diff --git a/tools/chatgui-android/router-tests/src/test/kotlin/com/utun/chat/data/CallAudioLifecycleTest.kt b/tools/chatgui-android/router-tests/src/test/kotlin/com/utun/chat/data/CallAudioLifecycleTest.kt
index 9646f133..bc0c0a7c 100644
--- a/tools/chatgui-android/router-tests/src/test/kotlin/com/utun/chat/data/CallAudioLifecycleTest.kt
+++ b/tools/chatgui-android/router-tests/src/test/kotlin/com/utun/chat/data/CallAudioLifecycleTest.kt
@@ -205,4 +205,23 @@ class CallAudioLifecycleTest {
         assertTrue(diagnostic("record stop failed")); assertTrue(diagnostic("track pause failed"))
         assertEquals(1, stops())
     }
+
+    @Test fun zeroCallIdCannotAcquireResourcesAndBackgroundStopCannotReleaseThem() {
+        assertThrows(IllegalArgumentException::class.java) { engine.start(0) }
+        assertTrue(NativeLib.callAudioCommands.isEmpty()); assertTrue(diagnostic("zero call id"))
+        start()
+        var failure: Exception? = null
+        Thread { try { engine.stop() } catch (e: Exception) { failure = e } }.apply { start(); join() }
+        assertTrue(failure is IllegalStateException); assertTrue(engine.isActive()); assertEquals(0, stops())
+        assertFalse(AudioRecord.created.single().released); assertTrue(diagnostic("stop outside main"))
+    }
+
+    @Test fun lateTelecomOwnershipPreventsRestoringTheFallbackModeDuringStop() {
+        start()
+        engine.bindTelecom(UtunConnection())
+        manager.mode = AudioManager.MODE_IN_COMMUNICATION
+        engine.stop()
+        assertEquals(AudioManager.MODE_IN_COMMUNICATION, manager.mode)
+        assertEquals(false, field("modeOwned")); assertEquals(1, stops())
+    }
 }