Fix Python 3.13 websockets deprecation warning (#1949)

Author: jlowin

pyproject.toml

@@ -15,6 +15,7 @@ dependencies = [
     "pydantic[email]>=2.11.7",
     "pyperclip>=1.9.0",
     "openapi-core>=0.19.5",
+    "websockets>=15.0.1",
 ]
 
 requires-python = ">=3.10"
@@ -41,7 +42,6 @@ classifiers = [
 ]
 
 [project.optional-dependencies]
-websockets = ["websockets>=15.0.1"]
 openai = ["openai>=1.102.0"]
 
 [dependency-groups]

src/fastmcp/client/oauth_callback.py

@@ -289,6 +289,7 @@ async def callback_handler(request: Request):
             port=port,
             lifespan="off",
             log_level="warning",
+            ws="websockets-sansio",
         )
     )
 

src/fastmcp/server/server.py

@@ -1566,6 +1566,7 @@ async def run_http_async(
         config_kwargs: dict[str, Any] = {
             "timeout_graceful_shutdown": 0,
             "lifespan": "on",
+            "ws": "websockets-sansio",
         }
         config_kwargs.update(_uvicorn_config_from_user)
 

src/fastmcp/utilities/tests.py

@@ -66,6 +66,7 @@ def _run_server(mcp_server: FastMCP, transport: Literal["sse"], port: int) -> No
             host="127.0.0.1",
             port=port,
             log_level="error",
+            ws="websockets-sansio",
         )
     )
     uvicorn_server.run()

tests/client/test_sse.py

@@ -96,7 +96,9 @@ def run_nested_server(host: str, port: int) -> None:
     mount = Starlette(routes=[Mount("/nest-inner", app=app)])
     mount2 = Starlette(routes=[Mount("/nest-outer", app=mount)])
     server = uvicorn.Server(
-        config=uvicorn.Config(app=mount2, host=host, port=port, log_level="error")
+        config=uvicorn.Config(
+            app=mount2, host=host, port=port, log_level="error", ws="websockets-sansio"
+        )
     )
     server.run()
 

tests/client/test_streamable_http.py

@@ -103,6 +103,7 @@ def run_nested_server(host: str, port: int) -> None:
             port=port,
             log_level="error",
             lifespan="on",
+            ws="websockets-sansio",
         )
     )
     server.run()

tests/server/auth/test_oauth_proxy.py

@@ -243,7 +243,13 @@ async def start(self):
                 self.port = s.getsockname()[1]
 
         self.base_url = f"http://localhost:{self.port}"
-        config = Config(self.app, host="localhost", port=self.port, log_level="error")
+        config = Config(
+            self.app,
+            host="localhost",
+            port=self.port,
+            log_level="error",
+            ws="websockets-sansio",
+        )
         self.server = Server(config)
 
         # Start server in background