xum (maintained by Coder) is an open-source agent harness and orchestration framework built to manage, coordinate, and execute developer-focused AI agent sessions across local and cloud environments. xum structures agent execution around standardized tool configurations, custom skills, and environment context. It natively integrates Model Context Protocol (MCP) servers and LLM configurations (such as Claude), coordinating tool calls, background workflows, and editor extensions through dedicated workspace definitions. What distinguishes xum from standard interactive CLI chat tools is its focus on harness orchestration: it manages state persistence, session retry routines, compaction identity across restarts, and modular skill directories (`.agents/skills`) rather than functioning merely as a single-turn conversational interface. The project is open source and hosted publicly under Coder's GitHub repository, fitting into modern automated agent setups and developer workspace stacks.
Tags: agent harness, ai agent, cli, coding agent, developer tools, OpenSource