GitHub Copilot Weekly Release Adds Claude Fable 5.1 and VS Code Agent Merge
What shipped
GitHub's Copilot weekly release for the week of August 31, published September 4, 2026. It expands model choice, enforces content exclusions across more surfaces, and ships VS Code 1.136 with Agent Merge in public preview.
What changed
- Claude Fable 5.1 is now available to Copilot Pro+, Max, Business, and Enterprise users.
- Gemini 3.8 Flash is rolling out to Copilot Pro, Pro+, Max, Business, and Enterprise users.
- Copilot app and Copilot CLI now honor content exclusions, keeping sensitive code out of context during agentic workflows.
- The GitHub Copilot harness is now generally available in Copilot for JetBrains.
- VS Code 1.136: Agent Merge enters public preview, resolving review feedback, failed checks, and merge conflicts to get pull requests merge-ready. Multi-root workspaces (experimental) bring Copilot and Claude agent sessions to every folder, and chat sessions now organize into a hierarchy.
Why a builder cares
Agent Merge previews the last mile of the agentic loop: GitHub already reviews your code, now it resolves the feedback. Combine that with Fable 5.1 at the Pro+ tier and content exclusions enforced in the CLI, and Copilot covers more of the merge-ready path without leaving the toolchain.