diff --git a/android/app/src/main/cpp/pstr_mpv.cpp b/android/app/src/main/cpp/pstr_mpv.cpp
index dffa0ba..ff1d808 100644
--- a/android/app/src/main/cpp/pstr_mpv.cpp
+++ b/android/app/src/main/cpp/pstr_mpv.cpp
@@ -323,8 +323,11 @@ class Player {
         // needs no window, and a load that cannot get one plays audio anyway —
         // waiting for a surface here is what made background playback fail after
         // a five-second stall.
-        if (!audio.empty()) set_string("alang", audio);
-        if (!subtitle.empty()) set_string("slang", subtitle);
+        //
+        // Set even when empty: mpv keeps both across `loadfile`, so a file
+        // with no language preference used to inherit the last one's.
+        set_string("alang", audio);
+        set_string("slang", subtitle);
         set_string("sid", subtitles ? "auto" : "no");
         pending_start_.store(std::max(0.0, start));
         // Retire the outgoing file's position, duration and end flag *before*
diff --git a/android/app/src/main/java/io/narl/protonstream/playback/NativeMpvHost.kt b/android/app/src/main/java/io/narl/protonstream/playback/NativeMpvHost.kt
index 8815ca8..7fa0fd4 100644
--- a/android/app/src/main/java/io/narl/protonstream/playback/NativeMpvHost.kt
+++ b/android/app/src/main/java/io/narl/protonstream/playback/NativeMpvHost.kt
@@ -322,7 +322,17 @@ class NativeMpvHost private constructor(private val nativeHandle: Long) : Libmpv
     fun selectTrack(track: MpvTrack?) {
         val audio = track?.type == "audio"
         withOpenHandle { nativeSelectTrack(it, audio, track?.id ?: -1) }
-        refreshTracks()
+        // mpv makes the switch on its own thread and lists it a moment later,
+        // so a track list read back now still ticks the old track. The tick
+        // moves here, and a read shortly after confirms it.
+        val type = if (audio) "audio" else "sub"
+        mutableTracks.value = mutableTracks.value.map {
+            if (it.type == type) it.copy(selected = it.id == track?.id) else it
+        }
+        scope.launch(Dispatchers.Default) {
+            delay(TRACK_SETTLE_MS)
+            refreshTracks()
+        }
     }
 
     /**
@@ -558,6 +568,9 @@ class NativeMpvHost private constructor(private val nativeHandle: Long) : Libmpv
         private const val CACHED_UNTIL = 13
         private const val LOADED = 14
 
+        /** How long after a track switch mpv's track list is read again. */
+        private const val TRACK_SETTLE_MS = 300L
+
         init {
             System.loadLibrary("pstr_android")
             System.loadLibrary("pstr_mpv")
diff --git a/docs/BUGS.md b/docs/BUGS.md
index 8f7607d..938168d 100644
--- a/docs/BUGS.md
+++ b/docs/BUGS.md
@@ -12,20 +12,27 @@ All of B14–B33 came out of a static review of the Android client
 device** — there was no Android acceptance harness to reproduce them with, which
 is itself B42. Each states the reasoning that identifies it; treat the
 reproduction step as part of the fix. The remediation order is `plan.md` at the
-repository root; Phases 1 to 5 of it have landed except for the tail of B41 and
-one row of Phase 5's table — everything from B14 to B39 is below in **Fixed**,
-and B41 states which of its items are done.
+repository root; Phases 1 to 5 of it have landed except for one row of Phase
+5's table — everything from B14 to B39 is below in **Fixed**, and B41's items
+have all landed.
 
 ### B41 — assorted correctness and hygiene defects
 
-Individually small, grouped so they are not lost. The items marked **Landed**
-came with Phases 4 and 5; the rest are still open, which is why this entry is.
-What remains is one item: the asynchronous track-list read-back.
+Individually small, grouped so they are not lost. Every item has now landed;
+the entry stays here, with B42, until a device run confirms them.
 
-- `NativeMpvHost.kt:131-135` reads the track list back immediately after an
-  asynchronous property set, so the selection tick lags by up to a second;
-  `alang`/`slang` are applied only at load (`pstr_mpv.cpp:225-227`), so a
-  language change takes effect one episode late.
+- **Landed.** `NativeMpvHost.selectTrack` read the track list back straight
+  after setting `aid`/`sid`, before mpv had made the switch, so the tick in the
+  track chooser stayed on the old track until the next poll, up to a second
+  later. The tick now moves when the track is chosen, and the list is read again
+  300 ms after. The second half of the report, a language change landing one
+  episode late, did not hold up: the choice is saved from the chosen track, and
+  the next episode loads with it. What was wrong nearby is that `load` set
+  `alang` and `slang` only when they were not empty, and mpv keeps both across
+  `loadfile`, so a file with no language preference took the previous file's.
+  Both are set on every load now. The iOS client had the same early read in
+  `MpvPlayer.select` and takes the same fix; it already set both languages on
+  every load.
 - **Landed.** `NativeMpvHost.kt` polled on `Dispatchers.Main.immediate`, and
   `tracks_json` issues five `mpv_get_property` calls per track — 51 synchronous
   property reads on the UI thread for a 10-track file, contending on the core
diff --git a/ios/ProtonStream/Player/MpvPlayer.swift b/ios/ProtonStream/Player/MpvPlayer.swift
index 1fce6c8..bf68f4b 100644
--- a/ios/ProtonStream/Player/MpvPlayer.swift
+++ b/ios/ProtonStream/Player/MpvPlayer.swift
@@ -32,7 +32,7 @@ struct MpvTrack: Identifiable, Hashable {
     let type: String
     let language: String
     let title: String
-    let selected: Bool
+    var selected: Bool
     /// The container marks it as the default choice.
     var isDefault = false
     /// The container marks it as forced: on-screen text only, by convention.
@@ -303,7 +303,18 @@ final class MpvPlayer {
     /// A track, or none: `nil` turns subtitles off.
     func select(type: String, track: MpvTrack?) {
         setString(type == "audio" ? "aid" : "sid", track.map { String($0.id) } ?? "no")
-        refreshTracks()
+        // mpv makes the switch on its own thread and lists it a moment later,
+        // so a track list read back now still ticks the old track. The tick
+        // moves here, and a read shortly after confirms it.
+        tracks = tracks.map { listed in
+            var listed = listed
+            if listed.type == type { listed.selected = listed.id == track?.id }
+            return listed
+        }
+        Task { [weak self] in
+            try? await Task.sleep(for: .milliseconds(300))
+            self?.refreshTracks()
+        }
     }
 
     /// Showing no picture while backgrounded keeps the audio playing: iOS