ADR-001: CRM Module Architecture Pattern

Status

Accepted

Context

We need to integrate a comprehensive CRM system into our existing QR Contact Card Generator platform. The CRM must support viral growth mechanics, AI-powered enrichment, and social graph visualization while maintaining performance at scale.

Decision

We will implement the CRM as a modular microservice within the existing monolith, following a hybrid architecture pattern that allows for future extraction into a standalone service.

Architecture Pattern: Modular Monolith with Service Boundaries

Platform Monolith
├── Core Services (existing)
│   ├── User Management
│   ├── QR Generator
│   └── Analytics
└── CRM Module (new)
    ├── Contact Service
    ├── Enrichment Service
    ├── Social Graph Service
    └── Viral Engine

Rationale

1. Gradual Migration Path: Start within monolith, extract when needed
2. Shared Infrastructure: Reuse auth, billing, and database connections
3. Faster Development: No inter-service communication overhead initially
4. Clear Boundaries: Service interfaces defined for future extraction
5. Performance: In-process calls faster than network calls

Consequences

Positive

• Faster time to market
• Easier debugging and testing
• Shared transaction boundaries
• No network latency for CRM operations
• Simpler deployment initially

Negative

• Coupled deployments initially
• Shared resource constraints
• Potential for boundary violations
• Refactoring needed for extraction

Implementation Guidelines

1. Clear Module Boundaries: Use Rust modules with public interfaces
2. Database Separation: CRM tables in separate schema
3. Event-Driven Communication: Use internal event bus
4. Dependency Injection: Prepare for service extraction
5. API Versioning: Design APIs for external consumption

Alternatives Considered

1. Separate Microservice: Rejected due to complexity overhead
2. Embedded Library: Rejected due to limited scalability
3. Third-party CRM: Rejected due to viral mechanics requirements