A low-level stateful-graph orchestration framework from LangChain, MIT licensed, with Python and JS/TS implementations, and Klarna, Replit and Elastic named as production users in the README. Its lineage is stated in the acknowledgements - inspired by Google Pregel and Apache Beam, interface borrowing from NetworkX - which means the BSP graph-computation model applied to agents: nodes are model calls or tool executions, edges are control flow, state is an explicit object. The value is not in the loop-the-model-with-tools layer but in four runtime capabilities: durable execution (resume exactly where it stopped after a crash), human-in-the-loop interrupts (approval can stay suspended for hours or days), separate short-term and long-term memory, and LangSmith execution-path tracing. Its actual claim is that agent reliability is a runtime problem, not a model problem. Usable without LangChain; any CompiledStateGraph can be handed to Deep Agents above it as a sub-agent. 42.1k stars. We have not run it and have not verified checkpoint-resume consistency, so it is graded as pending reproduction.