This would be much more interesting if it detailed how the prompt/skills were reverse-engineered. As it is it seems like this could just be the output from “hey Claude write me a system prompt that works like Claude Design”.
They have never attempted to hide their system prompts in fact they explicitly publish them for Claude (https://platform.claude.com/docs/en/release-notes/system-pro...) and Claude Code they provide a proxy option which then makes it trivial to see the full requests and responses including the prompts and tool usage...
honestly, i think you can just look at the network tab and see the "content" of the skills. Same has been true for their excel addin and bunch of other things.
That would enable Anthropic to block the technique.