diff --git a/src/celeste/client.py b/src/celeste/client.py
index 213fc5db..7cd5aeaa 100644
--- a/src/celeste/client.py
+++ b/src/celeste/client.py
@@ -237,7 +237,7 @@ def _stream(
 
     @classmethod
     @abstractmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[Content]]:
         """Provider-specific parameter mappers."""
         ...
 
diff --git a/src/celeste/modalities/audio/providers/elevenlabs/client.py b/src/celeste/modalities/audio/providers/elevenlabs/client.py
index 50c76814..cc230ed4 100644
--- a/src/celeste/modalities/audio/providers/elevenlabs/client.py
+++ b/src/celeste/modalities/audio/providers/elevenlabs/client.py
@@ -11,6 +11,7 @@
 from celeste.providers.elevenlabs.text_to_speech.streaming import (
     ElevenLabsTextToSpeechStream as _ElevenLabsTextToSpeechStream,
 )
+from celeste.types import AudioContent
 
 from ...client import AudioClient
 from ...io import (
@@ -40,7 +41,7 @@ class ElevenLabsAudioClient(ElevenLabsTextToSpeechMixin, AudioClient):
     """ElevenLabs audio client (TTS)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[AudioContent]]:
         return ELEVENLABS_PARAMETER_MAPPERS
 
     async def speak(
diff --git a/src/celeste/modalities/audio/providers/elevenlabs/parameters.py b/src/celeste/modalities/audio/providers/elevenlabs/parameters.py
index 479a0d2d..a2fd69f0 100644
--- a/src/celeste/modalities/audio/providers/elevenlabs/parameters.py
+++ b/src/celeste/modalities/audio/providers/elevenlabs/parameters.py
@@ -13,6 +13,7 @@
 from celeste.providers.elevenlabs.text_to_speech.parameters import (
     VoiceMapper as _VoiceMapper,
 )
+from celeste.types import AudioContent
 
 from ...parameters import AudioParameter
 
@@ -41,7 +42,7 @@ class LanguageCodeMapper(_LanguageCodeMapper):
     name = AudioParameter.LANGUAGE
 
 
-ELEVENLABS_PARAMETER_MAPPERS: list[ParameterMapper] = [
+ELEVENLABS_PARAMETER_MAPPERS: list[ParameterMapper[AudioContent]] = [
     VoiceMapper(),
     SpeedMapper(),
     OutputFormatMapper(),
diff --git a/src/celeste/modalities/audio/providers/google/client.py b/src/celeste/modalities/audio/providers/google/client.py
index 800346e5..96ea1d2b 100644
--- a/src/celeste/modalities/audio/providers/google/client.py
+++ b/src/celeste/modalities/audio/providers/google/client.py
@@ -9,6 +9,7 @@
 from celeste.providers.google.cloud_tts.client import (
     GoogleCloudTTSClient as GoogleCloudTTSMixin,
 )
+from celeste.types import AudioContent
 
 from ...client import AudioClient
 from ...io import (
@@ -23,7 +24,7 @@ class GoogleAudioClient(GoogleCloudTTSMixin, AudioClient):
     """Google audio client (Cloud TTS)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[AudioContent]]:
         return GOOGLE_PARAMETER_MAPPERS
 
     async def speak(
diff --git a/src/celeste/modalities/audio/providers/google/parameters.py b/src/celeste/modalities/audio/providers/google/parameters.py
index 2083ba19..437f4769 100644
--- a/src/celeste/modalities/audio/providers/google/parameters.py
+++ b/src/celeste/modalities/audio/providers/google/parameters.py
@@ -13,6 +13,7 @@
 from celeste.providers.google.cloud_tts.parameters import (
     VoiceMapper as _VoiceMapper,
 )
+from celeste.types import AudioContent
 
 from ...parameters import AudioParameter
 
@@ -63,7 +64,7 @@ class OutputFormatMapper(_AudioEncodingMapper):
     }
 
 
-GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper] = [
+GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper[AudioContent]] = [
     VoiceMapper(),
     LanguageMapper(),
     OutputFormatMapper(),
diff --git a/src/celeste/modalities/audio/providers/gradium/client.py b/src/celeste/modalities/audio/providers/gradium/client.py
index 029a03e4..7ed7c061 100644
--- a/src/celeste/modalities/audio/providers/gradium/client.py
+++ b/src/celeste/modalities/audio/providers/gradium/client.py
@@ -11,6 +11,7 @@
 from celeste.providers.gradium.text_to_speech.streaming import (
     GradiumTextToSpeechStream as _GradiumTextToSpeechStream,
 )
+from celeste.types import AudioContent
 
 from ...client import AudioClient
 from ...io import (
@@ -40,7 +41,7 @@ class GradiumAudioClient(GradiumTextToSpeechMixin, AudioClient):
     """Gradium audio client (TTS)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[AudioContent]]:
         return GRADIUM_PARAMETER_MAPPERS
 
     async def speak(
diff --git a/src/celeste/modalities/audio/providers/gradium/parameters.py b/src/celeste/modalities/audio/providers/gradium/parameters.py
index 4d8ff942..e3e4f686 100644
--- a/src/celeste/modalities/audio/providers/gradium/parameters.py
+++ b/src/celeste/modalities/audio/providers/gradium/parameters.py
@@ -7,6 +7,7 @@
 from celeste.providers.gradium.text_to_speech.parameters import (
     VoiceMapper as _VoiceMapper,
 )
+from celeste.types import AudioContent
 
 from ...parameters import AudioParameter
 
@@ -23,7 +24,7 @@ class OutputFormatMapper(_OutputFormatMapper):
     name = AudioParameter.OUTPUT_FORMAT
 
 
-GRADIUM_PARAMETER_MAPPERS: list[ParameterMapper] = [
+GRADIUM_PARAMETER_MAPPERS: list[ParameterMapper[AudioContent]] = [
     VoiceMapper(),
     OutputFormatMapper(),
 ]
diff --git a/src/celeste/modalities/audio/providers/openai/client.py b/src/celeste/modalities/audio/providers/openai/client.py
index e712f1e8..bd7daeed 100644
--- a/src/celeste/modalities/audio/providers/openai/client.py
+++ b/src/celeste/modalities/audio/providers/openai/client.py
@@ -6,6 +6,7 @@
 from celeste.parameters import ParameterMapper
 from celeste.providers.openai.audio import config
 from celeste.providers.openai.audio.client import OpenAIAudioClient as OpenAIAudioMixin
+from celeste.types import AudioContent
 
 from ...client import AudioClient
 from ...io import AudioFinishReason, AudioInput, AudioOutput
@@ -17,7 +18,7 @@ class OpenAIAudioClient(OpenAIAudioMixin, AudioClient):
     """OpenAI audio client (TTS)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[AudioContent]]:
         return OPENAI_PARAMETER_MAPPERS
 
     async def speak(
diff --git a/src/celeste/modalities/audio/providers/openai/parameters.py b/src/celeste/modalities/audio/providers/openai/parameters.py
index 5754f960..80a0cc53 100644
--- a/src/celeste/modalities/audio/providers/openai/parameters.py
+++ b/src/celeste/modalities/audio/providers/openai/parameters.py
@@ -10,6 +10,7 @@
 from celeste.providers.openai.audio.parameters import (
     VoiceMapper as _VoiceMapper,
 )
+from celeste.types import AudioContent
 
 from ...parameters import AudioParameter
 
@@ -32,7 +33,7 @@ class OutputFormatMapper(_ResponseFormatMapper):
     name = AudioParameter.OUTPUT_FORMAT
 
 
-OPENAI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+OPENAI_PARAMETER_MAPPERS: list[ParameterMapper[AudioContent]] = [
     VoiceMapper(),
     SpeedMapper(),
     OutputFormatMapper(),
diff --git a/src/celeste/modalities/embeddings/providers/google/client.py b/src/celeste/modalities/embeddings/providers/google/client.py
index 39bfff97..aa857cad 100644
--- a/src/celeste/modalities/embeddings/providers/google/client.py
+++ b/src/celeste/modalities/embeddings/providers/google/client.py
@@ -18,7 +18,7 @@ class GoogleEmbeddingsClient(GoogleEmbeddingsMixin, EmbeddingsClient):
     """Google embeddings client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[EmbeddingsContent]]:
         """Return parameter mappers for Google embeddings."""
         return GOOGLE_PARAMETER_MAPPERS
 
diff --git a/src/celeste/modalities/embeddings/providers/google/parameters.py b/src/celeste/modalities/embeddings/providers/google/parameters.py
index 639ae14c..664b307d 100644
--- a/src/celeste/modalities/embeddings/providers/google/parameters.py
+++ b/src/celeste/modalities/embeddings/providers/google/parameters.py
@@ -4,6 +4,7 @@
 from celeste.providers.google.embeddings.parameters import (
     OutputDimensionalityMapper as _OutputDimensionalityMapper,
 )
+from celeste.types import EmbeddingsContent
 
 from ...parameters import EmbeddingsParameter
 
@@ -14,7 +15,7 @@ class DimensionsMapper(_OutputDimensionalityMapper):
     name = EmbeddingsParameter.DIMENSIONS
 
 
-GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper] = [
+GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper[EmbeddingsContent]] = [
     DimensionsMapper(),
 ]
 
diff --git a/src/celeste/modalities/images/providers/bfl/client.py b/src/celeste/modalities/images/providers/bfl/client.py
index 6842afd2..73a9d949 100644
--- a/src/celeste/modalities/images/providers/bfl/client.py
+++ b/src/celeste/modalities/images/providers/bfl/client.py
@@ -7,6 +7,7 @@
 from celeste.providers.bfl.images import config as bfl_config
 from celeste.providers.bfl.images.client import BFLImagesClient as _BFLImagesClient
 from celeste.providers.bfl.images.utils import encode_image
+from celeste.types import ImageContent
 
 from ...client import ImagesClient
 from ...io import ImageFinishReason, ImageInput, ImageOutput
@@ -18,7 +19,7 @@ class BFLImagesClient(_BFLImagesClient, ImagesClient):
     """BFL images client (generate + edit)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return BFL_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/images/providers/bfl/parameters.py b/src/celeste/modalities/images/providers/bfl/parameters.py
index f5c64c5e..187d53ed 100644
--- a/src/celeste/modalities/images/providers/bfl/parameters.py
+++ b/src/celeste/modalities/images/providers/bfl/parameters.py
@@ -29,11 +29,12 @@
     WidthMapper as _WidthMapper,
 )
 from celeste.providers.bfl.images.utils import add_reference_images
+from celeste.types import ImageContent
 
 from ...parameters import ImageParameter
 
 
-class AspectRatioMapper(ParameterMapper):
+class AspectRatioMapper(ParameterMapper[ImageContent]):
     """Map aspect_ratio to BFL width/height parameters.
 
     Converts 'WxH' string to width/height, rounded to nearest multiple of 16.
@@ -91,7 +92,7 @@ class GuidanceMapper(_GuidanceMapper):
     name = ImageParameter.GUIDANCE
 
 
-class ReferenceImagesMapper(ParameterMapper):
+class ReferenceImagesMapper(ParameterMapper[ImageContent]):
     name = ImageParameter.REFERENCE_IMAGES
 
     def map(
@@ -108,7 +109,7 @@ def map(
         return add_reference_images(request, validated_value)
 
 
-BFL_PARAMETER_MAPPERS: list[ParameterMapper] = [
+BFL_PARAMETER_MAPPERS: list[ParameterMapper[ImageContent]] = [
     AspectRatioMapper(),
     PromptUpsamplingMapper(),
     SeedMapper(),
diff --git a/src/celeste/modalities/images/providers/byteplus/client.py b/src/celeste/modalities/images/providers/byteplus/client.py
index 7827381f..97ec1dd1 100644
--- a/src/celeste/modalities/images/providers/byteplus/client.py
+++ b/src/celeste/modalities/images/providers/byteplus/client.py
@@ -13,6 +13,7 @@
 from celeste.providers.byteplus.images.streaming import (
     BytePlusImagesStream as _BytePlusImagesStream,
 )
+from celeste.types import ImageContent
 
 from ...client import ImagesClient
 from ...io import (
@@ -94,7 +95,7 @@ class BytePlusImagesClient(BytePlusImagesMixin, ImagesClient):
     """BytePlus images client (generate + streaming)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return BYTEPLUS_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/images/providers/byteplus/parameters.py b/src/celeste/modalities/images/providers/byteplus/parameters.py
index 9942fc78..a74cb55e 100644
--- a/src/celeste/modalities/images/providers/byteplus/parameters.py
+++ b/src/celeste/modalities/images/providers/byteplus/parameters.py
@@ -7,6 +7,7 @@
 from celeste.providers.byteplus.images.parameters import (
     WatermarkMapper as _WatermarkMapper,
 )
+from celeste.types import ImageContent
 
 from ...parameters import ImageParameter
 
@@ -25,7 +26,7 @@ class WatermarkMapper(_WatermarkMapper):
     name = ImageParameter.WATERMARK
 
 
-BYTEPLUS_PARAMETER_MAPPERS: list[ParameterMapper] = [
+BYTEPLUS_PARAMETER_MAPPERS: list[ParameterMapper[ImageContent]] = [
     AspectRatioMapper(),
     QualityMapper(),
     WatermarkMapper(),
diff --git a/src/celeste/modalities/images/providers/google/client.py b/src/celeste/modalities/images/providers/google/client.py
index 5f2d3a89..bf16bebd 100644
--- a/src/celeste/modalities/images/providers/google/client.py
+++ b/src/celeste/modalities/images/providers/google/client.py
@@ -44,7 +44,7 @@ def model_post_init(self, __context: object) -> None:
         object.__setattr__(self, "_strategy", strategy)
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return [*GEMINI_PARAMETER_MAPPERS, *IMAGEN_PARAMETER_MAPPERS]
 
     async def generate(
diff --git a/src/celeste/modalities/images/providers/google/gemini.py b/src/celeste/modalities/images/providers/google/gemini.py
index 51f333df..530342b3 100644
--- a/src/celeste/modalities/images/providers/google/gemini.py
+++ b/src/celeste/modalities/images/providers/google/gemini.py
@@ -44,7 +44,7 @@ class GeminiImagesClient(GoogleGenerateContentClient, ImagesClient):
     """Google Gemini client for images modality (generate + edit)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return GEMINI_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/images/providers/google/imagen.py b/src/celeste/modalities/images/providers/google/imagen.py
index c415fc33..d2faa1a7 100644
--- a/src/celeste/modalities/images/providers/google/imagen.py
+++ b/src/celeste/modalities/images/providers/google/imagen.py
@@ -19,7 +19,7 @@ class ImagenImagesClient(GoogleImagenClient, ImagesClient):
     """Google Imagen client for images modality (generate)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return IMAGEN_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/images/providers/google/parameters.py b/src/celeste/modalities/images/providers/google/parameters.py
index 5c15e730..5feb4c0b 100644
--- a/src/celeste/modalities/images/providers/google/parameters.py
+++ b/src/celeste/modalities/images/providers/google/parameters.py
@@ -19,6 +19,7 @@
 from celeste.providers.google.imagen.parameters import (
     SampleCountMapper as _ImagenSampleCountMapper,
 )
+from celeste.types import ImageContent
 
 from ...parameters import ImageParameter
 
@@ -41,32 +42,32 @@ class ImagenNumImagesMapper(_ImagenSampleCountMapper):
     name = ImageParameter.NUM_IMAGES
 
 
-IMAGEN_PARAMETER_MAPPERS: list[ParameterMapper] = [
+IMAGEN_PARAMETER_MAPPERS: list[ParameterMapper[ImageContent]] = [
     ImagenAspectRatioMapper(),
     ImagenQualityMapper(),
     ImagenNumImagesMapper(),
 ]
 
 
-class GeminiAspectRatioMapper(_GeminiAspectRatioMapper):
+class GeminiAspectRatioMapper(_GeminiAspectRatioMapper[ImageContent]):
     """Map aspect_ratio to Gemini generationConfig.imageConfig.aspectRatio."""
 
     name = ImageParameter.ASPECT_RATIO
 
 
-class GeminiQualityMapper(_GeminiImageSizeMapper):
+class GeminiQualityMapper(_GeminiImageSizeMapper[ImageContent]):
     """Map quality to Gemini generationConfig.imageConfig.imageSize."""
 
     name = ImageParameter.QUALITY
 
 
-class GeminiReferenceImagesMapper(_GeminiMediaContentMapper):
+class GeminiReferenceImagesMapper(_GeminiMediaContentMapper[ImageContent]):
     """Map reference_images to Gemini contents.parts."""
 
     name = ImageParameter.REFERENCE_IMAGES
 
 
-GEMINI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+GEMINI_PARAMETER_MAPPERS: list[ParameterMapper[ImageContent]] = [
     GeminiAspectRatioMapper(),
     GeminiQualityMapper(),
     GeminiReferenceImagesMapper(),
diff --git a/src/celeste/modalities/images/providers/ollama/client.py b/src/celeste/modalities/images/providers/ollama/client.py
index d1bbf264..c600c7c3 100644
--- a/src/celeste/modalities/images/providers/ollama/client.py
+++ b/src/celeste/modalities/images/providers/ollama/client.py
@@ -9,6 +9,7 @@
 from celeste.providers.ollama.generate.streaming import (
     OllamaGenerateStream as _OllamaGenerateStream,
 )
+from celeste.types import ImageContent
 
 from ...client import ImagesClient
 from ...io import (
@@ -54,7 +55,7 @@ class OllamaImagesClient(OllamaGenerateClient, ImagesClient):
     """Ollama images client (generate only, no edit support yet)."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return OLLAMA_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/images/providers/ollama/parameters.py b/src/celeste/modalities/images/providers/ollama/parameters.py
index c91b9e24..02e5748b 100644
--- a/src/celeste/modalities/images/providers/ollama/parameters.py
+++ b/src/celeste/modalities/images/providers/ollama/parameters.py
@@ -19,11 +19,12 @@
 from celeste.providers.ollama.generate.parameters import (
     WidthMapper as _WidthMapper,
 )
+from celeste.types import ImageContent
 
 from ...parameters import ImageParameter
 
 
-class AspectRatioMapper(ParameterMapper):
+class AspectRatioMapper(ParameterMapper[ImageContent]):
     """Map aspect_ratio to Ollama's width and height parameters.
 
     Parses 'WxH' string and delegates to native mappers.
@@ -69,7 +70,7 @@ class NegativePromptMapper(_NegativePromptMapper):
     name = ImageParameter.NEGATIVE_PROMPT
 
 
-OLLAMA_PARAMETER_MAPPERS: list[ParameterMapper] = [
+OLLAMA_PARAMETER_MAPPERS: list[ParameterMapper[ImageContent]] = [
     AspectRatioMapper(),
     StepsMapper(),
     SeedMapper(),
diff --git a/src/celeste/modalities/images/providers/openai/client.py b/src/celeste/modalities/images/providers/openai/client.py
index e440bf79..325e04c9 100644
--- a/src/celeste/modalities/images/providers/openai/client.py
+++ b/src/celeste/modalities/images/providers/openai/client.py
@@ -11,6 +11,7 @@
 from celeste.providers.openai.images.streaming import (
     OpenAIImagesStream as _OpenAIImagesStream,
 )
+from celeste.types import ImageContent
 
 from ...client import ImagesClient
 from ...io import (
@@ -35,7 +36,7 @@ class OpenAIImagesClient(OpenAIImagesMixin, ImagesClient):
     """OpenAI images client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return OPENAI_PARAMETER_MAPPERS
 
     def _init_request(self, inputs: ImageInput) -> dict[str, Any]:
diff --git a/src/celeste/modalities/images/providers/openai/parameters.py b/src/celeste/modalities/images/providers/openai/parameters.py
index 84485d6c..4896f16c 100644
--- a/src/celeste/modalities/images/providers/openai/parameters.py
+++ b/src/celeste/modalities/images/providers/openai/parameters.py
@@ -10,6 +10,7 @@
 from celeste.providers.openai.images.parameters import (
     SizeMapper as _SizeMapper,
 )
+from celeste.types import ImageContent
 
 from ...parameters import ImageParameter
 
@@ -32,7 +33,7 @@ class QualityMapper(_QualityMapper):
     name = ImageParameter.QUALITY
 
 
-OPENAI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+OPENAI_PARAMETER_MAPPERS: list[ParameterMapper[ImageContent]] = [
     AspectRatioMapper(),
     PartialImagesMapper(),
     QualityMapper(),
diff --git a/src/celeste/modalities/images/providers/xai/client.py b/src/celeste/modalities/images/providers/xai/client.py
index 6c27e0ee..1b10e2ab 100644
--- a/src/celeste/modalities/images/providers/xai/client.py
+++ b/src/celeste/modalities/images/providers/xai/client.py
@@ -6,6 +6,7 @@
 from celeste.parameters import ParameterMapper
 from celeste.providers.xai.images import config
 from celeste.providers.xai.images.client import XAIImagesClient as XAIImagesMixin
+from celeste.types import ImageContent
 
 from ...client import ImagesClient
 from ...io import (
@@ -20,7 +21,7 @@ class XAIImagesClient(XAIImagesMixin, ImagesClient):
     """xAI images client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[ImageContent]]:
         return XAI_PARAMETER_MAPPERS
 
     def _init_request(self, inputs: ImageInput) -> dict[str, Any]:
diff --git a/src/celeste/modalities/images/providers/xai/parameters.py b/src/celeste/modalities/images/providers/xai/parameters.py
index 3078a095..edb77d08 100644
--- a/src/celeste/modalities/images/providers/xai/parameters.py
+++ b/src/celeste/modalities/images/providers/xai/parameters.py
@@ -10,6 +10,7 @@
 from celeste.providers.xai.images.parameters import (
     ResponseFormatMapper as _ResponseFormatMapper,
 )
+from celeste.types import ImageContent
 
 from ...parameters import ImageParameter
 
@@ -32,7 +33,7 @@ class OutputFormatMapper(_ResponseFormatMapper):
     name = ImageParameter.OUTPUT_FORMAT
 
 
-XAI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+XAI_PARAMETER_MAPPERS: list[ParameterMapper[ImageContent]] = [
     AspectRatioMapper(),
     NumImagesMapper(),
     OutputFormatMapper(),
diff --git a/src/celeste/modalities/text/providers/anthropic/client.py b/src/celeste/modalities/text/providers/anthropic/client.py
index e28b289d..05be71bb 100644
--- a/src/celeste/modalities/text/providers/anthropic/client.py
+++ b/src/celeste/modalities/text/providers/anthropic/client.py
@@ -54,7 +54,7 @@ class AnthropicTextClient(AnthropicMessagesClient, TextClient):
     """Anthropic text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return ANTHROPIC_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/anthropic/parameters.py b/src/celeste/modalities/text/providers/anthropic/parameters.py
index 3c29d718..0470a3f8 100644
--- a/src/celeste/modalities/text/providers/anthropic/parameters.py
+++ b/src/celeste/modalities/text/providers/anthropic/parameters.py
@@ -19,6 +19,7 @@
 from celeste.providers.anthropic.messages.parameters import (
     WebSearchMapper as _WebSearchMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -72,7 +73,7 @@ class WebSearchMapper(_WebSearchMapper):
     name = TextParameter.WEB_SEARCH
 
 
-ANTHROPIC_PARAMETER_MAPPERS: list[ParameterMapper] = [
+ANTHROPIC_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     ThinkingBudgetMapper(),
diff --git a/src/celeste/modalities/text/providers/cohere/client.py b/src/celeste/modalities/text/providers/cohere/client.py
index cdfb793f..8f3fd25a 100644
--- a/src/celeste/modalities/text/providers/cohere/client.py
+++ b/src/celeste/modalities/text/providers/cohere/client.py
@@ -28,7 +28,7 @@ class CohereTextClient(CohereChatClient, TextClient):
     """Cohere text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return COHERE_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/cohere/parameters.py b/src/celeste/modalities/text/providers/cohere/parameters.py
index 726e6605..94b328e9 100644
--- a/src/celeste/modalities/text/providers/cohere/parameters.py
+++ b/src/celeste/modalities/text/providers/cohere/parameters.py
@@ -16,6 +16,7 @@
 from celeste.providers.cohere.chat.parameters import (
     ThinkingMapper as _ThinkingMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -65,7 +66,7 @@ class OutputSchemaMapper(_ResponseFormatMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-COHERE_PARAMETER_MAPPERS: list[ParameterMapper] = [
+COHERE_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     ThinkingBudgetMapper(),
diff --git a/src/celeste/modalities/text/providers/deepseek/client.py b/src/celeste/modalities/text/providers/deepseek/client.py
index 40e6010e..356c1003 100644
--- a/src/celeste/modalities/text/providers/deepseek/client.py
+++ b/src/celeste/modalities/text/providers/deepseek/client.py
@@ -27,7 +27,7 @@ class DeepSeekTextClient(DeepSeekChatClient, TextClient):
     """DeepSeek text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return DEEPSEEK_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/deepseek/parameters.py b/src/celeste/modalities/text/providers/deepseek/parameters.py
index 4dd6bd27..f5e65101 100644
--- a/src/celeste/modalities/text/providers/deepseek/parameters.py
+++ b/src/celeste/modalities/text/providers/deepseek/parameters.py
@@ -10,6 +10,7 @@
 from celeste.protocols.chatcompletions.parameters import (
     TemperatureMapper as _TemperatureMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -32,7 +33,7 @@ class OutputSchemaMapper(_ResponseFormatMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-DEEPSEEK_PARAMETER_MAPPERS: list[ParameterMapper] = [
+DEEPSEEK_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     OutputSchemaMapper(),
diff --git a/src/celeste/modalities/text/providers/google/client.py b/src/celeste/modalities/text/providers/google/client.py
index 0d3f0236..d418be5a 100644
--- a/src/celeste/modalities/text/providers/google/client.py
+++ b/src/celeste/modalities/text/providers/google/client.py
@@ -31,7 +31,7 @@ class GoogleTextClient(GoogleGenerateContentClient, TextClient):
     """Google text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return GOOGLE_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/google/parameters.py b/src/celeste/modalities/text/providers/google/parameters.py
index 2a61e808..d9a0702e 100644
--- a/src/celeste/modalities/text/providers/google/parameters.py
+++ b/src/celeste/modalities/text/providers/google/parameters.py
@@ -19,29 +19,30 @@
 from celeste.providers.google.generate_content.parameters import (
     WebSearchMapper as _WebSearchMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
 
-class TemperatureMapper(_TemperatureMapper):
+class TemperatureMapper(_TemperatureMapper[TextContent]):
     """Map temperature to Google's generationConfig.temperature parameter."""
 
     name = TextParameter.TEMPERATURE
 
 
-class MaxTokensMapper(_MaxOutputTokensMapper):
+class MaxTokensMapper(_MaxOutputTokensMapper[TextContent]):
     """Map max_tokens to Google's generationConfig.maxOutputTokens parameter."""
 
     name = TextParameter.MAX_TOKENS
 
 
-class ThinkingBudgetMapper(_ThinkingBudgetMapper):
+class ThinkingBudgetMapper(_ThinkingBudgetMapper[TextContent]):
     """Map thinking_budget to Google's generationConfig.thinkingConfig.thinkingBudget parameter."""
 
     name = TextParameter.THINKING_BUDGET
 
 
-class ThinkingLevelMapper(_ThinkingLevelMapper):
+class ThinkingLevelMapper(_ThinkingLevelMapper[TextContent]):
     """Map thinking_level to Google's generationConfig.thinkingConfig.thinkingLevel parameter."""
 
     name = TextParameter.THINKING_LEVEL
@@ -53,13 +54,13 @@ class OutputSchemaMapper(_ResponseJsonSchemaMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-class WebSearchMapper(_WebSearchMapper):
+class WebSearchMapper(_WebSearchMapper[TextContent]):
     """Map web_search to Google's tools parameter."""
 
     name = TextParameter.WEB_SEARCH
 
 
-GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper] = [
+GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     ThinkingBudgetMapper(),
diff --git a/src/celeste/modalities/text/providers/groq/client.py b/src/celeste/modalities/text/providers/groq/client.py
index b48ea373..97b6d4dc 100644
--- a/src/celeste/modalities/text/providers/groq/client.py
+++ b/src/celeste/modalities/text/providers/groq/client.py
@@ -26,7 +26,7 @@ class GroqTextClient(GroqChatClient, TextClient):
     """Groq text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return GROQ_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/groq/parameters.py b/src/celeste/modalities/text/providers/groq/parameters.py
index 0a55f443..d1ce11ce 100644
--- a/src/celeste/modalities/text/providers/groq/parameters.py
+++ b/src/celeste/modalities/text/providers/groq/parameters.py
@@ -10,6 +10,7 @@
 from celeste.providers.groq.chat.parameters import (
     ResponseFormatMapper as _ResponseFormatMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -32,7 +33,7 @@ class OutputSchemaMapper(_ResponseFormatMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-GROQ_PARAMETER_MAPPERS: list[ParameterMapper] = [
+GROQ_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     OutputSchemaMapper(),
diff --git a/src/celeste/modalities/text/providers/huggingface/client.py b/src/celeste/modalities/text/providers/huggingface/client.py
index c403c07d..d586198d 100644
--- a/src/celeste/modalities/text/providers/huggingface/client.py
+++ b/src/celeste/modalities/text/providers/huggingface/client.py
@@ -28,7 +28,7 @@ class HuggingFaceTextClient(HuggingFaceChatClient, TextClient):
     """HuggingFace text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return HUGGINGFACE_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/huggingface/parameters.py b/src/celeste/modalities/text/providers/huggingface/parameters.py
index bd0aa238..c03adb46 100644
--- a/src/celeste/modalities/text/providers/huggingface/parameters.py
+++ b/src/celeste/modalities/text/providers/huggingface/parameters.py
@@ -10,6 +10,7 @@
 from celeste.providers.huggingface.chat.parameters import (
     ResponseFormatMapper as _ResponseFormatMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -32,7 +33,7 @@ class OutputSchemaMapper(_ResponseFormatMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-HUGGINGFACE_PARAMETER_MAPPERS: list[ParameterMapper] = [
+HUGGINGFACE_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     OutputSchemaMapper(),
diff --git a/src/celeste/modalities/text/providers/mistral/client.py b/src/celeste/modalities/text/providers/mistral/client.py
index 2a30fc88..cf621e83 100644
--- a/src/celeste/modalities/text/providers/mistral/client.py
+++ b/src/celeste/modalities/text/providers/mistral/client.py
@@ -28,7 +28,7 @@ class MistralTextClient(MistralChatClient, TextClient):
     """Mistral text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return MISTRAL_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/mistral/parameters.py b/src/celeste/modalities/text/providers/mistral/parameters.py
index 1f545d5a..fc96729c 100644
--- a/src/celeste/modalities/text/providers/mistral/parameters.py
+++ b/src/celeste/modalities/text/providers/mistral/parameters.py
@@ -13,6 +13,7 @@
 from celeste.providers.mistral.chat.parameters import (
     ResponseFormatMapper as _ResponseFormatMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -29,7 +30,7 @@ class MaxTokensMapper(_MaxTokensMapper):
     name = TextParameter.MAX_TOKENS
 
 
-class ThinkingBudgetMapper(ParameterMapper):
+class ThinkingBudgetMapper(ParameterMapper[TextContent]):
     """Map thinking_budget to Mistral's prompt_mode parameter."""
 
     name = TextParameter.THINKING_BUDGET
@@ -62,7 +63,7 @@ class OutputSchemaMapper(_ResponseFormatMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-MISTRAL_PARAMETER_MAPPERS: list[ParameterMapper] = [
+MISTRAL_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     ThinkingBudgetMapper(),
diff --git a/src/celeste/modalities/text/providers/moonshot/client.py b/src/celeste/modalities/text/providers/moonshot/client.py
index 165d72e3..9640d6e8 100644
--- a/src/celeste/modalities/text/providers/moonshot/client.py
+++ b/src/celeste/modalities/text/providers/moonshot/client.py
@@ -28,7 +28,7 @@ class MoonshotTextClient(MoonshotChatClient, TextClient):
     """Moonshot text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return MOONSHOT_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/moonshot/parameters.py b/src/celeste/modalities/text/providers/moonshot/parameters.py
index 3a232519..480cf175 100644
--- a/src/celeste/modalities/text/providers/moonshot/parameters.py
+++ b/src/celeste/modalities/text/providers/moonshot/parameters.py
@@ -10,6 +10,7 @@
 from celeste.protocols.chatcompletions.parameters import (
     TemperatureMapper as _TemperatureMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -32,7 +33,7 @@ class OutputSchemaMapper(_ResponseFormatMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-MOONSHOT_PARAMETER_MAPPERS: list[ParameterMapper] = [
+MOONSHOT_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     OutputSchemaMapper(),
diff --git a/src/celeste/modalities/text/providers/openai/client.py b/src/celeste/modalities/text/providers/openai/client.py
index 51156916..175c2cfa 100644
--- a/src/celeste/modalities/text/providers/openai/client.py
+++ b/src/celeste/modalities/text/providers/openai/client.py
@@ -31,7 +31,7 @@ class OpenAITextClient(OpenAIResponsesMixin, TextClient):
     """OpenAI text client using Responses API."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return OPENAI_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/openai/parameters.py b/src/celeste/modalities/text/providers/openai/parameters.py
index c13b2c53..96b6381b 100644
--- a/src/celeste/modalities/text/providers/openai/parameters.py
+++ b/src/celeste/modalities/text/providers/openai/parameters.py
@@ -19,6 +19,7 @@
 from celeste.protocols.openresponses.parameters import (
     WebSearchMapper as _WebSearchMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -59,7 +60,7 @@ class ThinkingBudgetMapper(_ReasoningEffortMapper):
     name = TextParameter.THINKING_BUDGET
 
 
-OPENAI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+OPENAI_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     OutputSchemaMapper(),
diff --git a/src/celeste/modalities/text/providers/openresponses/client.py b/src/celeste/modalities/text/providers/openresponses/client.py
index 0185c1fc..6fc23c3a 100644
--- a/src/celeste/modalities/text/providers/openresponses/client.py
+++ b/src/celeste/modalities/text/providers/openresponses/client.py
@@ -52,7 +52,7 @@ class OpenResponsesTextClient(OpenResponsesMixin, TextClient):
     """OpenResponses text client using Responses API."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return OPENRESPONSES_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/openresponses/parameters.py b/src/celeste/modalities/text/providers/openresponses/parameters.py
index 52305abe..378237bd 100644
--- a/src/celeste/modalities/text/providers/openresponses/parameters.py
+++ b/src/celeste/modalities/text/providers/openresponses/parameters.py
@@ -10,6 +10,7 @@
 from celeste.protocols.openresponses.parameters import (
     TextFormatMapper as _TextFormatMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -32,7 +33,7 @@ class OutputSchemaMapper(_TextFormatMapper):
     name = TextParameter.OUTPUT_SCHEMA
 
 
-OPENRESPONSES_PARAMETER_MAPPERS: list[ParameterMapper] = [
+OPENRESPONSES_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     OutputSchemaMapper(),
diff --git a/src/celeste/modalities/text/providers/xai/client.py b/src/celeste/modalities/text/providers/xai/client.py
index 91f0ad07..71dfc4c0 100644
--- a/src/celeste/modalities/text/providers/xai/client.py
+++ b/src/celeste/modalities/text/providers/xai/client.py
@@ -29,7 +29,7 @@ class XAITextClient(XAIResponsesClient, TextClient):
     """xAI text client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[TextContent]]:
         return XAI_PARAMETER_MAPPERS
 
     async def generate(
diff --git a/src/celeste/modalities/text/providers/xai/parameters.py b/src/celeste/modalities/text/providers/xai/parameters.py
index 7b1b88ce..064d79fc 100644
--- a/src/celeste/modalities/text/providers/xai/parameters.py
+++ b/src/celeste/modalities/text/providers/xai/parameters.py
@@ -22,6 +22,7 @@
 from celeste.protocols.openresponses.parameters import (
     XSearchMapper as _XSearchMapper,
 )
+from celeste.types import TextContent
 
 from ...parameters import TextParameter
 
@@ -68,7 +69,7 @@ class CodeExecutionMapper(_CodeExecutionMapper):
     name = TextParameter.CODE_EXECUTION
 
 
-XAI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+XAI_PARAMETER_MAPPERS: list[ParameterMapper[TextContent]] = [
     TemperatureMapper(),
     MaxTokensMapper(),
     ThinkingBudgetMapper(),
diff --git a/src/celeste/modalities/videos/providers/byteplus/client.py b/src/celeste/modalities/videos/providers/byteplus/client.py
index 05d06d2f..f4672079 100644
--- a/src/celeste/modalities/videos/providers/byteplus/client.py
+++ b/src/celeste/modalities/videos/providers/byteplus/client.py
@@ -8,6 +8,7 @@
 from celeste.providers.byteplus.videos.client import (
     BytePlusVideosClient as BytePlusVideosMixin,
 )
+from celeste.types import VideoContent
 
 from ...client import VideosClient
 from ...io import VideoInput, VideoOutput
@@ -19,7 +20,7 @@ class BytePlusVideosClient(BytePlusVideosMixin, VideosClient):
     """BytePlus client for video generation."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[VideoContent]]:
         return BYTEPLUS_PARAMETER_MAPPERS
 
     def _init_request(self, inputs: VideoInput) -> dict[str, Any]:
diff --git a/src/celeste/modalities/videos/providers/byteplus/parameters.py b/src/celeste/modalities/videos/providers/byteplus/parameters.py
index ee409973..6fff0c41 100644
--- a/src/celeste/modalities/videos/providers/byteplus/parameters.py
+++ b/src/celeste/modalities/videos/providers/byteplus/parameters.py
@@ -19,6 +19,7 @@
 from celeste.providers.byteplus.videos.parameters import (
     ResolutionMapper as _ResolutionMapper,
 )
+from celeste.types import VideoContent
 
 from ...parameters import VideoParameter
 
@@ -59,7 +60,7 @@ class LastFrameMapper(_LastFrameMapper):
     name = VideoParameter.LAST_FRAME
 
 
-BYTEPLUS_PARAMETER_MAPPERS: list[ParameterMapper] = [
+BYTEPLUS_PARAMETER_MAPPERS: list[ParameterMapper[VideoContent]] = [
     AspectRatioMapper(),
     ResolutionMapper(),
     DurationMapper(),
diff --git a/src/celeste/modalities/videos/providers/google/client.py b/src/celeste/modalities/videos/providers/google/client.py
index 171aff38..fdbbaaa8 100644
--- a/src/celeste/modalities/videos/providers/google/client.py
+++ b/src/celeste/modalities/videos/providers/google/client.py
@@ -7,6 +7,7 @@
 from celeste.parameters import ParameterMapper
 from celeste.providers.google.veo import config
 from celeste.providers.google.veo.client import GoogleVeoClient as GoogleVeoMixin
+from celeste.types import VideoContent
 
 from ...client import VideosClient
 from ...io import VideoInput, VideoOutput
@@ -18,7 +19,7 @@ class GoogleVideosClient(GoogleVeoMixin, VideosClient):
     """Google client for video generation."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[VideoContent]]:
         return GOOGLE_PARAMETER_MAPPERS
 
     def _init_request(self, inputs: VideoInput) -> dict[str, Any]:
diff --git a/src/celeste/modalities/videos/providers/google/parameters.py b/src/celeste/modalities/videos/providers/google/parameters.py
index 30ad7610..13e56274 100644
--- a/src/celeste/modalities/videos/providers/google/parameters.py
+++ b/src/celeste/modalities/videos/providers/google/parameters.py
@@ -19,6 +19,7 @@
 from celeste.providers.google.veo.parameters import (
     ResolutionMapper as _ResolutionMapper,
 )
+from celeste.types import VideoContent
 
 from ...parameters import VideoParameter
 
@@ -59,7 +60,7 @@ class LastFrameMapper(_LastFrameMapper):
     name = VideoParameter.LAST_FRAME
 
 
-GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper] = [
+GOOGLE_PARAMETER_MAPPERS: list[ParameterMapper[VideoContent]] = [
     AspectRatioMapper(),
     ResolutionMapper(),
     DurationMapper(),
diff --git a/src/celeste/modalities/videos/providers/openai/client.py b/src/celeste/modalities/videos/providers/openai/client.py
index e2284499..4509616e 100644
--- a/src/celeste/modalities/videos/providers/openai/client.py
+++ b/src/celeste/modalities/videos/providers/openai/client.py
@@ -9,6 +9,7 @@
 from celeste.providers.openai.videos.client import (
     OpenAIVideosClient as OpenAIVideosMixin,
 )
+from celeste.types import VideoContent
 
 from ...client import VideosClient
 from ...io import VideoInput, VideoOutput
@@ -20,7 +21,7 @@ class OpenAIVideosClient(OpenAIVideosMixin, VideosClient):
     """OpenAI client for video generation."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[VideoContent]]:
         return OPENAI_PARAMETER_MAPPERS
 
     def _init_request(self, inputs: VideoInput) -> dict[str, Any]:
diff --git a/src/celeste/modalities/videos/providers/openai/parameters.py b/src/celeste/modalities/videos/providers/openai/parameters.py
index 81ddb945..0f133c73 100644
--- a/src/celeste/modalities/videos/providers/openai/parameters.py
+++ b/src/celeste/modalities/videos/providers/openai/parameters.py
@@ -19,6 +19,7 @@
 from celeste.providers.openai.videos.parameters import (
     SizeMapper as _SizeMapper,
 )
+from celeste.types import VideoContent
 
 from ...parameters import VideoParameter
 
@@ -58,7 +59,7 @@ def _compute_size(aspect_ratio: str, resolution: str) -> str:
     return f"{width}x{height}"
 
 
-class AspectRatioMapper(ParameterMapper):
+class AspectRatioMapper(ParameterMapper[VideoContent]):
     """Store aspect_ratio for later combination with resolution."""
 
     name = VideoParameter.ASPECT_RATIO
@@ -107,7 +108,7 @@ class DurationMapper(_SecondsMapper):
     name = VideoParameter.DURATION
 
 
-OPENAI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+OPENAI_PARAMETER_MAPPERS: list[ParameterMapper[VideoContent]] = [
     AspectRatioMapper(),
     ResolutionMapper(),
     DurationMapper(),
diff --git a/src/celeste/modalities/videos/providers/xai/client.py b/src/celeste/modalities/videos/providers/xai/client.py
index 8acdf485..fc3c8b50 100644
--- a/src/celeste/modalities/videos/providers/xai/client.py
+++ b/src/celeste/modalities/videos/providers/xai/client.py
@@ -6,6 +6,7 @@
 from celeste.parameters import ParameterMapper
 from celeste.providers.xai.videos import config
 from celeste.providers.xai.videos.client import XAIVideosClient as XAIVideosMixin
+from celeste.types import VideoContent
 
 from ...client import VideosClient
 from ...io import VideoInput, VideoOutput
@@ -17,7 +18,7 @@ class XAIVideosClient(XAIVideosMixin, VideosClient):
     """xAI client for video generation."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[VideoContent]]:
         return XAI_PARAMETER_MAPPERS
 
     def _init_request(self, inputs: VideoInput) -> dict[str, Any]:
diff --git a/src/celeste/modalities/videos/providers/xai/parameters.py b/src/celeste/modalities/videos/providers/xai/parameters.py
index aa355485..db411e1d 100644
--- a/src/celeste/modalities/videos/providers/xai/parameters.py
+++ b/src/celeste/modalities/videos/providers/xai/parameters.py
@@ -10,6 +10,7 @@
 from celeste.providers.xai.videos.parameters import (
     ResolutionMapper as _ResolutionMapper,
 )
+from celeste.types import VideoContent
 
 from ...parameters import VideoParameter
 
@@ -32,7 +33,7 @@ class ResolutionMapper(_ResolutionMapper):
     name = VideoParameter.RESOLUTION
 
 
-XAI_PARAMETER_MAPPERS: list[ParameterMapper] = [
+XAI_PARAMETER_MAPPERS: list[ParameterMapper[VideoContent]] = [
     DurationMapper(),
     AspectRatioMapper(),
     ResolutionMapper(),
diff --git a/src/celeste/parameters.py b/src/celeste/parameters.py
index fa5fcac9..2657fc28 100644
--- a/src/celeste/parameters.py
+++ b/src/celeste/parameters.py
@@ -11,7 +11,7 @@ class Parameters(TypedDict, total=False):
     """Base parameters for all capabilities."""
 
 
-class ParameterMapper(ABC):
+class ParameterMapper[Content](ABC):
     """Base class for provider-specific parameter transformation."""
 
     name: ClassVar[StrEnum]
@@ -31,7 +31,7 @@ def map(self, request: dict[str, Any], value: Any, model: Model) -> dict[str, An
         """
         ...
 
-    def parse_output(self, content: Any, value: object | None) -> Any:  # noqa: ANN401
+    def parse_output(self, content: Content, value: object | None) -> Content:
         """Optionally transform parsed content based on parameter value (default: return unchanged)."""
         return content
 
@@ -47,7 +47,7 @@ def _validate_value(self, value: Any, model: Model) -> Any:  # noqa: ANN401
         return constraint(value)
 
 
-class FieldMapper(ParameterMapper):
+class FieldMapper[Content](ParameterMapper[Content]):
     """Maps a parameter directly to a flat request field after validation."""
 
     field: ClassVar[str]
diff --git a/src/celeste/protocols/chatcompletions/parameters.py b/src/celeste/protocols/chatcompletions/parameters.py
index dfe4607e..39173118 100644
--- a/src/celeste/protocols/chatcompletions/parameters.py
+++ b/src/celeste/protocols/chatcompletions/parameters.py
@@ -10,19 +10,19 @@
 from celeste.types import TextContent
 
 
-class TemperatureMapper(FieldMapper):
+class TemperatureMapper(FieldMapper[TextContent]):
     """Map temperature to Chat Completions temperature field."""
 
     field = "temperature"
 
 
-class MaxTokensMapper(FieldMapper):
+class MaxTokensMapper(FieldMapper[TextContent]):
     """Map max_tokens to Chat Completions max_tokens field."""
 
     field = "max_tokens"
 
 
-class ResponseFormatMapper(ParameterMapper):
+class ResponseFormatMapper(ParameterMapper[TextContent]):
     """Map output_schema to Chat Completions response_format field.
 
     Default uses json_object mode (no schema validation server-side).
diff --git a/src/celeste/protocols/openresponses/parameters.py b/src/celeste/protocols/openresponses/parameters.py
index 635b27b6..4f7a6d39 100644
--- a/src/celeste/protocols/openresponses/parameters.py
+++ b/src/celeste/protocols/openresponses/parameters.py
@@ -11,19 +11,19 @@
 from celeste.types import TextContent
 
 
-class TemperatureMapper(FieldMapper):
+class TemperatureMapper(FieldMapper[TextContent]):
     """Map temperature to Responses temperature field."""
 
     field = "temperature"
 
 
-class MaxOutputTokensMapper(FieldMapper):
+class MaxOutputTokensMapper(FieldMapper[TextContent]):
     """Map max_tokens to Responses max_output_tokens field."""
 
     field = "max_output_tokens"
 
 
-class TextFormatMapper(ParameterMapper):
+class TextFormatMapper(ParameterMapper[TextContent]):
     """Map output_schema to Responses text.format field.
 
     Handles both single BaseModel and list[BaseModel] types.
@@ -92,7 +92,7 @@ def parse_output(self, content: TextContent, value: object | None) -> TextConten
         return TypeAdapter(value).validate_python(parsed)
 
 
-class ReasoningEffortMapper(ParameterMapper):
+class ReasoningEffortMapper(ParameterMapper[TextContent]):
     """Map reasoning_effort to Responses reasoning.effort field."""
 
     def map(
@@ -110,7 +110,7 @@ def map(
         return request
 
 
-class VerbosityMapper(ParameterMapper):
+class VerbosityMapper(ParameterMapper[TextContent]):
     """Map verbosity to Responses text.verbosity field."""
 
     def map(
@@ -128,7 +128,7 @@ def map(
         return request
 
 
-class WebSearchMapper(ParameterMapper):
+class WebSearchMapper(ParameterMapper[TextContent]):
     """Map web_search to Responses tools array."""
 
     def map(
@@ -146,7 +146,7 @@ def map(
         return request
 
 
-class XSearchMapper(ParameterMapper):
+class XSearchMapper(ParameterMapper[TextContent]):
     """Map x_search to Responses tools array (search X/Twitter)."""
 
     def map(
@@ -164,7 +164,7 @@ def map(
         return request
 
 
-class CodeExecutionMapper(ParameterMapper):
+class CodeExecutionMapper(ParameterMapper[TextContent]):
     """Map code_execution to Responses tools array."""
 
     def map(
diff --git a/src/celeste/providers/anthropic/messages/parameters.py b/src/celeste/providers/anthropic/messages/parameters.py
index 2b63bdaf..7146653e 100644
--- a/src/celeste/providers/anthropic/messages/parameters.py
+++ b/src/celeste/providers/anthropic/messages/parameters.py
@@ -11,37 +11,37 @@
 from celeste.types import TextContent
 
 
-class TemperatureMapper(FieldMapper):
+class TemperatureMapper(FieldMapper[TextContent]):
     """Map temperature to Anthropic temperature field."""
 
     field = "temperature"
 
 
-class TopPMapper(FieldMapper):
+class TopPMapper(FieldMapper[TextContent]):
     """Map top_p to Anthropic top_p field."""
 
     field = "top_p"
 
 
-class TopKMapper(FieldMapper):
+class TopKMapper(FieldMapper[TextContent]):
     """Map top_k to Anthropic top_k field."""
 
     field = "top_k"
 
 
-class MaxTokensMapper(FieldMapper):
+class MaxTokensMapper(FieldMapper[TextContent]):
     """Map max_tokens to Anthropic max_tokens field."""
 
     field = "max_tokens"
 
 
-class StopSequencesMapper(FieldMapper):
+class StopSequencesMapper(FieldMapper[TextContent]):
     """Map stop_sequences to Anthropic stop_sequences field."""
 
     field = "stop_sequences"
 
 
-class ThinkingMapper(ParameterMapper):
+class ThinkingMapper(ParameterMapper[TextContent]):
     """Map thinking to Anthropic thinking field.
 
     Accepts provider-native values:
@@ -67,7 +67,7 @@ def map(
         return request
 
 
-class WebSearchMapper(ParameterMapper):
+class WebSearchMapper(ParameterMapper[TextContent]):
     """Map web_search to Anthropic tools field."""
 
     def map(
@@ -90,7 +90,7 @@ def map(
         return request
 
 
-class OutputFormatMapper(ParameterMapper):
+class OutputFormatMapper(ParameterMapper[TextContent]):
     """Map output_schema to Anthropic output_format field.
 
     Handles both single BaseModel and list[BaseModel] types.
diff --git a/src/celeste/providers/bfl/images/parameters.py b/src/celeste/providers/bfl/images/parameters.py
index 39f92de1..7ee1a3ed 100644
--- a/src/celeste/providers/bfl/images/parameters.py
+++ b/src/celeste/providers/bfl/images/parameters.py
@@ -5,9 +5,10 @@
 from celeste.constraints import Int
 from celeste.models import Model
 from celeste.parameters import FieldMapper, ParameterMapper
+from celeste.types import ImageContent
 
 
-class WidthMapper(ParameterMapper):
+class WidthMapper(ParameterMapper[ImageContent]):
     """Map width to BFL width field."""
 
     def map(
@@ -24,7 +25,7 @@ def map(
         return request
 
 
-class HeightMapper(ParameterMapper):
+class HeightMapper(ParameterMapper[ImageContent]):
     """Map height to BFL height field."""
 
     def map(
@@ -41,37 +42,37 @@ def map(
         return request
 
 
-class PromptUpsamplingMapper(FieldMapper):
+class PromptUpsamplingMapper(FieldMapper[ImageContent]):
     """Map prompt_upsampling to BFL prompt_upsampling field."""
 
     field = "prompt_upsampling"
 
 
-class SeedMapper(FieldMapper):
+class SeedMapper(FieldMapper[ImageContent]):
     """Map seed to BFL seed field."""
 
     field = "seed"
 
 
-class SafetyToleranceMapper(FieldMapper):
+class SafetyToleranceMapper(FieldMapper[ImageContent]):
     """Map safety_tolerance to BFL safety_tolerance field."""
 
     field = "safety_tolerance"
 
 
-class OutputFormatMapper(FieldMapper):
+class OutputFormatMapper(FieldMapper[ImageContent]):
     """Map output_format to BFL output_format field."""
 
     field = "output_format"
 
 
-class StepsMapper(FieldMapper):
+class StepsMapper(FieldMapper[ImageContent]):
     """Map steps to BFL steps field."""
 
     field = "steps"
 
 
-class GuidanceMapper(FieldMapper):
+class GuidanceMapper(FieldMapper[ImageContent]):
     """Map guidance to BFL guidance field."""
 
     field = "guidance"
diff --git a/src/celeste/providers/byteplus/images/parameters.py b/src/celeste/providers/byteplus/images/parameters.py
index b2bbbe02..661db818 100644
--- a/src/celeste/providers/byteplus/images/parameters.py
+++ b/src/celeste/providers/byteplus/images/parameters.py
@@ -1,15 +1,16 @@
 """BytePlus Images API parameter mappers."""
 
 from celeste.parameters import FieldMapper
+from celeste.types import ImageContent
 
 
-class SizeMapper(FieldMapper):
+class SizeMapper(FieldMapper[ImageContent]):
     """Map size to BytePlus size field."""
 
     field = "size"
 
 
-class WatermarkMapper(FieldMapper):
+class WatermarkMapper(FieldMapper[ImageContent]):
     """Map watermark to BytePlus watermark field."""
 
     field = "watermark"
diff --git a/src/celeste/providers/byteplus/videos/parameters.py b/src/celeste/providers/byteplus/videos/parameters.py
index b0ea3f1e..55eaa1d3 100644
--- a/src/celeste/providers/byteplus/videos/parameters.py
+++ b/src/celeste/providers/byteplus/videos/parameters.py
@@ -5,9 +5,10 @@
 from celeste.exceptions import ValidationError
 from celeste.models import Model
 from celeste.parameters import ParameterMapper
+from celeste.types import VideoContent
 
 
-class DurationMapper(ParameterMapper):
+class DurationMapper(ParameterMapper[VideoContent]):
     """Map duration parameter to BytePlus text prompt format.
 
     Appends --duration to the text prompt.
@@ -32,7 +33,7 @@ def map(
         return request
 
 
-class ResolutionMapper(ParameterMapper):
+class ResolutionMapper(ParameterMapper[VideoContent]):
     """Map resolution parameter to BytePlus text prompt format.
 
     Appends --resolution to the text prompt.
@@ -57,7 +58,7 @@ def map(
         return request
 
 
-class AspectRatioMapper(ParameterMapper):
+class AspectRatioMapper(ParameterMapper[VideoContent]):
     """Map aspect_ratio parameter to BytePlus text prompt format.
 
     Appends --ratio to the text prompt.
@@ -82,7 +83,7 @@ def map(
         return request
 
 
-class ReferenceImagesMapper(ParameterMapper):
+class ReferenceImagesMapper(ParameterMapper[VideoContent]):
     """Map reference_images to BytePlus content array format.
 
     Adds images with role="reference_image" to the content array.
@@ -109,7 +110,7 @@ def map(
         return request
 
 
-class FirstFrameMapper(ParameterMapper):
+class FirstFrameMapper(ParameterMapper[VideoContent]):
     """Map first_frame to BytePlus content array format.
 
     Adds image with role="first_frame" to the content array.
@@ -139,7 +140,7 @@ def map(
         return request
 
 
-class LastFrameMapper(ParameterMapper):
+class LastFrameMapper(ParameterMapper[VideoContent]):
     """Map last_frame to BytePlus content array format.
 
     Adds image with role="last_frame" to the content array.
diff --git a/src/celeste/providers/cohere/chat/parameters.py b/src/celeste/providers/cohere/chat/parameters.py
index e10433ad..c9ea4de3 100644
--- a/src/celeste/providers/cohere/chat/parameters.py
+++ b/src/celeste/providers/cohere/chat/parameters.py
@@ -11,19 +11,19 @@
 from celeste.types import TextContent
 
 
-class TemperatureMapper(FieldMapper):
+class TemperatureMapper(FieldMapper[TextContent]):
     """Map temperature to Cohere temperature field."""
 
     field = "temperature"
 
 
-class MaxTokensMapper(FieldMapper):
+class MaxTokensMapper(FieldMapper[TextContent]):
     """Map max_tokens to Cohere max_tokens field."""
 
     field = "max_tokens"
 
 
-class ThinkingMapper(ParameterMapper):
+class ThinkingMapper(ParameterMapper[TextContent]):
     """Map thinking to Cohere thinking field."""
 
     def map(
@@ -46,7 +46,7 @@ def map(
         return request
 
 
-class ResponseFormatMapper(ParameterMapper):
+class ResponseFormatMapper(ParameterMapper[TextContent]):
     """Map output_schema to Cohere response_format field.
 
     Handles both single BaseModel and list[BaseModel] types.
diff --git a/src/celeste/providers/elevenlabs/text_to_speech/parameters.py b/src/celeste/providers/elevenlabs/text_to_speech/parameters.py
index 788d5050..a90f9ec5 100644
--- a/src/celeste/providers/elevenlabs/text_to_speech/parameters.py
+++ b/src/celeste/providers/elevenlabs/text_to_speech/parameters.py
@@ -4,9 +4,10 @@
 
 from celeste.models import Model
 from celeste.parameters import FieldMapper, ParameterMapper
+from celeste.types import AudioContent
 
 
-class VoiceMapper(FieldMapper):
+class VoiceMapper(FieldMapper[AudioContent]):
     """Map voice parameter to ElevenLabs URL path.
 
     Note: Voice ID goes in URL path, not request body.
@@ -17,7 +18,7 @@ class VoiceMapper(FieldMapper):
     field = "_voice_id"
 
 
-class OutputFormatMapper(ParameterMapper):
+class OutputFormatMapper(ParameterMapper[AudioContent]):
     """Map response_format parameter to ElevenLabs output_format field."""
 
     def map(
@@ -36,7 +37,7 @@ def map(
         return request
 
 
-class SpeedMapper(ParameterMapper):
+class SpeedMapper(ParameterMapper[AudioContent]):
     """Map speed parameter to ElevenLabs voice_settings.speed field."""
 
     def map(
@@ -57,7 +58,7 @@ def map(
         return request
 
 
-class LanguageCodeMapper(ParameterMapper):
+class LanguageCodeMapper(ParameterMapper[AudioContent]):
     """Map language parameter to ElevenLabs language_code field.
 
     Only supported by eleven_turbo_v2_5 and eleven_flash_v2_5 models.
diff --git a/src/celeste/providers/google/cloud_tts/parameters.py b/src/celeste/providers/google/cloud_tts/parameters.py
index 047b81e9..2e12c185 100644
--- a/src/celeste/providers/google/cloud_tts/parameters.py
+++ b/src/celeste/providers/google/cloud_tts/parameters.py
@@ -5,9 +5,10 @@
 from celeste.mime_types import AudioMimeType
 from celeste.models import Model
 from celeste.parameters import ParameterMapper
+from celeste.types import AudioContent
 
 
-class VoiceMapper(ParameterMapper):
+class VoiceMapper(ParameterMapper[AudioContent]):
     """Map voice to Google Cloud TTS voice.name field."""
 
     def map(
@@ -25,7 +26,7 @@ def map(
         return request
 
 
-class LanguageMapper(ParameterMapper):
+class LanguageMapper(ParameterMapper[AudioContent]):
     """Map language to Google Cloud TTS voice.languageCode field."""
 
     locale_map: ClassVar[dict[str, str]] = {}
@@ -52,7 +53,7 @@ def map(
         return request
 
 
-class PromptMapper(ParameterMapper):
+class PromptMapper(ParameterMapper[AudioContent]):
     """Map prompt to Google Cloud TTS input.prompt field."""
 
     def map(
@@ -69,7 +70,7 @@ def map(
         return request
 
 
-class AudioEncodingMapper(ParameterMapper):
+class AudioEncodingMapper(ParameterMapper[AudioContent]):
     """Map audio_encoding to Google Cloud TTS audioConfig.audioEncoding field."""
 
     encoding_map: ClassVar[dict[AudioMimeType, str]] = {}
diff --git a/src/celeste/providers/google/embeddings/parameters.py b/src/celeste/providers/google/embeddings/parameters.py
index fad69e00..3cd75eae 100644
--- a/src/celeste/providers/google/embeddings/parameters.py
+++ b/src/celeste/providers/google/embeddings/parameters.py
@@ -4,9 +4,10 @@
 
 from celeste.models import Model
 from celeste.parameters import ParameterMapper
+from celeste.types import EmbeddingsContent
 
 
-class OutputDimensionalityMapper(ParameterMapper):
+class OutputDimensionalityMapper(ParameterMapper[EmbeddingsContent]):
     """Map dimensions to Google Embeddings outputDimensionality field."""
 
     def map(
diff --git a/src/celeste/providers/google/generate_content/parameters.py b/src/celeste/providers/google/generate_content/parameters.py
index ed6f54d9..e7e979ae 100644
--- a/src/celeste/providers/google/generate_content/parameters.py
+++ b/src/celeste/providers/google/generate_content/parameters.py
@@ -13,7 +13,7 @@
 from celeste.types import TextContent
 
 
-class TemperatureMapper(ParameterMapper):
+class TemperatureMapper[Content](ParameterMapper[Content]):
     """Map temperature to Google generationConfig.temperature field."""
 
     def map(
@@ -31,7 +31,7 @@ def map(
         return request
 
 
-class MaxOutputTokensMapper(ParameterMapper):
+class MaxOutputTokensMapper[Content](ParameterMapper[Content]):
     """Map max_tokens to Google generationConfig.maxOutputTokens field."""
 
     def map(
@@ -49,7 +49,7 @@ def map(
         return request
 
 
-class ThinkingBudgetMapper(ParameterMapper):
+class ThinkingBudgetMapper[Content](ParameterMapper[Content]):
     """Map thinkingBudget to Google generationConfig.thinkingConfig.thinkingBudget field."""
 
     def map(
@@ -69,7 +69,7 @@ def map(
         return request
 
 
-class ThinkingLevelMapper(ParameterMapper):
+class ThinkingLevelMapper[Content](ParameterMapper[Content]):
     """Map thinkingLevel to Google generationConfig.thinkingConfig.thinkingLevel field."""
 
     def map(
@@ -89,7 +89,7 @@ def map(
         return request
 
 
-class AspectRatioMapper(ParameterMapper):
+class AspectRatioMapper[Content](ParameterMapper[Content]):
     """Map aspect_ratio to Google generationConfig.imageConfig.aspectRatio field."""
 
     def map(
@@ -109,7 +109,7 @@ def map(
         return request
 
 
-class ImageSizeMapper(ParameterMapper):
+class ImageSizeMapper[Content](ParameterMapper[Content]):
     """Map image_size to Google generationConfig.imageConfig.imageSize field."""
 
     def map(
@@ -129,7 +129,7 @@ def map(
         return request
 
 
-class MediaContentMapper(ParameterMapper):
+class MediaContentMapper[Content](ParameterMapper[Content]):
     """Map reference_images to Google contents.parts field."""
 
     def _build_image_part(self, image: ImageArtifact) -> dict[str, Any]:
@@ -181,7 +181,7 @@ def map(
         return request
 
 
-class WebSearchMapper(ParameterMapper):
+class WebSearchMapper[Content](ParameterMapper[Content]):
     """Map web_search to Google tools field."""
 
     def map(
@@ -199,7 +199,7 @@ def map(
         return request
 
 
-class ResponseJsonSchemaMapper(ParameterMapper):
+class ResponseJsonSchemaMapper(ParameterMapper[TextContent]):
     """Map output_schema to Google generationConfig.responseJsonSchema field."""
 
     def map(
diff --git a/src/celeste/providers/google/imagen/parameters.py b/src/celeste/providers/google/imagen/parameters.py
index fd24bbd5..8784026b 100644
--- a/src/celeste/providers/google/imagen/parameters.py
+++ b/src/celeste/providers/google/imagen/parameters.py
@@ -4,9 +4,10 @@
 
 from celeste.models import Model
 from celeste.parameters import ParameterMapper
+from celeste.types import ImageContent
 
 
-class SampleCountMapper(ParameterMapper):
+class SampleCountMapper(ParameterMapper[ImageContent]):
     """Map num_images to Google Imagen parameters.sampleCount field."""
 
     def map(
@@ -24,7 +25,7 @@ def map(
         return request
 
 
-class AspectRatioMapper(ParameterMapper):
+class AspectRatioMapper(ParameterMapper[ImageContent]):
     """Map aspect_ratio to Google Imagen parameters.aspectRatio field."""
 
     def map(
@@ -42,7 +43,7 @@ def map(
         return request
 
 
-class ImageSizeMapper(ParameterMapper):
+class ImageSizeMapper(ParameterMapper[ImageContent]):
     """Map image_size to Google Imagen parameters.imageSize field."""
 
     def map(
diff --git a/src/celeste/providers/google/interactions/parameters.py b/src/celeste/providers/google/interactions/parameters.py
index c990a949..f6b271be 100644
--- a/src/celeste/providers/google/interactions/parameters.py
+++ b/src/celeste/providers/google/interactions/parameters.py
@@ -12,7 +12,7 @@
 from celeste.types import TextContent
 
 
-class TemperatureMapper(ParameterMapper):
+class TemperatureMapper(ParameterMapper[TextContent]):
     """Map temperature to Google Interactions generation_config.temperature field."""
 
     def map(
@@ -30,7 +30,7 @@ def map(
         return request
 
 
-class MaxOutputTokensMapper(ParameterMapper):
+class MaxOutputTokensMapper(ParameterMapper[TextContent]):
     """Map max_tokens to Google Interactions generation_config.max_output_tokens field."""
 
     def map(
@@ -50,7 +50,7 @@ def map(
         return request
 
 
-class ThinkingBudgetMapper(ParameterMapper):
+class ThinkingBudgetMapper(ParameterMapper[TextContent]):
     """Map thinking_budget to Interactions generation_config.thinking_config.thinking_budget."""
 
     def map(
@@ -70,7 +70,7 @@ def map(
         return request
 
 
-class ThinkingLevelMapper(ParameterMapper):
+class ThinkingLevelMapper(ParameterMapper[TextContent]):
     """Map thinking_level to Interactions generation_config.thinking_level field."""
 
     def map(
@@ -88,13 +88,13 @@ def map(
         return request
 
 
-class PreviousInteractionIdMapper(FieldMapper):
+class PreviousInteractionIdMapper(FieldMapper[TextContent]):
     """Map previous_interaction_id for stateful conversations."""
 
     field = "previous_interaction_id"
 
 
-class BackgroundMapper(ParameterMapper):
+class BackgroundMapper(ParameterMapper[TextContent]):
     """Map background mode for long-running operations."""
 
     def map(
@@ -112,7 +112,7 @@ def map(
         return request
 
 
-class GoogleSearchMapper(ParameterMapper):
+class GoogleSearchMapper(ParameterMapper[TextContent]):
     """Map google_search to Google Interactions tools field."""
 
     def map(
@@ -131,7 +131,7 @@ def map(
         return request
 
 
-class CodeExecutionMapper(ParameterMapper):
+class CodeExecutionMapper(ParameterMapper[TextContent]):
     """Map code_execution to Google Interactions tools field."""
 
     def map(
@@ -150,7 +150,7 @@ def map(
         return request
 
 
-class UrlContextMapper(ParameterMapper):
+class UrlContextMapper(ParameterMapper[TextContent]):
     """Map url_context to Google Interactions tools field."""
 
     def map(
@@ -169,7 +169,7 @@ def map(
         return request
 
 
-class ResponseFormatMapper(ParameterMapper):
+class ResponseFormatMapper(ParameterMapper[TextContent]):
     """Map response_format to Google Interactions response_format field."""
 
     def map(
@@ -254,7 +254,7 @@ def _remove_unsupported_fields(self, schema: dict[str, Any]) -> dict[str, Any]:
         return result
 
 
-class MediaContentMapper(ParameterMapper):
+class MediaContentMapper(ParameterMapper[TextContent]):
     """Map reference_images to Google Interactions input content."""
 
     def _build_image_part(self, image: ImageArtifact) -> dict[str, Any]:
@@ -317,13 +317,13 @@ def map(
         return request
 
 
-class ResponseModalitiesMapper(FieldMapper):
+class ResponseModalitiesMapper(FieldMapper[TextContent]):
     """Map response_modalities for multimodal output generation."""
 
     field = "response_modalities"
 
 
-class SystemInstructionMapper(FieldMapper):
+class SystemInstructionMapper(FieldMapper[TextContent]):
     """Map system_instruction for system prompts."""
 
     field = "system_instruction"
diff --git a/src/celeste/providers/google/veo/parameters.py b/src/celeste/providers/google/veo/parameters.py
index 8b98110b..7905138a 100644
--- a/src/celeste/providers/google/veo/parameters.py
+++ b/src/celeste/providers/google/veo/parameters.py
@@ -5,10 +5,11 @@
 from celeste.exceptions import ValidationError
 from celeste.models import Model
 from celeste.parameters import ParameterMapper
+from celeste.types import VideoContent
 from celeste.utils import detect_mime_type
 
 
-class AspectRatioMapper(ParameterMapper):
+class AspectRatioMapper(ParameterMapper[VideoContent]):
     """Map aspect_ratio to Google Veo parameters.aspectRatio field."""
 
     def map(
@@ -27,7 +28,7 @@ def map(
         return request
 
 
-class ResolutionMapper(ParameterMapper):
+class ResolutionMapper(ParameterMapper[VideoContent]):
     """Map resolution to Google Veo parameters.resolution field."""
 
     def map(
@@ -46,7 +47,7 @@ def map(
         return request
 
 
-class DurationSecondsMapper(ParameterMapper):
+class DurationSecondsMapper(ParameterMapper[VideoContent]):
     """Map duration to Google Veo parameters.durationSeconds field."""
 
     def map(
@@ -69,7 +70,7 @@ def map(
         return request
 
 
-class ReferenceImagesMapper(ParameterMapper):
+class ReferenceImagesMapper(ParameterMapper[VideoContent]):
     """Map reference_images to Google Veo instances.referenceImages field."""
 
     def map(
@@ -104,7 +105,7 @@ def map(
         return request
 
 
-class FirstFrameMapper(ParameterMapper):
+class FirstFrameMapper(ParameterMapper[VideoContent]):
     """Map first_frame to Google Veo instances.image field."""
 
     def map(
@@ -131,7 +132,7 @@ def map(
         return request
 
 
-class LastFrameMapper(ParameterMapper):
+class LastFrameMapper(ParameterMapper[VideoContent]):
     """Map last_frame to Google Veo instances.lastFrame field."""
 
     def map(
diff --git a/src/celeste/providers/gradium/text_to_speech/parameters.py b/src/celeste/providers/gradium/text_to_speech/parameters.py
index 594f0b90..1ff78ff3 100644
--- a/src/celeste/providers/gradium/text_to_speech/parameters.py
+++ b/src/celeste/providers/gradium/text_to_speech/parameters.py
@@ -4,15 +4,16 @@
 
 from celeste.models import Model
 from celeste.parameters import FieldMapper, ParameterMapper
+from celeste.types import AudioContent
 
 
-class VoiceMapper(FieldMapper):
+class VoiceMapper(FieldMapper[AudioContent]):
     """Map voice to Gradium voice_id field."""
 
     field = "voice_id"
 
 
-class PaddingBonusMapper(ParameterMapper):
+class PaddingBonusMapper(ParameterMapper[AudioContent]):
     """Map padding_bonus to Gradium json_config.padding_bonus field."""
 
     def map(
@@ -30,7 +31,7 @@ def map(
         return request
 
 
-class OutputFormatMapper(FieldMapper):
+class OutputFormatMapper(FieldMapper[AudioContent]):
     """Map output_format to Gradium output_format field."""
 
     field = "output_format"
diff --git a/src/celeste/providers/mistral/chat/parameters.py b/src/celeste/providers/mistral/chat/parameters.py
index 22e24c16..664246f3 100644
--- a/src/celeste/providers/mistral/chat/parameters.py
+++ b/src/celeste/providers/mistral/chat/parameters.py
@@ -10,9 +10,10 @@
     ResponseFormatMapper as _ResponseFormatMapper,
 )
 from celeste.structured_outputs import StrictRefResolvingJsonSchemaGenerator
+from celeste.types import TextContent
 
 
-class WebSearchMapper(ParameterMapper):
+class WebSearchMapper(ParameterMapper[TextContent]):
     """Map web_search to Mistral tools field."""
 
     def map(
diff --git a/src/celeste/providers/ollama/generate/parameters.py b/src/celeste/providers/ollama/generate/parameters.py
index b94a20fe..cb08e66f 100644
--- a/src/celeste/providers/ollama/generate/parameters.py
+++ b/src/celeste/providers/ollama/generate/parameters.py
@@ -11,9 +11,10 @@
 from celeste.constraints import Int
 from celeste.models import Model
 from celeste.parameters import FieldMapper, ParameterMapper
+from celeste.types import ImageContent
 
 
-class WidthMapper(ParameterMapper):
+class WidthMapper(ParameterMapper[ImageContent]):
     """Map width to Ollama width field."""
 
     def map(
@@ -30,7 +31,7 @@ def map(
         return request
 
 
-class HeightMapper(ParameterMapper):
+class HeightMapper(ParameterMapper[ImageContent]):
     """Map height to Ollama height field."""
 
     def map(
@@ -47,13 +48,13 @@ def map(
         return request
 
 
-class StepsMapper(FieldMapper):
+class StepsMapper(FieldMapper[ImageContent]):
     """Map steps to Ollama steps field."""
 
     field = "steps"
 
 
-class SeedMapper(ParameterMapper):
+class SeedMapper(ParameterMapper[ImageContent]):
     """Map seed to Ollama options.seed field (nested)."""
 
     def map(
@@ -71,7 +72,7 @@ def map(
         return request
 
 
-class NegativePromptMapper(FieldMapper):
+class NegativePromptMapper(FieldMapper[ImageContent]):
     """Map negative_prompt to Ollama negative_prompt field."""
 
     field = "negative_prompt"
diff --git a/src/celeste/providers/openai/audio/parameters.py b/src/celeste/providers/openai/audio/parameters.py
index 4a9591b9..aaf02421 100644
--- a/src/celeste/providers/openai/audio/parameters.py
+++ b/src/celeste/providers/openai/audio/parameters.py
@@ -5,21 +5,22 @@
 from celeste.mime_types import AudioMimeType
 from celeste.models import Model
 from celeste.parameters import FieldMapper, ParameterMapper
+from celeste.types import AudioContent
 
 
-class VoiceMapper(FieldMapper):
+class VoiceMapper(FieldMapper[AudioContent]):
     """Map voice to OpenAI voice field."""
 
     field = "voice"
 
 
-class SpeedMapper(FieldMapper):
+class SpeedMapper(FieldMapper[AudioContent]):
     """Map speed to OpenAI speed field."""
 
     field = "speed"
 
 
-class ResponseFormatMapper(ParameterMapper):
+class ResponseFormatMapper(ParameterMapper[AudioContent]):
     """Map response_format to OpenAI response_format field."""
 
     def map(
@@ -56,7 +57,7 @@ def map(
         return request
 
 
-class InstructionsMapper(FieldMapper):
+class InstructionsMapper(FieldMapper[AudioContent]):
     """Map instructions to OpenAI instructions field."""
 
     field = "instructions"
diff --git a/src/celeste/providers/openai/images/parameters.py b/src/celeste/providers/openai/images/parameters.py
index ab6b4de0..465522f7 100644
--- a/src/celeste/providers/openai/images/parameters.py
+++ b/src/celeste/providers/openai/images/parameters.py
@@ -1,51 +1,52 @@
 """OpenAI Images API parameter mappers."""
 
 from celeste.parameters import FieldMapper
+from celeste.types import ImageContent
 
 
-class SizeMapper(FieldMapper):
+class SizeMapper(FieldMapper[ImageContent]):
     """Map size to OpenAI size field."""
 
     field = "size"
 
 
-class PartialImagesMapper(FieldMapper):
+class PartialImagesMapper(FieldMapper[ImageContent]):
     """Map partial_images to OpenAI partial_images field."""
 
     field = "partial_images"
 
 
-class QualityMapper(FieldMapper):
+class QualityMapper(FieldMapper[ImageContent]):
     """Map quality to OpenAI quality field."""
 
     field = "quality"
 
 
-class BackgroundMapper(FieldMapper):
+class BackgroundMapper(FieldMapper[ImageContent]):
     """Map background to OpenAI background field."""
 
     field = "background"
 
 
-class OutputFormatMapper(FieldMapper):
+class OutputFormatMapper(FieldMapper[ImageContent]):
     """Map output_format to OpenAI output_format field."""
 
     field = "output_format"
 
 
-class StyleMapper(FieldMapper):
+class StyleMapper(FieldMapper[ImageContent]):
     """Map style to OpenAI style field."""
 
     field = "style"
 
 
-class ModerationMapper(FieldMapper):
+class ModerationMapper(FieldMapper[ImageContent]):
     """Map moderation to OpenAI moderation field."""
 
     field = "moderation"
 
 
-class OutputCompressionMapper(FieldMapper):
+class OutputCompressionMapper(FieldMapper[ImageContent]):
     """Map output_compression to OpenAI output_compression field."""
 
     field = "output_compression"
diff --git a/src/celeste/providers/openai/videos/parameters.py b/src/celeste/providers/openai/videos/parameters.py
index 951f55c1..d6d1072e 100644
--- a/src/celeste/providers/openai/videos/parameters.py
+++ b/src/celeste/providers/openai/videos/parameters.py
@@ -4,9 +4,10 @@
 
 from celeste.models import Model
 from celeste.parameters import FieldMapper, ParameterMapper
+from celeste.types import VideoContent
 
 
-class SecondsMapper(ParameterMapper):
+class SecondsMapper(ParameterMapper[VideoContent]):
     """Map seconds to OpenAI seconds field."""
 
     def map(
@@ -27,7 +28,7 @@ def map(
         return request
 
 
-class SizeMapper(ParameterMapper):
+class SizeMapper(ParameterMapper[VideoContent]):
     """Map size to OpenAI size field."""
 
     def map(
@@ -44,7 +45,7 @@ def map(
         return request
 
 
-class InputReferenceMapper(FieldMapper):
+class InputReferenceMapper(FieldMapper[VideoContent]):
     """Map input_reference to OpenAI input_reference field."""
 
     field = "input_reference"
diff --git a/src/celeste/providers/xai/images/parameters.py b/src/celeste/providers/xai/images/parameters.py
index 2429db9f..7bfa9630 100644
--- a/src/celeste/providers/xai/images/parameters.py
+++ b/src/celeste/providers/xai/images/parameters.py
@@ -7,21 +7,22 @@
 """
 
 from celeste.parameters import FieldMapper
+from celeste.types import ImageContent
 
 
-class AspectRatioMapper(FieldMapper):
+class AspectRatioMapper(FieldMapper[ImageContent]):
     """Map aspect_ratio to xAI aspect_ratio field."""
 
     field = "aspect_ratio"
 
 
-class NumImagesMapper(FieldMapper):
+class NumImagesMapper(FieldMapper[ImageContent]):
     """Map num_images to xAI n field."""
 
     field = "n"
 
 
-class ResponseFormatMapper(FieldMapper):
+class ResponseFormatMapper(FieldMapper[ImageContent]):
     """Map response_format to xAI response_format field."""
 
     field = "response_format"
diff --git a/src/celeste/providers/xai/videos/parameters.py b/src/celeste/providers/xai/videos/parameters.py
index 3a80504a..1aaa13f5 100644
--- a/src/celeste/providers/xai/videos/parameters.py
+++ b/src/celeste/providers/xai/videos/parameters.py
@@ -1,21 +1,22 @@
 """xAI Videos API parameter mappers."""
 
 from celeste.parameters import FieldMapper
+from celeste.types import VideoContent
 
 
-class DurationMapper(FieldMapper):
+class DurationMapper(FieldMapper[VideoContent]):
     """Map duration to xAI duration field."""
 
     field = "duration"
 
 
-class AspectRatioMapper(FieldMapper):
+class AspectRatioMapper(FieldMapper[VideoContent]):
     """Map aspect_ratio to xAI aspect_ratio field."""
 
     field = "aspect_ratio"
 
 
-class ResolutionMapper(FieldMapper):
+class ResolutionMapper(FieldMapper[VideoContent]):
     """Map resolution to xAI resolution field."""
 
     field = "resolution"
diff --git a/templates/modalities/{modality_slug}/providers/{provider_slug}/client.py.template b/templates/modalities/{modality_slug}/providers/{provider_slug}/client.py.template
index 32bd9960..b1845070 100644
--- a/templates/modalities/{modality_slug}/providers/{provider_slug}/client.py.template
+++ b/templates/modalities/{modality_slug}/providers/{provider_slug}/client.py.template
@@ -40,7 +40,7 @@ class {Provider}{Modality}Client({Provider}{Api}Mixin, {Modality}Client):
     """{Provider} {modality} client."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[{Content}]]:
         return {PROVIDER}_PARAMETER_MAPPERS
 
     def _stream_class(self) -> type[{Modality}Stream]:
diff --git a/templates/modalities/{modality_slug}/providers/{provider_slug}/parameters.py.template b/templates/modalities/{modality_slug}/providers/{provider_slug}/parameters.py.template
index 800756e3..e4b03630 100644
--- a/templates/modalities/{modality_slug}/providers/{provider_slug}/parameters.py.template
+++ b/templates/modalities/{modality_slug}/providers/{provider_slug}/parameters.py.template
@@ -1,6 +1,7 @@
 """{Provider} parameter mappers for {modality}."""
 
 from celeste.parameters import ParameterMapper
+from celeste.types import {Content}
 from celeste.providers.{provider}.{api}.parameters import (
     ExampleMapper as _ExampleMapper,
 )
@@ -14,7 +15,7 @@ class AspectRatioMapper(_ExampleMapper):
     name = {Modality}Parameter.ASPECT_RATIO
 
 
-{PROVIDER}_PARAMETER_MAPPERS: list[ParameterMapper] = [
+{PROVIDER}_PARAMETER_MAPPERS: list[ParameterMapper[{Content}]] = [
     AspectRatioMapper(),
 ]
 
diff --git a/templates/protocols/{protocol_slug}/parameters.py.template b/templates/protocols/{protocol_slug}/parameters.py.template
index a651765c..4726c206 100644
--- a/templates/protocols/{protocol_slug}/parameters.py.template
+++ b/templates/protocols/{protocol_slug}/parameters.py.template
@@ -7,7 +7,7 @@ from celeste.parameters import ParameterMapper
 
 
 # PATTERN 1: Simple flat mapping
-# class TemperatureMapper(ParameterMapper):
+# class TemperatureMapper(ParameterMapper[TextContent]):
 #     """Map temperature to {Protocol} temperature field."""
 #
 #     def map(
@@ -26,7 +26,7 @@ from celeste.parameters import ParameterMapper
 
 
 # PATTERN 2: Nested mapping
-# class ReasoningEffortMapper(ParameterMapper):
+# class ReasoningEffortMapper(ParameterMapper[TextContent]):
 #     """Map reasoning_effort to {Protocol} reasoning.effort field."""
 #
 #     def map(
@@ -45,7 +45,7 @@ from celeste.parameters import ParameterMapper
 
 
 # PATTERN 3: Response format with parse_output
-# class ResponseFormatMapper(ParameterMapper):
+# class ResponseFormatMapper(ParameterMapper[TextContent]):
 #     """Map output_schema to {Protocol} response_format field."""
 #
 #     def map(
diff --git a/templates/providers/{provider_slug}/{api_slug}/parameters.py.template b/templates/providers/{provider_slug}/{api_slug}/parameters.py.template
index ac1d480d..95e1a23e 100644
--- a/templates/providers/{provider_slug}/{api_slug}/parameters.py.template
+++ b/templates/providers/{provider_slug}/{api_slug}/parameters.py.template
@@ -15,7 +15,7 @@ from celeste.parameters import ParameterMapper
 
 # PATTERN 1: Simple flat mapping
 # Use when provider expects flat request body: {"param": value}
-class ExampleParamMapper(ParameterMapper):
+class ExampleParamMapper[Content](ParameterMapper[Content]):
     """Map example_param to {Provider} example_param field."""
 
     def map(
@@ -36,7 +36,7 @@ class ExampleParamMapper(ParameterMapper):
 
 # PATTERN 2: Nested mapping
 # Use when provider expects nested structure: {"parameters": {"param": value}}
-class NestedParamMapper(ParameterMapper):
+class NestedParamMapper[Content](ParameterMapper[Content]):
     """Map nested_param to {Provider} parameters.nestedParam field."""
 
     def map(
diff --git a/tests/unit_tests/test_client.py b/tests/unit_tests/test_client.py
index 87e4712a..0c39046d 100644
--- a/tests/unit_tests/test_client.py
+++ b/tests/unit_tests/test_client.py
@@ -36,11 +36,11 @@ class _TestInput(Input):
 def _create_test_mapper(
     param_name: StrEnum,
     map_key: str | None = None,
-) -> ParameterMapper:
+) -> ParameterMapper[str]:
     """Create a test parameter mapper instance."""
     actual_map_key = map_key if map_key is not None else param_name.value
 
-    class TestMapperClass(ParameterMapper):
+    class TestMapperClass(ParameterMapper[str]):
         """Test mapper implementation."""
 
         name = param_name
@@ -66,11 +66,11 @@ def parse_output(
 def _create_transform_mapper(
     param_name: StrEnum,
     map_key: str | None = None,
-) -> ParameterMapper:
+) -> ParameterMapper[str]:
     """Create a test parameter mapper that transforms output."""
     actual_map_key = map_key if map_key is not None else param_name.value
 
-    class TransformMapperClass(ParameterMapper):
+    class TransformMapperClass(ParameterMapper[str]):
         """Test mapper with output transformation."""
 
         name = param_name
@@ -116,7 +116,7 @@ class ConcreteModalityClient(ModalityClient[_TestInput, Output, Parameters, str]
     """Concrete ModalityClient implementation for testing."""
 
     @classmethod
-    def parameter_mappers(cls) -> list[ParameterMapper]:
+    def parameter_mappers(cls) -> list[ParameterMapper[str]]:
         return []
 
     def _init_request(self, inputs: _TestInput) -> dict[str, Any]:
@@ -169,7 +169,7 @@ class ClientWithMapper(ConcreteModalityClient):
             """Client with custom parameter mapper."""
 
             @classmethod
-            def parameter_mappers(cls) -> list[ParameterMapper]:
+            def parameter_mappers(cls) -> list[ParameterMapper[str]]:
                 return [_create_test_mapper(ParamEnum.TEST_PARAM)]
 
         client = ClientWithMapper(
@@ -198,7 +198,7 @@ class ClientWithMultipleMappers(ConcreteModalityClient):
             """Client with multiple parameter mappers."""
 
             @classmethod
-            def parameter_mappers(cls) -> list[ParameterMapper]:
+            def parameter_mappers(cls) -> list[ParameterMapper[str]]:
                 return [
                     _create_test_mapper(ParamEnum.FIRST_PARAM),
                     _create_test_mapper(ParamEnum.SECOND_PARAM),
@@ -244,7 +244,7 @@ class ClientWithTransformMapper(ConcreteModalityClient):
             """Client with output transformation mapper."""
 
             @classmethod
-            def parameter_mappers(cls) -> list[ParameterMapper]:
+            def parameter_mappers(cls) -> list[ParameterMapper[str]]:
                 return [_create_transform_mapper(ParamEnum.TEST_PARAM)]
 
         client = ClientWithTransformMapper(
@@ -275,7 +275,7 @@ async def test_predict_applies_transform_output(
 
         class ClientWithTransformMapper(ConcreteModalityClient):
             @classmethod
-            def parameter_mappers(cls) -> list[ParameterMapper]:
+            def parameter_mappers(cls) -> list[ParameterMapper[str]]:
                 return [_create_transform_mapper(ParamEnum.TEST_PARAM)]
 
         client = ClientWithTransformMapper(
@@ -299,7 +299,7 @@ async def test_predict_no_transform_without_param(
 
         class ClientWithTransformMapper(ConcreteModalityClient):
             @classmethod
-            def parameter_mappers(cls) -> list[ParameterMapper]:
+            def parameter_mappers(cls) -> list[ParameterMapper[str]]:
                 return [_create_transform_mapper(ParamEnum.TEST_PARAM)]
 
         client = ClientWithTransformMapper(
diff --git a/tests/unit_tests/test_parameters.py b/tests/unit_tests/test_parameters.py
index 8741e218..23b7b7c0 100644
--- a/tests/unit_tests/test_parameters.py
+++ b/tests/unit_tests/test_parameters.py
@@ -68,7 +68,7 @@ def test_parse_output_default_returns_content_unchanged(self) -> None:
         """Test that ParameterMapper.parse_output default returns content unchanged."""
         from celeste.parameters import ParameterMapper
 
-        class TestMapper(ParameterMapper):
+        class TestMapper(ParameterMapper[TextContent]):
             name = Parameter.TEMPERATURE
 
             def map(
@@ -88,7 +88,7 @@ def test_validate_value_with_none_returns_none(self) -> None:
         """Test that _validate_value returns None when value is None."""
         from celeste.parameters import ParameterMapper
 
-        class TestMapper(ParameterMapper):
+        class TestMapper(ParameterMapper[TextContent]):
             name = Parameter.TEMPERATURE
 
             def map(
@@ -112,7 +112,7 @@ def test_validate_value_with_missing_constraint_passes_through(self) -> None:
         """Missing constraints pass through without error."""
         from celeste.parameters import ParameterMapper
 
-        class TestMapper(ParameterMapper):
+        class TestMapper(ParameterMapper[TextContent]):
             name = Parameter.TEMPERATURE
 
             def map(
@@ -137,7 +137,7 @@ def test_validate_value_with_valid_constraint_calls_constraint(self) -> None:
         """Test that _validate_value calls constraint when parameter is supported."""
         from celeste.parameters import ParameterMapper
 
-        class TestMapper(ParameterMapper):
+        class TestMapper(ParameterMapper[TextContent]):
             name = Parameter.TEMPERATURE
 
             def map(
@@ -165,7 +165,7 @@ def test_validate_value_with_valid_constraint_returns_validated_value(self) -> N
         """Test that _validate_value returns constraint-validated value."""
         from celeste.parameters import ParameterMapper
 
-        class TestMapper(ParameterMapper):
+        class TestMapper(ParameterMapper[TextContent]):
             name = Parameter.TEMPERATURE
 
             def map(