feat: enhance call end coordination with state management

- Added support for tracking call end states (pending, speaking, cancelled) in CallEndCoordinator.
- Introduced a callback mechanism for state changes to allow external handling of call end states.
- Updated pipeline and tests to accommodate new state management features, ensuring proper handling of call end scenarios.

backend/tests/test_call_lifecycle.py

@@ -19,20 +19,26 @@ from services.pipecat.processors import CallEndingUserMuteStrategy
 class CallEndCoordinatorTest(unittest.IsolatedAsyncioTestCase):
     async def asyncSetUp(self):
         self.reasons: list[str] = []
+        self.states: list[tuple[str, bool]] = []
 
         async def queue_end(reason: str) -> None:
             self.reasons.append(reason)
 
-        self.coordinator = CallEndCoordinator(queue_end)
+        async def record_state(state: str, interruptible: bool) -> None:
+            self.states.append((state, interruptible))
+
+        self.coordinator = CallEndCoordinator(queue_end, record_state)
 
     async def test_generated_closing_text_waits_for_audio_stop(self):
         self.coordinator.begin_response()
         self.coordinator.begin("prompt_end_call")
+        await asyncio.sleep(0)
         await self.coordinator.finish_after_current_speech(has_text=True)
 
         self.assertEqual(self.reasons, [])
         await self.coordinator.observe(BotStartedSpeakingFrame())
         self.assertEqual(self.reasons, [])
+        self.assertEqual(self.states[-1], ("speaking", False))
         await self.coordinator.observe(BotStoppedSpeakingFrame())
         self.assertEqual(self.reasons, ["prompt_end_call"])
 
@@ -71,12 +77,17 @@ class CallEndCoordinatorTest(unittest.IsolatedAsyncioTestCase):
     async def test_interruptible_end_keeps_input_open_and_can_be_cancelled(self):
         self.coordinator.begin_response()
         self.coordinator.begin("user_goodbye", interruptible=True)
+        await asyncio.sleep(0)
+        self.assertEqual(self.states[-1], ("pending", True))
         await self.coordinator.finish_after_current_speech(has_text=True)
         await self.coordinator.observe(BotStartedSpeakingFrame())
+        self.assertEqual(self.states[-1], ("speaking", True))
 
         self.assertTrue(self.coordinator.ending)
         self.assertTrue(self.coordinator.accepts_input)
         self.assertTrue(self.coordinator.cancel_pending_end())
+        await asyncio.sleep(0)
+        self.assertEqual(self.states[-1], ("cancelled", False))
         self.assertFalse(self.coordinator.ending)
         self.assertTrue(self.coordinator.accepts_input)
         self.assertTrue(self.coordinator.speaking)