fix(stdio): always set windowsHide on Windows, not just in Electron

.changeset/fix-stdio-windows-hide.md

@@ -0,0 +1,5 @@
+---
+'@modelcontextprotocol/client': patch
+---
+
+Always set `windowsHide` when spawning stdio server processes on Windows, not just in Electron environments. Prevents unwanted console windows in non-Electron Windows applications.

packages/client/src/client/stdio.ts

@@ -126,7 +126,7 @@ export class StdioClientTransport implements Transport {
                 },
                 stdio: ['pipe', 'pipe', this._serverParams.stderr ?? 'inherit'],
                 shell: false,
-                windowsHide: process.platform === 'win32' && isElectron(),
+                windowsHide: process.platform === 'win32',
                 cwd: this._serverParams.cwd
             });
 
@@ -258,7 +258,3 @@ export class StdioClientTransport implements Transport {
         });
     }
 }
-
-function isElectron() {
-    return 'type' in process;
-}

packages/client/test/client/crossSpawn.test.ts

@@ -152,4 +152,54 @@ describe('StdioClientTransport using cross-spawn', () => {
         // verify message is sent correctly
         expect(mockProcess.stdin.write).toHaveBeenCalled();
     });
+
+    describe('windowsHide', () => {
+        const originalPlatform = process.platform;
+
+        afterEach(() => {
+            Object.defineProperty(process, 'platform', {
+                value: originalPlatform
+            });
+        });
+
+        test('should set windowsHide to true on Windows', async () => {
+            Object.defineProperty(process, 'platform', {
+                value: 'win32'
+            });
+
+            const transport = new StdioClientTransport({
+                command: 'test-command'
+            });
+
+            await transport.start();
+
+            expect(mockSpawn).toHaveBeenCalledWith(
+                'test-command',
+                [],
+                expect.objectContaining({
+                    windowsHide: true
+                })
+            );
+        });
+
+        test('should set windowsHide to false on non-Windows', async () => {
+            Object.defineProperty(process, 'platform', {
+                value: 'linux'
+            });
+
+            const transport = new StdioClientTransport({
+                command: 'test-command'
+            });
+
+            await transport.start();
+
+            expect(mockSpawn).toHaveBeenCalledWith(
+                'test-command',
+                [],
+                expect.objectContaining({
+                    windowsHide: false
+                })
+            );
+        });
+    });
 });