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WebKit Sandbox Repro
Supports UIby kentcdodds
Minimal diagnostic MCP app to test postMessage transport behavior in Safari/WebKit hosts.
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Works in:claude
Exposes:Resources
What it does
This is a technical diagnostic tool designed to isolate a specific postMessage transport bug occurring in Safari/WebKit-based hosts. It renders a minimal UI that attempts a JSON-RPC handshake (ui/initialize) with the host to verify if the sandbox proxy is correctly forwarding messages.
Key features
- Handshake Validation: Sends
ui/initializeand waits for a response to confirm transport integrity. - Timeout Detection: Specifically flags failures when the host-side relay drops the message.
- Minimal Footprint: No heavy frameworks, just raw HTML/JS to ensure the bug is isolated to the transport layer.
Installation
Run the server via node:
npm install
npm run dev
In MCP Inspector, connect using:
- Command:
node - Arguments:
server.ts
Supported hosts
Confirmed for testing in MCP Inspector (Chromium and WebKit versions).
Quick install
npm run devInformation
- Pricing
- free
- Published
- 5/11/2026
- stars
