GitHub Copilot CLI 1.0.40-1 released with OAuth for MCP servers and smoother streaming

GitHub released Copilot CLI v1.0.40-1 on May 5, 2026, adding client_credentials OAuth grant type support for MCP servers (enabling fully headless authentication without a browser), smoother streaming text output, subagent model evaluation fixes, and reliability improvements for session management and plugin handling. Subagents now correctly evaluate tool search support for their own model instead of inheriting parent session settings. The /clear and /new commands properly reset active custom agent selection. Extensions now load in prompt mode (-p). Separately, GitHub Copilot in Visual Studio received its April 2026 update with cloud agent sessions, user-level custom agents, a new Debugger agent, expanded skills support, and C++ agent tools.