GitHub scales to 225M developers with AI agents, Copilot Fusion model routing

GitHub now hosts 225 million developers and processed 34.3 billion commits in the past year, with agents emerging as a major workload category. In this interview from GitHub Universe, Jay Parikh, executive vice president of CoreAI at Microsoft, discusses how the platform is rebuilding its infrastructure to handle agent-first workflows that span multiple devices and development environments.

Parikh details Copilot Fusion, GitHub's approach to routing tasks across multiple AI models, which includes a judge model that reviews drafts and multiple critique models that evaluate output quality. The system balances cost and quality tradeoffs as it scales from simple tasks to complex agent sessions.

The conversation covers infrastructure work behind GitHub's migration to Azure, measuring AI spending against business outcomes rather than token usage, and the open-source maintenance challenges of replacing 2,000 dependencies with 20 optimized components.