What problem does it solve? Building production AI agents requires explicit control over state, routing, and persistence, which ad-hoc prompt chains cannot provide. This Skill guides the design of LangGraph-based agents with visible, debuggable graph structures. ## Core Features & Use Cases - Graph Construction: Define StateGraph workflows with nodes, edges, and conditional routing for ReAct-style agents with tool calling. - State Management: Use reducers to append messages, merge findings, and accumulate sources across multiple agents sharing state. - Production Patterns: Apply checkpointers for persistence, human-in-the-loop interrupts, and exit conditions that prevent infinite loops. - Use Case: Build a research assistant where a researcher node accumulates findings and sources in shared state, then a writer node consumes the accumulated state to produce a cited report. ## Quick Start Ask the AI to build a LangGraph ReAct agent with a search tool and a calculator tool that loops until the task is complete.