I see this at the end of the README

> Swiftlet was built in collaboration with Claude Code.

Did this really happen (some sort of working with Anthropic or Claude Code team) or is it some kind of requirement when you develop some software with Claude Code (I see the other author is: https://github.com/claude), or sort of reuse some of its parts?

Is it like someone saying "built in collaboration with VS Code" or ".. in collaboration with <xyz> autocomplete plugin"?

Or merely a disclaimer about vibe-coding or AI written tool?

It means they used Claude code to write the software.

When you have Claude Code indepedently author commits and PRs and merge them in, it'll always credit itself as an author. I assume it showing up in the README is a byproduct of the same logic.