A developer leaked Anthropic’s real .claude folder containing 33 skills, a verifier subagent, and a seven-file harness. After integrating it locally, Claude stopped generating pointless tests and redundant confirmation prompts. The entire setup is now on GitHub with a one-line install script.

• A claimed "leaked" Anthropic internal .claude folder (33 skills, verifier subagent, 7-file harness) is being distributed via a one-line curl-to-bash install script on GitHub (Archive228/loopkit)
• Running curl-fsSL-piped-to-bash from an unverified repo to install unvetted "leaked" internal tooling is a significant security red flag, regardless of the productivity claims
• The claimed behavior changes (fewer test stubs, no false "done" markings, fewer confirmation prompts) are anecdotal and unverified, not benchmarked
• The framing pushes urgency ("bookmark before it disappears") which is a classic pressure tactic worth treating with suspicion rather than a substantive technical claim

A roughly 120,000-character system prompt for Anthropic’s Claude Fable 5 model has been leaked, revealing detailed behavior instructions, product information, refusal rules, and formatting guidelines. The prompt outlines how Claude should handle user requests, safety measures, available features, and external documentation searches.

• A ~120,000-character leak allegedly exposes Anthropic's full system prompt for "Claude Fable 5," including model names like claude-opus-4-8 and claude-sonnet-4-6.
• Claude Fable 5 and Claude Mythos 5 reportedly share the same core architecture, but the public Fable 5 has extra safety checks that Mythos 5 lacks for approved partners.
• The prompt instructs Claude to never render antml:voice_note blocks and to search docs.claude.com or support.claude.com before answering questions about current features, specs, or pricing.
• Safety rules detailed include refusing weapons/drug synthesis instructions and malware creation, avoiding persuasive text impersonating real public figures, and giving factual (not advisory) answers on legal/financial topics.

The entire source code for Anthropic’s Claude Code CLI has leaked due to an internal error during a package release. This includes nearly 2,000 TypeScript files and over 512,000 lines of code, exposing the application’s inner workings to competitors and developers. Anthropic has acknowledged the mistake and stated it was not a security breach.

• A packaging error in Claude Code v2.1.88 exposed a source map, leaking the entire ~2,000-file, 512,000+ line TypeScript codebase.
• The leaked code was quickly archived and uploaded to GitHub, gaining tens of thousands of forks within a short time.
• Anthropic says no customer data was exposed and calls it human error, not a security breach, while adding safeguards.
• Developers have already begun reverse-engineering internals, like Claude Code's memory architecture and background memory rewriting system.

Anthropic has confirmed its most powerful AI model, Claude Mythos, after a configuration error exposed details about it. The model is said to significantly outpace previous versions in reasoning and cybersecurity, but it also poses serious risks, with the potential for misuse in cyberattacks. Early access will be limited to cybersecurity-focused organizations due to these concerns.

• A configuration error accidentally leaked ~3,000 unpublished assets revealing Anthropic's next flagship model, internally called Mythos (or possibly Capybara)
• The model reportedly has advanced cyberattack capabilities that could outpace current defenses, so Anthropic plans to limit early access to cybersecurity organizations first
• This follows a real incident where a Chinese state-sponsored group already used Claude Code to breach about thirty organizations
• The model is described as highly resource-intensive, echoing GPT-4.5's cost/efficiency problems, with no confirmed release timeline or final name