Remove deprecated client parameter from FastMCPProxy (#2333)

docs/servers/proxy.mdx

@@ -317,7 +317,6 @@ proxy = FastMCPProxy(client_factory=create_client)
 
 ### Parameters
 
-- **`client`**: **[DEPRECATED]** A `Client` instance. Use `client_factory` instead for explicit session management.
 - **`client_factory`**: A callable that returns a `Client` instance when called. This gives you full control over session creation and reuse strategies.
 
 ### Explicit Session Management

src/fastmcp/server/proxy.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import inspect
-import warnings
 from collections.abc import Awaitable, Callable
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, cast
@@ -20,7 +19,6 @@ from mcp.types import (
 )
 from pydantic.networks import AnyUrl
 
-import fastmcp
 from fastmcp.client.client import Client, FastMCP1Server
 from fastmcp.client.elicitation import ElicitResult
 from fastmcp.client.logging import LogMessage
@@ -461,9 +459,8 @@ class FastMCPProxy(FastMCP):
 
     def __init__(
         self,
-        client: Client | None = None,
         *,
-        client_factory: ClientFactoryT | None = None,
+        client_factory: ClientFactoryT,
         **kwargs,
     ):
         """
@@ -473,9 +470,6 @@ class FastMCPProxy(FastMCP):
         Use FastMCP.as_proxy() for convenience with automatic session strategy.
 
         Args:
-            client: [DEPRECATED] A Client instance. Use client_factory instead for explicit
-                   session management. When provided, a client_factory will be automatically
-                   created that provides session isolation for backwards compatibility.
             client_factory: A callable that returns a Client instance when called.
                            This gives you full control over session creation and reuse.
                            Can be either a synchronous or asynchronous function.
@@ -484,29 +478,7 @@ class FastMCPProxy(FastMCP):
 
         super().__init__(**kwargs)
 
-        # Handle client and client_factory parameters
-        if client is not None and client_factory is not None:
-            raise ValueError("Cannot specify both 'client' and 'client_factory'")
-
-        if client is not None:
-            # Deprecated in 2.10.3
-            if fastmcp.settings.deprecation_warnings:
-                warnings.warn(
-                    "Passing 'client' to FastMCPProxy is deprecated. Use 'client_factory' instead for explicit session management. "
-                    "For automatic session strategy, use FastMCP.as_proxy().",
-                    DeprecationWarning,
-                    stacklevel=2,
-                )
-
-            # Create a factory that provides session isolation for backwards compatibility
-            def deprecated_client_factory():
-                return client.new()
-
-            self.client_factory = deprecated_client_factory
-        elif client_factory is not None:
-            self.client_factory = client_factory
-        else:
-            raise ValueError("Must specify 'client_factory'")
+        self.client_factory = client_factory
 
         # Replace the default managers with our specialized proxy managers.
         self._tool_manager = ProxyToolManager(

tests/deprecated/test_proxy_client.py

@@ -1,107 +0,0 @@
-"""Tests for deprecated FastMCPProxy client parameter."""
-
-import warnings
-
-import pytest
-
-from fastmcp import Client, FastMCP
-from fastmcp.server.proxy import FastMCPProxy, ProxyClient
-
-
-@pytest.fixture
-def simple_server():
-    """Create a simple FastMCP server for testing."""
-    server = FastMCP("TestServer")
-
-    @server.tool
-    def simple_tool() -> str:
-        return "test_result"
-
-    return server
-
-
-class TestDeprecatedClientParameter:
-    """Test the deprecated client parameter in FastMCPProxy."""
-
-    def test_client_parameter_deprecation_warning(self, simple_server):
-        """Test that using the client parameter raises a deprecation warning."""
-        client = Client(simple_server)
-
-        with warnings.catch_warnings(record=True) as w:
-            warnings.simplefilter("always")  # Ensure all warnings are captured
-
-            FastMCPProxy(client=client)
-
-            # Verify a deprecation warning was raised
-            assert len(w) == 1
-            assert issubclass(w[0].category, DeprecationWarning)
-            assert "client' to FastMCPProxy is deprecated" in str(w[0].message)
-            assert "client_factory" in str(w[0].message)
-
-    def test_client_parameter_still_works(self, simple_server):
-        """Test that the deprecated client parameter still functions."""
-        client = ProxyClient(simple_server)
-
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore")  # Suppress warnings for functionality test
-
-            proxy = FastMCPProxy(client=client)
-
-            # Verify the proxy was created successfully
-            assert proxy is not None
-            assert hasattr(proxy, "client_factory")
-            assert callable(proxy.client_factory)
-
-            # Verify the factory returns a new client instance (session isolation for backwards compatibility)
-            returned_client = proxy.client_factory()
-            assert returned_client is not client
-            assert isinstance(returned_client, type(client))
-
-    def test_cannot_specify_both_client_and_factory(self, simple_server):
-        """Test that specifying both client and client_factory raises an error."""
-        client = Client(simple_server)
-
-        def factory():
-            return Client(simple_server)
-
-        with pytest.raises(
-            ValueError, match="Cannot specify both 'client' and 'client_factory'"
-        ):
-            FastMCPProxy(client=client, client_factory=factory)
-
-    def test_must_specify_client_factory_when_no_client(self):
-        """Test that client_factory is required when client is not provided."""
-        with pytest.raises(ValueError, match="Must specify 'client_factory'"):
-            FastMCPProxy()
-
-    def test_client_factory_preferred_over_deprecated_client(self, simple_server):
-        """Test that the recommended client_factory approach works without warnings."""
-
-        def factory():
-            return ProxyClient(simple_server)
-
-        with warnings.catch_warnings(record=True) as w:
-            warnings.simplefilter("always")
-
-            proxy = FastMCPProxy(client_factory=factory)
-
-            # Verify no warnings were raised
-            assert len(w) == 0
-
-            # Verify the proxy works correctly
-            assert proxy is not None
-            assert proxy.client_factory is factory
-
-    async def test_deprecated_client_functional_test(self, simple_server):
-        """End-to-end test that deprecated client parameter still works functionally."""
-        client = ProxyClient(simple_server)
-
-        with warnings.catch_warnings():
-            warnings.simplefilter("ignore")
-
-            proxy = FastMCPProxy(client=client)
-
-        # Test that the proxy can actually handle requests
-        async with Client(proxy) as proxy_client:
-            result = await proxy_client.call_tool("simple_tool", {})
-            assert result.data == "test_result"