claude-mythos-preview to Retire June 30, Migrate to claude-mythos-5

Anthropic will retire claude-mythos-preview on June 30, 2026, according to the company’s official Model Deprecations page.

The model has been marked as deprecated, with claude-mythos-5 listed as the recommended replacement. Users currently relying on claude-mythos-preview will need to migrate ahead of the retirement date.

Note that claude-mythos-5 is currently invitation-only and gated behind Project Glasswing.

Source:
Anthropic Model Deprecations page
https://platform.claude.com/docs/en/about-claude/model-deprecations

Exact excerpt:

claude-mythos-preview — Deprecated | Retirement Date: June 30, 2026 | Recommended Replacement: claude-mythos-5

Users should begin planning their migration in the coming weeks.