Revert README, stdio/__init__.py, and test_stdio.py to match upstream…

… main

README.md

@@ -585,15 +585,12 @@ For low level server with Streamable HTTP implementations, see:
 - Stateful server: [`examples/servers/simple-streamablehttp/`](examples/servers/simple-streamablehttp/)
 - Stateless server: [`examples/servers/simple-streamablehttp-stateless/`](examples/servers/simple-streamablehttp-stateless/)
 
-
-
 The streamable HTTP transport supports:
 - Stateful and stateless operation modes
 - Resumability with event stores
-- JSON or SSE response formats  
+- JSON or SSE response formats
 - Better scalability for multi-node deployments
 
-
 ### Mounting to an Existing ASGI Server
 
 > **Note**: SSE transport is being superseded by [Streamable HTTP transport](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http).

src/mcp/client/stdio/__init__.py

@@ -179,18 +179,18 @@ async def stdin_writer():
             yield read_stream, write_stream
         finally:
             # Clean up process to prevent any dangling orphaned processes
-            if sys.platform == "win32":
-                await terminate_windows_process(process)
-            else:
-                # On Linux, terminating a process that has already exited raises ProcessLookupError.
-                # This can happen if the command failed to launch properly (as in this test case).
-                try:
+            try:
+                if sys.platform == "win32":
+                    await terminate_windows_process(process)
+                else:
                     process.terminate()
-                except ProcessLookupError:
-                    # Process already exited — safe to ignore
-                    pass
+            except ProcessLookupError:
+                # Process already exited, which is fine
+                pass
             await read_stream.aclose()
             await write_stream.aclose()
+            await read_stream_writer.aclose()
+            await write_stream_reader.aclose()
 
 
 def _get_executable_command(command: str) -> str:

tests/client/test_stdio.py

@@ -57,12 +57,7 @@ async def test_stdio_client():
 @pytest.mark.anyio
 async def test_stdio_client_bad_path():
     """Check that the connection doesn't hang if process errors."""
-
-    # Removed `-c` to simulate a real "file not found" error instead of
-    # executing a bad inline script.
-    # This ensures the subprocess fails to launch, which better matches
-    # the test's intent.
-    server_params = StdioServerParameters(command="python", args=["non-existent-file.py"])
+    server_params = StdioServerParameters(command="python", args=["-c", "non-existent-file.py"])
     async with stdio_client(server_params) as (read_stream, write_stream):
         async with ClientSession(read_stream, write_stream) as session:
             # The session should raise an error when the connection closes