On Friday, Anthropic said Claude Mythos would remain restricted. The company was clear about it: stronger safeguards were needed before any general release, and for now the model would stay limited to roughly 40 selected organizations through Project Glasswing. The next day, users started seeing "Mythos 1" inside Claude Code. The model appeared in the UI briefly, with a preview label reading "claude-mythos-1-preview," then disappeared again. TestingCatalog found new strings in the source code: "Access to the Claude Mythos model in Claude Code and Claude Security." Screenshots circulated on X. Then the traces were gone.