WebContainer network proxy and external API CORS limitations

StackBlitz WebContainers execute a Node.js runtime entirely within the browser using WebAssembly. While this environment supports standard npm package installations and local frameworks like Vite, all network traffic originating from the virtualized environment is proxied through the browser's native network stack.

When executing server-side code that attempts to fetch external resources, the requests are subject to the browser's standard Cross-Origin Resource Sharing (CORS) policies. This creates a challenge when testing integrations that rely on APIs which do not explicitly allow the origin where the StackBlitz editor is hosted.

How does the WebContainer environment handle requests to endpoints that fail CORS preflight checks? Are there specific configuration settings or headers available to bypass browser-level CORS restrictions for development-only integration testing?