mcp-mac-setup

Fix VS Code MCP server stdio launches on macOS when Node / pnpm is managed via nvm or fnm.

The Problem

When you launch VS Code from a GUI (Dock, Spotlight, Finder), it starts as a process whose environment is inherited from launchd — not from your interactive shell. That means none of the PATH modifications that live in ~/.zshrc, ~/.bash_profile, or similar files are applied.

Tools like nvm and fnm work by injecting themselves into your shell session at login:

# typical ~/.zshrc entry for nvm
export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"

This writes the active Node version's bin/ directory (e.g. ~/.nvm/versions/node/v22.19.0/bin) onto PATH. When VS Code opens a regular terminal it sources your rc file and everything works. But when VS Code spawns an MCP server as a child stdio process it does not source any shell config — the binary is just exec()'d directly.

The result: pnpm (and even node) are not found, and every stdio MCP server fails to start with a cryptic spawn pnpm ENOENT or command not found error.

Why this is a hard problem to solve in general

• macOS intentionally keeps GUI-launched application environments minimal for security and reproducibility reasons.
• VS Code does not source shell profiles when spawning non-terminal child processes (only the integrated terminal does this via a shell login trick).
• npm-managed global tools (like pnpm dlx) rely on a PATH-resident binary, so there is no stable "default" location to hard-code.
• The absolute path of the pnpm binary changes every time you switch Node versions with nvm/fnm (e.g. ~/.nvm/versions/node/v20.x.x/bin/pnpm → ~/.nvm/versions/node/v22.x.x/bin/pnpm).

This is a well-documented pain point across the community:

• microsoft/vscode#70248 — "Terminal: shell integration should source shell profile"
• Dozens of GitHub issues across MCP server repos where users report spawn pnpm ENOENT on macOS with nvm
• The VS Code docs for MCP servers note that you may need to ensure runtimes are on PATH, but don't provide a concrete fix for version-manager users

The shim approach

Because the path is version-specific and changes over time, a one-time hardcode is not enough. The right fix is a script that reads your current nvm/fnm state, resolves the real absolute path, and writes it directly into mcp.json — then you re-run it whenever you switch Node versions.

mcp-mac-setup does exactly this:

1. Detects your Node version manager (fnm, nvm, or PNPM_HOME fallback).
2. Resolves the absolute path to the active pnpm binary and its bin/ directory.
3. Rewrites every stdio server entry in ~/.../Code/User/mcp.json so that:
   • command is the absolute path to pnpm
   • env.PATH is a hardcoded string containing the active bin/ directory first

Quick Start

pnpm dlx @kylebrodeur/mcp-mac-setup

Then reload VS Code:

Cmd+Shift+P → Developer: Reload Window

All stdio MCP servers in your user-level mcp.json are updated. HTTP/SSE servers are left untouched.

Installation & Usage

One-shot (no install)

# fix all stdio servers
pnpm dlx @kylebrodeur/mcp-mac-setup

# fix a single server
pnpm dlx @kylebrodeur/mcp-mac-setup --server playwright

Global install

pnpm add -g @kylebrodeur/mcp-mac-setup

# then run any time you switch Node versions
mcp-mac-setup

From source

git clone https://github.com/kylebrodeur/mcp-mac-setup.git
cd mcp-mac-setup
node scripts/resolve-pnpm.js

CLI Options

VS Code Task

Instead of running the CLI manually, you can install a VS Code task into any project:

# adds a task to your current project's .vscode/tasks.json
pnpm dlx @kylebrodeur/mcp-mac-setup --install-task

Then run it with Cmd+Shift+P → Tasks: Run Task → Fix MCP pnpm path.

The task will also be offered for projects that clone this repo directly (see .vscode/tasks.json).

When to Re-run

Re-run mcp-mac-setup after:

• Upgrading your Node version with nvm use / fnm use
• Reinstalling pnpm (e.g. via corepack enable pnpm)
• Any change that moves the pnpm binary to a new absolute path

How It Works

~/.nvm/versions/node/v22.19.0/bin/
├── node       ← resolved by reading ~/.nvm/alias/default
└── pnpm       ← written into mcp.json as the absolute command

       ┌─────────────────────────────────────┐
       │  ~/.../Code/User/mcp.json (before)  │
       │  "command": "pnpm"                  │  ← not found in GUI PATH
       └─────────────────────────────────────┘
                         │ mcp-mac-setup
                         ▼
       ┌──────────────────────────────────────────────────────────┐
       │  ~/.../Code/User/mcp.json (after)                        │
       │  "command": "/Users/you/.nvm/versions/node/v22.19.0/     │
       │              bin/pnpm"                                    │
       │  "env": { "PATH": "/Users/you/.nvm/…/bin:~/Library/pnpm:│
       │            /usr/local/bin:/usr/bin:/bin" }                │
       └──────────────────────────────────────────────────────────┘

Detection priority:

1. fnm — checks ~/.local/share/fnm/aliases/default/bin/
2. nvm — reads ~/.nvm/alias/default to get the active version
3. PNPM_HOME / which pnpm — last-resort fallback (warns if used)

Requirements

• macOS (Linux is supported but the PATH problem is less common there)
• Node ≥ 18
• nvm or fnm managing your Node installation (fallback works for other setups)
• VS Code with MCP server support (GitHub Copilot or Copilot Chat)

Contributing

Issues and PRs welcome at github.com/kylebrodeur/mcp-mac-setup.

License

MIT