Google Open-Sources Harness2, a Recursive Agent Composition Framework

Google has released Harness2, an open-source framework for building recursive, hierarchically composed AI agent systems. Unlike flat agent pipelines, Harness2 allows agents to dynamically spawn and coordinate sub-agents in a tree structure, enabling more complex task decomposition and re-entrant planning loops. The framework is designed to integrate with existing LLM backends and tool-calling interfaces, making it relatively straightforward to layer on top of current agent infrastructure. For developers building multi-step autonomous workflows, Harness2 addresses one of the core engineering challenges: how to manage state, delegation, and error propagation across nested agent calls. This is a direct addition to the growing ecosystem of agent orchestration primitives and warrants evaluation alongside LangGraph, AutoGen, and similar frameworks.