Legend
| Symbol | Meaning | | Abbrev | Meaning |
|---|
| → | leads to | | API | application programming interface |
| & | and/with | | DDD | domain-driven design |
| w/ | with | | PRD | product requirements document |
Execute immediately. Add --plan flag if user wants to see plan first.
Design & architect software solutions based on requirements in $ARGUMENTS.
Thinking flags (optional):
- --think→standard design patterns & component architecture
- --think-hard→system-wide architecture & scalability planning
- --ultrathink→complete system redesign or critical architectural decisions
Examples:
/user:design --api --think - REST API design w/ patterns/user:design --ddd --think-hard - Deep domain modeling/user:design --api --ddd --ultrathink - Complete system architecture
Design focus w/ flags:
--api flag:
- Design REST or GraphQL APIs
- w/ --openapi: Generate OpenAPI 3.0 spec | w/ --graphql: Create GraphQL schema & resolvers
- Include auth, rate limiting & error handling | Design→scalability & maintainability
--ddd flag:
- Apply DDD principles | w/ --bounded-context: Define context boundaries & mappings
- Design entities, value objects & aggregates | Create domain services & events | Impl repository patterns
--prd flag:
- Create PRD | w/ --template: Use template (feature/api/integration/migration)
- Include user stories w/ acceptance criteria | Define success metrics & timelines | Document tech requirements
API Design Mode (--api)
REST API principles:
- Resource-oriented URLs w/ proper HTTP verbs | Consistent status codes & error formats
- Versioning strategy (URL/header/accept) | Pagination, filtering & sorting | HATEOAS→discoverability | OpenAPI docs
GraphQL principles:
- Clear type system w/ schemas | Efficient queries & mutations | Real-time subscriptions where needed
- DataLoader patterns→N+1 prevention | Field-level auth | Error handling practices
Common API elements:
- Auth (JWT/OAuth/API keys) | Rate limiting & throttling | Request/response validation
- Caching strategies | CORS & security headers | Monitoring & logging
DDD Mode (--ddd)
Building blocks:
- Entities: Objects w/ unique identity | Value Objects: Immutable objects by attributes
- Aggregates: Consistency boundaries w/ roots | Domain Services: Business logic not in entities
- Repositories: Abstract data access | Domain Events: Capture business events
Strategic patterns:
- Bounded contexts w/ clear boundaries | Context mapping (shared kernel, anti-corruption layer)
- Ubiquitous language within contexts | Event-driven architecture | CQRS where appropriate
Structure:
domain/ # Core business logic
application/ # Use cases & orchestration
infrastructure/ # External concerns
presentation/ # UI/API layer
PRD Mode (--prd)
Structure:
- Executive Overview: Problem statement & solution | Expected impact & ROI | Key stakeholders
- Goals & Success Metrics: Primary objectives (must-have) | Secondary goals (nice-to-have) | KPIs & measurement
- User Stories & Requirements: User personas & journeys | Functional requirements | Non-functional requirements | Acceptance criteria
- Technical Specs: Architecture overview | Tech choices | Integration points | Security requirements | Perf targets
- Timeline & Risks: Dev phases | Dependencies & blockers | Risk mitigation strategies
Integration
Combined modes:
- API+DDD: Design domain-driven APIs | API+PRD: Create API product requirements
- DDD+PRD: Document domain-driven architecture | All three: Complete system design
Best practices:
- Start w/ user needs & business goals | Design→change & evolution | Consider non-functional early
- Document decisions & rationale | Include examples & diagrams | Plan→testing & monitoring
Research requirements:
- Architecture patterns→C7 & industry practices | API standards→reference OpenAPI/REST/GraphQL specs
- DDD patterns→verify w/ Evans' book or official DDD | Tech choices→WebSearch recent comparisons & case studies
- Never design on assumptions - verify patterns | All decisions cite authoritative sources
Deliverables:
- API: Complete spec, impl guide, docs | DDD: Domain model, bounded contexts, architecture diagrams, code structure
- PRD: Requirements doc, user stories, success metrics, timeline