SuperBox Executor

Remote MCP server executor built on Cloudflare Workers + Durable Objects.

Architecture

MCP Client (VS Code / Cursor / Antigravity / Claude Desktop / ChatGPT)
    |
    |  POST /mcp?name=<server>
    v
Cloudflare Worker  (superbox-executor.workers.dev)
    |  validates name in R2 registry, routes to Durable Object by session ID
    v
McpSession Durable Object  (one per session)
    |  fetches Python source from GitHub, parses tools, runs on request
    v
TypeScript interpreter  ->  executes tool functions  ->  returns JSON-RPC response
    |
    +-- outbound HTTP via native fetch (requests.get/post/put/patch/delete)
    +-- JSON processing, dict/list ops, f-strings, common builtins

Setup

Prerequisites

• Node.js 22+
• Wrangler CLI (npm i -g wrangler)
• Cloudflare account (wrangler login)

1. Install dependencies

cd cloudflare
npm install

2. Create R2 bucket

wrangler r2 bucket create superbox-mcp-registry

For local dev, the preview bucket is superbox-mcp-registry-dev:

wrangler r2 bucket create superbox-mcp-registry-dev

3. Local development

npm run dev
# Worker available at http://localhost:8787

4. Deploy to production

npm run deploy
# URL: https://superbox-executor.<your-account>.workers.dev

Copy the deployed URL and set it in your backend .env:

CLOUDFLARE_WORKER_URL=https://superbox-executor.<your-account>.workers.dev

API

Health check

GET /health

MCP endpoint (Streamable HTTP, spec 2025-11-25)

POST /mcp?name=<server-name>
Content-Type: application/json

{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-11-25","capabilities":{},"clientInfo":{"name":"test","version":"0.0.1"}}}

Test mode (skip registry, provide repo directly)

POST /mcp?name=my-test&test_mode=true&repo_url=https://github.com/user/repo&entrypoint=main.py

Python execution model

Tools are executed by a lightweight TypeScript interpreter built into the Worker. Cloudflare Workers cannot run Pyodide (WASM bundle exceeds the 10 MB script limit, and eval() / new Function() are blocked at the V8 level), so this interpreter handles the patterns that cover the vast majority of published MCP servers.

Supported

• requests.get/post/put/patch/delete (mapped to native fetch)
• Dict, list, string, and numeric operations
• f-strings, if/elif/else, for loops, try/except
• Common builtins: int, float, str, bool, len, min, max, range, enumerate, zip
• JSON serialization / deserialization

Not supported

• httpx, aiohttp, or any HTTP library other than requests
• Packages with C extensions (pandas, numpy, cryptography, etc.)
• async def / await
• List/dict/set comprehensions
• Class definitions
• Complex stdlib usage (os, subprocess, socket, etc.)

uv, pip, and poetry are package managers -- what matters is what they install. Servers that install requests-based packages work. Servers that install httpx, C-extension packages, or rely on async patterns do not.

Real-time logs

wrangler tail superbox-executor --format pretty