# GitHub Claude Fable 5.1 is generally available in GitHub Copilot

- Product: GitHub (https://whatsnew.fyi/product/github)
- Vendor: GitHub
- Date: 2026-09-01
- Original notes: https://github.blog/changelog/2026-09-01-claude-fable-5-1-generally-available-in-github-copilot
- Permalink: https://whatsnew.fyi/product/github/releases/2026-09-01-claude-fable-5.1-is-generally-available-in-github

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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Claude Fable 5.1 from Anthropic is now available in GitHub Copilot. The latest model in Anthropic’s Mythos class, Claude Fable 5.1 is designed for long-horizon, autonomous coding and knowledge-work ta…

- **added** — Claude Fable 5.1 from Anthropic is now available in GitHub Copilot