Boolean and Rule-Based Paths

Not every decision needs an LLM.

Rule-Based Priority

Always check deterministic rules before calling an LLM.

def router_node(state):
    user = state.get("user")
    
    # 1. Deterministic Rule
    if not user.is_authenticated:
        return "login_flow"
        
    # 2. Deterministic Check
    if state["requests_count"] > 100:
        return "rate_limit_error"
        
    # 3. Only if rules pass, call LLM
    return "ai_router"

Why?

• Cost: if True costs $0.00. GPT-4 costs $0.03.
• Security: You don't want an LLM to "hallucinate" that a user is logged in. Hardcode the check.