Microsoft has put its Copilot harness into public preview in Foundry Agent Service, giving developers a managed execution layer for agents that use tools and work through multi-step tasks. Microsoft runs the agent loop and sandbox, while customers provide the model choice, knowledge, procedures and application-specific tools.
The preview combines reusable skills, supported Foundry and Model Context Protocol tools, file and code execution, and bounded delegation to built-in subagents. Agent definitions and supporting files can be kept in source control. Authentication and approval requirements are configured explicitly, and the harness manages working context as a task develops.
Microsoft also made long-running resilience for hosted agents generally available. That capability is intended for workflows that outlast a normal request and need to resume after interruptions. The company is positioning both releases as a way to avoid rebuilding orchestration, context handling and execution infrastructure for every agent application. The trade-off is an opinionated managed runtime rather than complete control of every layer. The Copilot harness is a public preview, so teams should treat interfaces and operational behavior as subject to change before broad production deployment.