ADR-001: Django + React Hybrid Architecture for License Management Platform

Status: APPROVED ✅ Date: November 24, 2025 Decision Makers: CODITECT Infrastructure Team, Hal Casteel (CTO) Related Documents: ARCHITECTURE-DECISION-DJANGO-REACT.md, project-plan.md V4.0

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Context

The CODITECT License Management Platform requires a robust, scalable, multi-tenant architecture to support:

1. Multi-tenant data isolation - Complete separation between customer organizations
2. Staff administration - Internal operations for user/tenant/license management
3. Customer self-service - Professional dashboard for end-user management
4. License API - High-performance API for CODITECT client authentication
5. OAuth2 authentication - Secure identity management via Google Cloud Identity Platform

Technology Constraint

The requirements.txt file specified Django 5.2.8 and django-multitenant 3.2.1, indicating a previous architectural decision had been made. However, all documentation referenced FastAPI, creating a mismatch.

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Decision

We will use a Django + React Hybrid Architecture with three distinct deployments:

┌─────────────────────────────────────────────────────────────┐
│                    GCP Load Balancer                         │
│           (SSL Termination + Path-Based Routing)             │
└─────────────┬──────────────┬──────────────┬─────────────────┘
              │              │              │
     ┌────────▼────────┐ ┌──▼──────────┐ ┌─▼──────────────┐
     │ Django Admin    │ │ Django REST │ │ React Frontend │
     │ (Staff Portal)  │ │ API         │ │ (Customer)     │
     │                 │ │             │ │                │
     │ admin.          │ │ api.        │ │ app.           │
     │ coditect.ai     │ │ coditect.ai │ │ coditect.ai    │
     └─────────────────┘ └─────────────┘ └────────────────┘
              │              │              │
              └──────────────┴──────────────┘
                           │
              ┌─────────────▼──────────────┐
              │ PostgreSQL 16 (Cloud SQL)  │
              │ + Redis Memorystore        │
              └────────────────────────────┘

Component Responsibilities

1. Django Admin (admin.coditect.ai)

Purpose: Internal staff operations Access: Staff-only (Django is_staff flag) Features:

• User management (create, edit, delete, permissions)
• Tenant CRUD (organizations, seat limits, pricing tiers)
• License provisioning (generate, revoke, transfer)
• Audit logs (django-simple-history)
• System configuration

Why Django Admin:

• ✅ Auto-generated from models (zero frontend code)
• ✅ Built-in security (CSRF, XSS protection, staff-only)
• ✅ Scalable (millions of records with pagination)
• ✅ Fast development (days instead of weeks)
• ✅ Modern UI available (django-admin-interface)

2. Django REST API (api.coditect.ai)

Purpose: External integrations and client authentication Access: Public (with authentication) Features:

• License acquisition endpoint (POST /api/v1/licenses/acquire)
• License heartbeat (POST /api/v1/licenses/heartbeat)
• License release (POST /api/v1/licenses/release)
• Stripe webhooks (POST /api/v1/webhooks/stripe)
• Public documentation (drf-spectacular)

Why Django REST Framework:

• ✅ Automatic serialization from models
• ✅ Built-in permissions system
• ✅ Auto-generated OpenAPI documentation
• ✅ Mature ecosystem (10+ years)

3. React Dashboard (app.coditect.ai)

Purpose: Customer self-service portal Access: Authenticated tenants/users Features:

• Tenant dashboard (usage metrics, active sessions)
• Team management (invite users, assign roles)
• Usage analytics (historical usage, forecasting)
• Billing portal (Stripe integration)
• Profile settings

Why React + TypeScript:

• ✅ Modern, professional user experience
• ✅ Type-safe development (TypeScript strict mode)
• ✅ Real-time updates (TanStack Query)
• ✅ Mobile-responsive (Tailwind CSS)
• ✅ Consistent with workflow.coditect.ai design system

---

Technology Stack

Backend: Django 5.2.8

Core Framework:

Django==5.2.8                    # Latest stable (Nov 2025)
djangorestframework==3.16.1      # REST API framework
django-multitenant==3.2.1        # Tenant isolation

Why Django 5.2.8:

• ✅ Security patches for CVE-2025-64459 (SQL injection)
• ✅ Enhanced ASGI support (async views)
• ✅ Improved multi-database support
• ✅ Better admin interface

Database & Caching:

psycopg[binary]==3.2.13          # PostgreSQL adapter
redis==5.2.0                     # Redis client
django-redis==5.4.0              # Django cache backend

Task Queue:

celery[redis]==5.4.0             # Async task queue
django-celery-beat==2.7.0        # Periodic tasks

Authentication:

authlib==1.4.0                   # OAuth2/OIDC client

Payments:

stripe==11.2.0                   # Stripe integration

Frontend: React 18 + TypeScript

Core Framework:

{
  "react": "^18.3.1",
  "typescript": "^5.3.3",
  "vite": "^5.0.0"
}

State Management & Routing:

{
  "@tanstack/react-query": "^5.18.0",
  "@tanstack/react-router": "^1.15.0",
  "zustand": "^4.5.0"
}

UI Components:

{
  "tailwindcss": "^3.4.0",
  "@radix-ui/react-*": "latest",
  "lucide-react": "^0.309.0"
}

Why This Stack:

• ✅ TypeScript strict mode catches errors at compile-time
• ✅ TanStack Query manages server state elegantly
• ✅ TanStack Router provides type-safe routing
• ✅ Shadcn/ui provides professional, accessible components
• ✅ Vite offers instant hot module replacement

Infrastructure: GCP + GKE

Deployed Infrastructure:

✅ GKE Cluster: coditect-cluster (3 nodes, us-central1)
✅ Cloud SQL: coditect-db (PostgreSQL 16, db-custom-2-8192)
✅ Redis Memorystore: (to be deployed)
✅ VPC Networking: Configured
✅ Secret Manager: Configured

Why GKE:

• ✅ Container orchestration (auto-scaling, self-healing)
• ✅ Zero-downtime deployments (rolling updates)
• ✅ Native GCP integration (Cloud SQL, Secret Manager)

---

Rationale

1. Multi-Tenant Isolation

django-multitenant 3.2.1 provides automatic tenant isolation:

# models.py
from django_multitenant.models import TenantModel

class License(TenantModel):
    tenant_id = models.CharField(max_length=255, db_index=True)
    seats_total = models.IntegerField()
    seats_used = models.IntegerField(default=0)

    class Meta:
        tenant_id = 'tenant_id'  # Automatic filtering

# views.py
from django_multitenant.utils import set_current_tenant

# Middleware sets tenant context from JWT
set_current_tenant(tenant)

# ALL queries automatically filtered by tenant_id
licenses = License.objects.all()  # Returns ONLY current tenant's licenses

Benefits:

• ✅ Zero manual filtering (eliminates bugs)
• ✅ Impossible to access other tenant's data
• ✅ Row-level security at ORM level
• ✅ Battle-tested (millions of tenants in production)

2. Django Admin for Staff Operations

Time Savings: 2-3 weeks of development avoided

Auto-Generated Features:

• User list/detail/edit/delete
• Tenant CRUD operations
• License provisioning with custom actions
• Audit log viewer (django-simple-history)

Security:

• Staff-only by default (is_staff=True required)
• CSRF protection enabled
• XSS prevention built-in
• Automatic SQL injection prevention

Modern UI:

pip install django-admin-interface

• Beautiful, responsive design
• Dark mode support
• Customizable colors and branding
• Mobile-friendly

3. React for Customer Experience

Professional UI:

• Matches workflow.coditect.ai design system
• Consistent header/footer across all CODITECT apps
• AZ1.AI branding (logo, colors, typography)
• Light/dark mode toggle

Real-Time Features:

// Automatic refetching with TanStack Query
const { data: usage } = useQuery({
  queryKey: ['usage', tenantId],
  queryFn: fetchUsage,
  refetchInterval: 30000  // Refresh every 30s
})

Type Safety:

// TypeScript prevents runtime errors
interface License {
  id: string
  seats_total: number
  seats_used: number
  expires_at: Date
}

// Compiler catches errors
const license: License = await api.getLicense(id)
console.log(license.seats_total)  // ✅ Valid
console.log(license.invalid_field)  // ❌ Compile error

4. Separation of Concerns

Django Admin vs React Dashboard:

Feature	Django Admin (Staff)	React Dashboard (Customer)
Audience	Internal staff	External customers
Access	is_staff=True	Tenant membership
Purpose	Management & ops	Self-service
UI	Functional, efficient	Beautiful, modern
Features	All models, system config	Limited to tenant data
Examples	Create tenant, configure pricing	View usage, invite team

This is the industry standard pattern:

• Stripe: Django Admin (staff) + React (customers)
• Instagram: Django Admin (moderation) + React (app)
• Spotify: Django backend + React frontend

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Alternatives Considered

Alternative 1: FastAPI + React

Pros:

• Native async/await support
• Excellent performance (Uvicorn/ASGI)
• Modern Python patterns

Cons:

• ❌ No built-in admin interface (must build from scratch = 2-3 weeks)
• ❌ Multi-tenancy requires custom implementation
• ❌ Smaller ecosystem than Django
• ❌ No battle-tested multi-tenant solution
• ❌ Mismatch with requirements.txt (Django already specified)

Decision: Rejected due to development time and lack of admin interface

Alternative 2: Django + Django Templates (No React)

Pros:

• Simpler deployment (single service)
• Django templates for both staff and customer

Cons:

• ❌ Poor customer experience (server-side rendering)
• ❌ No real-time updates without complex WebSocket setup
• ❌ Inconsistent with workflow.coditect.ai (React)
• ❌ Limited interactivity
• ❌ Mobile experience suffers

Decision: Rejected due to poor UX for customers

Alternative 3: Full React Admin (No Django Admin)

Pros:

• Consistent React codebase
• Modern admin UI

Cons:

• ❌ 2-3 weeks development time for admin
• ❌ Must build all CRUD operations manually
• ❌ Security risks (easier to make mistakes)
• ❌ Loses Django Admin's maturity

Decision: Rejected due to development time and security concerns

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Implementation Phases

Phase 0: Infrastructure ✅ COMPLETE

• GKE, Cloud SQL, Redis deployed
• Duration: Complete
• Status: 100%

Phase 1: Django Backend Foundation (4-5 days)

• Django project setup with multi-tenant models
• Django Admin configuration
• Django REST Framework API
• Celery task queue setup
• Output: admin.coditect.ai + api.coditect.ai working locally

Phase 2: React Frontend (3-4 days)

• React + TypeScript strict project with Vite
• OAuth2 authentication flow (Identity Platform)
• Tenant dashboard UI
• Team management interface
• Output: app.coditect.ai working locally

Phase 3: Identity Platform & Multi-Tenant (2-3 days)

• Cloud KMS deployment for license signing
• Identity Platform OAuth2 setup
• JWT middleware integration
• Output: End-to-end authentication working

Phase 4: License Management API (4-5 days)

• License acquire/heartbeat/release endpoints
• Redis atomic seat counting (Lua scripts)
• Cloud KMS license signing integration
• Output: CODITECT client can acquire licenses

Phase 5: Deployment & Testing (3-4 days)

• Dockerfiles for Django + React
• Deploy to GKE with ingress routing
• SSL certificates (Let's Encrypt or Google-managed)
• E2E testing + load testing
• Output: Production deployment live

Phase 6: Production Hardening (2 days)

• Monitoring (Prometheus + Grafana)
• Alerting (PagerDuty or Cloud Monitoring)
• Runbooks and documentation
• Output: Production-ready system

Total Estimated Duration: 18-23 days

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Consequences

Positive

1. Fast Development: Django Admin saves 2-3 weeks
2. Proven Multi-Tenancy: django-multitenant is battle-tested
3. Professional UX: React provides modern customer experience
4. Separation of Concerns: Staff tools vs customer tools cleanly separated
5. Security: Django's built-in security features reduce risk
6. Consistency: Matches workflow.coditect.ai design system
7. Scalability: Proven to scale to millions of users

Negative

1. Two Frameworks: Django + React requires expertise in both
2. Deployment Complexity: Three separate deployments (admin, api, app)
3. CORS Configuration: Must carefully configure cross-origin requests
4. State Synchronization: React must stay in sync with Django backend

Mitigation

1. Two Frameworks: Team has expertise in both; separation simplifies development
2. Deployment Complexity: GKE ingress handles routing elegantly
3. CORS: Django CORS middleware handles this automatically
4. State Sync: TanStack Query provides automatic cache invalidation

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Success Metrics

Technical KPIs

Metric	Target	Measurement
API Latency (p99)	< 500ms	Prometheus metrics
API Error Rate	< 1%	Application logs
Uptime	99.9%	GCP monitoring
Test Coverage (Backend)	≥ 80%	pytest --cov
Test Coverage (Frontend)	≥ 70%	vitest coverage

Business KPIs

Metric	Target	Measurement
License Acquisition Success Rate	≥ 99%	API logs
Heartbeat Reliability	≥ 99.9%	Redis monitoring
Active Sessions per Tenant	100-1000	Dashboard analytics
Staff Productivity (admin)	10+ tasks/hour	Admin usage logs

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Design System Consistency

Colors (from workflow.coditect.ai)

Primary Blue:

--primary-50: #f0f9ff;
--primary-100: #e0f2fe;
--primary-200: #bae6fd;
--primary-300: #7dd3fc;
--primary-400: #38bdf8;
--primary-500: #0ea5e9;  /* Primary brand color */
--primary-600: #0284c7;
--primary-700: #0369a1;
--primary-800: #075985;
--primary-900: #0c4a6e;

Typography

Font Stack:

font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto',
             'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans',
             'Droid Sans', 'Helvetica Neue', sans-serif;

Dark Mode

Strategy: CSS class-based (class)

// Tailwind config
darkMode: 'class'

// Toggle implementation
<html className={isDark ? 'dark' : ''}>

Standardized Header/Footer

All CODITECT applications must include:

• AZ1.AI logo (top-left)
• Consistent navigation (Home, Products, About, Contact)
• User profile dropdown (top-right)
• Footer with links (Privacy, Terms, Support, Documentation)

See ui-design-system.md for complete specifications.

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Compliance & Security

Multi-Tenant Isolation

Row-Level Security: Enforced at ORM level via django-multitenant Zero Manual Filtering: Automatic tenant_id filtering prevents data leakage Audit Logging: django-simple-history tracks all changes

Authentication & Authorization

Identity Platform: Google Cloud OAuth2/OIDC JWT Tokens: Signed with Cloud KMS (RSA-4096) Role-Based Access Control: Django permissions system

Data Protection

Encryption at Rest: Cloud SQL automatic encryption Encryption in Transit: HTTPS/TLS 1.3 only Secrets Management: Google Cloud Secret Manager

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References

• Django 5.2 Release Notes
• Django REST Framework Documentation
• django-multitenant Documentation
• React 18 Documentation
• TanStack Query Documentation
• workflow.coditect.ai Deployment Report

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Approval

Decision: APPROVED ✅ Date: November 24, 2025 Approved By: Hal Casteel, Founder/CEO/CTO Next Steps:

1. Update project-plan.md with Django + React architecture ✅
2. Update tasklist-with-checkboxes.md with implementation tasks
3. Create ui-design-system.md with detailed specifications
4. Create FRONTEND-IMPLEMENTATION-GUIDE.md
5. Begin Phase 1 implementation

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Document Version: 1.0 Last Updated: November 24, 2025 Status: APPROVED ✅ Related ADRs: None (this is ADR-001)