No, this isn't a bunch of markdown files, has been in the works since at least May and has been dogfooded inside Apple [1]: "Apple Partners With Anthropic for Claude-Powered AI Coding Platform"
[1]: https://www.macrumors.com/2025/05/02/apple-anthropic-ai-codi...
What is special about it besides the IDE integration? It is a bunch of markdown files with a search tool. It has no agentic capability so it is far behind state of the art dev tooling. Apple devs internally use Claude Code.