MSW AI Agent Bridge Monorepo

This monorepo provides a suite of tools that bridge AI agents with Mock Service Worker (MSW). It enables dynamic addition, updating, and removal of MSW network mocks directly from a command-line interface or AI tool execution, completely independently of the application source code restarts.

Demo

Walkthrough of the MCP-driven MSW workflow (browser bridge, live handler updates):

https://github.com/user-attachments/assets/06959759-b198-4cd1-ae2b-11ede32acd8e

Related MCP server: Dev Proxy MCP Server

Key features

• 🤖 Generate MSW handlers with AI

• ⚡ Update mocks without reloading the page

• 🌉 WebSocket bridge between Cli/MCP and the browser

• 🛠️ Scaffold MSW setup with msw-cli setup or MCP's /msw-setup prompt

• 💻 Terminal and script control via msw-cli

• ⚙️ Configurable port, persistence, and client targeting

• ✨ Agent skills for AI agents to use

Structure

This project is set up as a monorepo using pnpm and turbo.

• apps/docs (@msw-mcp/docs): Starlight documentation site for MSW Agent Tools (CLI, MCP, guides). Source lives under apps/docs/src/content/docs/.

• packages/msw-cli: The command-line interface (msw-cli) used by AI agents or developers to send dynamic handler updates. Run msw-cli setup to scaffold a project, then msw-cli open plus handler commands.

• packages/msw-mcp: The published Model Context Protocol server (msw-mcp) so assistants can manage mocks via MCP tools.

• packages/client (@msw-mcp/client): The browser/environment client that listens for updates and registers them with the local MSW setup.

• packages/core (@msw-mcp/core): The core daemon process and session management logic that brokers communication between the CLI or MCP server and the client.

Documentation site

From the repo root:

pnpm --filter @msw-mcp/docs dev

Opens the local docs dev server (default Astro port, often http://localhost:4321). Production search (Pagefind) is easiest to verify after pnpm --filter @msw-mcp/docs build and pnpm --filter @msw-mcp/docs preview.

More detail: apps/docs/README.md.

Quick setup: msw-cli

1. Install the CLI globally: npm install -g msw-cli (or use your package manager’s equivalent).

2. In a new project, run msw-cli setup and follow the printed steps for MSW + @msw-mcp/client.

3. Start a session, then drive handlers from the shell:

   msw-cli open
   msw-cli add "http.get('/api/user', () => HttpResponse.json({ id: 1 }))"
   msw-cli status
   msw-cli close

Full command reference, flags, and workflows: packages/msw-cli/README.md.

Quick setup: msw-mcp (MCP)

1. Register the server in your MCP client (example for JSON config):

   {
     "mcpServers": {
       "msw-mcp": {
         "command": "npx",
         "args": ["msw-mcp@latest"]
       }
     }
   }

2. In the client, use the /msw-setup prompt (or follow manual steps) so the browser app loads msw, @msw-mcp/client, and the worker bridge.

Installation options (VS Code, Claude Code, Cursor, etc.), architecture, MCP tools, and manual setup: packages/msw-mcp/README.md.

Development Scripts

Run these scripts from the root directory using pnpm:

• pnpm build: Compiles all packages using Turborepo.

• pnpm dev: Starts the development pipelines for all packages.

• pnpm format: Formats the code using Prettier.

• pnpm lint: Runs linting checks across the repository.

Getting Started

1. Install dependencies:

   pnpm install

2. Build the project:

   pnpm build

3. Use the CLI:
   You can navigate to the CLI directory or use it directly via node after building:

   node packages/msw-cli/build/index.js help

License

This project is licensed under the MIT License — see LICENSE.