GraphRAG — Automotive Requirements Knowledge Graph

A research tool for building LLM-powered, domain-specific knowledge graphs from automotive requirements text and querying them using Graph-Retrieval-Augmented-Generation (GraphRAG).

Targets ADAS and parking function requirements (SAE Level 2) with full traceability, consistency verification, natural language querying, and persistent graph storage via Neo4j AuraDB.

Built as a portfolio project supporting a PhD application in AI-based GraphRAG for automotive functions.

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Live Demo

Layer	URL
Frontend (Vercel)	https://graphrag-lab.vercel.app
Backend API (Render)	https://graphrag-lab-api.onrender.com
API Docs (Swagger)	https://graphrag-lab-api.onrender.com/docs

Note: The backend runs on Render's free tier and may take ~50 seconds to wake from cold start.

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Architecture

graphrag-lab/
├── backend/
│   ├── main.py                       # FastAPI app entrypoint + CORS config
│   ├── .python-version               # Pins Python 3.11.0 for Render
│   ├── models/schemas.py             # Pydantic data models
│   ├── services/
│   │   ├── ontology.py               # Automotive parking ontology (concepts, relations, rules)
│   │   ├── llm_extractor.py          # LLM-based entity + relation extraction (gemini-2.5-flash)
│   │   ├── graph_builder.py          # KG construction: LLM extraction → ontology backbone
│   │   ├── neo4j_service.py          # Neo4j AuraDB persistence + Cypher query runner
│   │   └── rag_engine.py             # GraphRAG = BFS traversal + LLM generation
│   ├── routers/
│   │   ├── requirements.py           # CRUD + batch verification endpoints
│   │   ├── graph.py                  # Build, inspect, Neo4j status endpoints
│   │   └── query.py                  # GraphRAG query + Cypher passthrough endpoints
│   └── data/
│       └── sample_requirements.json  # 18 rich ADAS parking requirements (SYS/APA/RPA/SUM/SEN/HMI/VER)
│
└── frontend/
    ├── src/
    │   ├── App.jsx                   # Root layout + routing
    │   ├── components/
    │   │   ├── Sidebar.jsx           # Navigation (6 tabs)
    │   │   ├── RequirementsPanel.jsx # Load sample data or upload JSON/CSV
    │   │   ├── GraphViewer.jsx       # Cytoscape.js interactive graph canvas
    │   │   ├── QueryPanel.jsx        # GraphRAG natural language query + answer
    │   │   ├── VerificationPanel.jsx # Rule-based ISO 26262 / SAE J3016 checks
    │   │   ├── TraceabilityPanel.jsx # Upstream/downstream dependency explorer
    │   │   └── CypherConsole.jsx     # Live Cypher query editor against Neo4j AuraDB
    │   └── lib/api.js                # Axios API client + all endpoint wrappers
    └── package.json

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Features

1. LLM-Based Knowledge Graph Construction

Graph building is a two-step pipeline:

Step 1 — LLM extraction (llm_extractor.py)

• Sends the full requirements batch to google/gemini-2.5-flash via OpenRouter in a single structured prompt
• Returns strict JSON: {"entities": [...], "relations": [...]}
• Temperature = 0.0 for near-deterministic output
• Entity types: sensor | function | concept | actor | safety_level | standard | system
• Relation types: mentions | depends_on | derives_from | implements | governed_by | conflicts_with | refines | part_of | uses | connected_to
• Falls back to keyword matching if no API key is set

Step 2 — Ontology backbone (graph_builder.py)

• Merges LLM output with deterministic ontology edges defined in ontology.py
• Scans requirement text for explicit cross-references (e.g. APA-001) and adds depends_on edges
• Validates DAG property; topological ordering enables certifiable dependency analysis

2. Neo4j AuraDB Integration

• After every graph build, the full graph is persisted to Neo4j AuraDB via Cypher MERGE
• Node labels: :Requirement and :Entity
• In-memory NetworkX DiGraph is used for fast BFS traversal during GraphRAG retrieval
• Neo4j failure is non-blocking — API response is not affected if Neo4j is down

3. Cypher Console

• Live query editor in the UI with 6 example Cypher queries pre-loaded
• Shows Neo4j connection status + node count badge
• Results rendered as a sortable table (columns + rows)
• Ctrl+Enter to run — calls POST /query/cypher on the backend

4. GraphRAG Query Engine

• Top-k node retrieval by TF-IDF-style keyword scoring against the graph
• BFS context expansion (depth 2) around seed nodes
• Graph context serialized into the LLM prompt alongside the question
• Answer is grounded in cited graph nodes — every response includes the traversal path
• Model: google/gemini-2.5-flash via OpenRouter

5. Requirements Input

• Load sample dataset — 18 rich automotive requirements covering SYS, APA, RPA, SUM, SEN, HMI, VER domains
• Upload your own — supports .json (array of requirement objects) and .csv files

6. Verification Engine

Rule-based, deterministic checks (no LLM required):

• SAE L2 requirements must include a driver monitoring obligation
• Safety requirements must reference an ISO 26262 ASIL level
• Performance requirements must contain quantitative thresholds
• Ambiguous language detection (appropriate, adequate, as needed, if possible, …)

7. Traceability Matrix

• Per-requirement upstream and downstream link explorer
• Link types: depends_on, derives_from, implements, conflicts_with
• Output suitable for ISO 26262 Part 8 traceability evidence

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Quick Start

Backend

cd backend
python -m venv .venv && source .venv/bin/activate   # Windows: .venv\Scripts\activate
pip install -r requirements.txt
cp .env.example .env   # add your keys
uvicorn main:app --reload --port 8000

API docs: http://localhost:8000/docs

Frontend

cd frontend
npm install
npm run dev

UI: http://localhost:5173

Walkthrough

1. Requirements → Load Sample Dataset (18 ADAS parking requirements)
2. Knowledge Graph → Generate Graph (LLM extracts entities + relations)
3. Click any node to inspect its properties and ontology links
4. GraphRAG Query → ask natural language questions; see the traversal path used
5. Verification → run ISO 26262 / SAE J3016 consistency checks
6. Traceability → explore upstream/downstream dependency chains
7. Cypher Console → run live Cypher queries against Neo4j AuraDB

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Environment Variables

Create backend/.env:

# Required for LLM-based graph extraction and GraphRAG queries
OPENROUTER_API_KEY=sk-or-v1-...

# Optional: override the model (default: google/gemini-2.5-flash)
OPENROUTER_MODEL=google/gemini-2.5-flash

# Required for Neo4j AuraDB persistence and Cypher Console
NEO4J_URI=neo4j+s://xxxxxxxx.databases.neo4j.io
NEO4J_USERNAME=neo4j
NEO4J_PASSWORD=your-password

# Or use OpenAI directly (model switches to gpt-4o automatically)
OPENAI_API_KEY=sk-...

The root endpoint (GET /) reports "llm_enabled": true / false and "llm_provider": "openrouter" | "openai" | "none".

Without any API key, the system falls back to keyword-based graph extraction and template-based query answers — fully functional for offline/demo use.

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Model Choice

Model	Provider	Cost	Used for
google/gemini-2.5-flash	OpenRouter	~$0.15/1M tokens	Graph extraction + GraphRAG queries
gpt-4o	OpenAI	~$2.50/1M tokens	Auto-selected if only OPENAI_API_KEY is set

At typical demo usage (10 graph builds + 50 queries), total cost ≈ $0.01–0.02.

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Design Decisions

Decision	Rationale
LLM extraction at temperature=0.0	Near-deterministic graph structure; consistent across runs
Ontology backbone merged after LLM	Guarantees domain concepts are always present regardless of LLM output
Dual storage: NetworkX + Neo4j	NetworkX for fast in-process BFS; Neo4j for durable Cypher queries
Rule-based verification (no ML)	Certifiable, auditable evidence for ISO 26262 functional safety
Cytoscape.js for visualization	Handles large graphs client-side; no server render needed
OpenRouter as LLM gateway	Single API key accesses 100+ models; easy model switching via env var
Render free tier + Vercel CDN	Zero-cost hosting for portfolio demo

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Roadmap

• LLM-based entity + relation extraction
• Neo4j AuraDB integration for persistent Cypher-queryable graph storage
• Cypher Console in UI
• File upload for custom requirements (JSON / CSV)
• Reload graph from Neo4j on service restart (currently requires manual rebuild)
• SHACL / SPARQL constraint validation layer
• Export to ReqIF format for integration with DOORS / Polarion
• Multi-document ingestion (PDF, DOCX, Excel requirement sheets)
• Conflict detection via constraint propagation and SAT solving
• Docker Compose for one-command local deployment

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References

• SAE J3016: Taxonomy and Definitions for Terms Related to Driving Automation Systems (2021)
• ISO 26262: Road vehicles — Functional safety (2018)
• ISO 21448: Road vehicles — Safety of the Intended Functionality (SOTIF) (2022)
• Edge, D. et al. (2024). From Local to Global: A Graph RAG Approach to Query-Focused Summarization. arXiv:2404.16130
• Baader, F. et al. (2003). The Description Logic Handbook. Cambridge University Press.
• Pan, J.Z. et al. (2023). Unifying Large Language Models and Knowledge Graphs: A Roadmap. IEEE TKDE.