LangGraph Implementation

Core Concepts

LangGraph builds stateful, multi-actor agent applications using a graph-based architecture:

• StateGraph: Builder class for defining graphs with shared state
• Nodes: Functions that read state and return partial updates
• Edges: Define execution flow (static or conditional)
• Channels: Internal state management (LastValue, BinaryOperatorAggregate)
• Checkpointer: Persistence for pause/resume capabilities

Implementation gates

Use these sequenced checks for persistence and human-in-the-loop flows (avoid “it should work” without evidence):

1. Checkpointed runs
   • Build config with {"configurable": {"thread_id": "<stable-id>"}} before invoke / ainvoke.
   • Pass: The same thread_id is reused for every turn of one conversation; a new conversation uses a new id.