What happened
On October 7, 2026, at an event in San Francisco, Microsoft made Microsoft Execution Containers (MXC) generally available. It is a containment layer: you define file, network destination, process and UI access in a JSON policy, enforced through OS mechanisms — AppContainer on Windows, Seatbelt on macOS, Bubblewrap on Linux. There are also OS session containers, WSL containers (Windows only) and an experimental MicroVM. The SDK is on GitHub under the MIT license.
The same day, GitHub made Copilot's local sandbox, which runs on MXC, generally available in the CLI, the Copilot app and VS Code (Agent Host) at no extra cost. Enterprises can enforce it through managed settings. The Copilot CLI can now discover locally running Ollama models in its /model picker.
Already supporting MXC: GitHub Copilot, OpenAI Codex, Replit and LM Studio; Claude Code, Perplexity and Manus are planned. Central policy via Intune and Entra-based agent identity are still "coming soon".
Why it matters
Until now each tool built its own sandbox. The OS is starting to provide a common policy format. Configuring "which files and which networks" in every tool can converge in one place.
What to do now
- Turn on Copilot's local sandbox on developer machines.
- Pilot MXC policies (Seatbelt on macOS, AppContainer on Windows).
- Wait for Intune/Entra before mandating central policy fleet-wide.