langgraph-fundamentals

You build agent workflows by defining a StateGraph with nodes and edges, using conditional edges for routing logic and Send tasks for parallel processing. This approach enforces compile-before-run execution and partial-state updates to ensure safe workflow orchestration.

State management in LangGraph uses reducers and partial-state updates within a directed graph. This enables complex workflows to maintain runtime context effectively and apply targeted updates without overwriting the entire state object.

Dynamic routing in a LangGraph directed graph is handled using conditional edges and the Command object. These mechanisms combine state updates with routing decisions to direct execution flow between nodes based on runtime data.

Yes, you can execute parallel tasks in LangGraph using the Send workload feature. This allows the directed graph to dispatch multiple node executions concurrently, enabling multi-step decision workflows and automation pipelines to process branches in parallel.

LangGraph prevents infinite loops through compile-before-run guarantees and robust error handling. Compiling the graph before execution validates the routing logic, while partial-state updates and runtime context tracking ensure safe agent execution.

Reducers are needed in a LangGraph state graph when workflows require complex state management. They process partial-state updates from parallel node executions, ensuring that concurrent branches merge state changes correctly without data loss.