langgraph-architecture

Recommendation : Use TypedDict for most cases. Use Pydantic when you need validation or complex nested structures. Single Graph when: Subgraphs when: Static Edges ( add_edge ): Dynamic Routing ( add_conditional_edges , Command , Send ): Best for: Best for: Best for: Before implementing: - Stateful conversations - Multi-turn interactions with memory - Human-in-the-loop - Approval gates, corrections, interventions - Complex control flow - Loops, branches, conditional routing - Multi-agent coordination - Multiple LLMs working together - Persistence - Resume from checkpoints, time travel debugging - Streaming - Real-time token streaming, progress updates - Reliability - Retries, error recovery, durability guarantees - All nodes share the same state schema - Simple linear or branching flow - < 10 nodes - Different state schemas needed - Reusable components across graphs - Team separation of concerns - Complex hierarchical workflows - Fixed flow known at build time - Clearer graph visualization - Easier to reason about - Runtime decisions based on state - Agent-driven navigation - Fan-out patterns - Short-lived subgraphs that should be atomic - Subgraphs with incompatible state schemas - Performance-critical paths without need for resume - Clear hierarchy - Centralized decision making - Different agent specializations - Collaborative agents - No clear hierarchy - Flexible...