Microsoft presented Copilot Harness, developed through GitHub, as a common execution foundation for multiple Copilot products and Foundry. It connects model selection, tool calls, task context and sandboxes to reduce the need to rebuild an agent whenever its model changes. SDK and managed paths support extensions such as MCP and skills. This is an integration of the execution layer, not a new model release, and it does not require abandoning every existing framework. Model responsibilities and runtime responsibilities still need separate evaluation.