Consumer Graph Service - Implementation Status

✅ PHASE 1-2 COMPLETE: Foundation Ready for Development

Build Status: ✅ SUCCESS - All code compiles without errors Test Status: ✅ PASS - All existing tests passing Deployment: 🟡 READY FOR LOCAL - Can run locally with Docker Neo4j

What’s Been Implemented

1. Neo4j Integration (pkg/neo4j/)

✅ Connection Management

Production-ready driver with connection pooling
Configurable pool sizes (50 local → 150 prod)
Automatic retry and timeout handling
Graceful shutdown on service termination

✅ Health Monitoring

Live connectivity checks
Database responsiveness testing
Integrated into /health endpoint
Returns detailed status (connected, pool_size, response_time)

2. Configuration System (internal/config/)

✅ Environment-Specific Configs

Local: bolt://localhost:7687 (unencrypted for dev)
Dev/Stage/Prod: bolt+routing:// (encrypted, ready for Neo4j Aura)
Connection pooling parameters tuned per environment
Full validation on startup

✅ Security-Ready

Credentials in config files (will move to AWS Secrets Manager)
FSD environment variable injection prepared
TLS encryption via URI scheme

3. Domain Models (internal/models/)

✅ Complete Data Model

User: user_id, zip, created_at
Product: product_id, upc, name, brand, category, norm_name
Offer: offer_id, title, points, start, end, priority
Relationships: Purchase, Similarity, Eligibility, AppliesTo
Recommendation: Full request/response models with defaults

4. Database Schema (internal/graph/schema/)

✅ Neo4j Schema Definition

Constraints: Unique on user_id, product_id, offer_id
Indexes: offer dates, product category, user zip, product brand
Idempotent: All DDL uses IF NOT EXISTS
Function: Initialize(ctx, client) applies all schema

5. Service Integration (cmd/service/, internal/server/)

✅ Main Application

Neo4j client lifecycle managed in main.go
Graceful startup and shutdown
Structured logging throughout
Error handling and exit codes

✅ Health Endpoint Enhancement

GET /health now includes Neo4j status
Returns 503 if Neo4j unavailable
JSON response with connection details

How to Run Locally

Step 1: Start Neo4j

docker run -d \
  --name neo4j \
  -p 7474:7474 -p 7687:7687 \
  -e NEO4J_AUTH=neo4j/local-password \
  neo4j:5.15

# Access Neo4j Browser at http://localhost:7474
# Login with neo4j/local-password

Step 2: Build and Run Service

make build
make run ENV=local

Step 3: Test Health Endpoint

curl http://localhost:8080/health | jq

Expected Output:

{
  "status": "healthy",
  "service": "consumer-graph",
  "neo4j": {
    "connected": true,
    "database": "neo4j",
    "pool_size": 50,
    "response_time_ms": 12,
    "last_check": "2025-11-07T15:30:45Z"
  }
}

Step 4: Initialize Schema (once implemented)

# Will be available after Phase 4
curl -X POST http://localhost:8080/api/v1/graph/schema/init

What’s Next: Remaining Implementation

Phase 3: Repositories & Services (Est: 4-5 hours)

Priority: HIGH - Core data access layer

Files to create:

internal/graph/repository/
├── user.go           # CreateUser, GetUser, CreatePurchase
├── product.go        # CreateProduct, GetProduct, CreateSimilarity
├── offer.go          # CreateOffer, GetOffer, CreateEligibility, CreateAppliesTo
├── recommendation.go # GetRecommendations (main query)
└── repository.go     # Common interfaces

Key Implementation:

The recommendation Cypher query from the design doc
Batch operations for bulk loading
Transaction management
Proper error handling

Phase 4: HTTP API Handlers (Est: 3-4 hours)

Priority: HIGH - Expose functionality via REST

Endpoints to implement:

✅ GET  /health
🚧 GET  /api/v1/recommendations?user_id={id}
🚧 POST /api/v1/graph/users
🚧 POST /api/v1/graph/products
🚧 POST /api/v1/graph/offers
🚧 POST /api/v1/graph/relationships/purchased
🚧 POST /api/v1/graph/relationships/similar
🚧 POST /api/v1/graph/relationships/eligible
🚧 POST /api/v1/graph/relationships/applies-to
🚧 POST /api/v1/graph/schema/init

Files to create:

internal/graph/handler/
├── recommendation.go  # GET /recommendations
├── graph.go           # POST graph operations
└── admin.go           # POST /schema/init

Phase 5: Testing (Est: 3-4 hours)

Priority: MEDIUM - Quality assurance

Tests to write:

Unit tests for repositories (with mocks)
Integration tests (with testcontainers)
Handler tests (with httptest)
End-to-end recommendation flow

Phase 6: Deployment (Est: 2-3 hours)

Priority: MEDIUM - Production readiness

Tasks:

Set up Neo4j Aura instance (or alternative)
Configure AWS Parameter Store for credentials
Update consumer-graph-mcp.yml with Neo4j vars
Deploy to dev environment
Load sample data
Performance testing

Phase 7: Documentation (Est: 1-2 hours)

Priority: LOW - Can be done incrementally

Docs to create/update:

README.md with setup instructions
API documentation (OpenAPI/Swagger)
Runbook for operations
Architecture diagrams

Estimated Timeline to Production

Phase	Description	Time	Status
1	Foundation (Neo4j client, config)	3h	✅ DONE
2	Models & Schema	2h	✅ DONE
3	Repositories & Services	4-5h	🚧 NEXT
4	HTTP API Handlers	3-4h	🚧 PENDING
5	Testing	3-4h	🚧 PENDING
6	Deployment	2-3h	🚧 PENDING
7	Documentation	1-2h	🚧 PENDING

Total Remaining: 13-18 hours Total Project: 18-23 hours (5h complete, 13-18h remaining)

Architecture Diagram

┌─────────────────────────────────────────────────┐
│         HTTP Handlers (Phase 4)                 │
│  GET  /recommendations                          │
│  POST /graph/{users,products,offers}            │
│  POST /relationships/{purchased,similar,...}    │
└──────────────────┬──────────────────────────────┘
                   │
┌──────────────────▼──────────────────────────────┐
│      Service Layer (Phase 3)                    │
│  • RecommendationService                        │
│  • GraphManagementService                       │
└──────────────────┬──────────────────────────────┘
                   │
┌──────────────────▼──────────────────────────────┐
│      Repository Layer (Phase 3)                 │
│  • UserRepository          ✅ Models            │
│  • ProductRepository       ✅ Models            │
│  • OfferRepository         ✅ Models            │
│  • RecommendationRepository ✅ Models           │
└──────────────────┬──────────────────────────────┘
                   │
┌──────────────────▼──────────────────────────────┐
│   ✅ Neo4j Client (pkg/neo4j/)                  │
│   ✅ Connection Pool                            │
│   ✅ Health Checks                              │
└──────────────────┬──────────────────────────────┘
                   │
┌──────────────────▼──────────────────────────────┐
│   Neo4j Database                                │
│   ✅ Schema (constraints & indexes defined)     │
│   🚧 Data (waiting for repositories)            │
└─────────────────────────────────────────────────┘

Key Files Reference

Configuration

Local: config/local/config.json - bolt://localhost:7687
Dev: config/dev/config.json - bolt+routing://dev-neo4j.neo4j.io:7687
Stage: config/stage/config.json - bolt+routing://stage-neo4j.neo4j.io:7687
Prod: config/prod/config.json - bolt+routing://prod-neo4j.neo4j.io:7687

Implementation Docs

IMPLEMENTATION_PLAN.md - Full technical specification
PROGRESS.md - Detailed progress tracking
STATUS.md - This file (executive summary)

Core Code

pkg/neo4j/client.go - Neo4j driver wrapper (170 lines)
pkg/neo4j/health.go - Health check logic (110 lines)
internal/models/ - All domain models (4 files, ~200 lines)
internal/graph/schema/schema.go - Schema DDL (140 lines)

Success Criteria

Phase 1-2 (COMPLETE) ✅

Phase 3 (Repositories)

Can create/read all node types
Can create all relationship types
Recommendation query executes
Query returns results in <100ms
Unit tests with mocks pass

Phase 4 (API)

All endpoints functional
Request validation works
Error responses correct
API tests pass

Production Ready

All tests pass (unit, integration, e2e)
Deployed to stage successfully
Performance meets targets (<100ms p95)
Monitoring and alerts configured
Documentation complete

Commands Cheat Sheet

# Development
make build              # Build the service
make run ENV=local      # Run locally
make test              # Run tests
make lint              # Run linters
make fmt               # Format code

# Docker Neo4j
docker run -d --name neo4j -p 7474:7474 -p 7687:7687 \
  -e NEO4J_AUTH=neo4j/local-password neo4j:5.15
docker stop neo4j && docker rm neo4j  # Clean up

# Testing
curl http://localhost:8080/health | jq
curl http://localhost:8080/api/v1/recommendations?user_id=U123 | jq

Questions & Next Steps

Decision Points

Neo4j Deployment
- ✅ Recommended: Neo4j Aura (fully managed)
- Alternative: Self-hosted on ECS
- Timeline: Decide before Phase 6
Data Loading Strategy
- Batch API endpoints (POST with arrays)
- Direct Kafka consumer
- S3 → Lambda → Neo4j
- Timeline: Decide during Phase 3
Testing Strategy
- Use testcontainers for integration tests?
- Mock vs real Neo4j for unit tests?
- Timeline: Decide before Phase 5

Immediate Next Steps

Review and approve Phase 1-2 work ← YOU ARE HERE
Implement UserRepository (start Phase 3)
Implement ProductRepository
Implement OfferRepository
Implement RecommendationRepository
Test repositories with local Neo4j
Implement HTTP handlers (start Phase 4)

Contact & Support

Implementation Plan: See IMPLEMENTATION_PLAN.md
Progress Tracking: See PROGRESS.md
Project Guidelines: See CLAUDE.md

Ready to continue? The foundation is solid. Phase 3 (repositories) is the next critical milestone.