Simplify proxy negotiation middleware API

🤖 Generated with OpenAI Codex

docs/servers/providers/proxy.mdx

@@ -390,13 +390,13 @@ Only reuse sessions when you know the backend is stateless (e.g. stateless HTTP)
 
 ### Forwarding Negotiation Metadata
 
-Add `ProxyNegotiationMetadataMiddleware` when a gateway built with `ProxyProvider` should also expose backend instructions and namespaced `_meta`:
+Add `ProxyNegotiationMiddleware` when a gateway built with `ProxyProvider` should also expose backend instructions and namespaced `_meta`:
 
 ```python
 from fastmcp import FastMCP
 from fastmcp.server.providers.proxy import (
     ProxyClient,
-    ProxyNegotiationMetadataMiddleware,
+    ProxyNegotiationMiddleware,
     ProxyProvider,
 )
 
@@ -404,7 +404,7 @@ backend = ProxyProvider(lambda: ProxyClient("http://backend:8000/mcp", mode="aut
 gateway = FastMCP(
     "Controlled Gateway",
     providers=[backend],
-    middleware=[ProxyNegotiationMetadataMiddleware(backend)],
+    middleware=[ProxyNegotiationMiddleware(backend)],
 )
 ```
 

fastmcp_slim/fastmcp/server/middleware/__init__.py

@@ -1,5 +1,3 @@
-from typing import TYPE_CHECKING
-
 from .authorization import AuthMiddleware
 from .middleware import (
     CallNext,
@@ -8,24 +6,10 @@ from .middleware import (
 )
 from .ping import PingMiddleware
 
-if TYPE_CHECKING:
-    from fastmcp.server.providers.proxy import (
-        ProxyNegotiationMetadataMiddleware as ProxyNegotiationMetadataMiddleware,
-    )
-
 __all__ = [
     "AuthMiddleware",
     "CallNext",
     "Middleware",
     "MiddlewareContext",
     "PingMiddleware",
-    "ProxyNegotiationMetadataMiddleware",
 ]
-
-
-def __getattr__(name: str) -> object:
-    if name == "ProxyNegotiationMetadataMiddleware":
-        from fastmcp.server.providers.proxy import ProxyNegotiationMetadataMiddleware
-
-        return ProxyNegotiationMetadataMiddleware
-    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")

fastmcp_slim/fastmcp/server/providers/proxy.py

@@ -1045,7 +1045,7 @@ class _NegotiationMetadata:
         )
 
 
-class ProxyNegotiationMetadataMiddleware(Middleware):
+class ProxyNegotiationMiddleware(Middleware):
     """Forward optional negotiation metadata from a ``ProxyProvider`` backend.
 
     The frontend always owns protocol versions, capabilities, cache policy, and
@@ -1344,9 +1344,7 @@ class FastMCPProxy(FastMCP):
         self.client_factory = client_factory
         provider = ProxyProvider(client_factory)
         self.add_provider(provider)
-        self.middleware.append(
-            ProxyNegotiationMetadataMiddleware(provider, identity=identity)
-        )
+        self.middleware.append(ProxyNegotiationMiddleware(provider, identity=identity))
         self._setup_proxy_ping_handler()
 
     async def _get_client(self) -> Client:

tests/server/providers/proxy/test_negotiation_metadata.py

@@ -11,13 +11,12 @@ from mcp_types.version import MODERN_PROTOCOL_VERSIONS
 from fastmcp import Client, FastMCP
 from fastmcp.client.transports import StreamableHttpTransport
 from fastmcp.server import create_proxy
-from fastmcp.server.middleware import (
-    CallNext,
-    Middleware,
-    MiddlewareContext,
-    ProxyNegotiationMetadataMiddleware,
+from fastmcp.server.middleware import CallNext, Middleware, MiddlewareContext
+from fastmcp.server.providers.proxy import (
+    ProxyClient,
+    ProxyNegotiationMiddleware,
+    ProxyProvider,
 )
-from fastmcp.server.providers.proxy import ProxyClient, ProxyProvider
 from fastmcp.utilities.http import find_available_port
 
 ResultT = TypeVar("ResultT", bound=mcp_types.Result)
@@ -132,7 +131,7 @@ def make_gateway(
     frontend_metadata: bool = False,
 ) -> FastMCP:
     provider = ProxyProvider(lambda: ProxyClient(upstream, mode=backend_mode))
-    negotiation = ProxyNegotiationMetadataMiddleware(provider, identity=identity)
+    negotiation = ProxyNegotiationMiddleware(provider, identity=identity)
     middleware: list[Middleware] = [negotiation]
     if frontend_metadata:
         middleware.append(FrontendMetadataMiddleware())
@@ -235,7 +234,7 @@ async def test_unavailable_backend_does_not_fail_negotiation(frontend_mode: str)
     gateway = FastMCP(
         "available-gateway",
         providers=[provider],
-        middleware=[ProxyNegotiationMetadataMiddleware(provider)],
+        middleware=[ProxyNegotiationMiddleware(provider)],
     )
     gateway.provider_error_strategy = "raise"
 
@@ -258,7 +257,7 @@ def test_gateway_construction_does_not_create_backend_client():
     FastMCP(
         "lazy-gateway",
         providers=[provider],
-        middleware=[ProxyNegotiationMetadataMiddleware(provider)],
+        middleware=[ProxyNegotiationMiddleware(provider)],
     )
 
     assert calls == 0
@@ -268,7 +267,7 @@ async def test_fastmcp_proxy_uses_public_negotiation_middleware():
     proxy = create_proxy(make_upstream(), name="convenience", identity="upstream")
 
     assert any(
-        isinstance(middleware, ProxyNegotiationMetadataMiddleware)
+        isinstance(middleware, ProxyNegotiationMiddleware)
         for middleware in proxy.middleware
     )
     async with Client(proxy, mode="auto") as client: