MythosLM

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Glossary term

Glasswing program

Also: Glasswing

Glossary informational Reviewed Updated

The Glasswing program is Anthropic's selective access initiative that governs how the unrestricted Mythos editions are distributed to vetted organizations.

Scope

Often referred to simply as Glasswing, the program is the gatekeeper for unrestricted Mythos access. It ran the April 2026 Preview for around 50 orgs and remains the only route to Mythos 5 with classifiers lifted.

How it differs from Fable 5

Glasswing is invitation-only and concentrated in cyberdefense and critical-infrastructure use. Everyone else was meant to use the public, safeguarded Fable 5 edition.

Sources & further reading

Facts link to their source. Quotes stay under 15 words and are attributed; figures marked unofficial are third-party until Anthropic publishes system-card numbers.