GitHub Desktop 3.6: Worktrees and deeper Copilot integration

GitHub has rolled out GitHub Desktop 3.6, a major update designed to enhance developer productivity by bringing more of the Git workflow directly into the desktop application. This release introduces native support for Git worktrees, a feature that allows developers to work on multiple branches simultaneously within a single repository. This is particularly beneficial for scenarios involving coding agents, which often require isolated environments for parallel sessions, eliminating the need for frequent stashing, branch switching, or creating multiple repository clones. A core aspect of this update is the deeper integration of GitHub Copilot. The AI-powered coding assistant now plays a more central role in critical Git operations. Specifically, Copilot is now utilized for generating commit messages, offering more control and customization. Developers can provide custom instructions via `.github/copilot-instructions.md` or `AGENTS.md` files, ensuring that generated messages adhere to repository standards and individual coding styles. This feature aims to standardize commit hygiene and reduce the cognitive load associated with writing detailed commit messages. Moreover, GitHub Copilot has been enhanced to assist in one of the most challenging aspects of version control: resolving merge conflicts. When conflicts arise, Copilot can now provide explanations of the conflicting changes and suggest potential resolutions. Users can review, accept, or edit these suggestions before finalizing the merge, significantly simplifying a process that often causes friction and delays in development workflows. Underpinning these new Copilot features is a migration to the Copilot SDK. This new foundation offers increased flexibility in how Copilot operates within GitHub Desktop. Every Copilot feature now includes a model picker, allowing users to choose from various available models. Additionally, the update supports Bring Your Own Key (BYOK), enabling connection to third-party providers or even locally running models, catering to diverse developer preferences and organizational requirements. GitHub Desktop 3.6.0 is now available for macOS and Windows. While GitHub Desktop remains free, the Copilot-powered functionalities require an active GitHub Copilot subscription. The update will roll out progressively through automatic updates, or users can manually download the latest release from the GitHub Desktop website. This release marks a significant step towards a more integrated and AI-assisted development experience within the GitHub ecosystem.