Implementation Progress

Implementation Progress

✅ Completed (Phase 1-2)

Phase 1: Foundation - COMPLETE

All infrastructure for Neo4j integration is in place and tested.

Components Implemented:

1. ✅ Neo4j Go Driver Integration (pkg/neo4j/)

   • client.go: Connection management with pooling
   • health.go: Health check functionality
   • Full error handling and structured logging

2. ✅ Configuration System (internal/config/)

   • Added Neo4jConfig struct with all connection parameters
   • Environment-specific configs (local, dev, stage, prod)
   • Validation for Neo4j settings

3. ✅ Service Integration

   • Neo4j client initialization in main.go
   • Graceful shutdown handling
   • Health endpoint includes Neo4j status (/health)

4. ✅ Environment Configurations

   • config/local/config.json: Local development (bolt://localhost:7687)
   • config/dev/config.json: Dev environment (bolt+routing://)
   • config/stage/config.json: Staging environment
   • config/prod/config.json: Production environment

Build Status: ✅ Compiles successfully

Phase 2: Domain Models & Schema - COMPLETE

All data models and database schema defined.

Components Implemented:

1. ✅ Domain Models (internal/models/)

   • user.go: User node, PurchaseRelationship
   • product.go: Product node, SimilarityRelationship
   • offer.go: Offer node, EligibilityRelationship, AppliesToRelationship
   • recommendation.go: RecommendationRequest, Recommendation, Response models

2. ✅ Schema Initialization (internal/graph/schema/)

   • schema.go: Constraints and indexes for all node types
   • Unique constraints on user_id, product_id, offer_id
   • Indexes on offer dates, product category, user zip, product brand

---

🚧 In Progress / Next Steps (Phase 3-7)

Phase 3: Repositories & Services

Implement data access layer and business logic.

To Implement:

• internal/graph/repository/user.go - User CRUD operations
• internal/graph/repository/product.go - Product CRUD operations
• internal/graph/repository/offer.go - Offer CRUD operations
• internal/graph/repository/recommendation.go - Recommendation query implementation
• internal/graph/service/recommendation.go - Business logic layer
• internal/graph/service/graph_mgmt.go - Graph management operations

Key Features:

• Batch operations for bulk data loading
• Efficient Cypher queries with parameterization
• Transaction management
• Error handling and retry logic

Phase 4: HTTP API

Expose graph operations via REST API.

Endpoints to Implement:

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
GET  /api/v1/graph/health (already implemented)
POST /api/v1/graph/schema/init

Files to Create:

• internal/graph/handler/recommendation.go
• internal/graph/handler/graph.go
• internal/graph/handler/admin.go

Phase 5: Testing

Comprehensive test coverage.

Test Files to Create:

• pkg/neo4j/client_test.go - Unit tests for Neo4j client
• pkg/neo4j/health_test.go - Health check tests
• internal/graph/repository/*_test.go - Repository tests with mocks
• internal/graph/service/*_test.go - Service layer tests
• internal/graph/handler/*_test.go - HTTP handler tests

Integration Tests:

• Use testcontainers for Neo4j
• Load fixture data
• Test full recommendation flow
• Test concurrent access patterns

Phase 6: Observability

Enhanced metrics and monitoring.

Metrics to Add (pkg/metrics/):

func RecordGraphQueryDuration(ctx, queryType, durationMs)
func RecordGraphQueryError(ctx, queryType, err)
func RecordGraphConnectionPoolSize(ctx, size)
func RecordGraphNodeCount(ctx, label, count)

Phase 7: Deployment & Documentation

Production readiness.

To Complete:

• Update consumer-graph-mcp.yml with Neo4j environment variables
• Configure AWS Parameter Store for credentials
• Update README.md with setup instructions
• Create runbook for operations
• Performance testing and optimization

---

Quick Start (Current State)

Running Locally

1. Start Neo4j locally:

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

2. Build and run the service:

   make build
   make run ENV=local

3. Check health:

   curl http://localhost:8080/health

   Expected response (when Neo4j is running):

   {
     "status": "healthy",
     "service": "consumer-graph",
     "neo4j": {
       "connected": true,
       "database": "neo4j",
       "pool_size": 50,
       "response_time_ms": 15,
       "last_check": "2025-11-07T12:00:00Z"
     }
   }

Initialize Schema

Once the service is running, you can initialize the database schema:

# This endpoint will be implemented in Phase 4
curl -X POST http://localhost:8080/api/v1/graph/schema/init

---

File Structure

consumer-graph/
├── cmd/
│   └── service/
│       └── main.go                     ✅ Updated with Neo4j client
├── internal/
│   ├── config/
│   │   ├── config.go                  ✅ Added Neo4jConfig
│   │   └── envloader.go
│   ├── graph/
│   │   ├── handler/                   🚧 To implement
│   │   ├── repository/                🚧 To implement
│   │   ├── schema/
│   │   │   └── schema.go              ✅ Complete
│   │   └── service/                   🚧 To implement
│   ├── models/
│   │   ├── user.go                    ✅ Complete
│   │   ├── product.go                 ✅ Complete
│   │   ├── offer.go                   ✅ Complete
│   │   └── recommendation.go          ✅ Complete
│   └── server/
│       └── server.go                  ✅ Updated with Neo4j health
├── pkg/
│   ├── logging/                       ✅ Existing
│   ├── metrics/                       ✅ Existing
│   └── neo4j/
│       ├── client.go                  ✅ Complete
│       └── health.go                  ✅ Complete
├── config/
│   ├── local/config.json              ✅ Updated
│   ├── dev/config.json                ✅ Updated
│   ├── stage/config.json              ✅ Updated
│   └── prod/config.json               ✅ Updated
├── go.mod                             ✅ Updated with neo4j driver
├── Makefile                           ✅ Existing
├── CLAUDE.md                          ✅ Project guidelines
├── IMPLEMENTATION_PLAN.md             ✅ Detailed plan
└── PROGRESS.md                        ✅ This file

---

Next Immediate Actions

1. Implement Core Repositories (2-3 hours)

   • Start with UserRepository (CRUD + Purchases)
   • ProductRepository (CRUD + Similarity)
   • OfferRepository (CRUD + Eligibility + AppliesTo)

2. Implement Recommendation Repository (2 hours)

   • Core recommendation query from schema
   • Query optimization and testing

3. Implement HTTP Handlers (2-3 hours)

   • Recommendation endpoint
   • Graph management endpoints
   • Request validation

4. Testing (2-3 hours)

   • Unit tests for repositories
   • Integration tests with testcontainers
   • Handler tests

5. Deployment Configuration (1-2 hours)

   • FSD config updates
   • AWS Parameter Store setup
   • Documentation

Estimated Total Time to Production: 10-15 hours

---

Key Design Decisions

1. Connection Pooling

• Max pool size varies by environment (50 local, 150 prod)
• 5s connection timeout
• 1h max connection lifetime
• Automatic retry on transient failures

2. Encryption

• Controlled via URI scheme (bolt+routing:// for encrypted)
• Local development uses unencrypted bolt://
• All non-local environments use encrypted connections

3. Schema Management

• Constraints ensure data integrity
• Indexes optimize common query patterns
• Schema initialization is idempotent (IF NOT EXISTS)

4. Temporal Semantics

• as_of parameter for time-travel queries
• Eligibility edges only store start date
• Hydrator removes stale edges based on offer.end

5. Recommendation Algorithm

• Lookback 120 days for purchase history
• Exclude products purchased in last 14 days
• Cap at 80 candidates per seed product (bounded fan-out)
• Rank by similarity score × log(points)
• Return top 20 recommendations

---

Dependencies

Added

• github.com/neo4j/neo4j-go-driver/v5 v5.15.0

For Testing (to add)

• github.com/testcontainers/testcontainers-go
• github.com/testcontainers/testcontainers-go/modules/neo4j

---

References

• Neo4j Go Driver Docs
• Implementation Plan
• Neo4j Schema Design
• Project Guidelines