Change apply_update / _update_settings return type from set[str] to dict[str, Any]. The dict maps each changed field name to its pre-update value, enabling services to do granular diffing of complex settings objects. Existing call-site patterns ("field" in changed, if changed, iteration) work unchanged; set-difference sites use changed.keys() - {...}.

COMMUNITY_INTEGRATIONS.md

@@ -267,10 +267,10 @@ class MySTTService(STTService):
         self._settings = MySTTSettings(model=model, region=region)
 ```
 
-To react to runtime setting changes, override `_update_settings`. The base implementation applies the delta to `self._settings` and returns the set of field names that changed. Your override should call `super()` first, then act on the changed fields:
+To react to runtime setting changes, override `_update_settings`. The base implementation applies the delta to `self._settings` and returns a `dict` mapping each changed field name to its **pre-update** value. Your override should call `super()` first, then act on the changed fields:
 
 ```python
-async def _update_settings(self, update: STTSettings) -> set[str]:
+async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
     """Apply a settings update, reconfiguring the recognizer if needed."""
     changed = await super()._update_settings(update)
 
@@ -282,12 +282,14 @@ async def _update_settings(self, update: STTSettings) -> set[str]:
     return changed
 ```
 
+The dict keys work like a set for membership tests (`"language" in changed`) and truthiness (`if changed`). Use `changed.keys() - {"language"}` for set difference, or `changed["language"]` to inspect the previous value of a field.
+
 Note that, in this example, the service requires a reconnect to apply the new language. Consider, for each setting, whether your service requires reconnection or can apply changes in-place.
 
-If your service can't yet apply certain settings at runtime, call `self._warn_unhandled_updated_settings(changed)` with the set of unhandled field names so users get a clear log message:
+If your service can't yet apply certain settings at runtime, call `self._warn_unhandled_updated_settings(changed)` with the unhandled field names so users get a clear log message:
 
 ```python
-async def _update_settings(self, update: STTSettings) -> set[str]:
+async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
     changed = await super()._update_settings(update)
 
     if not changed:

src/pipecat/services/ai_service.py

@@ -10,7 +10,7 @@ Provides the foundation for all AI services in the Pipecat framework, including
 model management, settings handling, and frame processing lifecycle methods.
 """
 
-from typing import Any, AsyncGenerator, Dict, Set
+from typing import Any, AsyncGenerator, Dict
 
 from loguru import logger
 
@@ -97,12 +97,13 @@ class AIService(FrameProcessor):
         """
         pass
 
-    async def _update_settings(self, update: ServiceSettings) -> Set[str]:
+    async def _update_settings(self, update: ServiceSettings) -> Dict[str, Any]:
-        """Apply a settings update and return the set of changed field names.
+        """Apply a settings update and return the changed fields.
 
-        The update is applied to ``_settings`` and the changed-field set is
+        The update is applied to ``_settings`` and a dict mapping each changed
-        returned.  The ``model`` field is handled specially: when it changes,
+        field name to its **pre-update** value is returned.  The ``model``
-        ``set_model_name`` is called.
+        field is handled specially: when it changes, ``set_model_name`` is
+        called.
 
         Concrete services should override this method (calling ``super()``)
         to react to specific changed fields (e.g. reconnect on voice change).
@@ -111,7 +112,7 @@ class AIService(FrameProcessor):
             update: A settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = self._settings.apply_update(update)
 
@@ -119,16 +120,15 @@ class AIService(FrameProcessor):
             self.set_model_name(self._settings.model)
 
         if changed:
-            logger.info(f"{self.name}: updated settings fields: {changed}")
+            logger.info(f"{self.name}: updated settings fields: {set(changed)}")
 
         return changed
 
-    def _warn_unhandled_updated_settings(self, unhandled: Set[str]):
+    def _warn_unhandled_updated_settings(self, unhandled):
         """Log a warning for settings changes that won't take effect at runtime.
 
-        Convenience helper for ``_update_settings`` overrides.  Call with the
+        Convenience helper for ``_update_settings`` overrides.  Accepts any
-        set of field names that changed but that the service does not (yet)
+        iterable of field names (a ``dict``, ``set``, ``dict_keys``, etc.).
-        apply at runtime.
 
         Args:
             unhandled: Field names that changed but are not applied.

src/pipecat/services/assemblyai/stt.py

@@ -184,7 +184,7 @@ class AssemblyAISTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.
@@ -193,7 +193,7 @@ class AssemblyAISTTService(WebsocketSTTService):
             update: A :class:`STTSettings` (or ``AssemblyAISTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 

src/pipecat/services/aws/nova_sonic/llm.py

@@ -307,7 +307,7 @@ class AWSNovaSonicLLMService(LLMService):
     # settings
     #
 
-    async def _update_settings(self, update: LLMSettings) -> set[str]:
+    async def _update_settings(self, update: LLMSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.

src/pipecat/services/aws/stt.py

@@ -15,7 +15,7 @@ import os
 import random
 import string
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -140,7 +140,7 @@ class AWSTranscribeSTTService(WebsocketSTTService):
         }
         return encoding_map.get(encoding, encoding)
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.

src/pipecat/services/azure/stt.py

@@ -12,7 +12,7 @@ Speech SDK for real-time audio transcription.
 
 import asyncio
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -123,7 +123,7 @@ class AzureSTTService(STTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active recognizer.

src/pipecat/services/cartesia/stt.py

@@ -13,7 +13,7 @@ the Cartesia Live transcription API for real-time speech recognition.
 import json
 import urllib.parse
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -294,14 +294,14 @@ class CartesiaSTTService(WebsocketSTTService):
 
         await self._disconnect_websocket()
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Args:
             update: A :class:`STTSettings` (or ``CartesiaSTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 

src/pipecat/services/cartesia/tts.py

@@ -344,7 +344,7 @@ class CartesiaTTSService(AudioContextWordTTSService):
         """
         return True
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.

src/pipecat/services/deepgram/flux/stt.py

@@ -330,7 +330,7 @@ class DeepgramFluxSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.

src/pipecat/services/deepgram/stt.py

@@ -7,7 +7,7 @@
 """Deepgram speech-to-text service implementation."""
 
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Dict, Optional
+from typing import Any, AsyncGenerator, Dict, Optional
 
 from loguru import logger
 
@@ -195,7 +195,7 @@ class DeepgramSTTService(STTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update, keeping ``live_options`` in sync.
 
         Top-level ``model`` and ``language`` are the source of truth.  When

src/pipecat/services/deepgram/stt_sagemaker.py

@@ -15,7 +15,7 @@ languages, and various Deepgram features.
 import asyncio
 import json
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -163,7 +163,7 @@ class DeepgramSageMakerSTTService(STTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update, keeping ``live_options`` in sync.
 
         Top-level ``model`` and ``language`` are the source of truth.  When

src/pipecat/services/elevenlabs/stt.py

@@ -16,7 +16,7 @@ import io
 import json
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 import aiohttp
 from loguru import logger
@@ -294,7 +294,7 @@ class ElevenLabsSTTService(SegmentedSTTService):
         """
         return language_to_elevenlabs_language(language)
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Converts language to ElevenLabs format before applying and keeps
@@ -304,7 +304,7 @@ class ElevenLabsSTTService(SegmentedSTTService):
             update: A :class:`STTSettings` (or ``ElevenLabsSTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         # Convert language to ElevenLabs format before applying
         if is_given(update.language) and isinstance(update.language, Language):
@@ -543,7 +543,7 @@ class ElevenLabsRealtimeSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update and reconnect if anything changed.
 
         Converts language to ElevenLabs format before applying and keeps
@@ -553,7 +553,7 @@ class ElevenLabsRealtimeSTTService(WebsocketSTTService):
             update: A :class:`STTSettings` (or ``ElevenLabsRealtimeSTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         # Convert language to ElevenLabs format before applying
         if is_given(update.language) and isinstance(update.language, Language):

src/pipecat/services/elevenlabs/tts.py

@@ -471,7 +471,7 @@ class ElevenLabsTTSService(AudioContextWordTTSService):
                 voice_settings[key] = val
         return voice_settings or None
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update, reconnecting as needed.
 
         Uses the declarative ``URL_FIELDS`` and ``VOICE_SETTINGS_FIELDS``
@@ -482,7 +482,7 @@ class ElevenLabsTTSService(AudioContextWordTTSService):
             update: A :class:`TTSSettings` (or ``ElevenLabsTTSSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 
@@ -520,7 +520,7 @@ class ElevenLabsTTSService(AudioContextWordTTSService):
             # Reconnect applies all settings; only warn about fields not handled
             # by voice settings or URL changes.
             handled = ElevenLabsTTSSettings.URL_FIELDS | ElevenLabsTTSSettings.VOICE_SETTINGS_FIELDS
-            self._warn_unhandled_updated_settings(changed - handled)
+            self._warn_unhandled_updated_settings(changed.keys() - handled)
 
         return changed
 
@@ -964,14 +964,14 @@ class ElevenLabsHttpTTSService(WordTTSService):
     def _set_voice_settings(self):
         return build_elevenlabs_voice_settings(self._settings)
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update and rebuild voice settings.
 
         Args:
             update: A :class:`TTSSettings` (or ``ElevenLabsHttpTTSSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
         if changed:

src/pipecat/services/fal/stt.py

@@ -12,7 +12,7 @@ transcription using segmented audio processing.
 
 import os
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -251,7 +251,7 @@ class FalSTTService(SegmentedSTTService):
         """
         return language_to_fal_language(language)
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update, converting language if changed."""
         changed = await super()._update_settings(update)
 

src/pipecat/services/fish/tts.py

@@ -12,7 +12,7 @@ for streaming text-to-speech synthesis with customizable voice parameters.
 
 import uuid
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Literal, Optional
+from typing import Any, AsyncGenerator, Literal, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -184,7 +184,7 @@ class FishAudioTTSService(InterruptibleTTSService):
         """
         return True
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update and reconnect if needed.
 
         Any change to voice or model triggers a WebSocket reconnect.
@@ -193,7 +193,7 @@ class FishAudioTTSService(InterruptibleTTSService):
             update: A :class:`TTSSettings` (or ``FishAudioTTSSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
         if changed:

src/pipecat/services/gladia/stt.py

@@ -379,7 +379,7 @@ class GladiaSTTService(WebsocketSTTService):
         await super().start(frame)
         await self._connect()
 
-    async def _update_settings(self, update: GladiaSTTSettings) -> set[str]:
+    async def _update_settings(self, update: GladiaSTTSettings) -> dict[str, Any]:
         """Apply settings update.
 
         Settings are stored but not applied to the active session.
@@ -388,7 +388,7 @@ class GladiaSTTService(WebsocketSTTService):
             update: A settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 

src/pipecat/services/google/gemini_live/llm.py

@@ -804,7 +804,7 @@ class GeminiLiveLLMService(LLMService):
         """
         return True
 
-    async def _update_settings(self, update: LLMSettings) -> set[str]:
+    async def _update_settings(self, update: LLMSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.

src/pipecat/services/google/stt.py

@@ -630,7 +630,7 @@ class GoogleSTTService(STTService):
         logger.debug(f"Switching STT languages to: {languages}")
         await self._update_settings(GoogleSTTSettings(languages=list(languages)))
 
-    async def _update_settings(self, update: GoogleSTTSettings) -> set[str]:
+    async def _update_settings(self, update: GoogleSTTSettings) -> dict[str, Any]:
         """Apply settings update and reconnect if anything changed.
 
         Handles ``language`` from base ``set_language`` by converting it to
@@ -642,7 +642,7 @@ class GoogleSTTService(STTService):
             update: A settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         from pipecat.services.settings import is_given
 

src/pipecat/services/google/tts.py

@@ -24,7 +24,7 @@ from pipecat.utils.tracing.service_decorators import traced_tts
 os.environ["GRPC_ENABLE_FORK_SUPPORT"] = "false"
 
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, List, Literal, Optional
+from typing import Any, AsyncGenerator, List, Literal, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -680,7 +680,7 @@ class GoogleHttpTTSService(TTSService):
         """
         return language_to_google_tts_language(language)
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Override to handle speaking_rate validation.
 
         Args:
@@ -1024,7 +1024,7 @@ class GoogleTTSService(GoogleBaseTTSService):
             credentials, credentials_path
         )
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Override to handle speaking_rate validation.
 
         Args:
@@ -1259,14 +1259,14 @@ class GeminiTTSService(GoogleBaseTTSService):
                 f"Current rate of {self.sample_rate}Hz may cause issues."
             )
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update with voice validation.
 
         Args:
             update: Settings delta. Can include 'voice', 'prompt', etc.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         if is_given(update.voice) and update.voice not in self.AVAILABLE_VOICES:
             logger.warning(f"Voice '{update.voice}' not in known voices list. Using anyway.")

src/pipecat/services/gradium/stt.py

@@ -13,7 +13,7 @@ WebSocket API for streaming audio transcription.
 import base64
 import json
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -171,14 +171,14 @@ class GradiumSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update, sync params, and reconnect.
 
         Args:
             update: A :class:`STTSettings` (or ``GradiumSTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
         if not changed:

src/pipecat/services/gradium/tts.py

@@ -7,7 +7,7 @@
 import base64
 import json
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -119,14 +119,14 @@ class GradiumTTSService(InterruptibleWordTTSService):
         """
         return True
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update and reconnect if voice changed.
 
         Args:
             update: A :class:`TTSSettings` (or ``GradiumTTSSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         prev_voice = self._voice_id
         changed = await super()._update_settings(update)

src/pipecat/services/inworld/tts.py

@@ -165,7 +165,7 @@ class InworldHttpTTSService(WordTTSService):
         """
         return True
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.

src/pipecat/services/llm_service.py

@@ -313,14 +313,14 @@ class LLMService(UserTurnCompletionLLMServiceMixin, AIService):
             await self._cancel_sequential_runner_task()
         await self._cancel_summary_task()
 
-    async def _update_settings(self, update: LLMSettings) -> set[str]:
+    async def _update_settings(self, update: LLMSettings) -> dict[str, Any]:
         """Apply a settings update, handling turn-completion fields.
 
         Args:
             update: An LLM settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 

src/pipecat/services/neuphonic/tts.py

@@ -14,7 +14,7 @@ import asyncio
 import base64
 import json
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 import aiohttp
 from loguru import logger
@@ -181,7 +181,7 @@ class NeuphonicTTSService(InterruptibleTTSService):
         """
         return language_to_neuphonic_lang_code(language)
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update and reconnect with new configuration."""
         changed = await super()._update_settings(update)
         if changed:

src/pipecat/services/nvidia/stt.py

@@ -9,7 +9,7 @@
 import asyncio
 from concurrent.futures import CancelledError as FuturesCancelledError
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, List, Mapping, Optional
+from typing import Any, AsyncGenerator, List, Mapping, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -579,14 +579,14 @@ class NvidiaSegmentedSTTService(SegmentedSTTService):
         self._config = self._create_recognition_config()
         logger.debug(f"Initialized NvidiaSegmentedSTTService with model: {self.model_name}")
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update and sync internal state.
 
         Args:
             update: A :class:`STTSettings` (or ``NvidiaSegmentedSTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 

src/pipecat/services/openai/stt.py

@@ -17,7 +17,7 @@ Provides two STT services:
 import base64
 import json
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Literal, Optional, Union
+from typing import Any, AsyncGenerator, Literal, Optional, Union
 
 from loguru import logger
 
@@ -268,7 +268,7 @@ class OpenAIRealtimeSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update and send session update if needed.
 
         Keeps ``_language_code`` and ``_prompt`` in sync with settings
@@ -278,7 +278,7 @@ class OpenAIRealtimeSTTService(WebsocketSTTService):
             update: A :class:`STTSettings` (or ``OpenAIRealtimeSTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 

src/pipecat/services/playht/tts.py

@@ -15,7 +15,7 @@ import json
 import struct
 import warnings
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 import aiohttp
 from loguru import logger
@@ -215,7 +215,7 @@ class PlayHTTTSService(InterruptibleTTSService):
         """
         return True
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update.
 
         Settings are stored but not applied to the active connection.

src/pipecat/services/rime/tts.py

@@ -13,7 +13,7 @@ using Rime's API for streaming and batch audio synthesis.
 import base64
 import json
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 import aiohttp
 from loguru import logger
@@ -271,7 +271,7 @@ class RimeTTSService(AudioContextWordTTSService):
         self._extra_msg_fields["inlineSpeedAlpha"] = ",".join(speed_vals + [str(speed)])
         return f"[{text}]"
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update and reconnect if voice changed."""
         prev_voice = self._voice_id
         changed = await super()._update_settings(update)
@@ -977,7 +977,7 @@ class RimeNonJsonTTSService(InterruptibleTTSService):
         except Exception as e:
             yield ErrorFrame(error=f"Unknown error occurred: {e}")
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update and reconnect if necessary.
 
         Since all settings are WebSocket URL query parameters,

src/pipecat/services/sarvam/stt.py

@@ -13,7 +13,7 @@ can handle multiple audio formats for Indian language speech recognition.
 
 import base64
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Dict, Literal, Optional
+from typing import Any, AsyncGenerator, Dict, Literal, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -306,14 +306,14 @@ class SarvamSTTService(STTService):
                 if self._socket_client:
                     await self._socket_client.flush()
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update, validate, sync state, and reconnect.
 
         Args:
             update: A :class:`STTSettings` (or ``SarvamSTTSettings``) delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
 
         Raises:
             ValueError: If a setting is not supported by the current model.

src/pipecat/services/sarvam/tts.py

@@ -42,7 +42,7 @@ import base64
 import json
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import AsyncGenerator, Dict, List, Optional, Tuple
+from typing import Any, AsyncGenerator, Dict, List, Optional, Tuple
 
 import aiohttp
 from loguru import logger
@@ -953,12 +953,12 @@ class SarvamTTSService(InterruptibleTTSService):
         if isinstance(frame, (LLMFullResponseEndFrame, EndFrame)):
             await self.flush_audio()
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a settings update and resend config if voice changed."""
         changed = await super()._update_settings(update)
         if "voice" in changed:
             await self._send_config()
-        self._warn_unhandled_updated_settings(changed - {"voice"})
+        self._warn_unhandled_updated_settings(changed.keys() - {"voice"})
         return changed
 
     async def _connect(self):

src/pipecat/services/settings.py

@@ -19,7 +19,7 @@ Key concepts:
   service's current settings *and* for update objects.  Fields set to
   ``NOT_GIVEN`` are simply skipped when applying an update.
 - **apply_update**: Applies a delta onto a target settings object and returns
-  the set of field names that actually changed.
+  a dict mapping each changed field name to its previous value.
 - **from_mapping**: Constructs a settings object from a plain dict,
   supporting field aliases (e.g. ``"voice_id"`` → ``"voice"``).
 - **Extras**: Unknown keys land in the ``extra`` dict so services that have
@@ -30,7 +30,7 @@ from __future__ import annotations
 
 import copy
 from dataclasses import dataclass, field, fields
-from typing import TYPE_CHECKING, Any, ClassVar, Dict, Mapping, Optional, Set, Type, TypeVar
+from typing import TYPE_CHECKING, Any, ClassVar, Dict, Mapping, Optional, Type, TypeVar
 
 from loguru import logger
 
@@ -140,8 +140,8 @@ class ServiceSettings:
         result.update(self.extra)
         return result
 
-    def apply_update(self: _S, update: _S) -> Set[str]:
+    def apply_update(self: _S, update: _S) -> Dict[str, Any]:
-        """Apply *update* onto this settings object, returning changed field names.
+        """Apply *update* onto this settings object, returning changed fields.
 
         Only fields in *update* that are **given** (i.e. not ``NOT_GIVEN``)
         are considered.  A field is "changed" if its new value differs from
@@ -154,17 +154,19 @@ class ServiceSettings:
             update: A settings object of the same type containing the delta.
 
         Returns:
-            The set of field names whose values actually changed.
+            A dict mapping each changed field name to its **pre-update** value.
+            Use ``changed.keys()`` for the set of names, or index with
+            ``changed["field"]`` to inspect the old value.
 
         Examples::
 
             current = TTSSettings(voice="alice", language="en")
             delta = TTSSettings(voice="bob")
             changed = current.apply_update(delta)
-            # changed == {"voice"}
+            # changed == {"voice": "alice"}
             # current.voice == "bob", current.language == "en"
         """
-        changed: Set[str] = set()
+        changed: Dict[str, Any] = {}
         for f in fields(self):
             if f.name == "extra":
                 continue
@@ -174,14 +176,14 @@ class ServiceSettings:
             old_val = getattr(self, f.name)
             if old_val != new_val:
                 setattr(self, f.name, new_val)
-                changed.add(f.name)
+                changed[f.name] = old_val
 
         # Merge extra
         for key, new_val in update.extra.items():
             old_val = self.extra.get(key, NOT_GIVEN)
             if old_val != new_val:
                 self.extra[key] = new_val
-                changed.add(key)
+                changed[key] = old_val
 
         return changed
 

src/pipecat/services/soniox/stt.py

@@ -217,7 +217,7 @@ class SonioxSTTService(WebsocketSTTService):
         await super().start(frame)
         await self._connect()
 
-    async def _update_settings(self, update: SonioxSTTSettings) -> set[str]:
+    async def _update_settings(self, update: SonioxSTTSettings) -> dict[str, Any]:
         """Apply a settings update, keeping ``input_params`` in sync.
 
         Top-level ``model`` is the source of truth.  When it is given in
@@ -231,7 +231,7 @@ class SonioxSTTService(WebsocketSTTService):
             update: A settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         model_given = is_given(getattr(update, "model", NOT_GIVEN))
 

src/pipecat/services/speechmatics/stt.py

@@ -480,7 +480,7 @@ class SpeechmaticsSTTService(STTService):
         await super().start(frame)
         await self._connect()
 
-    async def _update_settings(self, update: SpeechmaticsSTTSettings) -> set[str]:
+    async def _update_settings(self, update: SpeechmaticsSTTSettings) -> dict[str, Any]:
         """Apply settings update, reconnecting only when necessary.
 
         Fields are classified into three categories (see
@@ -497,7 +497,7 @@ class SpeechmaticsSTTService(STTService):
             update: A settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
 
@@ -505,7 +505,7 @@ class SpeechmaticsSTTService(STTService):
             return changed
 
         no_reconnect = SpeechmaticsSTTSettings.HOT_FIELDS | SpeechmaticsSTTSettings.LOCAL_FIELDS
-        needs_reconnect = bool(changed - no_reconnect)
+        needs_reconnect = bool(changed.keys() - no_reconnect)
 
         if needs_reconnect:
             # Connection-level fields changed — rebuild the SDK config

src/pipecat/services/stt_service.py

@@ -236,19 +236,19 @@ class STTService(AIService):
         await super().cleanup()
         await self._cancel_ttfb_timeout()
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply an STT settings update.
 
         Handles ``model`` (via parent). Does **not** call ``set_language``
         — concrete services should override this method and handle language
         changes (including any reconnect logic) based on the returned
-        changed-field set.
+        changed-field dict.
 
         Args:
             update: An STT settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         changed = await super()._update_settings(update)
         return changed

src/pipecat/services/tts_service.py

@@ -432,20 +432,20 @@ class TTSService(AIService):
             if not (agg_type == aggregation_type and func == transform_function)
         ]
 
-    async def _update_settings(self, update: TTSSettings) -> set[str]:
+    async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
         """Apply a TTS settings update.
 
         Handles ``model`` (via parent) and syncs ``_voice_id`` when voice
         changes.  Translates language values before applying.  Does **not**
         call ``set_voice`` or ``set_model`` directly — concrete services
         should override this method and handle reconnect logic based on the
-        returned changed-field set.
+        returned changed-field dict.
 
         Args:
             update: A TTS settings delta.
 
         Returns:
-            Set of field names whose values actually changed.
+            Dict mapping changed field names to their previous values.
         """
         # Translate language *before* applying so the stored value is canonical
         if is_given(update.language) and update.language is not None:

src/pipecat/services/ultravox/llm.py

@@ -329,7 +329,7 @@ class UltravoxRealtimeLLMService(LLMService):
         changed = await super()._update_settings(update)
         if "output_medium" in changed:
             await self._update_output_medium(self._settings.output_medium)
-        self._warn_unhandled_updated_settings(changed - {"output_medium"})
+        self._warn_unhandled_updated_settings(changed.keys() - {"output_medium"})
         return changed
 
     #

src/pipecat/services/whisper/base_stt.py

@@ -11,7 +11,7 @@ interface, including language mapping, metrics generation, and error handling.
 """
 
 from dataclasses import dataclass, field
-from typing import AsyncGenerator, Optional
+from typing import Any, AsyncGenerator, Optional
 
 from loguru import logger
 from openai import AsyncOpenAI
@@ -174,7 +174,7 @@ class BaseWhisperSTTService(SegmentedSTTService):
     def _create_client(self, api_key: Optional[str], base_url: Optional[str]):
         return AsyncOpenAI(api_key=api_key, base_url=base_url)
 
-    async def _update_settings(self, update: STTSettings) -> set[str]:
+    async def _update_settings(self, update: STTSettings) -> dict[str, Any]:
         """Apply a settings update, syncing instance variables.
 
         Keeps ``_language``, ``_prompt``, and ``_temperature`` in sync with

tests/test_settings.py

@@ -100,7 +100,8 @@ class TestApplyUpdate:
         current = TTSSettings(voice="alice", language="en")
         delta = TTSSettings(voice="bob")
         changed = current.apply_update(delta)
-        assert changed == {"voice"}
+        assert changed.keys() == {"voice"}
+        assert changed["voice"] == "alice"  # old value
         assert current.voice == "bob"
         assert current.language == "en"
 
@@ -108,14 +109,14 @@ class TestApplyUpdate:
         current = TTSSettings(voice="alice", language="en")
         delta = TTSSettings(voice="alice")
         changed = current.apply_update(delta)
-        assert changed == set()
+        assert changed == {}
         assert current.voice == "alice"
 
     def test_apply_update_not_given_skipped(self):
         current = TTSSettings(voice="alice", language="en")
         delta = TTSSettings()  # all NOT_GIVEN
         changed = current.apply_update(delta)
-        assert changed == set()
+        assert changed == {}
         assert current.voice == "alice"
         assert current.language == "en"
 
@@ -123,7 +124,9 @@ class TestApplyUpdate:
         current = LLMSettings(temperature=0.7, max_tokens=100)
         delta = LLMSettings(temperature=0.9, max_tokens=200, top_p=0.95)
         changed = current.apply_update(delta)
-        assert changed == {"temperature", "max_tokens", "top_p"}
+        assert changed.keys() == {"temperature", "max_tokens", "top_p"}
+        assert changed["temperature"] == 0.7
+        assert changed["max_tokens"] == 100
         assert current.temperature == 0.9
         assert current.max_tokens == 200
         assert current.top_p == 0.95
@@ -135,6 +138,7 @@ class TestApplyUpdate:
         delta.extra = {"speed": 1.2}
         changed = current.apply_update(delta)
         assert "speed" in changed
+        assert changed["speed"] == 1.0  # old value
         assert current.extra == {"speed": 1.2, "stability": 0.5}
 
     def test_apply_update_extra_no_change(self):
@@ -143,13 +147,14 @@ class TestApplyUpdate:
         delta = TTSSettings()
         delta.extra = {"speed": 1.0}
         changed = current.apply_update(delta)
-        assert changed == set()
+        assert changed == {}
 
     def test_apply_update_model_field(self):
         current = ServiceSettings(model="old-model")
         delta = ServiceSettings(model="new-model")
         changed = current.apply_update(delta)
-        assert changed == {"model"}
+        assert changed.keys() == {"model"}
+        assert changed["model"] == "old-model"
         assert current.model == "new-model"
 
     def test_apply_update_none_is_a_valid_value(self):
@@ -165,6 +170,7 @@ class TestApplyUpdate:
         delta = TTSSettings(language="en")
         changed = current.apply_update(delta)
         assert "language" in changed
+        assert changed["language"] is None  # old value was None
         assert current.language == "en"
 
 
@@ -293,7 +299,9 @@ class TestRoundtrip:
         delta = TTSSettings.from_mapping(raw)
 
         changed = current.apply_update(delta)
-        assert changed == {"voice", "speed"}
+        assert changed.keys() == {"voice", "speed"}
+        assert changed["voice"] == "alice"
+        assert changed["speed"] == 1.0
         assert current.voice == "bob"
         assert current.language == "en"
         assert current.extra["speed"] == 1.2
@@ -303,6 +311,7 @@ class TestRoundtrip:
         current = LLMSettings(model="gpt-4o", temperature=0.7)
         delta = LLMSettings.from_mapping({"model": "gpt-4o-mini", "temperature": 0.9})
         changed = current.apply_update(delta)
-        assert changed == {"model", "temperature"}
+        assert changed.keys() == {"model", "temperature"}
+        assert changed["model"] == "gpt-4o"
         assert current.model == "gpt-4o-mini"
         assert current.temperature == 0.9