Anthropic
This page shows Anthropic's complete history in The Diff. Each entry documents a detected change. Unchanged documents are verified each week but shown only in the full diff summary.
2026-09-19 · anthropic — Anthropic publishes Claude Fable 5.1 and Mythos 5.1 model cards, both deployed under ASL-3
Transparency & Annual Report · detected weekly pass, 2026-09-19
Before:
how we're addressing potential risks. Claude Opus 5 Claude Sonnet 5 Claude Fable 5 Claude Mythos 5 Claude Opus 4.8 Claude Opus 4.7
After:
how we're addressing potential risks. Claude Fable 5.1 Claude Mythos 5.1 Claude Opus 5 Claude Sonnet 5 Claude Fable 5 Claude Mythos 5 Claude Opus 4.8 Claude Opus 4.7
The page grew from 18,124 to 20,410 words. A 2,279-word insertion adds full model cards for Claude Fable 5.1 and Claude Mythos 5.1, stating a September 2026 release date, that both were deployed with ASL-3 protections and treated as having CB-1 capabilities, and that the two are the same underlying model differing only in safeguards, with Mythos 5.1 restricted to trusted access programs and Claude Security. The insertion reports RSP evaluation conclusions for chemical and biological weapons, novel weapons development, and automated AI research and development; safeguards evaluation results in the suicide and self-harm domain, including a stated pre-launch change to the claude.ai system prompt; computer-use attack success rates; and ExploitGym cyber and protein-design bio results. The alignment risk assessment is stated as moved "from very low to low" in the August 2026 Risk Report. Last unchanged 2026-09-12.
2026-09-19 · anthropic — Anthropic adds Claude Mythos models to the deprecation table, one already deprecated
Model Deprecations · detected weekly pass, 2026-09-19
Before:
API model name Current state Deprecated Tentative retirement date claude-fable-5-1 Active N/A Not sooner than September 1, 2027 claude-fable-5 Active N/A Not sooner than June 9, 2027 claude-opus-5 Active N/A Not sooner than July 24, 2027
After:
API model name Current state Deprecated Tentative retirement date claude-fable-5-1 Active N/A Not sooner than September 1, 2027 claude-mythos-5-1 Active N/A Not sooner than September 1, 2027 claude-fable-5 Active N/A Not sooner than June 9, 2027 claude-mythos-5 Active N/A Not sooner than June 9, 2027 claude-mythos-preview Deprecated June 9, 2026 To be announced claude-opus-5 Active N/A Not sooner than July 24, 2027
Three rows were added to the model status table: claude-mythos-5-1 and claude-mythos-5, both Active, with tentative retirement dates of September 1, 2027 and June 9, 2027; and claude-mythos-preview, listed as Deprecated on June 9, 2026 with a retirement date of "To be announced." No existing row changed. Last unchanged 2026-09-12.
2026-09-12 · anthropic — Anthropic adds Korea-specific privacy compliance disclosures
Privacy Policy · detected weekly pass, 2026-09-12
Before:
Privacy Policy Effective July 8, 2026 Previous Version English Anthropic is an AI safety and research company working to build reliable, interpretable, and steerable AI systems.
After:
Privacy Policy Effective September 10, 2026 Previous Version English Anthropic is an AI safety and research company working to build reliable, interpretable, and steerable AI systems. Supplemental Disclosures for Residents of the Republic of Korea This section applies to the extent that Anthropic is subject to the Personal Information Protection Act ("PIPA"), and supplements the information in the Privacy Policy. Items of Personal Data Collected and Purpose of Use: Name, birthdate, sex, native-foreigner-code, and DI (duplication information). Purpose: Identity verification, Fraud and abuse monitoring.
Effective date changed from July 8, 2026 to September 10, 2026. New section added governing PIPA compliance for Republic of Korea residents, including requirements for collecting identity verification data and managing cross-border personal data transfers. Last unchanged between 2026-08-28 and 2026-09-12.
2026-09-05 · anthropic — claude-fable-5-1 added to the model lifecycle table
Claude Model Deprecations · detected weekly pass, 2026-09-05
Before:
API model name Current state Deprecated Tentative retirement date claude-fable-5 Active N/A Not sooner than June 9, 2027 claude-opus-5 Active N/A Not sooner than July 24, 2027
After:
API model name Current state Deprecated Tentative retirement date claude-fable-5-1 Active N/A Not sooner than September 1, 2027 claude-fable-5 Active N/A Not sooner than June 9, 2027 claude-opus-5 Active N/A Not sooner than July 24, 2027
One row added; no existing row's state or retirement date changed. Change interval 2026-08-31 to 2026-09-05. The pass counted 40 changed spans for this source, but the other 39 are navigation chrome and the disappearance of sixteen "Loading" placeholders present in the 2026-08-28 capture, not document text.
All Anthropic governance documents in The Diff, whether changed or not: