fix(android): 2s transport-ack lockout so Prev/Next isn't undone by stale poll

android/app/src/main/java/com/fabledsword/minstrel/player/MinstrelForwardingPlayer.kt

@@ -189,6 +189,7 @@ class MinstrelForwardingPlayer(
             return
         }
         super.seekTo(mediaItemIndex, positionMs)
+        remoteState.markUserTransport(SystemClock.elapsedRealtime())
         scope.launch {
             runCatching {
                 active.avTransport.seekToTrack(mediaItemIndex + 1)
@@ -214,6 +215,7 @@ class MinstrelForwardingPlayer(
         // then delegate to Sonos Next. PollLoop reconciles cursor via
         // Track index if they diverge.
         super.seekToNextMediaItem()
+        remoteState.markUserTransport(SystemClock.elapsedRealtime())
         scope.launch {
             runCatching { active.avTransport.next() }
                 .onFailure { handleSoapFailure(active, it) }
@@ -234,6 +236,7 @@ class MinstrelForwardingPlayer(
         // Super first for immediate local cursor advance (UI feedback);
         // then delegate to Sonos Previous. PollLoop reconciles.
         super.seekToPreviousMediaItem()
+        remoteState.markUserTransport(SystemClock.elapsedRealtime())
         scope.launch {
             runCatching { active.avTransport.previous() }
                 .onFailure { handleSoapFailure(active, it) }

android/app/src/main/java/com/fabledsword/minstrel/player/PlayerController.kt

@@ -525,11 +525,19 @@ class PlayerController @Inject constructor(
         val newPos = effectivePosition.coerceAtLeast(0)
         val newDur = effectiveDuration(upnpActive, remoteState.durationMs, controller.duration)
         val newBuf = controller.bufferedPosition.coerceAtLeast(0)
-        // Forward-only. If desiredIdx < queueIndex, the user just pressed Next
-        // and Sonos's poll hasn't caught up yet -- walking backward would undo
-        // their press (logcat 2026-06-04 showed exactly that jump-back-then-
-        // forward cycle). Mirrors maybeSyncLocalCursor's forward-only policy.
-        val trackChanged = desiredIdx > current.queueIndex && desiredIdx in queueRefs.indices
+        // Two guards against undoing the user's transport action while
+        // remoteState is mid-refresh from the next SOAP poll:
+        //  1. Forward-only: a backward move from desiredIdx < queueIndex
+        //     would undo a Next press (logcat 2026-06-04).
+        //  2. Transport-ack lockout: even forward moves are ignored within
+        //     TRANSPORT_ACK_WINDOW_MS of a user transport action, so a Prev
+        //     press isn't undone by a stale remoteState reading the older
+        //     pre-press track.
+        val sinceTransport = SystemClock.elapsedRealtime() - remoteState.lastUserTransportAtMs
+        val inTransportAckWindow = sinceTransport < TRANSPORT_ACK_WINDOW_MS
+        val trackChanged = !inTransportAckWindow &&
+            desiredIdx > current.queueIndex &&
+            desiredIdx in queueRefs.indices
         val somethingChanged = trackChanged ||
             current.isPlaying != effectiveIsPlaying ||
             current.positionMs != newPos ||
@@ -667,6 +675,7 @@ class PlayerController @Inject constructor(
         const val MINSTREL_SOURCE_KEY: String = "minstrel_source"
         private const val MS_PER_SECOND = 1_000L
         private const val MAX_INTERPOLATION_DRIFT_MS = 5_000L
+        private const val TRANSPORT_ACK_WINDOW_MS = 2_000L
     }
 }
 

android/app/src/main/java/com/fabledsword/minstrel/player/RemotePlayerState.kt

@@ -27,6 +27,18 @@ class RemotePlayerState @Inject constructor() {
     @Volatile var lastError: Throwable? = null; private set
     @Volatile var trackNumber: Int = 0; private set
 
+    // SystemClock.elapsedRealtime() at the last user-initiated transport
+    // (next/prev/seekToIndex). PlayerController.tickPositionPoll uses this to
+    // suppress track-change adjustments during the window where remoteState
+    // hasn't yet refreshed from the next SOAP poll -- without it the polling
+    // tick would walk the cursor back to Sonos's pre-press track and undo
+    // user input. Set from MinstrelForwardingPlayer's transport overrides.
+    @Volatile var lastUserTransportAtMs: Long = 0L; private set
+
+    fun markUserTransport(nowMs: Long) {
+        lastUserTransportAtMs = nowMs
+    }
+
     @Volatile private var consecutivePollFailures: Int = 0
 
     fun applyPositionInfo(positionMs: Long, durationMs: Long, trackUri: String, trackNumber: Int) {
@@ -64,6 +76,7 @@ class RemotePlayerState @Inject constructor() {
         lastError = null
         consecutivePollFailures = 0
         trackNumber = 0
+        lastUserTransportAtMs = 0L
     }
 
     private companion object {