fix: use direct Header params instead of Depends for SDK detection

The library client's _convert_body tries to construct Depends return
types from body params, which fails for non-Pydantic types like
SdkType enum. Use direct Header() parameters with None defaults
instead - the library client simply skips these optional params
and the route falls through to OpenAI default behavior.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Sébastien Han <seb@redhat.com>

Author: leseb

src/llama_stack_api/models/fastapi_routes.py

@@ -19,7 +19,6 @@
 
 from llama_stack_api.messages.models import ANTHROPIC_VERSION
 from llama_stack_api.router_utils import create_path_dependency, standard_responses
-from llama_stack_api.sdk_detection import SdkType
 from llama_stack_api.version import LLAMA_STACK_API_V1
 
 from .api import Models
@@ -35,18 +34,6 @@
 get_model_request = create_path_dependency(GetModelRequest)
 
 
-def _detect_sdk_from_headers(
-    anthropic_version: Annotated[str | None, Header(alias="anthropic-version")] = None,
-    x_goog_api_key: Annotated[str | None, Header(alias="x-goog-api-key")] = None,
-) -> SdkType:
-    """Detect SDK type from request headers via FastAPI dependency injection."""
-    if anthropic_version:
-        return SdkType.ANTHROPIC
-    if x_goog_api_key:
-        return SdkType.GOOGLE
-    return SdkType.OPENAI
-
-
 def create_router(impl: Models) -> APIRouter:
     """Create a FastAPI router for the Models API.
 
@@ -72,15 +59,16 @@ def create_router(impl: Models) -> APIRouter:
         },
     )
     async def list_models(
-        sdk: Annotated[SdkType, Depends(_detect_sdk_from_headers)] = SdkType.OPENAI,
+        anthropic_version: Annotated[str | None, Header(alias="anthropic-version")] = None,
+        x_goog_api_key: Annotated[str | None, Header(alias="x-goog-api-key")] = None,
     ) -> OpenAIListModelsResponse | Response:
-        if sdk == SdkType.ANTHROPIC:
+        if anthropic_version:
             anthropic_result = await impl.anthropic_list_models()
             return JSONResponse(
                 content=anthropic_result.model_dump(exclude_none=True),
                 headers={"anthropic-version": ANTHROPIC_VERSION},
             )
-        elif sdk == SdkType.GOOGLE:
+        elif x_goog_api_key:
             google_result = await impl.google_list_models()
             return JSONResponse(content=google_result.model_dump(exclude_none=True))
 
@@ -97,11 +85,12 @@ async def list_models(
     )
     async def get_model(
         model_request: Annotated[GetModelRequest, Depends(get_model_request)],
-        sdk: Annotated[SdkType, Depends(_detect_sdk_from_headers)] = SdkType.OPENAI,
+        anthropic_version: Annotated[str | None, Header(alias="anthropic-version")] = None,
+        x_goog_api_key: Annotated[str | None, Header(alias="x-goog-api-key")] = None,
     ) -> Model | Response:
         model = await impl.get_model(model_request)
 
-        if sdk == SdkType.ANTHROPIC:
+        if anthropic_version:
             anthropic_model = AnthropicModelInfo(
                 id=model.identifier,
                 display_name=model.identifier,
@@ -111,7 +100,7 @@ async def get_model(
                 content=anthropic_model.model_dump(exclude_none=True),
                 headers={"anthropic-version": ANTHROPIC_VERSION},
             )
-        elif sdk == SdkType.GOOGLE:
+        elif x_goog_api_key:
             google_model = GoogleModelInfo(
                 name=f"models/{model.identifier}",
                 display_name=model.identifier,