Chapter 02 — Architecture Overview

2.1 System Architecture Diagram

The complete 9-node data flow of the AFP system. Each node is a distinct LangGraph processing unit with defined state inputs, outputs, and conditional routing edges. Diamond shapes represent decision nodes (Classifier/Router, Hallucination Guard); all other shapes represent action nodes.

Node 0: User Input

Node 1: Intent & ReAct Router

greeting abusive vague legal/finance ReAct / OOS

Node 2: Greeting & Small Talk

Node 3: Abusive / Reject Query

Node 4: Cross- Questioning (LLM)

Node 5: Pinecone Retrieval (MRL 256d)

Node 6: Web Search (Tavily)

retrieved context

Generation & Guardrails

Node 7: LLM Generation

Node 8: Halluc. Guard

grounded ✓

not grounded

Node 9: ReAct Fallback Prompt

Final Output Grounded · Cited · Safe (Nodes 2, 3, 4, 7, 9 converge here)

Figure 1 — AFP v2.0: 9-Node Agentic LangGraph Architecture. Node 0 (User Input) → Node 1 (Intent & ReAct Router) → conditional dispatch to Nodes 2–6 → Generation & Guardrails (Nodes 7–9) → Final Output. Real-time web search (Node 6) is reached either directly for out-of-scope queries or via Human-in-the-Loop authorization when retrieval confidence is low.

2.2 Data Flow Summary

Step	Node(s)	Action
User query enters system	Node 0	Single entry point. LangGraph state initialized.
Intent classification	Node 1	5-way routing: greeting / abusive / vague / legal-finance / ReAct-OOS
Trivial query handling	Nodes 2 & 3	Greeting or abusive — resolved immediately, no vector DB hit.
Vague query clarification	Node 4	LLM asks follow-up questions. Max 2 rounds before forced retrieval.
Semantic retrieval	Node 5	Pinecone Serverless. Jina v3 MRL 256d. Confidence score computed.
Web search fallback	Node 6	Tavily API. Activated for OOS queries or HITL-authorized <45% confidence.
Answer generation	Node 7	Context-bound LLM synthesis. Professional formatting enforced.
Hallucination verification	Node 8	LLM-as-judge. Grounded → output. Not grounded → Node 9.
Grounding retry	Node 9	ReAct Fallback Prompt. Reformulates and retries generation.
Final output	All paths	Grounded · Cited · Safe. Convergence for Nodes 2, 3, 4, 7, 9.

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