LangGraph Functional API

Build workflows using decorators instead of explicit graph construction.

Overview

• Sequential workflows with conditional branching
• Orchestrator-worker patterns with parallel execution
• Workflows needing persistence and checkpointing
• Human-in-the-loop approval flows
• Simpler alternative to explicit StateGraph construction

Core Concepts

Graph API vs Functional API

Graph API (explicit):           Functional API (implicit):
StateGraph → add_node →        @task functions +
add_edge → compile              @entrypoint orchestration