[BUG] MCP Fails on native Windows

Environment

• Platform (select one): Claude Max Sub
• Claude CLI version: 1.0.51
• Operating System: Windows 11
• Terminal:  Powershell

Bug Description

The MCP functionality is not working on Windows (native installation). When attempting to add a stdio MCP.

Steps to Reproduce

1. Open a terminal (e.g., PowerShell, Cmd).
2. Attempt to add a context using the claude mcp add command, for example:

claude mcp add context7 -- "npx -y @upstash/context7-mcp"

Expected Behavior

The MCP should be successfully added - It's working on WSL2 on the same machine.

Actual Behavior

The MCP command fails with the following error log, indicating a "Connection closed" issue:

{
  "debug": "Error stack: McpError: MCP error -32000: Connection closed\n    at ka1._onclose (file:///C:/Users/FooBar/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1336:15216)\n    at _transport.onclose (file:///C:/Users/FooBar/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1336:14535)\n    at ChildProcess.<anonymous> (file:///C:/Users/FooBar/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:1338:1459)\n    at ChildProcess.emit (node:events:518:28)\n    at ChildProcess.emit (node:domain:489:12)\n    at LbQ.A.emit (file:///C:/Users/FooBar/AppData/Roaming/npm/node_modules/@anthropic-ai/claude-code/cli.js:320:155823)\n    at maybeClose (node:internal/child_process:1104:16)\n    at Socket.<anonymous> (node:internal/child_process:456:11)\n    at Socket.emit (node:events:518:28)\n    at Socket.emit (node:domain:489:12)",
  "timestamp": "2025-07-11T23:43:11.730Z",
  "sessionId": "8c2cb375-4da4-48e2-9d0f-f37c8f0ccae7",
  "cwd": "D:\\FooBar\\bpress"
}