---
title: "Architecture Overview"
description: "High-level overview of TraceRTM system architecture, design principles, and technology stack"
---

# Architecture Overview

TraceRTM is built on a modern, scalable architecture designed for requirements traceability at scale. This document provides a comprehensive overview of the system's design principles, components, and technology choices.

## Design Philosophy

TraceRTM follows several core architectural principles:

### Agent-Native Design

TraceRTM is designed from the ground up for AI-agent interaction:

- **Structured APIs** - All operations exposed through well-typed REST APIs
- **Deterministic responses** - Consistent, predictable response formats
- **Batch operations** - Efficient bulk processing for agent workflows
- **Event-driven updates** - Real-time notifications for state changes

### Graph-First Data Model

Requirements traceability is fundamentally a graph problem:

- **Items as nodes** - Requirements, test cases, and artifacts are vertices
- **Links as edges** - Relationships form directed edges between items
- **Traversal queries** - Impact analysis and coverage via graph algorithms
- **Hybrid storage** - PostgreSQL for ACID + Neo4j for graph queries

### Multi-Tenancy

Enterprise-ready isolation and customization:

- **Organization-level isolation** - Complete data separation between orgs
- **Project-scoped access** - Fine-grained permissions per project
- **Customizable workflows** - Per-project item types and statuses
- **Audit compliance** - Full audit trail for regulated industries

---

## System Architecture

```
┌─────────────────────────────────────────────────────────────────────┐
│                         Client Layer                                │
├─────────────────────────────────────────────────────────────────────┤
│  Web App (React)  │  CLI (Python)  │  SDKs  │  AI Agents           │
└────────┬──────────┴────────┬───────┴───┬────┴────────┬─────────────┘
         │                   │           │             │
         ▼                   ▼           ▼             ▼
┌─────────────────────────────────────────────────────────────────────┐
│                          API Gateway                                │
│                     (Auth, Rate Limiting, Routing)                  │
└────────────────────────────┬────────────────────────────────────────┘
                             │
         ┌───────────────────┼───────────────────┐
         ▼                   ▼                   ▼
┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
│   REST API      │ │   WebSocket     │ │   GraphQL       │
│   (FastAPI)     │ │   (Real-time)   │ │   (Optional)    │
└────────┬────────┘ └────────┬────────┘ └────────┬────────┘
         │                   │                   │
         └───────────────────┼───────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────────────────┐
│                       Service Layer                                 │
├─────────────────────────────────────────────────────────────────────┤
│ Project │ Item │ Link │ Workflow │ Search │ Report │ Sync │ AI     │
│ Service │ Svc  │ Svc  │ Service  │ Service│ Service│ Svc  │ Service│
└────────────────────────────┬────────────────────────────────────────┘
                             │
         ┌───────────────────┼───────────────────┐
         ▼                   ▼                   ▼
┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
│   Repository    │ │   Cache Layer   │ │   Event Bus     │
│   Layer         │ │   (Redis)       │ │   (Redis PubSub)│
└────────┬────────┘ └────────┬────────┘ └────────┬────────┘
         │                   │                   │
         └───────────────────┼───────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────────────────┐
│                       Data Layer                                    │
├─────────────────────────────────────────────────────────────────────┤
│  PostgreSQL     │  Neo4j          │  Meilisearch   │  Object Store  │
│  (Primary)      │  (Graph)        │  (Full-text)   │  (Attachments) │
└─────────────────┴─────────────────┴────────────────┴────────────────┘
```

---

## Technology Stack

### Backend

| Component | Technology | Purpose |
|-----------|------------|---------|
| **API Framework** | FastAPI (Python 3.11+) | High-performance async REST API |
| **ORM** | SQLAlchemy 2.0 | Database abstraction, migrations |
| **Validation** | Pydantic v2 | Request/response validation |
| **Authentication** | WorkOS | SSO, SAML, SCIM provisioning |
| **Task Queue** | Celery + Redis | Background job processing |

### Frontend

| Component | Technology | Purpose |
|-----------|------------|---------|
| **Framework** | React 18 + TypeScript | UI components and state |
| **Routing** | TanStack Router | Type-safe routing |
| **State** | TanStack Query | Server state management |
| **UI Library** | shadcn/ui + Tailwind | Component library |
| **Visualization** | D3.js, React Flow | Graph visualization |

### Data Storage

| Component | Technology | Purpose |
|-----------|------------|---------|
| **Primary DB** | PostgreSQL 16 | Transactional data, ACID compliance |
| **Graph DB** | Neo4j 5.x | Link traversal, impact analysis |
| **Search** | Meilisearch | Full-text search, fuzzy matching |
| **Cache** | Redis 7 | Session cache, rate limiting |
| **Object Store** | S3/MinIO | File attachments, exports |

### Infrastructure

| Component | Technology | Purpose |
|-----------|------------|---------|
| **Container** | Docker | Application packaging |
| **Orchestration** | Kubernetes | Production deployment |
| **CI/CD** | GitHub Actions | Automated testing, deployment |
| **Monitoring** | Prometheus + Grafana | Metrics and alerting |
| **Logging** | ELK Stack | Centralized logging |

---

## Core Components

### API Server

The API server is the primary entry point for all client interactions:

```python
# Simplified API structure
from fastapi import FastAPI, Depends
from tracertm.api.routers import projects, items, links, reports

app = FastAPI(
    title="TraceRTM API",
    version="1.0.0",
    docs_url="/docs",
)

# Mount routers
app.include_router(projects.router, prefix="/v1/projects", tags=["projects"])
app.include_router(items.router, prefix="/v1/items", tags=["items"])
app.include_router(links.router, prefix="/v1/links", tags=["links"])
app.include_router(reports.router, prefix="/v1/reports", tags=["reports"])
```

Key features:
- Async request handling with uvicorn/gunicorn
- OpenAPI spec generation for SDK generation
- Middleware chain for auth, logging, rate limiting
- Health check endpoints for load balancers

### Service Layer

Business logic is encapsulated in service classes:

```python
class ItemService:
    """Service for item operations."""

    def __init__(
        self,
        item_repo: ItemRepository,
        link_repo: LinkRepository,
        search_service: SearchService,
        event_bus: EventBus,
    ):
        self.item_repo = item_repo
        self.link_repo = link_repo
        self.search_service = search_service
        self.event_bus = event_bus

    async def create_item(
        self,
        project_id: str,
        data: CreateItemInput,
        user_id: str,
    ) -> Item:
        """Create a new item with validation and indexing."""
        # Validate project access
        # Create item in database
        # Index in search engine
        # Emit creation event
        # Return created item
```

### Repository Layer

Data access is abstracted through repositories:

```python
class ItemRepository:
    """Repository for item data access."""

    def __init__(self, session: AsyncSession):
        self.session = session

    async def get_by_id(self, item_id: str) -> Item | None:
        """Get item by ID."""
        stmt = select(ItemModel).where(ItemModel.id == item_id)
        result = await self.session.execute(stmt)
        return result.scalar_one_or_none()

    async def list_by_project(
        self,
        project_id: str,
        filters: ItemFilters,
        pagination: Pagination,
    ) -> PaginatedResult[Item]:
        """List items with filtering and pagination."""
```

---

## Data Flow

### Request Processing

1. **API Gateway** receives request, validates JWT
2. **Middleware** checks rate limits, logs request
3. **Router** dispatches to appropriate handler
4. **Handler** validates input via Pydantic
5. **Service** executes business logic
6. **Repository** performs database operations
7. **Response** serialized and returned

### Event-Driven Updates

When state changes occur:

1. **Service** performs operation
2. **Service** publishes event to Redis PubSub
3. **WebSocket** server receives event
4. **WebSocket** broadcasts to subscribed clients
5. **Background workers** process async tasks

```python
# Event publishing example
class EventBus:
    async def publish(self, event: Event):
        await self.redis.publish(
            f"events:{event.project_id}",
            event.model_dump_json()
        )
```

---

## Scalability Design

### Horizontal Scaling

- **Stateless API servers** - Scale by adding instances
- **Shared Redis** - Session and cache coordination
- **Database pooling** - PgBouncer for connection management
- **Read replicas** - Scale read operations independently

### Performance Optimization

- **Async I/O** - Non-blocking database and HTTP operations
- **Connection pooling** - Reuse database connections
- **Caching strategy** - Redis for frequently accessed data
- **Bulk operations** - Batch inserts/updates for efficiency

### High Availability

- **Multi-AZ deployment** - Database and services across zones
- **Load balancing** - Distribute traffic across instances
- **Circuit breakers** - Graceful degradation on failures
- **Health checks** - Automatic instance replacement

---

## Security Architecture

### Authentication

- **API Keys** - For service-to-service and CLI authentication
- **OAuth 2.0** - For user authentication via WorkOS
- **SSO/SAML** - Enterprise identity provider integration
- **JWT tokens** - Short-lived access tokens with refresh

### Authorization

```python
# Permission check example
class PermissionChecker:
    async def check_project_access(
        self,
        user_id: str,
        project_id: str,
        required_permission: Permission,
    ) -> bool:
        membership = await self.get_membership(user_id, project_id)
        if not membership:
            return False
        return membership.role.has_permission(required_permission)
```

### Data Security

- **Encryption at rest** - Database and object storage encryption
- **Encryption in transit** - TLS 1.3 for all connections
- **Field-level encryption** - Sensitive custom fields
- **Audit logging** - All mutations logged for compliance

---

## Integration Points

### External Systems

| Integration | Protocol | Purpose |
|-------------|----------|---------|
| **Jira** | REST API | Issue synchronization |
| **GitHub** | Webhooks | Code reference linking |
| **GitLab** | Webhooks | Code reference linking |
| **Jenkins** | REST API | Test result import |
| **Slack** | Webhooks | Notifications |
| **Teams** | Webhooks | Notifications |

### AI/Agent Integration

```python
# Agent-optimized endpoints
@router.post("/items/bulk")
async def bulk_create_items(
    items: list[CreateItemInput],
    service: ItemService = Depends(get_item_service),
) -> list[Item]:
    """
    Create multiple items in a single transaction.
    Optimized for AI agent bulk operations.
    """
    return await service.bulk_create(items)
```

---

## Deployment Models

### Self-Hosted

For organizations requiring on-premises deployment:

- Docker Compose for development/small teams
- Kubernetes Helm charts for production
- Support for air-gapped environments

### Cloud-Hosted

Managed TraceRTM instances:

- Multi-tenant SaaS offering
- Single-tenant dedicated instances
- Region-specific deployments for data residency

---

## Related Documentation

- [Frontend Architecture](/docs/development/architecture/frontend) - React application design
- [Backend Architecture](/docs/development/architecture/backend) - API server design
- [Database Schema](/docs/development/architecture/database) - Data model design
- [Infrastructure](/docs/development/architecture/infrastructure) - Deployment architecture
