msh

Deterministic execution runtime for AI coding agents.
Auto-handles prompts, truncates output, redacts secrets, and lets you undo agent changes.

---

Why msh?

Raw shell execution breaks when agents run unattended:

• Interactive prompts ([y/N], passwords) hang the agent forever
• Large compiler or test dumps blow the context window
• Secrets leak into model history
• Bad edits have no clean undo
• ANSI noise pollutes output

msh sits between the agent and the OS. It returns structured, bounded, redacted results and records what changed so you can reverse it.

---

Quick Start

1. Install

macOS / Linux

curl -fsSL https://raw.githubusercontent.com/msh-protocol/msh/main/scripts/install.sh | bash

Windows

irm https://raw.githubusercontent.com/msh-protocol/msh/main/scripts/install.ps1 | iex

Go

go install github.com/msh-protocol/msh/cmd/msh@latest

2. Teach your agent

Install the official skill for Antigravity, Cursor, Windsurf, Claude Code, and OpenCode:

# Add to current project
npx skills add msh-protocol/msh

# Or install globally across all projects on your machine
npx skills add msh-protocol/msh -g

Or configure via the msh CLI:

# Generate rules and skills in the current workspace
msh init

# Or install globally for all Antigravity projects
msh init --global

---

Core Commands

Run a command

msh git status
msh npm run build
msh pytest -v

Outputs are sanitized, truncated, secret-redacted, and prompts are auto-handled.

msh --max-lines 500 git log
msh --timeout 1m python script.py
msh --pty npm test

Undo agent changes

msh undo                  # last run
msh undo 42               # specific run
msh undo 42 --file src/index.ts

Guardrails

msh guard check "rm -rf /"
msh guard list
msh --strict-workspace "cat ../../etc/passwd"

Shadow worktrees

msh branch create hypo-cache
msh branch run hypo-cache "npm test"
msh branch diff hypo-cache
msh branch merge hypo-cache -m "verified"
# or
msh branch abort hypo-cache

MCP server

{
  "mcpServers": {
    "msh": {
      "command": "msh",
      "args": ["mcp"]
    }
  }
}

Fleet dashboard

msh fleet start

Opens http://localhost:9000.

---

SDKs

Python

pip install msh-protocol

from msh import exec
res = exec("npm test", max_output_lines=200)

TypeScript

npm install @msh-protocol/client

import { exec } from '@msh-protocol/client';
const res = await exec('git status');

JSON mode

msh exec "npm run build" --max-lines 500

---

What it handles

Problem	Raw shell	msh
Interactive prompts	Hangs	Auto-answers or blocks cleanly
Large logs	Blows context	Truncates (head + tail)
Secrets in output	Leaked	Redacted
Bad file edits	Manual fix	msh undo
ANSI noise	Corrupts output	Stripped
Destructive commands	Runs	Blocked by guardrails
Tool calling	Free text	Structured JSON

---

License

Apache 2.0