diff --git a/COMMUNITY_INTEGRATIONS.md b/COMMUNITY_INTEGRATIONS.md
index c7e4c8e90..c79d34b57 100644
--- a/COMMUNITY_INTEGRATIONS.md
+++ b/COMMUNITY_INTEGRATIONS.md
@@ -325,14 +325,14 @@ svc = MyTTSService(
 
 AI services support runtime configuration changes via `*UpdateSettingsFrame`s (e.g. `STTUpdateSettingsFrame`, `TTSUpdateSettingsFrame`, `LLMUpdateSettingsFrame`).
 
-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. A common implementation might look like:
+To react to runtime setting changes, override `_update_settings`. The base implementation applies the delta to `self._settings` and returns a delta-mode settings object of the same type with changed fields set to their **pre-update** values (unchanged fields are `NOT_GIVEN`). Your override should call `super()` first, then act on the changed fields. A common implementation might look like:
 
 ```python
-async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
+async def _update_settings(self, update: TTSSettings) -> TTSSettings:
     """Apply a settings update, reconfiguring the connection if needed."""
     changed = await super()._update_settings(update)
 
-    if not changed:
+    if not changed.given_fields():
         return changed
 
     await self._disconnect()
@@ -341,24 +341,24 @@ async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
     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.
+Use `is_given(changed.language)` to check whether a specific field changed, and `changed.given_fields()` to get a dict of all changed fields. Use `changed.given_fields().keys() - {"language"}` for set difference, or access old values directly with typed attributes (e.g. `changed.language`).
 
 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 any 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.given_fields())` with any unhandled field names so users get a clear log message:
 
 ```python
-async def _update_settings(self, update: TTSSettings) -> dict[str, Any]:
+async def _update_settings(self, update: TTSSettings) -> TTSSettings:
     changed = await super()._update_settings(update)
 
-    if not changed:
+    if not changed.given_fields():
         return changed
 
-    if "language" in changed:
+    if is_given(changed.language):
         await self._update_language()
     else:
         # TODO: this should be temporary - handle changes to other settings soon!
-        self._warn_unhandled_updated_settings(changed.keys() - {"language"})
+        self._warn_unhandled_updated_settings(changed.given_fields().keys() - {"language"})
 
     return changed
 ```
diff --git a/src/pipecat/services/ai_service.py b/src/pipecat/services/ai_service.py
index dd9ef1dba..0bf70b226 100644
--- a/src/pipecat/services/ai_service.py
+++ b/src/pipecat/services/ai_service.py
@@ -24,7 +24,7 @@ from pipecat.frames.frames import (
 )
 from pipecat.metrics.metrics import MetricsData
 from pipecat.processors.frame_processor import FrameDirection, FrameProcessor
-from pipecat.services.settings import ServiceSettings
+from pipecat.services.settings import ServiceSettings, is_given
 
 
 class AIService(FrameProcessor):
@@ -104,13 +104,13 @@ class AIService(FrameProcessor):
         """
         pass
 
-    async def _update_settings(self, delta: ServiceSettings) -> Dict[str, Any]:
+    async def _update_settings(self, delta: ServiceSettings) -> ServiceSettings:
         """Apply a settings delta and return the changed fields.
 
-        The delta is applied to ``_settings`` and a dict mapping each changed
-        field name to its **pre-update** value is returned.  The ``model``
-        field is handled specially: when it changes, ``set_model_name`` is
-        called.
+        The delta is applied to ``_settings`` and a delta-mode settings object
+        is returned with changed fields set to their **pre-update** values.
+        The ``model`` 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).
@@ -119,15 +119,17 @@ class AIService(FrameProcessor):
             delta: A delta-mode settings object.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with changed fields set to their
+            previous values. Unchanged fields are ``NOT_GIVEN``.
         """
         changed = self._settings.apply_update(delta)
 
-        if "model" in changed:
+        if is_given(changed.model):
             self._sync_model_name_to_metrics()
 
-        if changed:
-            logger.info(f"{self.name}: updated settings fields: {set(changed)}")
+        changed_fields = changed.given_fields()
+        if changed_fields:
+            logger.info(f"{self.name}: updated settings fields: {set(changed_fields)}")
 
         return changed
 
diff --git a/src/pipecat/services/assemblyai/stt.py b/src/pipecat/services/assemblyai/stt.py
index f52c1d935..4479b9687 100644
--- a/src/pipecat/services/assemblyai/stt.py
+++ b/src/pipecat/services/assemblyai/stt.py
@@ -353,18 +353,18 @@ class AssemblyAISTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> STTSettings:
         """Apply a settings delta and reconnect to apply changes.
 
         Args:
             delta: A settings delta with updated values.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with changed fields.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # Reconnect to apply updated settings (they become WS query params)
diff --git a/src/pipecat/services/asyncai/tts.py b/src/pipecat/services/asyncai/tts.py
index 42c0a09a4..8be275dfa 100644
--- a/src/pipecat/services/asyncai/tts.py
+++ b/src/pipecat/services/asyncai/tts.py
@@ -202,17 +202,17 @@ class AsyncAITTSService(WebsocketTTSService):
         self._receive_task = None
         self._keepalive_task = None
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> Settings:
         """Apply a settings delta.
 
         Settings are stored but not applied to the active connection.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
 
         return changed
 
diff --git a/src/pipecat/services/aws/nova_sonic/llm.py b/src/pipecat/services/aws/nova_sonic/llm.py
index b1f56dbbd..5ed6eaab7 100644
--- a/src/pipecat/services/aws/nova_sonic/llm.py
+++ b/src/pipecat/services/aws/nova_sonic/llm.py
@@ -445,14 +445,14 @@ class AWSNovaSonicLLMService(LLMService):
     # settings
     #
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply a settings delta.
 
         Settings are stored but not applied to the active connection.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # TODO: someday we could reconnect here to apply updated settings.
@@ -460,7 +460,7 @@ class AWSNovaSonicLLMService(LLMService):
         # await self._disconnect()
         # await self._start_connecting()
 
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
 
         return changed
 
diff --git a/src/pipecat/services/aws/stt.py b/src/pipecat/services/aws/stt.py
index eed1a321d..31ec479d4 100644
--- a/src/pipecat/services/aws/stt.py
+++ b/src/pipecat/services/aws/stt.py
@@ -15,7 +15,7 @@ import os
 import random
 import string
 from dataclasses import dataclass
-from typing import Any, AsyncGenerator, Optional
+from typing import AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -158,11 +158,11 @@ class AWSTranscribeSTTService(WebsocketSTTService):
         }
         return encoding_map.get(encoding, encoding)
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> Settings:
         """Apply a settings delta and reconnect if anything changed."""
         changed = await super()._update_settings(delta)
 
-        if changed and self._websocket:
+        if changed.given_fields() and self._websocket:
             await self._disconnect()
             await self._connect()
 
diff --git a/src/pipecat/services/azure/stt.py b/src/pipecat/services/azure/stt.py
index 857b166cb..666ffd974 100644
--- a/src/pipecat/services/azure/stt.py
+++ b/src/pipecat/services/azure/stt.py
@@ -12,7 +12,7 @@ Speech SDK for real-time audio transcription.
 
 import asyncio
 from dataclasses import dataclass
-from typing import Any, AsyncGenerator, Optional
+from typing import AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -26,7 +26,7 @@ from pipecat.frames.frames import (
     TranscriptionFrame,
 )
 from pipecat.services.azure.common import language_to_azure_language
-from pipecat.services.settings import STTSettings
+from pipecat.services.settings import STTSettings, is_given
 from pipecat.services.stt_latency import AZURE_TTFS_P99
 from pipecat.services.stt_service import STTService
 from pipecat.transcriptions.language import Language
@@ -176,11 +176,11 @@ class AzureSTTService(STTService):
         """
         return language_to_azure_language(language)
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> Settings:
         """Apply a settings delta and reconnect if language changed."""
         changed = await super()._update_settings(delta)
 
-        if "language" in changed:
+        if is_given(changed.language):
             self._speech_config.speech_recognition_language = (
                 self._settings.language or language_to_azure_language(Language.EN_US)
             )
diff --git a/src/pipecat/services/cartesia/stt.py b/src/pipecat/services/cartesia/stt.py
index 85d43bcd3..1013f13ed 100644
--- a/src/pipecat/services/cartesia/stt.py
+++ b/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
-from typing import Any, AsyncGenerator, Optional
+from typing import AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -309,24 +309,25 @@ class CartesiaSTTService(WebsocketSTTService):
 
         await self._disconnect_websocket()
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> Settings:
         """Apply a settings delta.
 
         Args:
             delta: A :class:`STTSettings` (or ``CartesiaSTTService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose ``given_fields()`` contains
+            only the fields that actually changed.
         """
         changed = await super()._update_settings(delta)
 
         # TODO: someday we could reconnect here to apply updated settings.
         # Code might look something like the below:
-        # if changed:
+        # if changed.given_fields():
         #     await self._disconnect()
         #     await self._connect()
 
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
 
         return changed
 
diff --git a/src/pipecat/services/deepgram/flux/stt.py b/src/pipecat/services/deepgram/flux/stt.py
index 64d4e87b9..d42face8c 100644
--- a/src/pipecat/services/deepgram/flux/stt.py
+++ b/src/pipecat/services/deepgram/flux/stt.py
@@ -28,7 +28,7 @@ from pipecat.frames.frames import (
     UserStartedSpeakingFrame,
     UserStoppedSpeakingFrame,
 )
-from pipecat.services.settings import NOT_GIVEN, STTSettings, _NotGiven
+from pipecat.services.settings import NOT_GIVEN, STTSettings, _NotGiven, is_given
 from pipecat.services.stt_service import WebsocketSTTService
 from pipecat.transcriptions.language import Language
 from pipecat.utils.time import time_now_iso8601
@@ -448,7 +448,7 @@ class DeepgramFluxSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> STTSettings:
         """Apply a settings delta.
 
         Configure-able fields (keyterm, eot_threshold, eager_eot_threshold,
@@ -457,14 +457,16 @@ class DeepgramFluxSTTService(WebsocketSTTService):
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
-        configure_fields = changed.keys() & self._CONFIGURE_FIELDS
+        configure_fields = changed.given_fields().keys() & self._CONFIGURE_FIELDS
         if configure_fields and self._websocket and self._websocket.state is State.OPEN:
             await self._send_configure(configure_fields)
 
-        self._warn_unhandled_updated_settings(changed.keys() - self._CONFIGURE_FIELDS)
+        self._warn_unhandled_updated_settings(
+            changed.given_fields().keys() - self._CONFIGURE_FIELDS
+        )
 
         return changed
 
diff --git a/src/pipecat/services/deepgram/sagemaker/stt.py b/src/pipecat/services/deepgram/sagemaker/stt.py
index 1087b124f..b383633c8 100644
--- a/src/pipecat/services/deepgram/sagemaker/stt.py
+++ b/src/pipecat/services/deepgram/sagemaker/stt.py
@@ -208,11 +208,11 @@ class DeepgramSageMakerSTTService(STTService):
         """
         return True
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> STTSettings:
         """Apply a settings delta and warn about unhandled changes."""
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # Sync extra to fields after the update so self._settings stays unambiguous
@@ -224,7 +224,7 @@ class DeepgramSageMakerSTTService(STTService):
         # await self._disconnect()
         # await self._connect()
 
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
 
         return changed
 
diff --git a/src/pipecat/services/deepgram/sagemaker/tts.py b/src/pipecat/services/deepgram/sagemaker/tts.py
index 70be4a00e..ab2e8c45d 100644
--- a/src/pipecat/services/deepgram/sagemaker/tts.py
+++ b/src/pipecat/services/deepgram/sagemaker/tts.py
@@ -15,7 +15,7 @@ streaming audio output.
 import asyncio
 import json
 from dataclasses import dataclass
-from typing import Any, AsyncGenerator, Optional
+from typing import AsyncGenerator, Optional
 
 from loguru import logger
 
@@ -33,7 +33,7 @@ from pipecat.frames.frames import (
 )
 from pipecat.processors.frame_processor import FrameDirection
 from pipecat.services.aws.sagemaker.bidi_client import SageMakerBidiClient
-from pipecat.services.settings import TTSSettings
+from pipecat.services.settings import TTSSettings, is_given
 from pipecat.services.tts_service import TTSService
 from pipecat.utils.tracing.service_decorators import traced_tts
 
@@ -234,7 +234,7 @@ class DeepgramSageMakerTTSService(TTSService):
             logger.debug("Disconnected from Deepgram TTS on SageMaker")
             await self._call_event_handler("on_disconnected")
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a settings delta and reconnect if necessary.
 
         Since all settings are part of the SageMaker session query string,
@@ -242,11 +242,11 @@ class DeepgramSageMakerTTSService(TTSService):
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # Deepgram uses voice as the model, so keep them in sync for metrics
-        if "voice" in changed:
+        if is_given(changed.voice):
             self._settings.model = self._settings.voice
             self._sync_model_name_to_metrics()
 
@@ -255,7 +255,7 @@ class DeepgramSageMakerTTSService(TTSService):
         # await self._disconnect()
         # await self._connect()
 
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
 
         return changed
 
diff --git a/src/pipecat/services/deepgram/stt.py b/src/pipecat/services/deepgram/stt.py
index 7d849a160..d62b504da 100644
--- a/src/pipecat/services/deepgram/stt.py
+++ b/src/pipecat/services/deepgram/stt.py
@@ -485,11 +485,11 @@ class DeepgramSTTService(STTService):
         """
         return True
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> STTSettings:
         """Apply a settings delta and reconnect if anything changed."""
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # Sync extra to fields after the update so self._settings stays unambiguous
diff --git a/src/pipecat/services/deepgram/tts.py b/src/pipecat/services/deepgram/tts.py
index 9f2dc3976..bf0bbc72c 100644
--- a/src/pipecat/services/deepgram/tts.py
+++ b/src/pipecat/services/deepgram/tts.py
@@ -12,7 +12,7 @@ for generating speech from text using various voice models.
 
 import json
 from dataclasses import dataclass
-from typing import Any, AsyncGenerator, Optional
+from typing import AsyncGenerator, Optional
 
 import aiohttp
 from loguru import logger
@@ -26,7 +26,7 @@ from pipecat.frames.frames import (
     TTSAudioRawFrame,
     TTSStoppedFrame,
 )
-from pipecat.services.settings import TTSSettings
+from pipecat.services.settings import TTSSettings, is_given
 from pipecat.services.tts_service import TTSService, WebsocketTTSService
 from pipecat.utils.tracing.service_decorators import traced_tts
 
@@ -185,23 +185,23 @@ class DeepgramTTSService(WebsocketTTSService):
 
         await self._disconnect_websocket()
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a settings delta.
 
         Args:
             delta: A :class:`TTSSettings` (or ``DeepgramTTSService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with changed fields.
         """
         changed = await super()._update_settings(delta)
 
         # Deepgram uses voice as the model, so keep them in sync for metrics
-        if "voice" in changed:
+        if is_given(changed.voice):
             self._settings.model = self._settings.voice
             self._sync_model_name_to_metrics()
 
-        if changed:
+        if changed.given_fields():
             await self._disconnect()
             await self._connect()
 
diff --git a/src/pipecat/services/elevenlabs/stt.py b/src/pipecat/services/elevenlabs/stt.py
index daca9be3d..cf073d7ae 100644
--- a/src/pipecat/services/elevenlabs/stt.py
+++ b/src/pipecat/services/elevenlabs/stt.py
@@ -17,7 +17,7 @@ import io
 import json
 from dataclasses import dataclass, field
 from enum import Enum
-from typing import Any, AsyncGenerator, Optional
+from typing import AsyncGenerator, Optional
 
 import aiohttp
 from loguru import logger
@@ -593,18 +593,19 @@ class ElevenLabsRealtimeSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> Settings:
         """Apply a settings delta and reconnect if anything changed.
 
         Args:
             delta: A :class:`STTSettings` (or ``ElevenLabsRealtimeSTTService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose ``given_fields()`` contains
+            only the fields that actually changed.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         if self._websocket:
diff --git a/src/pipecat/services/elevenlabs/tts.py b/src/pipecat/services/elevenlabs/tts.py
index 8cfd1abe2..58e918b26 100644
--- a/src/pipecat/services/elevenlabs/tts.py
+++ b/src/pipecat/services/elevenlabs/tts.py
@@ -529,7 +529,7 @@ class ElevenLabsTTSService(WebsocketTTSService):
     def _set_voice_settings(self):
         return build_elevenlabs_voice_settings(self._settings)
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> Settings:
         """Apply a settings delta, reconnecting as needed.
 
         Uses the declarative ``URL_FIELDS`` and ``VOICE_SETTINGS_FIELDS``
@@ -540,29 +540,32 @@ class ElevenLabsTTSService(WebsocketTTSService):
             delta: A :class:`TTSSettings` (or ``ElevenLabsTTSService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose ``given_fields()`` contains
+            only the fields that actually changed.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # Rebuild voice settings for next context
         self._voice_settings = self._set_voice_settings()
 
-        url_changed = bool(changed.keys() & self.Settings.URL_FIELDS)
-        voice_settings_changed = bool(changed.keys() & self.Settings.VOICE_SETTINGS_FIELDS)
+        url_changed = bool(changed.given_fields().keys() & self.Settings.URL_FIELDS)
+        voice_settings_changed = bool(
+            changed.given_fields().keys() & self.Settings.VOICE_SETTINGS_FIELDS
+        )
 
         if url_changed:
             logger.debug(
-                f"URL-level setting changed ({changed.keys() & self.Settings.URL_FIELDS}), "
+                f"URL-level setting changed ({changed.given_fields().keys() & self.Settings.URL_FIELDS}), "
                 f"reconnecting WebSocket"
             )
             await self._disconnect()
             await self._connect()
         elif voice_settings_changed:
             logger.debug(
-                f"Voice settings changed ({changed.keys() & self.Settings.VOICE_SETTINGS_FIELDS}), "
+                f"Voice settings changed ({changed.given_fields().keys() & self.Settings.VOICE_SETTINGS_FIELDS}), "
                 f"closing current context to apply changes"
             )
             audio_contexts = self.get_audio_contexts()
@@ -574,7 +577,7 @@ class ElevenLabsTTSService(WebsocketTTSService):
             # Reconnect applies all settings; only warn about fields not handled
             # by voice settings or URL changes.
             handled = self.Settings.URL_FIELDS | self.Settings.VOICE_SETTINGS_FIELDS
-            self._warn_unhandled_updated_settings(changed.keys() - handled)
+            self._warn_unhandled_updated_settings(changed.given_fields().keys() - handled)
 
         return changed
 
@@ -1087,17 +1090,18 @@ class ElevenLabsHttpTTSService(TTSService):
     def _set_voice_settings(self):
         return build_elevenlabs_voice_settings(self._settings)
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> Settings:
         """Apply a settings delta and rebuild voice settings.
 
         Args:
             delta: A :class:`TTSSettings` (or ``ElevenLabsHttpTTSService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose ``given_fields()`` contains
+            only the fields that actually changed.
         """
         changed = await super()._update_settings(delta)
-        if changed:
+        if changed.given_fields():
             self._voice_settings = self._set_voice_settings()
         return changed
 
diff --git a/src/pipecat/services/fish/tts.py b/src/pipecat/services/fish/tts.py
index 92cb54701..349a1ef21 100644
--- a/src/pipecat/services/fish/tts.py
+++ b/src/pipecat/services/fish/tts.py
@@ -234,7 +234,7 @@ class FishAudioTTSService(InterruptibleTTSService):
         """
         return True
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> Settings:
         """Apply a settings delta and reconnect if needed.
 
         Any change to voice or model triggers a WebSocket reconnect.
@@ -243,11 +243,11 @@ class FishAudioTTSService(InterruptibleTTSService):
             delta: A :class:`TTSSettings` (or ``FishAudioTTSService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with only the changed fields set.
         """
         changed = await super()._update_settings(delta)
 
-        if changed:
+        if changed.given_fields():
             await self._disconnect()
             await self._connect()
 
diff --git a/src/pipecat/services/gladia/stt.py b/src/pipecat/services/gladia/stt.py
index 2ce2a15b5..59106c84a 100644
--- a/src/pipecat/services/gladia/stt.py
+++ b/src/pipecat/services/gladia/stt.py
@@ -469,7 +469,7 @@ class GladiaSTTService(WebsocketSTTService):
         await super().start(frame)
         await self._connect()
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply settings delta.
 
         Settings are stored but not applied to the active session.
@@ -478,11 +478,11 @@ class GladiaSTTService(WebsocketSTTService):
             delta: A settings delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with only the changed fields set.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # TODO: someday we could reconnect here to apply updated settings.
@@ -492,7 +492,7 @@ class GladiaSTTService(WebsocketSTTService):
         # await self._disconnect()
         # await self._connect()
 
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
 
         return changed
 
diff --git a/src/pipecat/services/google/gemini_live/llm.py b/src/pipecat/services/google/gemini_live/llm.py
index 5c9e5f8b3..d19336e5b 100644
--- a/src/pipecat/services/google/gemini_live/llm.py
+++ b/src/pipecat/services/google/gemini_live/llm.py
@@ -870,14 +870,14 @@ class GeminiLiveLLMService(LLMService):
         """
         return True
 
-    async def _update_settings(self, delta: LLMSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: LLMSettings) -> LLMSettings:
         """Apply a settings delta.
 
         Settings are stored but not applied to the active connection.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         # TODO: someday we could reconnect here to apply updated settings.
@@ -885,7 +885,7 @@ class GeminiLiveLLMService(LLMService):
         # await self._disconnect()
         # await self._connect()
 
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
 
         return changed
 
diff --git a/src/pipecat/services/google/stt.py b/src/pipecat/services/google/stt.py
index 173b201fe..b4c93e56d 100644
--- a/src/pipecat/services/google/stt.py
+++ b/src/pipecat/services/google/stt.py
@@ -671,7 +671,7 @@ class GoogleSTTService(STTService):
         logger.debug(f"Switching STT languages to: {languages}")
         await self._update_settings(self.Settings(languages=list(languages)))
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply settings delta and reconnect if anything changed.
 
         Handles ``language`` from base ``set_language`` by converting it to
@@ -683,7 +683,8 @@ class GoogleSTTService(STTService):
             delta: A settings delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose given fields are the ones that
+            actually changed (values are the *previous* values).
         """
         from pipecat.services.settings import is_given
 
@@ -706,7 +707,7 @@ class GoogleSTTService(STTService):
 
         changed = await super()._update_settings(delta)
 
-        if changed:
+        if changed.given_fields():
             await self._reconnect_if_needed()
 
         return changed
diff --git a/src/pipecat/services/google/tts.py b/src/pipecat/services/google/tts.py
index 3455a8125..d1ade46da 100644
--- a/src/pipecat/services/google/tts.py
+++ b/src/pipecat/services/google/tts.py
@@ -740,7 +740,7 @@ class GoogleHttpTTSService(TTSService):
         """
         return language_to_google_tts_language(language)
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Override to handle speaking_rate validation.
 
         Args:
@@ -1112,7 +1112,7 @@ class GoogleTTSService(GoogleBaseTTSService):
             credentials, credentials_path
         )
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Override to handle speaking_rate validation.
 
         Args:
@@ -1395,14 +1395,15 @@ class GeminiTTSService(GoogleBaseTTSService):
                 f"Current rate of {self.sample_rate}Hz may cause issues."
             )
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a settings delta with voice validation.
 
         Args:
             delta: Settings delta. Can include 'voice', 'prompt', etc.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose given fields are the ones that
+            actually changed (values are the *previous* values).
         """
         if is_given(delta.voice) and delta.voice not in self.AVAILABLE_VOICES:
             logger.warning(f"Voice '{delta.voice}' not in known voices list. Using anyway.")
diff --git a/src/pipecat/services/gradium/stt.py b/src/pipecat/services/gradium/stt.py
index c328dceab..1de671f41 100644
--- a/src/pipecat/services/gradium/stt.py
+++ b/src/pipecat/services/gradium/stt.py
@@ -203,17 +203,17 @@ class GradiumSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> Settings:
         """Apply a settings delta, sync params, and reconnect.
 
         Args:
             delta: A :class:`STTSettings` (or ``GradiumSTTService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with only the changed fields set.
         """
         changed = await super()._update_settings(delta)
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         if self._websocket:
diff --git a/src/pipecat/services/gradium/tts.py b/src/pipecat/services/gradium/tts.py
index f63f931ad..9d7e67d29 100644
--- a/src/pipecat/services/gradium/tts.py
+++ b/src/pipecat/services/gradium/tts.py
@@ -21,7 +21,7 @@ from pipecat.frames.frames import (
     TTSAudioRawFrame,
     TTSStoppedFrame,
 )
-from pipecat.services.settings import TTSSettings
+from pipecat.services.settings import TTSSettings, is_given
 from pipecat.services.tts_service import WebsocketTTSService
 from pipecat.utils.tracing.service_decorators import traced_tts
 
@@ -149,21 +149,21 @@ class GradiumTTSService(WebsocketTTSService):
         """
         return True
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> Settings:
         """Apply a settings delta and reconnect if voice changed.
 
         Args:
             delta: A :class:`TTSSettings` (or ``GradiumTTSService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with only the changed fields set.
         """
         changed = await super()._update_settings(delta)
-        if "voice" in changed:
+        if is_given(changed.voice):
             await self._disconnect()
             await self._connect()
         else:
-            self._warn_unhandled_updated_settings(changed)
+            self._warn_unhandled_updated_settings(changed.given_fields())
         return changed
 
     def _build_msg(self, text: str = "", context_id: str = "") -> dict:
diff --git a/src/pipecat/services/grok/realtime/llm.py b/src/pipecat/services/grok/realtime/llm.py
index bfa192aad..bd9da4989 100644
--- a/src/pipecat/services/grok/realtime/llm.py
+++ b/src/pipecat/services/grok/realtime/llm.py
@@ -118,7 +118,9 @@ class GrokRealtimeLLMSettings(LLMSettings):
 
     # -- apply_update override -----------------------------------------------
 
-    def apply_update(self, delta: "GrokRealtimeLLMService.Settings") -> Dict[str, Any]:
+    def apply_update(
+        self, delta: "GrokRealtimeLLMService.Settings"
+    ) -> "GrokRealtimeLLMService.Settings":
         """Merge a delta, keeping ``system_instruction`` in sync with SP.
 
         When the delta contains ``session_properties``, it **replaces** the
@@ -131,13 +133,13 @@ class GrokRealtimeLLMSettings(LLMSettings):
 
         # 2. SP → top-level: if the SP was just replaced and carries
         #    instructions that the delta didn't set at top level, pull it up.
-        if "session_properties" in changed and is_given(self.session_properties):
+        if is_given(changed.session_properties) and is_given(self.session_properties):
             sp = self.session_properties
-            if "system_instruction" not in changed and sp.instructions is not None:
+            if not is_given(changed.system_instruction) and sp.instructions is not None:
                 old_si = self.system_instruction
                 self.system_instruction = sp.instructions
                 if old_si != self.system_instruction:
-                    changed["system_instruction"] = old_si
+                    changed.system_instruction = old_si
 
         # 3. Top-level → SP: ensure SP mirrors the authoritative top-level
         #    values.  Covers all cases: top-level-only delta, SP-only delta,
@@ -582,7 +584,7 @@ class GrokRealtimeLLMService(LLMService):
                 return
             await self.push_error(error_msg=f"Error sending client event: {e}", exception=e)
 
-    async def _update_settings(self, delta):
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply a settings delta, sending a session update when needed."""
         # Capture audio config before the update — a wholesale SP replacement
         # would lose it since the new SP likely has audio=None.
@@ -592,13 +594,13 @@ class GrokRealtimeLLMService(LLMService):
         changed = await super()._update_settings(delta)
 
         # Re-establish audio config if it was lost during SP replacement.
-        if "session_properties" in changed and input_rate and output_rate:
+        if is_given(changed.session_properties) and input_rate and output_rate:
             self._ensure_audio_config(input_rate, output_rate)
 
         handled = {"session_properties", "system_instruction"}
-        if changed.keys() & handled:
+        if changed.given_fields().keys() & handled:
             await self._send_session_update()
-        self._warn_unhandled_updated_settings(changed.keys() - handled)
+        self._warn_unhandled_updated_settings(changed.given_fields().keys() - handled)
         return changed
 
     async def _send_session_update(self):
diff --git a/src/pipecat/services/inworld/tts.py b/src/pipecat/services/inworld/tts.py
index 334c3c617..e0d8cb340 100644
--- a/src/pipecat/services/inworld/tts.py
+++ b/src/pipecat/services/inworld/tts.py
@@ -826,14 +826,14 @@ class InworldTTSService(WebsocketTTSService):
 
         await self._disconnect_websocket()
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a settings delta.
 
         Settings are stored but not applied to the active connection.
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         await self._disconnect()
diff --git a/src/pipecat/services/llm_service.py b/src/pipecat/services/llm_service.py
index 7944f413a..e317c4c27 100644
--- a/src/pipecat/services/llm_service.py
+++ b/src/pipecat/services/llm_service.py
@@ -59,7 +59,7 @@ from pipecat.processors.aggregators.llm_response import (
 from pipecat.processors.aggregators.openai_llm_context import OpenAILLMContext
 from pipecat.processors.frame_processor import FrameDirection
 from pipecat.services.ai_service import AIService
-from pipecat.services.settings import LLMSettings
+from pipecat.services.settings import LLMSettings, is_given
 from pipecat.turns.user_turn_completion_mixin import UserTurnCompletionLLMServiceMixin
 from pipecat.utils.context.llm_context_summarization import (
     DEFAULT_SUMMARIZATION_TIMEOUT,
@@ -345,18 +345,19 @@ class LLMService(UserTurnCompletionLLMServiceMixin, AIService):
         else:
             self._settings.system_instruction = completion_instructions
 
-    async def _update_settings(self, delta: LLMSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: LLMSettings) -> LLMSettings:
         """Apply a settings delta, handling turn-completion fields.
 
         Args:
             delta: An LLM settings delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode ``LLMSettings`` with changed fields set to their
+            previous values.
         """
         changed = await super()._update_settings(delta)
 
-        if "filter_incomplete_user_turns" in changed:
+        if is_given(changed.filter_incomplete_user_turns):
             self._filter_incomplete_user_turns = (
                 self._settings.filter_incomplete_user_turns or False
             )
@@ -373,14 +374,14 @@ class LLMService(UserTurnCompletionLLMServiceMixin, AIService):
                 self._settings.system_instruction = self._base_system_instruction
                 self._base_system_instruction = None
 
-        if "user_turn_completion_config" in changed and self._filter_incomplete_user_turns:
+        if is_given(changed.user_turn_completion_config) and self._filter_incomplete_user_turns:
             self.set_user_turn_completion_config(self._settings.user_turn_completion_config)
             self._compose_system_instruction()
 
         if (
-            "system_instruction" in changed
+            is_given(changed.system_instruction)
             and self._filter_incomplete_user_turns
-            and "filter_incomplete_user_turns" not in changed
+            and not is_given(changed.filter_incomplete_user_turns)
         ):
             # system_instruction changed while turn completion is active.
             # Treat the new value as the new base and recompose.
diff --git a/src/pipecat/services/lmnt/tts.py b/src/pipecat/services/lmnt/tts.py
index 0ca91a107..2acdba213 100644
--- a/src/pipecat/services/lmnt/tts.py
+++ b/src/pipecat/services/lmnt/tts.py
@@ -233,18 +233,18 @@ class LmntTTSService(InterruptibleTTSService):
 
         await self._disconnect_websocket()
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> Settings:
         """Apply a settings delta.
 
         Args:
             delta: A :class:`TTSSettings` (or ``LmntTTSService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with only the changed fields set.
         """
         changed = await super()._update_settings(delta)
 
-        if changed:
+        if changed.given_fields():
             await self._disconnect()
             await self._connect()
 
diff --git a/src/pipecat/services/neuphonic/tts.py b/src/pipecat/services/neuphonic/tts.py
index b345a0ff4..584cd2a31 100644
--- a/src/pipecat/services/neuphonic/tts.py
+++ b/src/pipecat/services/neuphonic/tts.py
@@ -212,10 +212,10 @@ class NeuphonicTTSService(InterruptibleTTSService):
         """
         return language_to_neuphonic_lang_code(language)
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> Settings:
         """Apply a settings delta and reconnect with new configuration."""
         changed = await super()._update_settings(delta)
-        if changed:
+        if changed.given_fields():
             await self._disconnect()
             await self._connect()
             logger.info(f"Switching TTS to settings: [{self._settings}]")
diff --git a/src/pipecat/services/nvidia/stt.py b/src/pipecat/services/nvidia/stt.py
index fcca14741..a4588559d 100644
--- a/src/pipecat/services/nvidia/stt.py
+++ b/src/pipecat/services/nvidia/stt.py
@@ -637,18 +637,18 @@ class NvidiaSegmentedSTTService(SegmentedSTTService):
         self._config = self._create_recognition_config()
         logger.debug(f"Initialized NvidiaSegmentedSTTService with model: {self._settings.model}")
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> Settings:
         """Apply a settings delta and sync internal state.
 
         Args:
             delta: A :class:`STTSettings` (or ``NvidiaSegmentedSTTService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with only the changed fields set.
         """
         changed = await super()._update_settings(delta)
 
-        if changed:
+        if changed.given_fields():
             self._config = self._create_recognition_config()
 
         return changed
diff --git a/src/pipecat/services/nvidia/tts.py b/src/pipecat/services/nvidia/tts.py
index 5e7a20a3c..aae69b9d4 100644
--- a/src/pipecat/services/nvidia/tts.py
+++ b/src/pipecat/services/nvidia/tts.py
@@ -186,16 +186,16 @@ class NvidiaTTSService(TTSService):
                 stacklevel=2,
             )
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply a settings delta.
 
         Settings are stored but not applied to the active connection.
         """
         changed = await super()._update_settings(delta)
-        if not changed:
+        if not changed.given_fields():
             return changed
         # TODO: reconnect gRPC client to apply changed settings.
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
         return changed
 
     def _initialize_client(self):
diff --git a/src/pipecat/services/openai/realtime/llm.py b/src/pipecat/services/openai/realtime/llm.py
index faaa19884..f757680ba 100644
--- a/src/pipecat/services/openai/realtime/llm.py
+++ b/src/pipecat/services/openai/realtime/llm.py
@@ -126,7 +126,9 @@ class OpenAIRealtimeLLMSettings(LLMSettings):
 
     # -- apply_update override -----------------------------------------------
 
-    def apply_update(self, delta: "OpenAIRealtimeLLMService.Settings") -> Dict[str, Any]:
+    def apply_update(
+        self, delta: "OpenAIRealtimeLLMService.Settings"
+    ) -> "OpenAIRealtimeLLMService.Settings":
         """Merge a delta, keeping ``model``/``system_instruction`` in sync with SP.
 
         When the delta contains ``session_properties``, it **replaces** the
@@ -140,18 +142,18 @@ class OpenAIRealtimeLLMSettings(LLMSettings):
         # 2. SP → top-level: if the SP was just replaced and carries
         #    model/instructions that the delta didn't set at top level,
         #    pull them up.
-        if "session_properties" in changed and is_given(self.session_properties):
+        if is_given(changed.session_properties) and is_given(self.session_properties):
             sp = self.session_properties
-            if "model" not in changed and sp.model is not None:
+            if not is_given(changed.model) and sp.model is not None:
                 old_model = self.model
                 self.model = sp.model
                 if old_model != self.model:
-                    changed["model"] = old_model
-            if "system_instruction" not in changed and sp.instructions is not None:
+                    changed.model = old_model
+            if not is_given(changed.system_instruction) and sp.instructions is not None:
                 old_si = self.system_instruction
                 self.system_instruction = sp.instructions
                 if old_si != self.system_instruction:
-                    changed["system_instruction"] = old_si
+                    changed.system_instruction = old_si
 
         # 3. Top-level → SP: ensure SP mirrors the authoritative top-level
         #    values.  Covers all cases: top-level-only delta, SP-only delta,
@@ -673,13 +675,13 @@ class OpenAIRealtimeLLMService(LLMService):
             # treat a send-side error as fatal.
             await self.push_error(error_msg=f"Error sending client event: {e}", exception=e)
 
-    async def _update_settings(self, delta):
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply a settings delta, sending a session update when needed."""
         changed = await super()._update_settings(delta)
         handled = {"session_properties", "system_instruction"}
-        if changed.keys() & handled:
+        if changed.given_fields().keys() & handled:
             await self._send_session_update()
-        self._warn_unhandled_updated_settings(changed.keys() - handled)
+        self._warn_unhandled_updated_settings(changed.given_fields().keys() - handled)
         return changed
 
     async def _send_session_update(self):
diff --git a/src/pipecat/services/openai/stt.py b/src/pipecat/services/openai/stt.py
index 39ca60b25..a963dfb22 100644
--- a/src/pipecat/services/openai/stt.py
+++ b/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 Any, AsyncGenerator, Literal, Optional, Union
+from typing import AsyncGenerator, Literal, Optional, Union
 
 from loguru import logger
 
@@ -369,7 +369,7 @@ class OpenAIRealtimeSTTService(WebsocketSTTService):
         """
         return True
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> Settings:
         """Apply a settings delta and send session update if needed.
 
         Sends a ``session.update`` to the server when the session is active.
@@ -378,11 +378,12 @@ class OpenAIRealtimeSTTService(WebsocketSTTService):
             delta: A :class:`STTSettings` (or ``OpenAIRealtimeSTTService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose ``given_fields()`` contains
+            only the fields that actually changed.
         """
         changed = await super()._update_settings(delta)
 
-        if changed and self._session_ready:
+        if changed.given_fields() and self._session_ready:
             await self._send_session_update()
 
         return changed
diff --git a/src/pipecat/services/openai_realtime_beta/openai.py b/src/pipecat/services/openai_realtime_beta/openai.py
index 0a6315986..96574070d 100644
--- a/src/pipecat/services/openai_realtime_beta/openai.py
+++ b/src/pipecat/services/openai_realtime_beta/openai.py
@@ -503,10 +503,10 @@ class OpenAIRealtimeBetaLLMService(LLMService):
             # treat a send-side error as fatal.
             await self.push_error(error_msg=f"Error sending client event: {e}", exception=e)
 
-    async def _update_settings(self, delta):
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply a settings delta."""
         changed = await super()._update_settings(delta)
-        self._warn_unhandled_updated_settings(changed.keys())
+        self._warn_unhandled_updated_settings(changed.given_fields().keys())
         return changed
 
     async def _send_session_update(self):
diff --git a/src/pipecat/services/piper/tts.py b/src/pipecat/services/piper/tts.py
index 1b0037abb..f2a06e62c 100644
--- a/src/pipecat/services/piper/tts.py
+++ b/src/pipecat/services/piper/tts.py
@@ -121,16 +121,16 @@ class PiperTTSService(TTSService):
         """
         return True
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply a settings delta.
 
         Settings are stored but not applied to the active connection.
         """
         changed = await super()._update_settings(delta)
-        if not changed:
+        if not changed.given_fields():
             return changed
         # TODO: voice changes would require re-downloading and loading the model.
-        self._warn_unhandled_updated_settings(changed)
+        self._warn_unhandled_updated_settings(changed.given_fields())
         return changed
 
     @traced_tts
diff --git a/src/pipecat/services/rime/tts.py b/src/pipecat/services/rime/tts.py
index 24a5d152b..55364d7d1 100644
--- a/src/pipecat/services/rime/tts.py
+++ b/src/pipecat/services/rime/tts.py
@@ -394,7 +394,7 @@ class RimeTTSService(WebsocketTTSService):
         self._extra_msg_fields["inlineSpeedAlpha"] = ",".join(speed_vals + [str(speed)])
         return f"[{text}]"
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a settings delta and reconnect if necessary.
 
         Since all settings are WebSocket URL query parameters,
@@ -402,7 +402,7 @@ class RimeTTSService(WebsocketTTSService):
         """
         changed = await super()._update_settings(delta)
 
-        if changed and self._websocket:
+        if changed.given_fields() and self._websocket:
             await self._disconnect()
             await self._connect()
 
@@ -1199,7 +1199,7 @@ class RimeNonJsonTTSService(InterruptibleTTSService):
         except Exception as e:
             yield ErrorFrame(error=f"Unknown error occurred: {e}")
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a settings delta and reconnect if necessary.
 
         Since all settings are WebSocket URL query parameters,
@@ -1207,7 +1207,7 @@ class RimeNonJsonTTSService(InterruptibleTTSService):
         """
         changed = await super()._update_settings(delta)
 
-        if changed:
+        if changed.given_fields():
             logger.debug("Settings changed, reconnecting WebSocket with new parameters")
             await self._disconnect()
             await self._connect()
diff --git a/src/pipecat/services/sarvam/stt.py b/src/pipecat/services/sarvam/stt.py
index 8d0a38810..09d9359d0 100644
--- a/src/pipecat/services/sarvam/stt.py
+++ b/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 Any, AsyncGenerator, Dict, Literal, Optional
+from typing import AsyncGenerator, Dict, Literal, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -369,14 +369,14 @@ class SarvamSTTService(STTService):
                 if self._socket_client:
                     await self._socket_client.flush()
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> STTSettings:
         """Apply a settings delta, validate, sync state, and reconnect.
 
         Args:
             delta: A :class:`STTSettings` (or ``SarvamSTTService.Settings``) delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with changed fields.
 
         Raises:
             ValueError: If a setting is not supported by the current model.
@@ -398,11 +398,11 @@ class SarvamSTTService(STTService):
 
         # Language and prompt are WebSocket connect-time parameters; reconnect to apply.
         reconnect_fields = {"language", "prompt"}
-        if changed.keys() & reconnect_fields:
+        if changed.given_fields().keys() & reconnect_fields:
             await self._disconnect()
             await self._connect()
 
-        unhandled = {k: v for k, v in changed.items() if k not in reconnect_fields}
+        unhandled = {k: v for k, v in changed.given_fields().items() if k not in reconnect_fields}
         if unhandled:
             self._warn_unhandled_updated_settings(unhandled)
 
diff --git a/src/pipecat/services/sarvam/tts.py b/src/pipecat/services/sarvam/tts.py
index 91ee088cf..e143bec4a 100644
--- a/src/pipecat/services/sarvam/tts.py
+++ b/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 Any, AsyncGenerator, ClassVar, Dict, List, Optional, Tuple
+from typing import AsyncGenerator, ClassVar, Dict, List, Optional, Tuple
 
 import aiohttp
 from loguru import logger
@@ -1060,11 +1060,11 @@ class SarvamTTSService(InterruptibleTTSService):
         if isinstance(frame, (LLMFullResponseEndFrame, EndFrame)):
             await self.flush_audio()
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a settings delta and resend config if voice changed."""
         changed = await super()._update_settings(delta)
 
-        if changed:
+        if changed.given_fields():
             await self._send_config()
 
         return changed
diff --git a/src/pipecat/services/settings.py b/src/pipecat/services/settings.py
index a0bf3cd58..9181ba221 100644
--- a/src/pipecat/services/settings.py
+++ b/src/pipecat/services/settings.py
@@ -190,7 +190,7 @@ class ServiceSettings:
         result.update(self.extra)
         return result
 
-    def apply_update(self: _S, delta: _S) -> Dict[str, Any]:
+    def apply_update(self: _S, delta: _S) -> _S:
         """Merge a delta-mode object into this store-mode object.
 
         Only fields in *delta* that are **given** (i.e. not ``NOT_GIVEN``)
@@ -204,9 +204,11 @@ class ServiceSettings:
             delta: A delta-mode settings object of the same type.
 
         Returns:
-            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.
+            A delta-mode settings instance of the same type, with changed
+            fields set to their **pre-update** (old) values and unchanged
+            fields left as ``NOT_GIVEN``.  Use ``changed.given_fields()``
+            for the set of changed names, or access fields directly with
+            typed attribute access (e.g. ``is_given(changed.voice)``).
 
         Examples::
 
@@ -215,10 +217,10 @@ class ServiceSettings:
             # delta-mode object (only voice is set)
             delta = TTSSettings(voice="bob")
             changed = current.apply_update(delta)
-            # changed == {"voice": "alice"}
+            # is_given(changed.voice) is True, changed.voice == "alice"
             # current.voice == "bob", current.language == "en"
         """
-        changed: Dict[str, Any] = {}
+        changed: _S = type(self)()  # delta-mode: all NOT_GIVEN
         for f in fields(self):
             if f.name == "extra":
                 continue
@@ -228,14 +230,19 @@ class ServiceSettings:
             old_val = getattr(self, f.name)
             if old_val != new_val:
                 setattr(self, f.name, new_val)
-                changed[f.name] = old_val
+                # Store the old value. Use None as a stand-in when the old
+                # value was NOT_GIVEN, since NOT_GIVEN is the "unset"
+                # sentinel in delta mode and would hide the change.  In
+                # store-mode objects (the normal case) this never triggers
+                # because validate_complete() ensures no NOT_GIVEN fields.
+                setattr(changed, f.name, None if isinstance(old_val, _NotGiven) else old_val)
 
         # Merge extra
         for key, new_val in delta.extra.items():
             old_val = self.extra.get(key, NOT_GIVEN)
             if old_val != new_val:
                 self.extra[key] = new_val
-                changed[key] = old_val
+                changed.extra[key] = old_val
 
         return changed
 
diff --git a/src/pipecat/services/soniox/stt.py b/src/pipecat/services/soniox/stt.py
index f123d850c..a19dfb757 100644
--- a/src/pipecat/services/soniox/stt.py
+++ b/src/pipecat/services/soniox/stt.py
@@ -9,7 +9,7 @@
 import json
 import time
 from dataclasses import dataclass, field
-from typing import Any, AsyncGenerator, List, Optional
+from typing import AsyncGenerator, List, Optional
 
 from loguru import logger
 from pydantic import BaseModel
@@ -297,18 +297,18 @@ class SonioxSTTService(WebsocketSTTService):
         await super().start(frame)
         await self._connect()
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> STTSettings:
         """Apply settings delta and reconnect if anything changed.
 
         Args:
             delta: A settings delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object with changed fields.
         """
         changed = await super()._update_settings(delta)
 
-        if changed:
+        if changed.given_fields():
             await self._disconnect()
             await self._connect()
 
diff --git a/src/pipecat/services/speechmatics/stt.py b/src/pipecat/services/speechmatics/stt.py
index ae8e35850..2009d044b 100644
--- a/src/pipecat/services/speechmatics/stt.py
+++ b/src/pipecat/services/speechmatics/stt.py
@@ -537,7 +537,7 @@ class SpeechmaticsSTTService(STTService):
         await super().start(frame)
         await self._connect()
 
-    async def _update_settings(self, delta: Settings) -> dict[str, Any]:
+    async def _update_settings(self, delta: Settings) -> Settings:
         """Apply settings delta, reconnecting only when necessary.
 
         Fields are classified into three categories (see
@@ -554,25 +554,28 @@ class SpeechmaticsSTTService(STTService):
             delta: A settings delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode settings object whose given fields are the ones that
+            actually changed (values are the *previous* values).
         """
         changed = await super()._update_settings(delta)
 
-        if not changed:
+        if not changed.given_fields():
             return changed
 
         no_reconnect = self.Settings.HOT_FIELDS | self.Settings.LOCAL_FIELDS
-        needs_reconnect = bool(changed.keys() - no_reconnect)
+        needs_reconnect = bool(changed.given_fields().keys() - no_reconnect)
 
         if needs_reconnect:
-            logger.debug(f"{self} settings update requires reconnect: {changed.keys()}")
+            logger.debug(
+                f"{self} settings update requires reconnect: {changed.given_fields().keys()}"
+            )
             # Connection-level fields changed — rebuild the SDK config
             # from the now-updated self._settings, then reconnect.
             self._config = self._build_config(self._settings)
             await self._disconnect()
             await self._connect()
-        elif changed.keys() & self.Settings.HOT_FIELDS:
-            logger.debug(f"{self} applying hot settings update: {changed.keys()}")
+        elif changed.given_fields().keys() & self.Settings.HOT_FIELDS:
+            logger.debug(f"{self} applying hot settings update: {changed.given_fields().keys()}")
             if self._config.enable_diarization:
                 # Only hot-updatable fields changed — push to the live session.
                 self._config.speaker_config.focus_speakers = self._settings.focus_speakers
@@ -582,13 +585,13 @@ class SpeechmaticsSTTService(STTService):
                     self._client.update_diarization_config(self._config.speaker_config)
             else:
                 logger.debug(
-                    f"{self} hot settings updated but diarization not enabled: {changed.keys()}. ignoring."
+                    f"{self} hot settings updated but diarization not enabled: {changed.given_fields().keys()}. ignoring."
                 )
                 # Diarization not enabled — the new settings will take effect
                 # if/when diarization is enabled, which does require a reconnect.
-        elif changed.keys() & self.Settings.LOCAL_FIELDS:
+        elif changed.given_fields().keys() & self.Settings.LOCAL_FIELDS:
             logger.debug(
-                f"{self} local settings update, no special action required: {changed.keys()}"
+                f"{self} local settings update, no special action required: {changed.given_fields().keys()}"
             )
             # Only local fields changed — no need to push to the STT engine,
             # the new settings will take effect immediately.
diff --git a/src/pipecat/services/stt_service.py b/src/pipecat/services/stt_service.py
index ebf007f6f..ce206904e 100644
--- a/src/pipecat/services/stt_service.py
+++ b/src/pipecat/services/stt_service.py
@@ -270,20 +270,21 @@ class STTService(AIService):
         await self._cancel_ttfb_timeout()
         await self._cancel_keepalive_task()
 
-    async def _update_settings(self, delta: STTSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: STTSettings) -> STTSettings:
         """Apply an STT settings delta.
 
         Handles ``model`` (via parent). Translates ``Language`` enum values
         before applying so the stored value is a service-specific string.
         Concrete services should override this method and handle language
         changes (including any reconnect logic) based on the returned
-        changed-field dict.
+        changed-field object.
 
         Args:
             delta: An STT settings delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode ``STTSettings`` with changed fields set to their
+            previous values.
         """
         # Translate language *before* applying so the stored value is canonical
         if is_given(delta.language) and isinstance(delta.language, Language):
diff --git a/src/pipecat/services/tts_service.py b/src/pipecat/services/tts_service.py
index da1bcaf87..770fbcd12 100644
--- a/src/pipecat/services/tts_service.py
+++ b/src/pipecat/services/tts_service.py
@@ -591,7 +591,7 @@ class TTSService(AIService):
             if not (agg_type == aggregation_type and func == transform_function)
         ]
 
-    async def _update_settings(self, delta: TTSSettings) -> dict[str, Any]:
+    async def _update_settings(self, delta: TTSSettings) -> TTSSettings:
         """Apply a TTS settings delta.
 
         Translates language to service-specific value before applying.
@@ -600,7 +600,8 @@ class TTSService(AIService):
             delta: A TTS settings delta.
 
         Returns:
-            Dict mapping changed field names to their previous values.
+            A delta-mode ``TTSSettings`` with changed fields set to their
+            previous values.
         """
         # Translate language *before* applying so the stored value is canonical
         if is_given(delta.language) and isinstance(delta.language, Language):
diff --git a/src/pipecat/services/ultravox/llm.py b/src/pipecat/services/ultravox/llm.py
index fe8a97549..89d7cc411 100644
--- a/src/pipecat/services/ultravox/llm.py
+++ b/src/pipecat/services/ultravox/llm.py
@@ -57,7 +57,7 @@ from pipecat.processors.aggregators.openai_llm_context import (
 )
 from pipecat.processors.frame_processor import FrameDirection
 from pipecat.services.llm_service import FunctionCallFromLLM, LLMService
-from pipecat.services.settings import NOT_GIVEN, LLMSettings, _NotGiven
+from pipecat.services.settings import NOT_GIVEN, LLMSettings, _NotGiven, is_given
 from pipecat.utils.time import time_now_iso8601
 
 try:
@@ -383,11 +383,11 @@ class UltravoxRealtimeLLMService(LLMService):
             await self.cancel_task(self._receive_task, timeout=1.0)
             self._receive_task = None
 
-    async def _update_settings(self, delta: Settings):
+    async def _update_settings(self, delta: Settings) -> Settings:
         changed = await super()._update_settings(delta)
-        if "output_medium" in changed:
+        if is_given(changed.output_medium):
             await self._update_output_medium(self._settings.output_medium)
-        self._warn_unhandled_updated_settings(changed.keys() - {"output_medium"})
+        self._warn_unhandled_updated_settings(changed.given_fields().keys() - {"output_medium"})
         return changed
 
     #
diff --git a/tests/test_settings.py b/tests/test_settings.py
index 8ffe355ad..559a52249 100644
--- a/tests/test_settings.py
+++ b/tests/test_settings.py
@@ -102,8 +102,8 @@ class TestApplyUpdate:
         current = TTSSettings(voice="alice", language="en")
         delta = TTSSettings(voice="bob")
         changed = current.apply_update(delta)
-        assert changed.keys() == {"voice"}
-        assert changed["voice"] == "alice"  # old value
+        assert set(changed.given_fields()) == {"voice"}
+        assert changed.voice == "alice"  # old value
         assert current.voice == "bob"
         assert current.language == "en"
 
@@ -111,14 +111,14 @@ class TestApplyUpdate:
         current = TTSSettings(voice="alice", language="en")
         delta = TTSSettings(voice="alice")
         changed = current.apply_update(delta)
-        assert changed == {}
+        assert changed.given_fields() == {}
         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 == {}
+        assert changed.given_fields() == {}
         assert current.voice == "alice"
         assert current.language == "en"
 
@@ -126,9 +126,9 @@ 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.keys() == {"temperature", "max_tokens", "top_p"}
-        assert changed["temperature"] == 0.7
-        assert changed["max_tokens"] == 100
+        assert set(changed.given_fields()) == {"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
@@ -139,8 +139,8 @@ class TestApplyUpdate:
         delta = TTSSettings()
         delta.extra = {"speed": 1.2}
         changed = current.apply_update(delta)
-        assert "speed" in changed
-        assert changed["speed"] == 1.0  # old value
+        assert "speed" in changed.extra
+        assert changed.extra["speed"] == 1.0  # old value
         assert current.extra == {"speed": 1.2, "stability": 0.5}
 
     def test_apply_update_extra_no_change(self):
@@ -149,14 +149,14 @@ class TestApplyUpdate:
         delta = TTSSettings()
         delta.extra = {"speed": 1.0}
         changed = current.apply_update(delta)
-        assert changed == {}
+        assert changed.given_fields() == {}
 
     def test_apply_update_model_field(self):
         current = ServiceSettings(model="old-model")
         delta = ServiceSettings(model="new-model")
         changed = current.apply_update(delta)
-        assert changed.keys() == {"model"}
-        assert changed["model"] == "old-model"
+        assert set(changed.given_fields()) == {"model"}
+        assert changed.model == "old-model"
         assert current.model == "new-model"
 
     def test_apply_update_none_is_a_valid_value(self):
@@ -164,15 +164,15 @@ class TestApplyUpdate:
         current = TTSSettings()
         delta = TTSSettings(language=None)
         changed = current.apply_update(delta)
-        assert "language" in changed
+        assert is_given(changed.language)
         assert current.language is None
 
     def test_apply_update_none_to_value(self):
         current = TTSSettings(language=None)
         delta = TTSSettings(language="en")
         changed = current.apply_update(delta)
-        assert "language" in changed
-        assert changed["language"] is None  # old value was None
+        assert is_given(changed.language)
+        assert changed.language is None  # old value was None
         assert current.language == "en"
 
 
@@ -301,9 +301,9 @@ class TestRoundtrip:
         delta = TTSSettings.from_mapping(raw)
 
         changed = current.apply_update(delta)
-        assert changed.keys() == {"voice", "speed"}
-        assert changed["voice"] == "alice"
-        assert changed["speed"] == 1.0
+        assert set(changed.given_fields()) == {"voice", "speed"}
+        assert changed.voice == "alice"
+        assert changed.extra["speed"] == 1.0
         assert current.voice == "bob"
         assert current.language == "en"
         assert current.extra["speed"] == 1.2
@@ -313,8 +313,8 @@ 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.keys() == {"model", "temperature"}
-        assert changed["model"] == "gpt-4o"
+        assert set(changed.given_fields()) == {"model", "temperature"}
+        assert changed.model == "gpt-4o"
         assert current.model == "gpt-4o-mini"
         assert current.temperature == 0.9
 
@@ -348,7 +348,7 @@ class TestDeepgramSTTSettingsApplyUpdate:
         changed = current.apply_update(delta)
 
         assert current.punctuate is False
-        assert "punctuate" in changed
+        assert is_given(changed.punctuate)
         # Other fields are untouched
         assert current.model == "nova-3-general"
         assert current.language == "en"
@@ -362,7 +362,7 @@ class TestDeepgramSTTSettingsApplyUpdate:
         changed = current.apply_update(delta)
 
         assert current.model == "nova-2"
-        assert "model" in changed
+        assert is_given(changed.model)
 
     def test_apply_update_language(self):
         """language field is updated directly."""
@@ -373,14 +373,14 @@ class TestDeepgramSTTSettingsApplyUpdate:
         changed = current.apply_update(delta)
 
         assert current.language == "es"
-        assert "language" in changed
+        assert is_given(changed.language)
 
     def test_apply_update_no_change(self):
         """Delta with same values should report no changes."""
         current = self._make_store()
         delta = DeepgramSTTSettings(punctuate=True)
         changed = current.apply_update(delta)
-        assert changed == {}
+        assert changed.given_fields() == {}
 
     def test_apply_update_multiple_fields(self):
         """Multiple flat fields updated at once."""
@@ -392,7 +392,7 @@ class TestDeepgramSTTSettingsApplyUpdate:
         assert current.model == "nova-2"
         assert current.language == "fr"
         assert current.punctuate is False
-        assert changed.keys() == {"model", "language", "punctuate"}
+        assert set(changed.given_fields()) == {"model", "language", "punctuate"}
 
 
 class TestDeepgramSTTSettingsFromMapping:
@@ -441,7 +441,7 @@ class TestDeepgramSTTSettingsFromMapping:
         assert current.diarize is True
         # Unchanged fields stay put
         assert current.model == "nova-3-general"
-        assert "punctuate" in changed
+        assert is_given(changed.punctuate)
 
     def test_roundtrip_model_via_dict(self):
         """Dict update with model should change top-level model field."""
@@ -455,7 +455,7 @@ class TestDeepgramSTTSettingsFromMapping:
         changed = current.apply_update(delta)
 
         assert current.model == "nova-2"
-        assert "model" in changed
+        assert is_given(changed.model)
 
 
 # ---------------------------------------------------------------------------
@@ -475,7 +475,7 @@ class TestDeepgramSageMakerSTTSettings:
 
         assert store.model == "nova-2"
         assert store.language == "en"
-        assert "model" in changed
+        assert is_given(changed.model)
 
 
 # ---------------------------------------------------------------------------
@@ -650,7 +650,7 @@ class TestOpenAIRealtimeSettingsApplyUpdate:
         delta = OpenAIRealtimeLLMSettings(model="gpt-realtime-2.0")
         changed = store.apply_update(delta)
 
-        assert "model" in changed
+        assert is_given(changed.model)
         assert store.model == "gpt-realtime-2.0"
         assert store.session_properties.model == "gpt-realtime-2.0"
 
@@ -660,7 +660,7 @@ class TestOpenAIRealtimeSettingsApplyUpdate:
         delta = OpenAIRealtimeLLMSettings(system_instruction="Be helpful.")
         changed = store.apply_update(delta)
 
-        assert "system_instruction" in changed
+        assert is_given(changed.system_instruction)
         assert store.system_instruction == "Be helpful."
         assert store.session_properties.instructions == "Be helpful."
 
@@ -678,7 +678,7 @@ class TestOpenAIRealtimeSettingsApplyUpdate:
         delta = OpenAIRealtimeLLMSettings(session_properties=new_sp)
         changed = store.apply_update(delta)
 
-        assert "session_properties" in changed
+        assert is_given(changed.session_properties)
         assert store.session_properties.output_modalities == ["text"]
         # Fields not in the new SP become None (wholesale replacement)
         # But model is synced from top-level
@@ -691,7 +691,7 @@ class TestOpenAIRealtimeSettingsApplyUpdate:
         delta = OpenAIRealtimeLLMSettings(session_properties=new_sp)
         changed = store.apply_update(delta)
 
-        assert "model" in changed
+        assert is_given(changed.model)
         assert store.model == "gpt-realtime-2.0"
         assert store.session_properties.model == "gpt-realtime-2.0"
 
@@ -702,7 +702,7 @@ class TestOpenAIRealtimeSettingsApplyUpdate:
         delta = OpenAIRealtimeLLMSettings(session_properties=new_sp)
         changed = store.apply_update(delta)
 
-        assert "system_instruction" in changed
+        assert is_given(changed.system_instruction)
         assert store.system_instruction == "New instructions."
         assert store.session_properties.instructions == "New instructions."
 
@@ -740,7 +740,7 @@ class TestOpenAIRealtimeSettingsApplyUpdate:
         delta = OpenAIRealtimeLLMSettings(temperature=0.5)
         changed = store.apply_update(delta)
 
-        assert "temperature" in changed
+        assert is_given(changed.temperature)
         assert store.temperature == 0.5
         # SP should be untouched (same object)
         assert store.session_properties is original_sp
@@ -811,7 +811,7 @@ class TestOpenAIRealtimeSettingsFromMapping:
         delta = OpenAIRealtimeLLMSettings.from_mapping(raw)
         changed = store.apply_update(delta)
 
-        assert "session_properties" in changed
+        assert is_given(changed.session_properties)
         assert store.session_properties.instructions == "Be concise."
         assert store.session_properties.output_modalities == ["text"]
         assert store.system_instruction == "Be concise."
@@ -848,7 +848,7 @@ class TestGrokRealtimeSettingsApplyUpdate:
         delta = GrokRealtimeLLMSettings(system_instruction="Be helpful.")
         changed = store.apply_update(delta)
 
-        assert "system_instruction" in changed
+        assert is_given(changed.system_instruction)
         assert store.system_instruction == "Be helpful."
         assert store.session_properties.instructions == "Be helpful."
 
@@ -866,7 +866,7 @@ class TestGrokRealtimeSettingsApplyUpdate:
         delta = GrokRealtimeLLMSettings(session_properties=new_sp)
         changed = store.apply_update(delta)
 
-        assert "session_properties" in changed
+        assert is_given(changed.session_properties)
         assert store.session_properties.voice == "Sal"
         # instructions is synced from top-level system_instruction
         assert store.session_properties.instructions == "Old instructions."
@@ -878,7 +878,7 @@ class TestGrokRealtimeSettingsApplyUpdate:
         delta = GrokRealtimeLLMSettings(session_properties=new_sp)
         changed = store.apply_update(delta)
 
-        assert "system_instruction" in changed
+        assert is_given(changed.system_instruction)
         assert store.system_instruction == "New instructions."
         assert store.session_properties.instructions == "New instructions."
 
@@ -906,7 +906,7 @@ class TestGrokRealtimeSettingsApplyUpdate:
         delta = GrokRealtimeLLMSettings(temperature=0.5)
         changed = store.apply_update(delta)
 
-        assert "temperature" in changed
+        assert is_given(changed.temperature)
         assert store.temperature == 0.5
         # SP should be untouched (same object)
         assert store.session_properties is original_sp
@@ -977,7 +977,7 @@ class TestGrokRealtimeSettingsFromMapping:
         delta = GrokRealtimeLLMSettings.from_mapping(raw)
         changed = store.apply_update(delta)
 
-        assert "session_properties" in changed
+        assert is_given(changed.session_properties)
         assert store.session_properties.instructions == "Be concise."
         assert store.session_properties.voice == "Eve"
         assert store.system_instruction == "Be concise."