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diff --git a/android/app/src/androidTest/kotlin/com/edde746/plezy/exoplayer/MatroskaLateTracksSeekDeviceTest.kt b/android/app/src/androidTest/kotlin/com/edde746/plezy/exoplayer/MatroskaLateTracksSeekDeviceTest.kt
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+++ b/android/app/src/androidTest/kotlin/com/edde746/plezy/exoplayer/MatroskaLateTracksSeekDeviceTest.kt
@@ -0,0 +1,170 @@
+package com.edde746.plezy.exoplayer
+
+import android.net.Uri
+import android.os.Handler
+import android.os.HandlerThread
+import android.util.Log
+import androidx.media3.common.MediaItem
+import androidx.media3.common.Player
+import androidx.media3.datasource.DefaultDataSource
+import androidx.media3.exoplayer.ExoPlayer
+import androidx.media3.exoplayer.source.ProgressiveMediaSource
+import androidx.media3.extractor.Extractor
+import androidx.media3.extractor.ExtractorsFactory
+import androidx.media3.extractor.mkv.MatroskaExtractor
+import androidx.media3.extractor.text.DefaultSubtitleParserFactory
+import androidx.test.platform.app.InstrumentationRegistry
+import com.edde746.plezy.libass.media.AssHandler
+import com.edde746.plezy.libass.media.parser.AssSubtitleParserFactory
+import java.io.File
+import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.atomic.AtomicBoolean
+import java.util.concurrent.atomic.AtomicReference
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * On-device coverage for MKV files whose SeekHead references Tracks after the Clusters (#1969).
+ *
+ * media3 1.11.0 builds the Matroska seek map at the end of the Cues element, which for these files
+ * is before the Tracks element parsed, so the map permanently reports unseekable and ExoPlayer
+ * coerces every seek to t=0 (ProgressiveMediaPeriod). The first test is a canary asserting the
+ * upstream defect against a stock MatroskaExtractor — when it fails after a media3 upgrade, the
+ * TrackAwareSeekMap repair in [CuelessSeekExtractorWrapper] can be retired. The second test drives
+ * the production wrapper stack and requires the seek to actually land.
+ */
+class MatroskaLateTracksSeekDeviceTest {
+  private companion object {
+    const val TAG = "MkvLateTracksSeek"
+    const val SEEK_TARGET_MS = 500L
+    const val SETTLE_MS = 2_000L
+  }
+
+  private class Session(
+    val handler: Handler,
+    val thread: HandlerThread,
+    val player: AtomicReference<ExoPlayer?>,
+    val fixture: File
+  )
+
+  @Test
+  fun stockMatroskaExtractorSnapsSeeksToStart() {
+    val result = runSeekScenario("stock") { MatroskaExtractor(DefaultSubtitleParserFactory()) }
+    assertFalse(
+      "upstream media3 now reports tracks-after-clusters MKVs seekable — " +
+        "the TrackAwareSeekMap repair in CuelessSeekExtractorWrapper can be retired",
+      result.seekable
+    )
+    assertTrue(
+      "unseekable media must snap the seek to the start, position=${result.positionAfterSeekMs}ms",
+      result.positionAfterSeekMs < SEEK_TARGET_MS / 2
+    )
+  }
+
+  @Test
+  fun wrappedExtractorKeepsSeekPosition() {
+    val result = runSeekScenario("wrapped") {
+      val assHandler = AssHandler()
+      CuelessSeekExtractorWrapper(ZlibMatroskaExtractor(AssSubtitleParserFactory(assHandler), assHandler))
+    }
+    assertTrue("wrapped extractor must report the item seekable", result.seekable)
+    assertTrue(
+      "seek to ${SEEK_TARGET_MS}ms must hold, position=${result.positionAfterSeekMs}ms",
+      result.positionAfterSeekMs >= SEEK_TARGET_MS / 2
+    )
+  }
+
+  private class ScenarioResult(val seekable: Boolean, val positionAfterSeekMs: Long)
+
+  private fun runSeekScenario(label: String, extractorFactory: () -> Extractor): ScenarioResult {
+    val session = openPaused(label, extractorFactory)
+    try {
+      val seekable = onPlayerThread(session) { it.isCurrentMediaItemSeekable }
+      session.handler.post { session.player.get()?.seekTo(SEEK_TARGET_MS) }
+      // The masked position is the seek target; the snap surfaces once the period resolves the
+      // seek, so give the load a moment before sampling the settled position.
+      Thread.sleep(SETTLE_MS)
+      val positionAfterSeekMs = onPlayerThread(session) { it.currentPosition }
+      Log.i(TAG, "==== $label: seekable=$seekable position=${positionAfterSeekMs}ms ====")
+      return ScenarioResult(seekable, positionAfterSeekMs)
+    } finally {
+      teardown(session)
+    }
+  }
+
+  private fun openPaused(label: String, extractorFactory: () -> Extractor): Session {
+    val instrumentation = InstrumentationRegistry.getInstrumentation()
+    val context = instrumentation.targetContext
+    val fixture = copyFixture(context)
+    val thread = HandlerThread("mkv-late-tracks-$label").apply { start() }
+    val handler = Handler(thread.looper)
+    val player = AtomicReference<ExoPlayer?>(null)
+    val ready = CountDownLatch(1)
+    val failed = AtomicBoolean(false)
+
+    handler.post {
+      val exo = ExoPlayer.Builder(context).build()
+      player.set(exo)
+      exo.addListener(
+        object : Player.Listener {
+          override fun onPlaybackStateChanged(playbackState: Int) {
+            if (playbackState == Player.STATE_READY) ready.countDown()
+          }
+
+          override fun onPlayerError(error: androidx.media3.common.PlaybackException) {
+            Log.e(TAG, "$label player error", error)
+            failed.set(true)
+            ready.countDown()
+          }
+        }
+      )
+      val source = ProgressiveMediaSource.Factory(
+        DefaultDataSource.Factory(context),
+        ExtractorsFactory { arrayOf(extractorFactory()) }
+      ).createMediaSource(MediaItem.fromUri(Uri.fromFile(fixture)))
+      exo.setMediaSource(source)
+      exo.playWhenReady = false
+      exo.prepare()
+    }
+
+    val session = Session(handler, thread, player, fixture)
+    if (!ready.await(30, TimeUnit.SECONDS) || failed.get()) {
+      teardown(session)
+      error("$label playback never became ready")
+    }
+    return session
+  }
+
+  private fun <T> onPlayerThread(session: Session, read: (ExoPlayer) -> T): T {
+    val value = AtomicReference<T>()
+    val done = CountDownLatch(1)
+    session.handler.post {
+      session.player.get()?.let { value.set(read(it)) }
+      done.countDown()
+    }
+    assertTrue("player thread stalled", done.await(5, TimeUnit.SECONDS))
+    return checkNotNull(value.get())
+  }
+
+  private fun teardown(session: Session) {
+    val done = CountDownLatch(1)
+    session.handler.post {
+      session.player.get()?.release()
+      done.countDown()
+    }
+    done.await(10, TimeUnit.SECONDS)
+    session.thread.quitSafely()
+    session.thread.join(5_000)
+    session.fixture.delete()
+  }
+
+  private fun copyFixture(context: android.content.Context): File {
+    val output = File.createTempFile("mkv-late-tracks-", ".mkv", context.cacheDir)
+    InstrumentationRegistry.getInstrumentation().context.assets
+      .open("ffmpeg/matroska_tracks_at_end.mkv")
+      .use { input -> output.outputStream().use { input.copyTo(it) } }
+    return output
+  }
+}