Microsoft Build 2026: Windows Wants to Be the Operating System for AI Agents

TL;DR: Microsoft Build 2026 was not a Copilot upgrade event. The real announcement was structural: Windows is being rebuilt as a controlled runtime for AI agents. The pieces that matter are MXC (an OS-level security sandbox for agents), seven new in-house MAI models plus on-device Aion models, the Surface RTX Spark De Box for local compute, and Project Solara for agent-first devices. The model is no longer the product. The execution layer around it is. I spend most of my week building agent workflows, research pipelines, and automation that has to keep running after the is over.