services(cartesia): make sure we close the client on exit

src/pipecat/services/cartesia.py

@@ -8,7 +8,7 @@ from cartesia import AsyncCartesia
 
 from typing import AsyncGenerator
 
-from pipecat.frames.frames import AudioRawFrame, Frame
+from pipecat.frames.frames import AudioRawFrame, CancelFrame, EndFrame, Frame, StartFrame
 from pipecat.services.ai_services import TTSService
 
 from loguru import logger
@@ -28,22 +28,33 @@ class CartesiaTTSService(TTSService):
         super().__init__(**kwargs)
 
         self._api_key = api_key
+        self._voice_id = voice_id
         self._model_id = model_id
         self._output_format = {
             "container": "raw",
             "encoding": encoding,
             "sample_rate": sample_rate,
         }
-
-        try:
-            self._client = AsyncCartesia(api_key=self._api_key)
-            self._voice = self._client.voices.get(id=voice_id)
-        except Exception as e:
-            logger.exception(f"{self} initialization error: {e}")
+        self._client = None
 
     def can_generate_metrics(self) -> bool:
         return True
 
+    async def start(self, frame: StartFrame):
+        try:
+            self._client = AsyncCartesia(api_key=self._api_key)
+            self._voice = self._client.voices.get(id=self._voice_id)
+        except Exception as e:
+            logger.exception(f"{self} initialization error: {e}")
+
+    async def stop(self, frame: EndFrame):
+        if self._client:
+            await self._client.close()
+
+    async def cancel(self, frame: CancelFrame):
+        if self._client:
+            await self._client.close()
+
     async def run_tts(self, text: str) -> AsyncGenerator[Frame, None]:
         logger.debug(f"Generating TTS: [{text}]")