Wait for shared Android stream output release before starting calls

tools/chatgui-android/app/src/main/java/com/utun/chat/data/StreamAudioMixer.kt

@@ -24,6 +24,16 @@ internal object StreamAudioMixer {
         LogManager.addLog("INFO", "stream", "mixer input detached id=${input.id} count=${inputs.size}")
     }
 
+    /** После join всех viewers, вне main thread; запуск новых viewers блокирует CallController. */
+    fun awaitIdle() {
+        val closing = synchronized(lock) {
+            check(inputs.isEmpty()) { "Stream mixer still has ${inputs.size} inputs after viewer release" }
+            worker
+        }
+        closing?.join()
+        LogManager.addLog("INFO", "stream", "shared audio output released for call")
+    }
+
     private fun run() {
         val audio = StreamAudioOutput(log = { LogManager.addLog("INFO", "stream", "mixer $it") })
         val mix = StreamMixBuffer()

tools/chatgui-android/app/src/main/java/com/utun/chat/data/StreamPlayerEngine.kt

@@ -33,7 +33,10 @@ class StreamPlayerEngine(private val group: Long, private val source: Long, priv
                 player.mutableStatus.value = R.string.stream_ended
                 player.stop()
             }
-            withContext(Dispatchers.IO) { for (player in stopped) player.worker?.join() }
+            withContext(Dispatchers.IO) {
+                for (player in stopped) player.worker?.join()
+                StreamAudioMixer.awaitIdle()
+            }
             players.removeAll(stopped.toSet())
             mutableViewing.value = players.isNotEmpty()
             LogManager.addLog("INFO", "stream", "viewers released for call count=${stopped.size}")