Subvolts take GitHub Copilot adds Anthropic's Claude Fable 5.1 for advanced coding tasks, with default data retention. Sep 1, 2026 Rated middle: a real update, not a headline event.
Claude Fable 5.1 is generally available in GitHub Copilot
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 tasks. In our internal testing, Claude Fable 5.1 demonstrated strong performance on substantial, long-running coding tasks, including deep codebase research, feature development, and complex agentic workflows. Unlike other Claude models in GitHub Copilot, Claude Fable 5.1 requires data retention by default to operate Anthropic’s safety classifiers. Zero data retention access is available for certain eligible enterprise customers. Continue reading for more details.
Opening of the original on GitHub Changelog: Copilot From Subvolts
Summary and analysis by Subvolts editorial, AI-assisted.
GitHub Copilot now offers Anthropic's Claude Fable 5.1, a model designed for long-horizon coding and knowledge work. Internal tests showed strong performance on tasks like codebase research and agentic workflows. Unlike other Claude models in Copilot, Fable 5.1 requires data retention by default for Anthropic's safety classifiers, though zero data retention is available for eligible enterprise customers. This model is billed at provider list pricing and is accessible to Copilot Pro+, Max, Business, and Enterprise users.
GitHub Copilot now offers Anthropic's Claude Fable 5.1, a model designed for long-horizon coding and knowledge work. Internal tests showed strong performance on tasks like codebase research and agentic workflows.
This integration brings a specialized coding model to GitHub Copilot, potentially enhancing productivity for complex tasks. The mandatory data retention for Fable 5.1, even for safety, contrasts with other Copilot models and raises privacy considerations for some users. Eligible enterprise customers can access zero data retention temporarily while Anthropic rolls out new safeguards. This move affects Copilot Business and Enterprise users who must enable the policy. Developers should monitor Anthropic's Enterprise Frontier Safeguards for future data handling options.
The Playbook: reusable how-tos, prompts, configs and tips pulled out of the news. From the Playbook, matched to the product and topics of this item.
- HeuristicGrounding AI models in user data for relevanceAI results improve when grounded in your specific files and business data. · 5 min
- Setting tipManage Claude Sonnet 5.5 access for Copilot Business/EnterpriseAdmins can manage Claude Sonnet 5.5 access via the model policy in Copilot settings for Business and Enterprise plans. · 5 min
- Troubleshooting fixRepair code issues with Copilot inline chatUse the new Fix action in diagnostic intention menus to have Copilot repair code issues. · 2 min
- Setting tipSelect Claude Sonnet 5.5 in GitHub Copilot's model pickerUsers can choose Claude Sonnet 5.5 within GitHub Copilot's model picker for Copilot Pro, Pro+, Max, Business, and Enterprise plans. · 1 min
Questions people ask
- Does Claude Fable 5.1 use my data for training?
- No, Anthropic states that retained data, including prompts and outputs, is used solely to operate safety classifiers and is not used to train Anthropic's models.
- How do I enable Claude Fable 5.1 in GitHub Copilot?
- Copilot Enterprise and Copilot Business plan administrators must enable the Claude Fable 5.1 policy in Copilot settings. The policy is off by default.
- Is Claude Fable 5.1 available to all Copilot users?
- No, Claude Fable 5.1 is available to Copilot Pro+, Max, Business, and Enterprise users. Administrators must also enable the specific policy.
More from GitHub Changelog: Copilot 63 more
Page generated Oct 19, 2026. Summaries are Subvolts' own; the story belongs to GitHub Changelog: Copilot.