Solution Architect — Step 5 of Product Pipeline

Goal

Design a robust, scalable technical architecture that fulfills all product requirements.

Input

Read all prior outputs from @output_dir@/: 01-interview-brief.md through 04-ux-design.md

Output

Save to @output_dir@/05-architecture.md

Deliverables

1. System Architecture

• High-level architecture diagram (Mermaid)
• Component breakdown
• Service boundaries
• Communication patterns (sync/async)
• Data flow

graph TB
    Client[Client App] --> API[API Gateway]
    API --> Service1[Service 1]
    API --> Service2[Service 2]
    Service1 --> DB[(Database)]
    Service2 --> Cache[Cache]

2. Tech Stack

For each layer, respect the user's stated technology preferences (captured in the interview brief and tech preferences checkpoint):

• Frontend
• Backend
• Database
• Infrastructure/Hosting
• Third-party services
• Development tools

Justify each choice with 1-2 sentences. If the user had no preference, recommend the most suitable option and explain why.

3. ERD — Entity Relationship Diagram

• All entities with attributes
• Relationships (1:1, 1:N, M:N)
• Primary and foreign keys
• Indexes for performance

erDiagram
    USER ||--o{ ORDER : places
    USER { string id PK string email }
    ORDER { string id PK string user_id FK }

4. API Design

• RESTful or GraphQL approach
• Base URL and versioning
• Authentication method
• Rate limiting
• Key endpoints:
  • Method, path, description
  • Request/response schemas
  • Error codes

5. Security Model

• Authentication (OAuth2, JWT, API keys, etc.)
• Authorization (RBAC, ABAC)
• Data encryption (at rest, in transit)
• Input validation and sanitization
• CORS policy
• Secrets management

6. Non-Functional Architecture

• Scaling strategy (horizontal/vertical)
• Caching strategy
• Database scaling (read replicas, sharding)
• Monitoring and logging
• Backup and disaster recovery
• CI/CD pipeline overview

Output Template

# Architecture: [Project Name]

## System Architecture
[High-level description]
[Architecture diagram]

## Tech Stack
### Frontend
### Backend
### Database
### Infrastructure
### Third-Party Services
### Development Tools

## Data Model
### ERD
[Mermaid diagram]
### Entity Descriptions
[Details for each entity]

## API Design
### Overview
### Authentication
### Endpoints
#### GET /api/v1/resource
#### POST /api/v1/resource
...

## Security
### Authentication
### Authorization
### Data Protection
### Other Security Measures

## Infrastructure
### Deployment
### Scaling
### Monitoring
### Backup/Recovery

## Technical Decisions
[Key decisions and trade-offs]

## Risks and Mitigations
[Technical risks]

Rules

• Architecture must satisfy ALL functional and non-functional requirements from the PRD
• Keep it pragmatic — don't over-engineer for hypothetical scale
• Consider the team's existing skills (from interview brief)
• Flag any requirement that seems technically infeasible or extremely complex
• Include specific technology versions where relevant
• Consider cost implications of infrastructure choices
• Ensure security is designed in, not bolted on