From f6005e0d670667245ce1f7b02a0e5e03b1e40fa5 Mon Sep 17 00:00:00 2001
From: roboomp <omp@can.ac>
Date: Fri, 26 Jun 2026 06:58:19 +0000
Subject: [PATCH] fix(mcp): hid stdio windows subprocess consoles

Set windowsHide for every Windows stdio MCP spawn path so direct .exe servers no longer open a visible cmd.exe window.

Added a regression test covering direct Windows executable MCP server launch options.

Fixes #3535
---
 packages/coding-agent/CHANGELOG.md            |  4 +++
 .../src/mcp/transports/stdio.test.ts          | 28 +++++++++++++++++++
 .../coding-agent/src/mcp/transports/stdio.ts  |  7 +++--
 3 files changed, 37 insertions(+), 2 deletions(-)
 create mode 100644 packages/coding-agent/src/mcp/transports/stdio.test.ts

diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 5cbb09c44..2f9ad861a 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed Windows stdio MCP server launches showing a separate `cmd.exe` window for direct executable servers; MCP subprocesses now set `windowsHide` on every Windows spawn path. ([#3535](https://github.com/can1357/oh-my-pi/issues/3535))
+
 ## [16.1.21] - 2026-06-26
 
 ### Fixed
diff --git a/packages/coding-agent/src/mcp/transports/stdio.test.ts b/packages/coding-agent/src/mcp/transports/stdio.test.ts
new file mode 100644
index 000000000..3e668796f
--- /dev/null
+++ b/packages/coding-agent/src/mcp/transports/stdio.test.ts
@@ -0,0 +1,28 @@
+import { describe, expect, it } from "bun:test";
+
+import { resolveStdioSpawnCommand } from "./stdio";
+
+describe("resolveStdioSpawnCommand", () => {
+	it("hides direct Windows executable MCP servers", async () => {
+		await expect(
+			resolveStdioSpawnCommand(
+				{ command: "server.exe", args: ["--stdio"] },
+				{ cwd: process.cwd(), env: {}, platform: "win32" },
+			),
+		).resolves.toEqual({
+			cmd: ["server.exe", "--stdio"],
+			windowsHide: true,
+		});
+	});
+
+	it("keeps off-Windows spawn options unchanged", async () => {
+		await expect(
+			resolveStdioSpawnCommand(
+				{ command: "server.exe", args: ["--stdio"] },
+				{ cwd: process.cwd(), env: {}, platform: "linux" },
+			),
+		).resolves.toEqual({
+			cmd: ["server.exe", "--stdio"],
+		});
+	});
+});
diff --git a/packages/coding-agent/src/mcp/transports/stdio.ts b/packages/coding-agent/src/mcp/transports/stdio.ts
index 23b46f0e3..1e7f0cf47 100644
--- a/packages/coding-agent/src/mcp/transports/stdio.ts
+++ b/packages/coding-agent/src/mcp/transports/stdio.ts
@@ -239,12 +239,15 @@ export async function resolveStdioSpawnCommand(
 	// Direct-spawn only when we resolved to a concrete file AND its extension
 	// is not a batch script. Everything else (resolved .cmd/.bat, or an
 	// unresolved extensionless command) goes through cmd.exe so PATHEXT runs.
+	// Every Windows stdio server launch hides its console window; otherwise
+	// direct .exe servers pop a visible cmd window while the MCP server lives.
+	const windowsHide = true;
 	const needsCmdExe = resolved === null || isWindowsBatchCommand(resolvedCommand);
-	if (!needsCmdExe) return { cmd: [resolvedCommand, ...args] };
+	if (!needsCmdExe) return { cmd: [resolvedCommand, ...args], windowsHide };
 
 	return {
 		cmd: [resolveComSpec(options.env), "/d", "/s", "/c", buildCmdExeCommand(resolvedCommand, args)],
-		windowsHide: true,
+		windowsHide,
 	};
 }