Share media playback devices and await cleanup before calls

tools/chatgui-android/app/src/test/java/com/utun/chat/data/StreamAudioOutputTest.kt

@@ -6,6 +6,7 @@ import java.util.ArrayDeque
 
 class StreamAudioOutputTest {
     private class Device(override val threshold: Int = 1) : StreamAudioOutput.Sink {
+        override var routeChanging = false
         override val bufferFrames = maxOf(960, threshold)
         override var head = 0L
         override val description: String get() = "fake threshold=$threshold"
@@ -84,6 +85,19 @@ class StreamAudioOutputTest {
         assertTrue(p.output.drained)
     }
 
+    @Test fun routeSwitchPreservesPlayerAndClockUntilOutputResumes() {
+        val p = Player(); p.input.add(ShortArray(960) { 7 }); p.step(0)
+        p.device.routeChanging = true
+        var videoSteps = 0
+        for (ms in 5L..30000L step 5) { p.step(ms); videoSteps++ }
+        assertEquals(6000, videoSteps)
+        assertFalse(p.device.closed); assertEquals(0L, p.output.played)
+        assertEquals(List(960) { 7.toShort() }, p.device.samples)
+        p.device.routeChanging = false
+        p.device.head = 480; p.step(30005)
+        assertTrue(p.output.drained)
+    }
+
     @Test fun intentionalPausePreservesPartialPcmAndSuspendsWatchdog() {
         val p = Player(); val pcm = ShortArray(960) { it.toShort() }; p.input.add(pcm); p.device.limit = 120
         p.step(0); p.step(5, true); p.step(10000, true)