I recently built a CLI and set of libraries for running Service Workers as application servers. The idea: instead of inventing new APIs, use the ones browsers already have (Cache API, FileSystem API, CookieStore, URLPattern, AsyncContext) and shim them for Node, Bun and Cloudflare when missing. The result is portable code that runs anywhere and follows rigorous specifications which coding agents like Claude Code already know how to use. `npm create shovel` to try it.