {
@@ -1024,7 +1106,7 @@ private struct VolumeControlStoreView: View {
             .frame(height: CompactSliderPresentation.interactionHeight)
         }
         .padding(.horizontal, 11)
-        .frame(height: 36)
+        .frame(height: CompactSliderPresentation.interactionHeight)
         .background(.black.opacity(0.13), in: RoundedRectangle(cornerRadius: 16))
         .overlay { RoundedRectangle(cornerRadius: 16).strokeBorder(.white.opacity(0.06)) }
         .opacity(isAvailable ? 1 : 0.48)
@@ -1236,9 +1318,7 @@ struct CompactVolumePresentation {
 }
 
 struct CompactSliderPresentation {
-    static let trackHeight: CGFloat = 3
-    static let thumbDiameter: CGFloat = 11
-    static let interactionHeight: CGFloat = 32
+    static let interactionHeight: CGFloat = 44
 
     static func normalizedProgress(
         value: Double,
diff --git a/IOSBleFeasibility/IOSBleFeasibility/FullLyricsView.swift b/IOSBleFeasibility/IOSBleFeasibility/FullLyricsView.swift
index 7fcf329..ef49ec0 100644
--- a/IOSBleFeasibility/IOSBleFeasibility/FullLyricsView.swift
+++ b/IOSBleFeasibility/IOSBleFeasibility/FullLyricsView.swift
@@ -150,6 +150,8 @@ struct FullLyricsView: View {
                     .overlay {
                         Circle().stroke(.white.opacity(0.10), lineWidth: 1)
                     }
+                    .padding(5)
+                    .contentShape(Rectangle())
             }
             .buttonStyle(FullLyricsPressStyle())
             .accessibilityLabel("关闭歌词")
@@ -203,6 +205,7 @@ struct FullLyricsView: View {
                                 .foregroundStyle(.white)
                                 .padding(.horizontal, 12)
                                 .padding(.vertical, 8)
+                                .frame(minHeight: 44)
                                 .background(.white.opacity(0.12), in: Capsule())
                                 .overlay {
                                     Capsule().stroke(.white.opacity(0.10), lineWidth: 1)
@@ -240,7 +243,7 @@ struct FullLyricsView: View {
                         .font(.callout.weight(.bold))
                         .foregroundStyle(.white)
                         .padding(.horizontal, 16)
-                        .frame(height: 36)
+                        .frame(height: 44)
                         .background(.white.opacity(0.12), in: Capsule())
                 }
                 .buttonStyle(.plain)
@@ -279,6 +282,7 @@ struct FullLyricsView: View {
                         .transition(.opacity)
                 }
             }
+            .frame(minHeight: 44)
             .contentShape(Rectangle())
         }
         .buttonStyle(.plain)
@@ -393,7 +397,7 @@ struct FullLyricsView: View {
 
     private var controls: some View {
         HStack(spacing: 32) {
-            controlButton(systemImage: "backward.fill", size: 52, action: onPrevious)
+            controlButton("上一首", systemImage: "backward.fill", size: 52, action: onPrevious)
             Button(action: onPlayPause) {
                 Image(systemName: isPlaying ? "pause.fill" : "play.fill")
                     .font(.system(size: 30, weight: .bold))
@@ -404,7 +408,7 @@ struct FullLyricsView: View {
             }
             .buttonStyle(FullLyricsPressStyle(pressedScale: 0.92))
             .accessibilityLabel(isPlaying ? "暂停" : "播放")
-            controlButton(systemImage: "forward.fill", size: 52, action: onNext)
+            controlButton("下一首", systemImage: "forward.fill", size: 52, action: onNext)
         }
         .padding(.top, 4)
         .disabled(!isConnected)
@@ -412,6 +416,7 @@ struct FullLyricsView: View {
     }
 
     private func controlButton(
+        _ title: String,
         systemImage: String,
         size: CGFloat,
         action: @escaping () -> Void
@@ -427,6 +432,7 @@ struct FullLyricsView: View {
                 }
         }
         .buttonStyle(FullLyricsPressStyle(pressedScale: 0.92))
+        .accessibilityLabel(AppLocalization.string(title))
     }
 
     private func scrollToCurrent(_ proxy: ScrollViewProxy) {
diff --git a/IOSBleFeasibility/IOSBleFeasibility/LiveActivityArtworkStore.swift b/IOSBleFeasibility/IOSBleFeasibility/LiveActivityArtworkStore.swift
index ae4dd68..f2c9c23 100644
--- a/IOSBleFeasibility/IOSBleFeasibility/LiveActivityArtworkStore.swift
+++ b/IOSBleFeasibility/IOSBleFeasibility/LiveActivityArtworkStore.swift
@@ -1,29 +1,62 @@
 import Foundation
 import UIKit
 
+/// A finite lease for BLE wake-up work and its asynchronous publication.
+final class BoundedBackgroundTask {
+    private var identifier: UIBackgroundTaskIdentifier = .invalid
+    private var deadline: DispatchWorkItem?
+    var isActive: Bool { identifier != .invalid }
+
+    init(name: String) {
+        guard UIApplication.shared.applicationState != .active else { return }
+        identifier = UIApplication.shared.beginBackgroundTask(withName: name) { [weak self] in
+            self?.end()
+        }
+        guard isActive else { return }
+        let item = DispatchWorkItem { [weak self] in self?.end() }
+        deadline = item
+        DispatchQueue.main.asyncAfter(deadline: .now() + 15, execute: item)
+    }
+
+    func end() {
+        deadline?.cancel()
+        deadline = nil
+        guard isActive else { return }
+        let task = identifier
+        identifier = .invalid
+        UIApplication.shared.endBackgroundTask(task)
+    }
+
+    deinit { end() }
+}
+
 struct LiveActivityArtworkWriteResult: Sendable {
     let succeeded: Bool
     let messages: [String]
 }
 
-private actor LiveActivityArtworkFileWriter {
+actor LiveActivityArtworkFileWriter {
     private let maxCachedFiles = 50
+    private let directoryOverride: URL?
+
+    init(directoryOverride: URL? = nil) { self.directoryOverride = directoryOverride }
+
+    private func directoryURL(fileManager: FileManager) -> URL? {
+        if let directoryOverride { return directoryOverride }
+        return fileManager.containerURL(
+            forSecurityApplicationGroupIdentifier: LiveActivitySharedConstants.appGroupIdentifier
+        )?.appendingPathComponent(LiveActivitySharedConstants.artworkDirectoryName, isDirectory: true)
+    }
 
     func write(data: Data, key: String, revision: Int) -> LiveActivityArtworkWriteResult {
         var messages = ["[LiveArtwork] write start key=\(key) revision=\(revision)"]
         let fileManager = FileManager.default
-        guard let containerURL = fileManager.containerURL(
-            forSecurityApplicationGroupIdentifier: LiveActivitySharedConstants.appGroupIdentifier
-        ) else {
+        guard let directoryURL = directoryURL(fileManager: fileManager) else {
             messages.append("[LiveArtwork] file validation failed reason=container unavailable")
             return LiveActivityArtworkWriteResult(succeeded: false, messages: messages)
         }
 
-        let directoryURL = containerURL.appendingPathComponent(
-            LiveActivitySharedConstants.artworkDirectoryName,
-            isDirectory: true
-        )
-        messages.append("[LiveArtwork] group container=\(containerURL.path)")
+        messages.append("[LiveArtwork] group container=\(directoryURL.deletingLastPathComponent().path)")
 
         do {
             try fileManager.createDirectory(at: directoryURL, withIntermediateDirectories: true)
@@ -35,7 +68,7 @@ private actor LiveActivityArtworkFileWriter {
             let fileURL = directoryURL.appendingPathComponent(
                 LiveActivitySharedConstants.artworkFileName(key: key, revision: revision)
             )
-            try data.write(to: fileURL, options: .atomic)
+            try data.write(to: fileURL, options: [.atomic, .completeFileProtectionUntilFirstUserAuthentication])
             guard fileManager.fileExists(atPath: fileURL.path) else {
                 messages.append("[LiveArtwork] file validation failed reason=file missing")
                 return LiveActivityArtworkWriteResult(succeeded: false, messages: messages)
@@ -52,13 +85,7 @@ private actor LiveActivityArtworkFileWriter {
 
     func removeAll() {
         let fileManager = FileManager.default
-        guard let containerURL = fileManager.containerURL(
-            forSecurityApplicationGroupIdentifier: LiveActivitySharedConstants.appGroupIdentifier
-        ) else { return }
-        let directoryURL = containerURL.appendingPathComponent(
-            LiveActivitySharedConstants.artworkDirectoryName,
-            isDirectory: true
-        )
+        guard let directoryURL = directoryURL(fileManager: fileManager) else { return }
         guard let urls = try? fileManager.contentsOfDirectory(
             at: directoryURL,
             includingPropertiesForKeys: nil
diff --git a/IOSBleFeasibility/IOSBleFeasibility/LiveActivityManager.swift b/IOSBleFeasibility/IOSBleFeasibility/LiveActivityManager.swift
index 9a24d8c..0679ad7 100644
--- a/IOSBleFeasibility/IOSBleFeasibility/LiveActivityManager.swift
+++ b/IOSBleFeasibility/IOSBleFeasibility/LiveActivityManager.swift
@@ -362,8 +362,10 @@ final class LiveActivityManager {
             return
         }
         updateInFlight = true
+        let backgroundTask = BoundedBackgroundTask(name: "Live Activity update")
 
         Task { [weak self] in
+            defer { backgroundTask.end() }
             guard let self else { return }
             let startedAt = Date()
             logger?("[LiveActivityPerf] update start reason=\(reason)")
@@ -489,16 +491,13 @@ final class LiveActivityManager {
             for await state in activity.activityStateUpdates {
                 await MainActor.run {
                     logger?("[LiveActivity] state changed state=\(state)")
-                    switch state {
-                    case .active, .stale:
+                    if state == .active || state == .stale {
                         self?.activity = activity
-                    case .ended, .dismissed:
+                    } else if state == .ended || state == .dismissed {
                         if self?.activity?.id == activity.id {
                             self?.activity = nil
                         }
                         self?.startCooldownUntil = Date().addingTimeInterval(5)
-                    @unknown default:
-                        break
                     }
                 }
             }
diff --git a/IOSBleFeasibility/IOSBleFeasibility/Localizable.xcstrings b/IOSBleFeasibility/IOSBleFeasibility/Localizable.xcstrings
index 20335e7..6fe1288 100644
--- a/IOSBleFeasibility/IOSBleFeasibility/Localizable.xcstrings
+++ b/IOSBleFeasibility/IOSBleFeasibility/Localizable.xcstrings
@@ -1,6 +1,8 @@
 {
   "sourceLanguage" : "zh-Hans",
   "strings" : {
+    "诊断暂不可用，请确认连接后重试" : {"localizations" : {"en" : {"stringUnit" : {"state" : "translated", "value" : "Diagnostics unavailable. Check the connection and try again."}}}},
+    "诊断请求超时，请重试" : {"localizations" : {"en" : {"stringUnit" : {"state" : "translated", "value" : "Diagnostics request timed out. Try again."}}}},
     "Sony 已连接" : { "localizations" : { "en" : { "stringUnit" : { "state" : "translated", "value" : "Sony connected" } } } },
     "上一次" : { "localizations" : { "en" : { "stringUnit" : { "state" : "translated", "value" : "Previous" } } } },
     "上一首" : { "localizations" : { "en" : { "stringUnit" : { "state" : "translated", "value" : "Previous track" } } } },
diff --git a/IOSBleFeasibility/IOSBleFeasibility/LyricDiagnosticView.swift b/IOSBleFeasibility/IOSBleFeasibility/LyricDiagnosticView.swift
index 5a445ea..4e309be 100644
--- a/IOSBleFeasibility/IOSBleFeasibility/LyricDiagnosticView.swift
+++ b/IOSBleFeasibility/IOSBleFeasibility/LyricDiagnosticView.swift
@@ -65,14 +65,20 @@ struct LyricDiagnosticView: View {
 
             Divider().overlay(.white.opacity(0.12))
 
-            Text(diagnostic?.statusTitle ?? "正在获取诊断")
+            Text(diagnostic?.statusTitle ?? (bleManager.lyricDiagnosticLoading
+                ? "正在获取诊断"
+                : AppLocalization.string("诊断暂不可用，请确认连接后重试")))
                 .font(.headline.weight(.semibold))
                 .foregroundStyle(.white)
-            Text(diagnostic?.humanReadableReason ?? "正在向 Sony 读取当前歌词状态。")
+            Text(bleManager.lyricDiagnosticRequestError.map { AppLocalization.string($0) }
+                ?? diagnostic?.humanReadableReason
+                ?? "正在向 Sony 读取当前歌词状态。")
                 .font(.subheadline)
                 .foregroundStyle(.white.opacity(0.72))
                 .fixedSize(horizontal: false, vertical: true)
-            Text(diagnostic?.suggestionText ?? "请稍等片刻。")
+            Text(diagnostic?.suggestionText ?? (bleManager.lyricDiagnosticLoading
+                ? "请稍等片刻。"
+                : AppLocalization.string("刷新诊断")))
                 .font(.callout.weight(.medium))
                 .foregroundStyle(.white.opacity(0.84))
                 .fixedSize(horizontal: false, vertical: true)
diff --git a/IOSBleFeasibility/IOSBleFeasibilityTests/PerformanceStabilityTests.swift b/IOSBleFeasibility/IOSBleFeasibilityTests/PerformanceStabilityTests.swift
index afb5ffd..5d4f7a0 100644
--- a/IOSBleFeasibility/IOSBleFeasibilityTests/PerformanceStabilityTests.swift
+++ b/IOSBleFeasibility/IOSBleFeasibilityTests/PerformanceStabilityTests.swift
@@ -1466,8 +1466,351 @@ final class PerformanceStabilityTests: XCTestCase {
             1,
             accuracy: 0.001
         )
-        XCTAssertLessThan(CompactSliderPresentation.thumbDiameter, 16)
-        XCTAssertGreaterThanOrEqual(CompactSliderPresentation.interactionHeight, 28)
+        XCTAssertGreaterThanOrEqual(CompactSliderPresentation.interactionHeight, 44)
+    }
+
+    @MainActor
+    func testPlayerSliderParticipatesInHitTesting() throws {
+        var value = 5.0
+        try withHostedPlayerSlider(value: Binding(get: { value }, set: { value = $0 })) { slider, window in
+            var effectiveAlpha: CGFloat = 1
+            var ancestor: UIView? = slider
+            while let view = ancestor {
+                effectiveAlpha *= view.alpha
+                ancestor = view.superview
+            }
+            XCTAssertGreaterThan(effectiveAlpha, 0.01, "The real control must stay in the hit-test tree")
+            let point = slider.convert(CGPoint(x: slider.bounds.midX, y: slider.bounds.midY), to: window)
+            let hitView = try XCTUnwrap(window.hitTest(point, with: nil))
+            XCTAssertTrue(hitView === slider || hitView.isDescendant(of: slider), "Visible track must hit the actual slider")
+            XCTAssertGreaterThanOrEqual(slider.bounds.height, 44)
+        }
+    }
+
+    @MainActor
+    func testPlayerSliderDragUpdatesAndFinishesOnce() throws {
+        for step: Double? in [1, nil] {
+            var value = 5.0
+            var edits: [Bool] = []
+            try withHostedPlayerSlider(
+                value: Binding(get: { value }, set: { value = $0 }),
+                step: step,
+                onEditingChanged: { edits.append($0) }
+            ) { slider, _ in
+                slider.sendActions(for: .touchDown)
+                slider.value = 8
+                slider.sendActions(for: .valueChanged)
+                slider.value = 12
+                slider.sendActions(for: .valueChanged)
+                XCTAssertEqual(value, 12, accuracy: 0.001)
+                XCTAssertEqual(edits, [true], "Dragging must keep one edit open until release")
+                slider.sendActions(for: .touchUpInside)
+                XCTAssertEqual(edits, [true, false])
+            }
+        }
+    }
+
+    @MainActor
+    func testPlayerSliderAccessibilityAdjustmentCompletesEdit() throws {
+        for step: Double? in [1, nil] {
+            var value = 5.0
+            var edits: [Bool] = []
+            try withHostedPlayerSlider(
+                value: Binding(get: { value }, set: { value = $0 }),
+                step: step,
+                onEditingChanged: { edits.append($0) }
+            ) { slider, _ in
+                slider.accessibilityIncrement()
+                XCTAssertGreaterThan(value, 5)
+                XCTAssertEqual(edits, [true, false], "A non-touch adjustment must commit seek/volume state")
+            }
+        }
+    }
+
+    @MainActor
+    func testDisabledPlayerSliderDoesNotChangeValueOrStartEditing() throws {
+        var value = 5.0
+        var edits: [Bool] = []
+        try withHostedPlayerSlider(
+            value: Binding(get: { value }, set: { value = $0 }),
+            isEnabled: false,
+            onEditingChanged: { edits.append($0) }
+        ) { slider, _ in
+            XCTAssertFalse(slider.isEnabled)
+            slider.sendActions(for: .touchDown)
+            slider.value = 12
+            slider.sendActions(for: .valueChanged)
+            slider.sendActions(for: .touchUpInside)
+            slider.accessibilityIncrement()
+            XCTAssertEqual(value, 5)
+            XCTAssertTrue(edits.isEmpty)
+        }
+    }
+
+    @MainActor
+    private func withHostedPlayerSlider(
+        value: Binding<Double>,
+        step: Double? = 1,
+        isEnabled: Bool = true,
+        onEditingChanged: @escaping (Bool) -> Void = { _ in },
+        assertions: (UISlider, UIWindow) throws -> Void
+    ) throws {
+        let host = UIHostingController(rootView: CompactPlayerSlider(
+            value: value,
+            range: 0...15,
+            step: step,
+            accentColor: .green,
+            isEnabled: isEnabled,
+            accessibilityLabel: "Volume",
+            accessibilityValue: "5 of 15",
+            onEditingChanged: onEditingChanged
+        ).frame(width: 280, height: 44))
+        let scene = UIApplication.shared.connectedScenes.compactMap { $0 as? UIWindowScene }.first
+        let previousKeyWindow = scene?.windows.first(where: \.isKeyWindow)
+        let window = scene.map(UIWindow.init(windowScene:)) ?? UIWindow(frame: CGRect(x: 0, y: 0, width: 320, height: 160))
+        window.rootViewController = host
+        window.makeKeyAndVisible()
+        defer {
+            window.isHidden = true
+            window.rootViewController = nil
+            previousKeyWindow?.makeKeyAndVisible()
+        }
+        host.view.layoutIfNeeded()
+        RunLoop.main.run(until: Date().addingTimeInterval(0.1))
+        host.view.layoutIfNeeded()
+
+        func findSlider(in view: UIView) -> UISlider? {
+            if let slider = view as? UISlider { return slider }
+            return view.subviews.lazy.compactMap { findSlider(in: $0) }.first
+        }
+        let slider = try XCTUnwrap(findSlider(in: host.view))
+        try assertions(slider, window)
+    }
+
+    @MainActor
+    func testLiveActivityArtworkWriterPublishesReadableRevisionAndRejectsOversizedData() async throws {
+        let directory = FileManager.default.temporaryDirectory.appendingPathComponent(UUID().uuidString)
+        defer { try? FileManager.default.removeItem(at: directory) }
+        let writer = LiveActivityArtworkFileWriter(directoryOverride: directory)
+        let image = UIGraphicsImageRenderer(size: CGSize(width: 80, height: 80)).image { context in
+            UIColor.green.setFill()
+            context.fill(CGRect(x: 0, y: 0, width: 80, height: 80))
+        }
+        let data = try XCTUnwrap(image.jpegData(compressionQuality: 0.78))
+        let result = await writer.write(data: data, key: "fixture", revision: 1)
+        XCTAssertTrue(result.succeeded)
+        let url = directory.appendingPathComponent(LiveActivitySharedConstants.artworkFileName(key: "fixture", revision: 1))
+        XCTAssertEqual(try Data(contentsOf: url), data)
+        XCTAssertNotNil(UIImage(contentsOfFile: url.path))
+        let oversized = await writer.write(data: Data(repeating: 0, count: 20_000), key: "fixture", revision: 2)
+        XCTAssertFalse(oversized.succeeded)
+        XCTAssertEqual(try Data(contentsOf: url), data, "A failed write must retain the last published revision")
+        await writer.removeAll()
+        XCTAssertFalse(FileManager.default.fileExists(atPath: url.path))
+    }
+
+    func testBackgroundCommandPolicyAllowsCurrentPreviewWithoutUnfreezingHeavyWork() {
+        func allowed(_ command: String, quality: String? = nil, id: String? = nil, control: Bool = false) -> Bool {
+            CommandWriteQueuePolicy.canRun(
+                appIsActive: false, isControl: control, command: command,
+                artworkID: id, artworkQuality: quality, currentArtworkID: "current"
+            )
+        }
+        XCTAssertTrue(allowed("ALBUM_ART_REQUEST", quality: "preview", id: "current"))
+        XCTAssertFalse(allowed("ALBUM_ART_REQUEST", quality: "hq", id: "current"))
+        XCTAssertFalse(allowed("ALBUM_ART_REQUEST", quality: "preview", id: "old"))
+        XCTAssertFalse(allowed("GET_PLAY_HISTORY_SINCE"))
+        XCTAssertFalse(allowed("GET_LYRIC_DIAGNOSTIC"))
+        XCTAssertTrue(allowed("NEXT", control: true))
+        let requests = [("GET_PLAY_HISTORY_SINCE", ""), ("ALBUM_ART_REQUEST", "hq"), ("ALBUM_ART_REQUEST", "preview")]
+        XCTAssertEqual(requests.firstIndex { allowed($0.0, quality: $0.1, id: "current") }, 2)
+    }
+
+    @MainActor
+    func testHistorySuccessfulPaginationStatsAndLoadMoreReleaseBusyState() async throws {
+        let store = PlaybackHistoryStore.shared
+        await clearPlaybackHistory(store)
+        let manager = BLETestManager(automaticallyStartBluetooth: false)
+        manager.configureResponseTests()
+        defer { manager.disconnectResponseTests() }
+        var requests: [(command: String, payload: [String: Any])] = []
+        let secondPageRequested = expectation(description: "next history page requested")
+        let statsRequested = expectation(description: "statistics requested after history completes")
+        manager.commandSenderForTesting = { command, payload in
+            requests.append((command, payload))
+            if command == "GET_PLAY_HISTORY_SINCE",
+               requests.filter({ $0.command == command }).count == 2 {
+                secondPageRequested.fulfill()
+            }
+            if command == "GET_PLAY_STATS", payload["range"] as? String == "TODAY" {
+                statsRequested.fulfill()
+            }
+            return true
+        }
+
+        manager.syncPlaybackHistory()
+        let firstID = try XCTUnwrap(requests.last?.payload["requestId"] as? String)
+        manager.receiveStatusForTesting(["type": "playHistorySince", "requestId": firstID,
+            "items": [["sessionId": 1, "title": "First"]], "hasMore": true, "lastSessionId": 1])
+        await fulfillment(of: [secondPageRequested], timeout: 2)
+        XCTAssertTrue(manager.isPlaybackHistorySyncing)
+        XCTAssertEqual(requests.last?.payload["afterSessionId"] as? Int64, 1)
+        let secondID = try XCTUnwrap(requests.last?.payload["requestId"] as? String)
+        XCTAssertNotEqual(firstID, secondID)
+        manager.receiveStatusForTesting(["type": "playHistorySince", "requestId": secondID,
+            "items": [["sessionId": 2, "title": "Second"]], "hasMore": false, "lastSessionId": 2])
+        await fulfillment(of: [statsRequested], timeout: 2)
+        XCTAssertFalse(manager.isPlaybackHistorySyncing)
+        XCTAssertEqual(manager.playbackHistorySessions.map(\.sessionId), [2, 1])
+        let savedSyncState = await loadPlaybackSyncState(store)
+        XCTAssertEqual(savedSyncState.lastSyncedSessionId, 2)
+
+        for range in ["TODAY", "WEEK", "MONTH"] {
+            XCTAssertEqual(requests.last?.payload["range"] as? String, range)
+            let requestID = try XCTUnwrap(requests.last?.payload["requestId"] as? String)
+            manager.receiveStatusForTesting(["type": "playStats", "requestId": requestID,
+                "range": range, "playCount": 2])
+        }
+        XCTAssertEqual(Set(manager.playbackStats.keys), Set(["TODAY", "WEEK", "MONTH"]))
+        XCTAssertEqual(manager.playbackStats["WEEK"]?.playCount, 2)
+
+        manager.loadMorePlaybackHistory()
+        XCTAssertEqual(requests.last?.command, "GET_PLAY_HISTORY_PAGE")
+        XCTAssertEqual(requests.last?.payload["beforeSessionId"] as? Int64, 1)
+        let requestsWhileLoading = requests.count
+        manager.loadMorePlaybackHistory()
+        XCTAssertEqual(requests.count, requestsWhileLoading, "Loading must prevent a duplicate page request")
+        let olderID = try XCTUnwrap(requests.last?.payload["requestId"] as? String)
+        manager.receiveStatusForTesting(["type": "playHistoryPage", "requestId": olderID,
+            "items": [], "hasMore": false])
+        let pageComplete = XCTNSPredicateExpectation(
+            predicate: NSPredicate { _, _ in manager.playbackHistoryStatus == "没有更多历史" }, object: nil
+        )
+        await fulfillment(of: [pageComplete], timeout: 2)
+        XCTAssertEqual(manager.playbackHistorySessions.map(\.sessionId), [2, 1])
+        manager.loadMorePlaybackHistory()
+        XCTAssertEqual(requests.count, requestsWhileLoading + 1, "A completed page must allow another request")
+        await clearPlaybackHistory(store)
+    }
+
+    @MainActor
+    func testHistoryMissingChunksAndDisconnectReleaseBusyStateAndIgnoreOldResponses() throws {
+        let manager = BLETestManager(automaticallyStartBluetooth: false)
+        manager.configureResponseTests()
+        var requests: [[String: Any]] = []
+        manager.commandSenderForTesting = { _, payload in requests.append(payload); return true }
+        defer { manager.disconnectResponseTests() }
+        manager.syncPlaybackHistory()
+        let firstID = try XCTUnwrap(requests.last?["requestId"] as? String)
+        XCTAssertTrue(manager.isPlaybackHistorySyncing)
+        manager.receiveStatusForTesting(["type": "historyPayloadStart", "requestId": firstID,
+            "responseType": "playHistorySince", "size": 10, "chunks": 2])
+        manager.receiveStatusForTesting(["type": "historyPayloadEnd", "requestId": firstID])
+        XCTAssertFalse(manager.isPlaybackHistorySyncing)
+        manager.syncPlaybackHistory()
+        XCTAssertTrue(manager.isPlaybackHistorySyncing)
+        manager.disconnectResponseTests()
+        XCTAssertFalse(manager.isPlaybackHistorySyncing)
+        manager.configureResponseTests()
+        manager.syncPlaybackHistory()
+        let newID = try XCTUnwrap(requests.last?["requestId"] as? String)
+        XCTAssertNotEqual(firstID, newID)
+        manager.receiveStatusForTesting(["type": "playHistorySince", "requestId": firstID,
+            "items": [], "hasMore": false, "lastSessionId": 0])
+        XCTAssertTrue(manager.isPlaybackHistorySyncing, "An old response must not finish a new request")
+    }
+
+    @MainActor
+    func testHistoryMalformedPayloadFailsAndAllowsRetry() async throws {
+        let manager = BLETestManager(automaticallyStartBluetooth: false)
+        manager.configureResponseTests()
+        var requestID = ""
+        manager.commandSenderForTesting = { _, payload in requestID = payload["requestId"] as? String ?? ""; return true }
+        defer { manager.disconnectResponseTests() }
+        manager.syncPlaybackHistory()
+        manager.receiveStatusForTesting(["type": "historyPayloadStart", "requestId": requestID,
+            "responseType": "playHistorySince", "size": 4, "chunks": 1])
+        manager.receiveStatusForTesting(["type": "historyPayloadChunk", "requestId": requestID,
+            "index": 0, "data": Data("nope".utf8).base64EncodedString()])
+        manager.receiveStatusForTesting(["type": "historyPayloadEnd", "requestId": requestID])
+        let failed = XCTNSPredicateExpectation(predicate: NSPredicate { _, _ in !manager.isPlaybackHistorySyncing }, object: nil)
+        await fulfillment(of: [failed], timeout: 2)
+        manager.syncPlaybackHistory()
+        XCTAssertTrue(manager.isPlaybackHistorySyncing)
+    }
+
+    @MainActor
+    func testHistoryTimeoutAndSendFailureAllowRetry() async {
+        let manager = BLETestManager(automaticallyStartBluetooth: false)
+        manager.configureResponseTests()
+        manager.commandSenderForTesting = { _, _ in false }
+        defer { manager.disconnectResponseTests() }
+        manager.syncPlaybackHistory()
+        XCTAssertFalse(manager.isPlaybackHistorySyncing)
+        manager.commandSenderForTesting = { _, _ in true }
+        manager.responseTimeoutForTesting = 0.05
+        manager.syncPlaybackHistory()
+        XCTAssertTrue(manager.isPlaybackHistorySyncing)
+        let timedOut = XCTNSPredicateExpectation(predicate: NSPredicate { _, _ in !manager.isPlaybackHistorySyncing }, object: nil)
+        await fulfillment(of: [timedOut], timeout: 2)
+        manager.syncPlaybackHistory()
+        XCTAssertTrue(manager.isPlaybackHistorySyncing)
+    }
+
+    @MainActor
+    func testStatsFailureAdvancesQueueAndDisconnectAllowsFreshRefresh() throws {
+        let manager = BLETestManager(automaticallyStartBluetooth: false)
+        manager.configureResponseTests()
+        var requests: [[String: Any]] = []
+        manager.commandSenderForTesting = { _, payload in requests.append(payload); return true }
+        defer { manager.disconnectResponseTests() }
+        manager.refreshPlaybackStats()
+        XCTAssertEqual(requests.last?["range"] as? String, "TODAY")
+        let requestID = try XCTUnwrap(requests.last?["requestId"] as? String)
+        manager.receiveStatusForTesting(["type": "playHistoryError", "requestId": requestID, "message": "failure"])
+        XCTAssertEqual(requests.last?["range"] as? String, "WEEK")
+        manager.disconnectResponseTests()
+        manager.configureResponseTests()
+        manager.refreshPlaybackStats()
+        XCTAssertEqual(requests.last?["range"] as? String, "TODAY")
+    }
+
+    @MainActor
+    func testDiagnosticSendFailureAndDisconnectedRefreshDoNotStayLoading() {
+        let manager = BLETestManager(automaticallyStartBluetooth: false)
+        manager.configureResponseTests()
+        var attempts = 0
+        manager.commandSenderForTesting = { _, _ in attempts += 1; return false }
+        manager.requestLyricDiagnostic(manual: true)
+        XCTAssertFalse(manager.lyricDiagnosticLoading)
+        XCTAssertNotNil(manager.lyricDiagnosticRequestError)
+        XCTAssertEqual(attempts, 1)
+        manager.disconnectResponseTests()
+        manager.requestLyricDiagnostic(manual: true)
+        XCTAssertFalse(manager.lyricDiagnosticLoading)
+        XCTAssertEqual(attempts, 1, "A cached song must not trigger an offline request")
+    }
+
+    @MainActor
+    func testDiagnosticDeadlineIsCancelledByNewRequestAndSuccessfulResponse() async {
+        let manager = BLETestManager(automaticallyStartBluetooth: false)
+        manager.configureResponseTests()
+        manager.commandSenderForTesting = { _, _ in true }
+        defer { manager.disconnectResponseTests() }
+        manager.responseTimeoutForTesting = 0.05
+        manager.requestLyricDiagnostic(manual: true)
+        manager.responseTimeoutForTesting = 1
+        manager.requestLyricDiagnostic(manual: true)
+        try? await Task.sleep(nanoseconds: 120_000_000)
+        XCTAssertTrue(manager.lyricDiagnosticLoading, "The cancelled old deadline must not finish the new request")
+        manager.receiveStatusForTesting(["type": "lyricDiagnostic", "trackId": "fixture-track", "status": "loaded"])
+        XCTAssertFalse(manager.lyricDiagnosticLoading)
+        XCTAssertNil(manager.lyricDiagnosticRequestError)
+        manager.responseTimeoutForTesting = 0.05
+        manager.requestLyricDiagnostic(manual: true)
+        let timedOut = XCTNSPredicateExpectation(predicate: NSPredicate { _, _ in !manager.lyricDiagnosticLoading }, object: nil)
+        await fulfillment(of: [timedOut], timeout: 2)
+        XCTAssertEqual(manager.lyricDiagnosticRequestError, "诊断请求超时，请重试")
     }
 
     func testA1AndA2DispatchAndOutOfOrderAssembly() {
diff --git a/PlayerAgentApp/build.gradle b/PlayerAgentApp/build.gradle
index 8221927..f2ba492 100644
--- a/PlayerAgentApp/build.gradle
+++ b/PlayerAgentApp/build.gradle
@@ -25,6 +25,7 @@ android {
 }
 
 dependencies {
+    implementation "androidx.core:core-ktx:1.13.1"
     implementation "androidx.room:room-runtime:2.6.1"
     implementation "androidx.recyclerview:recyclerview:1.3.2"
     kapt "androidx.room:room-compiler:2.6.1"
diff --git a/PlayerAgentApp/src/main/AndroidManifest.xml b/PlayerAgentApp/src/main/AndroidManifest.xml
index b97ce35..e2c9736 100644
--- a/PlayerAgentApp/src/main/AndroidManifest.xml
+++ b/PlayerAgentApp/src/main/AndroidManifest.xml
@@ -12,6 +12,9 @@
     <uses-permission
         android:name="android.permission.BLUETOOTH_ADMIN"
         android:maxSdkVersion="30" />
+    <uses-permission
+        android:name="android.permission.ACCESS_COARSE_LOCATION"
+        android:maxSdkVersion="30" />
     <uses-permission
         android:name="android.permission.ACCESS_FINE_LOCATION"
         android:maxSdkVersion="30" />
diff --git a/PlayerAgentApp/src/main/java/com/example/playeragent/MainActivity.kt b/PlayerAgentApp/src/main/java/com/example/playeragent/MainActivity.kt
index 85bc635..76d3143 100644
--- a/PlayerAgentApp/src/main/java/com/example/playeragent/MainActivity.kt
+++ b/PlayerAgentApp/src/main/java/com/example/playeragent/MainActivity.kt
@@ -27,6 +27,7 @@ import android.widget.GridLayout
 import android.widget.ImageView
 import android.widget.LinearLayout
 import android.widget.TextView
+import androidx.core.content.ContextCompat
 import com.example.playeragent.ble.ControllerScannerManager
 import com.example.playeragent.ble.BleHealthState
 import com.example.playeragent.classicbluetooth.RfcommClientManager
@@ -252,11 +253,7 @@ class MainActivity : Activity() {
             addAction(PlayerAgentForegroundService.ACTION_PLAYER_UI_STATE)
             addAction(PlayerAgentForegroundService.ACTION_QRC_WATCHER_STATUS)
         }
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
-            registerReceiver(logReceiver, filter, Context.RECEIVER_NOT_EXPORTED)
-        } else {
-            registerReceiver(logReceiver, filter)
-        }
+        ContextCompat.registerReceiver(this, logReceiver, filter, ContextCompat.RECEIVER_NOT_EXPORTED)
         PlayerNotificationListenerService.removeQqMusicArtworkListener(
             qqMusicArtworkListener
         )
@@ -2272,6 +2269,7 @@ class MainActivity : Activity() {
             permissions += Manifest.permission.BLUETOOTH_ADVERTISE
             permissions += Manifest.permission.BLUETOOTH_CONNECT
         } else {
+            permissions += Manifest.permission.ACCESS_COARSE_LOCATION
             permissions += Manifest.permission.ACCESS_FINE_LOCATION
             permissions += Manifest.permission.READ_EXTERNAL_STORAGE
         }
diff --git a/PlayerAgentApp/src/main/java/com/example/playeragent/ble/BleNotifyQueue.kt b/PlayerAgentApp/src/main/java/com/example/playeragent/ble/BleNotifyQueue.kt
index 7ca70f9..d1a0677 100644
--- a/PlayerAgentApp/src/main/java/com/example/playeragent/ble/BleNotifyQueue.kt
+++ b/PlayerAgentApp/src/main/java/com/example/playeragent/ble/BleNotifyQueue.kt
@@ -5,6 +5,7 @@ import android.bluetooth.BluetoothDevice
 import android.bluetooth.BluetoothGatt
 import android.bluetooth.BluetoothGattCharacteristic
 import android.bluetooth.BluetoothGattServer
+import android.bluetooth.BluetoothStatusCodes
 import android.os.Build
 import android.os.Handler
 import android.os.HandlerThread
@@ -1406,7 +1407,7 @@ class BleNotifyQueue(
                     characteristic,
                     false,
                     value
-                ) == BluetoothGatt.GATT_SUCCESS
+                ) == BluetoothStatusCodes.SUCCESS
             } else {
                 @Suppress("DEPRECATION")
                 characteristic.value = value
diff --git a/PlayerAgentApp/src/main/java/com/example/playeragent/ble/ControllerGattClientManager.kt b/PlayerAgentApp/src/main/java/com/example/playeragent/ble/ControllerGattClientManager.kt
index 719ff43..f6b5cd5 100644
--- a/PlayerAgentApp/src/main/java/com/example/playeragent/ble/ControllerGattClientManager.kt
+++ b/PlayerAgentApp/src/main/java/com/example/playeragent/ble/ControllerGattClientManager.kt
@@ -7,6 +7,7 @@ import android.bluetooth.BluetoothGattCallback
 import android.bluetooth.BluetoothGattCharacteristic
 import android.bluetooth.BluetoothGattDescriptor
 import android.bluetooth.BluetoothProfile
+import android.bluetooth.BluetoothStatusCodes
 import android.content.Context
 import android.os.Build
 import android.os.Handler
@@ -216,7 +217,7 @@ class ControllerGattClientManager(
                 gatt.writeDescriptor(
                     descriptor,
                     BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
-                ) == BluetoothGatt.GATT_SUCCESS
+                ) == BluetoothStatusCodes.SUCCESS
             } else {
                 @Suppress("DEPRECATION")
                 descriptor.value = BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
@@ -271,7 +272,7 @@ class ControllerGattClientManager(
                     characteristic,
                     value,
                     BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT
-                ) == BluetoothGatt.GATT_SUCCESS
+                ) == BluetoothStatusCodes.SUCCESS
             } else {
                 @Suppress("DEPRECATION")
                 characteristic.writeType = BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT
diff --git a/PlayerAgentApp/src/main/java/com/example/playeragent/media/CurrentLyricProbe.kt b/PlayerAgentApp/src/main/java/com/example/playeragent/media/CurrentLyricProbe.kt
index 71bed8b..976170e 100644
--- a/PlayerAgentApp/src/main/java/com/example/playeragent/media/CurrentLyricProbe.kt
+++ b/PlayerAgentApp/src/main/java/com/example/playeragent/media/CurrentLyricProbe.kt
@@ -325,10 +325,14 @@ object CurrentLyricProbe {
         )
     }
 
-    private fun containsChinese(value: String): Boolean {
+    internal fun containsChinese(value: String): Boolean {
         return value.any { character ->
-            Character.UnicodeScript.of(character.code) ==
-                Character.UnicodeScript.HAN
+            when (Character.UnicodeBlock.of(character)) {
+                Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS,
+                Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A,
+                Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS -> true
+                else -> character == '\u3007'
+            }
         }
     }
 
diff --git a/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcLyricCacheManager.kt b/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcLyricCacheManager.kt
index 063309e..4b7a6e4 100644
--- a/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcLyricCacheManager.kt
+++ b/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcLyricCacheManager.kt
@@ -21,13 +21,12 @@ class QrcLyricCacheManager(
         context = appContext,
         logger = logger
     )
-    private val parsedIndexStore = sharedParsedIndexStores.computeIfAbsent(
-        QrcLyricUtils.cacheDirectory(appContext).absolutePath
-    ) { path ->
-        QrcParsedCacheIndexStore(
+    private val parsedIndexStore = synchronized(sharedParsedIndexStores) {
+        val path = QrcLyricUtils.cacheDirectory(appContext).absolutePath
+        sharedParsedIndexStores[path] ?: QrcParsedCacheIndexStore(
             cacheDirectory = File(path),
             logger = logger
-        )
+        ).also { sharedParsedIndexStores[path] = it }
     }
     private val memoryCache =
         object : LinkedHashMap<String, ParsedLyric>(MAX_MEMORY_CACHE, 0.75f, true) {
diff --git a/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcParsedCacheIndexStore.kt b/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcParsedCacheIndexStore.kt
index bb7199f..9d61992 100644
--- a/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcParsedCacheIndexStore.kt
+++ b/PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcParsedCacheIndexStore.kt
@@ -4,8 +4,7 @@ import org.json.JSONArray
 import org.json.JSONObject
 import java.io.File
 import java.io.FileOutputStream
-import java.nio.file.Files
-import java.nio.file.StandardCopyOption
+import java.io.IOException
 import java.util.LinkedHashMap
 import java.util.concurrent.Executors
 import java.util.concurrent.ScheduledFuture
@@ -17,6 +16,7 @@ class QrcParsedCacheIndexStore(
     private val logger: (String) -> Unit
 ) {
     private val lock = Any()
+    private val writeLock = Any()
     private val entries = LinkedHashMap<String, Entry>()
     private val executor = Executors.newSingleThreadScheduledExecutor { runnable ->
         Thread(runnable, "QrcParsedIndexWriteThread").apply {
@@ -111,8 +111,9 @@ class QrcParsedCacheIndexStore(
         )
     }
 
-    private fun writeSnapshot() {
+    private fun writeSnapshot() = synchronized(writeLock) {
         val snapshot = synchronized(lock) { entries.values.toList() }
+        var temp: File? = null
         try {
             cacheDirectory.mkdirs()
             val value = JSONObject()
@@ -125,28 +126,19 @@ class QrcParsedCacheIndexStore(
                     }
                 )
                 .toString()
-            val temp = File(cacheDirectory, ".$INDEX_FILE_NAME.${System.nanoTime()}.tmp")
+            temp = File(cacheDirectory, ".$INDEX_FILE_NAME.${System.nanoTime()}.tmp")
             FileOutputStream(temp).use { output ->
                 output.write(value.toByteArray(Charsets.UTF_8))
                 output.fd.sync()
             }
-            runCatching {
-                Files.move(
-                    temp.toPath(),
-                    indexFile.toPath(),
-                    StandardCopyOption.ATOMIC_MOVE,
-                    StandardCopyOption.REPLACE_EXISTING
-                )
-            }.recoverCatching {
-                Files.move(
-                    temp.toPath(),
-                    indexFile.toPath(),
-                    StandardCopyOption.REPLACE_EXISTING
-                )
-            }.getOrThrow()
+            // Android's same-directory rename atomically replaces the file and
+            // is available on API 23. Never delete the previous index first.
+            if (!temp.renameTo(indexFile)) throw IOException("Index rename failed")
             logger("[QrcParsedIndex] saved entries=${snapshot.size}")
         } catch (exception: Exception) {
             logger("[QrcParsedIndex] save failed error=${exception.message}")
+        } finally {
+            temp?.delete()
         }
     }
 
diff --git a/PlayerAgentApp/src/test/java/com/example/playeragent/media/CurrentLyricProbeTest.kt b/PlayerAgentApp/src/test/java/com/example/playeragent/media/CurrentLyricProbeTest.kt
new file mode 100644
index 0000000..7535593
--- /dev/null
+++ b/PlayerAgentApp/src/test/java/com/example/playeragent/media/CurrentLyricProbeTest.kt
@@ -0,0 +1,18 @@
+package com.example.playeragent.media
+
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class CurrentLyricProbeTest {
+    @Test
+    fun hanDetectionUsesLegacyUnicodeBlocks() {
+        assertTrue(CurrentLyricProbe.containsChinese("歌词 test"))
+        assertTrue(CurrentLyricProbe.containsChinese("\u3400"))
+        assertTrue(CurrentLyricProbe.containsChinese("\uF900"))
+        assertTrue(CurrentLyricProbe.containsChinese("〇"))
+        assertFalse(CurrentLyricProbe.containsChinese("English lyrics"))
+        assertFalse(CurrentLyricProbe.containsChinese("かな 😀"))
+        assertFalse(CurrentLyricProbe.containsChinese(""))
+    }
+}
diff --git a/PlayerAgentApp/src/test/java/com/example/playeragent/media/QrcParsedCacheIndexStoreTest.kt b/PlayerAgentApp/src/test/java/com/example/playeragent/media/QrcParsedCacheIndexStoreTest.kt
index 01dd854..75b3461 100644
--- a/PlayerAgentApp/src/test/java/com/example/playeragent/media/QrcParsedCacheIndexStoreTest.kt
+++ b/PlayerAgentApp/src/test/java/com/example/playeragent/media/QrcParsedCacheIndexStoreTest.kt
@@ -55,6 +55,34 @@ class QrcParsedCacheIndexStoreTest {
         recovered.close()
     }
 
+    @Test
+    fun failedRenameRetainsDestinationCleansTemporaryFileAndCanRetry() {
+        val directory = temporaryFolder.newFolder("blocked-index")
+        val destination = File(directory, QrcParsedCacheIndexStore.INDEX_FILE_NAME)
+        destination.mkdir()
+        val retained = File(destination, "retained.txt").apply { writeText("retain") }
+        val logs = mutableListOf<String>()
+        val store = QrcParsedCacheIndexStore(directory) { logs += it }
+        try {
+            store.upsert(entry("song-a", "a.json", 30))
+            store.flushNow()
+            assertEquals("retain", retained.readText())
+            assertTrue(logs.any { it.contains("save failed") })
+            assertFalse(directory.listFiles().orEmpty().any { it.name.endsWith(".tmp") })
+            destination.deleteRecursively()
+            store.flushNow()
+            assertTrue(destination.isFile)
+            val restored = QrcParsedCacheIndexStore(directory) { }
+            try {
+                assertEquals(listOf("song-a"), restored.snapshot().map { it.songKey })
+            } finally {
+                restored.close()
+            }
+        } finally {
+            store.close()
+        }
+    }
+
     private fun entry(songKey: String, fileName: String, lines: Int) =
         QrcParsedCacheIndexStore.Entry(
             songKey = songKey,
diff --git a/docs/ALBUM_ART_ARCHITECTURE.md b/docs/ALBUM_ART_ARCHITECTURE.md
index 24a6a60..ec92f40 100644
--- a/docs/ALBUM_ART_ARCHITECTURE.md
+++ b/docs/ALBUM_ART_ARCHITECTURE.md
@@ -43,6 +43,7 @@
 12. V4 第三阶段的预测模型可以记录“已有精确 artwork cache”这一 readiness，但当前 QQ 音乐不暴露高置信下一/上一首 identity，因此没有执行候选图片预编码、跨端 Preview/HQ 预取或猜测式图片晋升。正式封面仍只按当前 trackId/generation 发布。
 13. TrackInfo、PlaybackState、Preview/HQ A1 和 CurrentWord 使用同一个经过 identity 复核的 wire generation；Sony 捕获一次传输 generation 后贯穿 Start/Chunk/End，迟到旧 generation 不能覆盖 iOS 或 Sony PlayerAgent 当前封面。
 14. Android notify callback 不能等同 L2CAP 已排空。封面 binary 使用 15ms 最小 pacing；command write 到达时同步预留 response quiet window，避免频繁切歌与 HQ 并发时写响应被 L2CAP hold queue 挤掉。该节流不作用于 JSON、歌词或 CurrentWord。
+15. iOS 在 inactive/background 收到当前歌曲 offer 后可请求 preview，命令队列跳过冻结的 HQ/同步请求并移除旧 artworkId 请求。offer、缓存命中、缩略图写入及 ActivityKit 发布使用有限后台任务，完成或系统到期结束，每个任务最多 15 秒；HQ 等重任务继续等待前台。共享缩略图原子写入并使用首次解锁后可读的文件保护，ContentState 仍只传 key/revision。此链路依赖系统提供 BLE 事件执行机会，后台调度及锁屏显示的本次验证边界见 [CONTROL_INTERACTION_AUDIT.md](CONTROL_INTERACTION_AUDIT.md)。
 
 ## 关键状态
 
diff --git a/docs/CONTROL_INTERACTION_AUDIT.md b/docs/CONTROL_INTERACTION_AUDIT.md
new file mode 100644
index 0000000..4707312
--- /dev/null
+++ b/docs/CONTROL_INTERACTION_AUDIT.md
@@ -0,0 +1,123 @@
+# iOS 滑杆、后台封面修复与全仓代码审计
+
+审计日期：2026-10-01。审计与修复基线为 `acef77b`；提交和合并状态以关联 GitHub PR 为准。
+
+iOS 音量无法拖动的原因已在模拟器中复现并修复；共用该控件的播放进度也一起修复。喇叭图标保持展示用途，直接拖动音量滑杆即可调节。随后按用户要求修复了后台封面更新及此前审计发现的四类问题，并处理 Sony lint 的全部 20 个错误。修复和自动化通过不能据此宣称整体代码没有缺陷，实机联动验收仍未执行。
+
+## 滑杆根因与修复
+
+旧版 [ContentView.swift](../IOSBleFeasibility/IOSBleFeasibility/ContentView.swift) 中的 `CompactPlayerSlider` 单独绘制轨道与滑块，再将实际接收触摸的 SwiftUI `Slider` 设置为 `.opacity(0.001)`。模拟器中的 `UIHostingController`、`UIWindow.hitTest` 测试确认实际控件有效透明度为 `0.001`，轨道中心没有命中该控件。修复前该回归测试有两项断言失败。
+
+现在由同一个可见的原生 `UISlider` 绘制并处理交互，通过 `UIViewRepresentable` 接入原有绑定。保留细轨道和小滑块外观，将实际触摸高度扩大到 44pt。音量仍按整数档位调整，播放进度仍连续调整；拖动期间保留本地编辑值，沿用原有拖动更新与松手最终提交，禁用时拒绝修改。VoiceOver 调整也完成一次完整的开始与结束回调。
+
+BLE UUID、命令名、歌词和封面 payload、A1/A2 header 均未修改；后台命令调度增加下文说明的当前 preview 例外。
+
+## 后台封面空白的根因与修复
+
+证据：[BLETestManager.swift](../IOSBleFeasibility/IOSBleFeasibility/BLETestManager.swift) 的 `flushCommandWriteQueue`、`albumArtSendCommand` 和 `publishLiveArtworkIfCurrent`。原先命令队列在非 active 状态冻结全部非控制请求，包含 `ALBUM_ART_REQUEST quality=preview`。后台切歌会清理旧歌曲的灵动岛封面，新歌曲即使收到 offer，也无法发出拉图请求；恢复前台才有机会取到新图。这是源码确认的调度缺口，没有用实机后台切歌进行复现。
+
+现在后台可发送当前 artworkId 的 preview，请求从队列中寻找可执行项，避免被冻结的历史或 HQ 请求挡住；切歌后的旧 artworkId 请求会被移除。HQ、历史、诊断和周期同步仍等待前台。BLE offer 到缩略图编码、共享文件写入与 ActivityKit 更新之间使用有限后台任务，各任务最多 15 秒；成功发布、回到前台、断线及系统/本地期限到达均会结束相应任务。已有缓存命中同样经过这条发布链路。
+
+共享 JPEG 使用原子写入和 `completeFileProtectionUntilFirstUserAuthentication`，支持设备首次解锁后在锁屏期间读取。保留 80×80 缩略图、20KB 文件上限、key/revision 和歌曲身份校验，迟到任务不能覆盖新歌曲；图片正文不进入 Live Activity ContentState。
+
+自动化覆盖当前 preview 放行、旧图及 HQ/历史/诊断冻结、绕过冻结队首、共享 JPEG 可解码、文件预算、失败写入保留上一个版本及清理。真实后台唤醒、锁屏文件权限和灵动岛显示未实机验证。后台更新仍取决于 iOS 提供的 BLE 事件执行机会，有限任务不是常驻运行保证，见 [Apple Core Bluetooth 后台说明](https://developer.apple.com/library/archive/documentation/NetworkingInternetWeb/Conceptual/CoreBluetooth_concepts/CoreBluetoothBackgroundProcessingForIOSApps/PerformingTasksWhileYourAppIsInTheBackground.html) 和 [UIKit 有限后台任务说明](https://developer.apple.com/documentation/uikit/extending-your-app-s-background-execution-time)。
+
+## 同批修复的交互问题
+
+| 问题 | 修复 | 验证依据 |
+|---|---|---|
+| 音量和进度共用的透明滑杆无法命中 | 使用可见原生控件，触摸高度 44pt | 修复前失败、修复后通过的控件命中测试 |
+| VoiceOver 等非触摸调节需要结束编辑并提交 | 非触摸修改完成一次编辑生命周期 | 原生无障碍调节回归测试 |
+| 设备详情或全屏歌词退出时立即打开诊断，存在弹窗切换竞争 | 记录目标，在原弹窗 `onDismiss` 后打开诊断 | 源码检查及完整 iOS 编译；未执行弹窗端到端测试 |
+| 更多菜单、歌词关闭、回到当前行、查看原因和歌词行触摸区域偏小 | 相关触摸区域至少 44pt，关闭按钮保留原图形尺寸 | 布局源码检查及完整 iOS 编译 |
+| 全屏歌词上一首和下一首缺少明确无障碍名称 | 增加本地化无障碍标签 | 源码检查及完整 iOS 编译 |
+
+新增回归测试位于 [PerformanceStabilityTests.swift](../IOSBleFeasibility/IOSBleFeasibilityTests/PerformanceStabilityTests.swift)：控件命中、连续拖动只结束一次编辑、无障碍调节提交，以及禁用时不更新值或开启编辑。音量档位和连续进度两种配置均有交互回调覆盖；这些测试没有连接 Sony 或验证远端实际音量。
+
+## 审计覆盖范围
+
+| 范围 | 本次检查 |
+|---|---|
+| iOS 播放界面 | 主界面两种布局、播放与音量绑定、歌词页、菜单、设置、历史与诊断入口；透明度、禁用状态、动作绑定和弹窗生命周期 |
+| iOS 状态与传输 | Observation stores、连接健康与重连、控制队列、音量合并、进度编辑、历史分包与请求收尾、歌词诊断期限、后台 preview 和共享缩略图、Live Activity 控制边界 |
+| Sony 端 | 页面导航和动作注册、媒体命令、音量诊断、QRC 缓存与 API 兼容、GATT 与权限 lint；全部现有 JVM 单测和 Debug 构建 |
+| Android Controller | 进度与音量 Compose 状态、动作和禁用条件、诊断请求；全部现有 JVM 单测、Debug 构建和 lint |
+| 工具与配置 | smoke 报告 Python 测试、42 个 shell 脚本语法、构建与 manifest 检查、改动和既有验收边界 |
+
+结构发现使用重新建立并在修复后刷新的完整代码图谱，调用关系结合真实源文件和 `rg` 核对。本次没有逐项执行全部产品验收场景；系统回调、蓝牙时序和跨端并发也不能仅靠图谱或单测证明正确。
+
+## 此前审计问题的修复结果
+
+P1 表示功能可能持续不可用或在声明支持的平台上崩溃；P2 表示局部交互或诊断状态异常。以下四项均已修复。
+
+### P1 历史同步在缺包或断线后无法重试
+
+证据：[BLETestManager.swift](../IOSBleFeasibility/IOSBleFeasibility/BLETestManager.swift) 的 `syncPlaybackHistory`、`loadMorePlaybackHistory`、`handleHistoryPayloadEnd` 和 `clearConnectionTransports`；[PlaybackHistoryView.swift](../IOSBleFeasibility/IOSBleFeasibility/PlaybackHistoryView.swift) 的刷新禁用条件。
+
+原先同步和分页设置忙碌状态，缺包、长度不符或 JSON 解码失败只记录日志并返回；断线没有重置历史传输和统计队列，也没有响应完成期限，刷新入口可能一直禁用。
+
+现在发送结果、无效 start/chunk、缺包、长度/JSON/envelope 错误、响应类型不符和结构化命令错误统一进入失败收尾。每个历史及统计请求有 30 秒完成期限，成功或失败都会取消期限并清理请求；失败的统计项继续下一项。断线及清空本地缓存重置传输 token、队列和忙碌状态，旧连接的异步解码/合并回调不能改写新连接的界面。同步游标不推进时停止循环并允许重试。回归覆盖缺包、坏 JSON、发送失败、超时、断线、旧响应隔离和统计队列恢复，以及正常分页、游标持久化、统计完成、加载中去重和完成后再次加载；不包含实机丢包注入。
+
+### P1 Sony 使用了高于声明最低版本的 Java API
+
+证据：[PlayerAgentApp/build.gradle](../PlayerAgentApp/build.gradle) 声明 `minSdk 23`，未开启 core library desugaring；修复前 lint 列出 15 个 `NewApi` 错误。
+
+- [CurrentLyricProbe.kt](../PlayerAgentApp/src/main/java/com/example/playeragent/media/CurrentLyricProbe.kt)：将 API 24 的 `Character.UnicodeScript` 改为兼容的 UnicodeBlock 汉字识别。
+- [QrcLyricCacheManager.kt](../PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcLyricCacheManager.kt)：将 API 24 的 `ConcurrentHashMap.computeIfAbsent` 改为同步的共享实例初始化。
+- [QrcParsedCacheIndexStore.kt](../PlayerAgentApp/src/main/java/com/example/playeragent/media/QrcParsedCacheIndexStore.kt)：移除 API 26 的 java.nio 文件移动；写入先 sync，再在同一目录 rename，失败保留旧索引并清理临时文件。写入串行化，避免 debounce 与 flush 相互覆盖。
+
+新增汉字识别及索引 rename 失败后恢复的 JVM 回归，既有索引持久化测试继续通过。另修复 3 个 `WrongConstant`（API 33 同步返回值使用 BluetoothStatusCodes.SUCCESS，异步 GATT 回调仍使用 GATT_SUCCESS）、1 个 `CoarseFineLocation`（旧系统 coarse/fine 权限配对）和 1 个 `UnspecifiedRegisterReceiverFlag`（ContextCompat 显式 NOT_EXPORTED）。保持 minSdk 23，没有新增 lint suppress 或降低门槛；没有在 Android 6/7 设备运行。
+
+### P2 歌词诊断请求未发出也会一直等待
+
+证据：[BLETestManager.swift](../IOSBleFeasibility/IOSBleFeasibility/BLETestManager.swift) 的 `requestLyricDiagnostic`、`sendCommand`、`handlePeripheralDisconnect`，以及 [LyricDiagnosticView.swift](../IOSBleFeasibility/IOSBleFeasibility/LyricDiagnosticView.swift) 的进入与刷新动作。
+
+原先请求只检查缓存曲目 ID，设置 loading 后即使 `sendCommand` 没有发出，也无法收尾；没有响应期限，断线或无响应时可能一直等待。
+
+现在请求先检查当前曲目、连接和前台状态，再检查发送入队结果；发送失败、Sony unavailable/结构化错误、10 秒响应超时和断线都会结束 loading 并显示本地化可重试原因。新请求取消旧期限，切歌取消旧等待，成功取消期限。回归覆盖发送失败、离线缓存曲目刷新、旧期限隔离、成功及超时；没有执行诊断页面实机端到端测试。
+
+### P2 旧 Android Controller 的音量回包可能覆盖拖动值
+
+证据：[ControllerAppUi.kt](../ControllerApp/src/main/java/com/example/controllerapp/ui/ControllerAppUi.kt) 的 `VolumeControl`。
+
+原先 `remember(playback.volumeCurrent, playback.volumeMax)` 会在旧回包到达时重建拖动值，使滑杆跳回或松手提交旧档位。
+
+按用户追加授权修复旧兼容模块。独立的 `VolumeSliderState` 在拖动时保留本地值，90ms 更新和松手提交都读取该值；松手后恢复远端状态，禁用/断线取消编辑，范围变化约束到合法档位。新增 JVM 回归覆盖旧回包、最终提交、范围缩小和取消编辑；没有执行 Compose UI 实机测试。
+
+## 自动化验证结果
+
+| 检查 | 结果 |
+|---|---|
+| 修复前的滑杆命中回归 | 预期失败：1 个测试，2 项断言失败 |
+| iOS 全部 XCTest | PASS，67 项，0 失败；iPhone 16 Pro 模拟器，iOS 18.3 |
+| Sony JVM 单测与 Debug 构建 | PASS，137 项测试，0 失败 |
+| Android Controller JVM 单测与 Debug 构建 | PASS，34 项测试，0 失败 |
+| Android Controller lint | PASS，0 errors / 30 warnings |
+| Sony lint | PASS，0 errors / 34 warnings；修复前 20 errors / 33 warnings |
+| smoke 报告 Python 单测 | PASS，49 项 |
+| shell 语法 | PASS，42 个脚本通过 `bash -n` |
+| 差异格式与既有改动保护 | `git diff --check` PASS；用户已有部署脚本和 InfoPlist 改动保持原内容，String Catalog 原条目保持原值，仅追加两个诊断提示 |
+
+Sony lint 的 20 个错误均已消除。仍有 34 个 warning，包含原有 33 个建议及显式引入与 Controller 一致的 androidx.core 1.13.1 后新增的依赖版本建议；没有为消除 warning 进行全仓依赖升级。既有 V4 验收记录是历史基线，见 [V4_ACCEPTANCE_STATUS.md](V4_ACCEPTANCE_STATUS.md)，本报告不改写此前的实机或性能验收结论。
+
+验证命令：
+
+```bash
+xcodebuild -project IOSBleFeasibility/IOSBleFeasibility.xcodeproj \
+  -scheme sonyMusic -destination 'platform=iOS Simulator,name=iPhone 16 Pro,OS=18.3' \
+  -parallel-testing-enabled NO CODE_SIGNING_ALLOWED=NO test
+
+bash gradlew :PlayerAgentApp:testDebugUnitTest :PlayerAgentApp:assembleDebug \
+  :PlayerAgentApp:lintDebug :ControllerApp:testDebugUnitTest \
+  :ControllerApp:assembleDebug :ControllerApp:lintDebug
+python3 -m unittest discover -s tools/smoke/tests -v
+git diff --check
+```
+
+Android 验证使用本机缓存的 JDK 17。上述 Xcode 命令用模拟器名称表达，实际执行时以同一模拟器的 ID 定位并将 DerivedData 与结果包放在仓库外。
+
+初次滑杆修复和工具验证保存在 `/tmp/musicble-control-audit-20261001/`，包括修复前的 `BeforeFix.xcresult`、修复后的 `InteractionAudit.xcresult` 和 `python-tests.log`。后台封面及四项审计修复的最终验证保存在 `/tmp/musicble-background-artwork-20261001/`，包括 `BackgroundAndAuditFinal2.xcresult`、`ios-tests-final2.log` 和 `android-checks.log`。最终 67 项通过结果替代了前两轮受测试蓝牙状态回调干扰的结果，以及新增成功路径测试误读私有字段导致的中间编译失败；该测试改为验证公开操作和状态，没有放宽生产代码访问权限。Python 和 shell 工具本轮没有继续修改，沿用同一工作区首轮通过结果。临时产物不提交到仓库。
+
+GitHub 提交前又在独立修复 worktree 中验证了只含本次改动的代码：iOS 67、Sony 137、Android Controller 34 项测试均通过，两端 Android Debug 构建和 lint 通过；本地化只包含本次新增的两个诊断提示。结果保存在 `/tmp/musicble-background-artwork-20261001/publish/IsolatedCommit.xcresult`、`publish/ios-tests.log` 和 `publish/android-checks.log`。GitHub PR 和合并后的 CI 是独立的交付检查。
+
+按用户要求没有实机演示、安装或跨设备 smoke；实机 quick/full smoke 均未执行，模拟器测试不替代 iPhone 与 Sony 的实际联动验收。GitHub 交付只包含本次修复、回归测试、文档及两个新增诊断提示，用户已有的部署脚本、InfoPlist 和其他本地化改动保留在原工作区。
diff --git a/docs/IOS_ARCHITECTURE.md b/docs/IOS_ARCHITECTURE.md
index e908b7d..2b60651 100644
--- a/docs/IOS_ARCHITECTURE.md
+++ b/docs/IOS_ARCHITECTURE.md
@@ -69,6 +69,10 @@ CoreBluetooth 使用 `com.musicblecontroller.sony.central.v1` 做状态恢复，
 
 用户控制与播放状态 fallback 共用串行 command write 队列，但普通 `GET_PLAYBACK_STATE` 会被更新的 fallback 或新的用户控制合并；前台恢复验证与 Health probe 的请求序列受保护。NEXT/PREVIOUS fallback 等待 1 秒，优先让 Sony 的正式 TrackInfo/PlaybackState 主动推送完成；新 trackId 一旦被接受即取消剩余 fallback。该策略不新增 Timer、不重发控制命令，也不改变 BLE 协议。
 
+后台队列允许用户控制和当前 artworkId 的 preview，请求可越过冻结的 HQ/历史/诊断项；旧封面请求会被清理。封面 offer 到 App Group 缩略图及 ActivityKit 发布使用有限后台任务，最多 15 秒或系统提前到期；不增加后台轮询。缩略图使用原子写入及首次解锁后可读的文件保护，完整边界见 [ALBUM_ART_ARCHITECTURE.md](ALBUM_ART_ARCHITECTURE.md)。
+
+`sendCommand` 返回能否入队，业务请求继续等待 Sony 响应。历史/统计请求有 30 秒完成期限，歌词诊断有 10 秒期限；发送失败、错误响应、缺包、解析失败、超时和断线清理请求及忙碌状态。断线或清空历史缓存使历史 transfer token 失效，旧异步回调不能写回新连接的界面；统计失败继续下一项，切歌或新的诊断请求取消旧诊断期限。
+
 ## 关键状态
 
 - 连接：`connectionStatus`、`connectionDisplayState`、`connectionHealthState`、`autoReconnectState`。