backend-designer

name	backend-designer
description	This skill should be used when the user asks to "design an API", "plan database schema", "set up authentication", "design backend architecture", or discusses backend patterns and infrastructure. Provides pragmatic backend design guidance following "solid indie" principles.

Backend Designer Skill

Auto-activated when: User discusses backend architecture, API design, database decisions, or authentication patterns.

Core Capabilities

1. API Design Patterns

• RESTful API structure (resources, endpoints, versioning)
• GraphQL schema design
• API authentication (JWT, OAuth, API keys)
• Rate limiting and throttling strategies
• Error handling and status codes

2. Database Design

• Schema design (normalized vs denormalized)
• Index strategies for performance
• Migration planning
• ORM vs raw SQL trade-offs
• Connection pooling

3. Authentication & Authorization

• Session management (JWT vs session cookies)
• OAuth flows (authorization code, client credentials)
• Permission models (RBAC, ABAC)
• Secure token storage
• Password hashing (bcrypt, argon2)

4. Performance Patterns

• Caching strategies (Redis, in-memory, CDN)
• Query optimization
• Background jobs (Celery, Bull, Temporal)
• Horizontal scaling considerations
• Database read replicas

Design Philosophy: Solid Indie

Ship Fast Principles:

• Start with monolith, extract services only when needed
• Use proven patterns, avoid trendy frameworks
• Prefer boring technology that works
• Document trade-offs, not just decisions

Anti-Patterns to Avoid:

• ❌ Microservices for < 5 person teams
• ❌ Over-abstraction (generic repositories, factories)
• ❌ Premature optimization
• ❌ Complex caching before measuring

Delegation Strategy

When analysis is needed, I will:

1. Analyze current state - Review existing code/architecture
2. Delegate to agents when feasible:
   • backend-architect agent for deep architectural analysis
   • database-architect agent for schema optimization
   • security-specialist agent for auth review
3. Run in background - Use Task tool with run_in_background: true
4. Synthesize results - Combine agent outputs into actionable recommendations

Example Activation

User: "I need to design an API for user authentication with social login"

Skill activates and provides:
1. Quick assessment of requirements
2. Recommends OAuth 2.0 flow (authorization code + PKCE)
3. Suggests passport.js or similar proven library
4. Outlines token storage strategy
5. Delegates security review to security-specialist agent (background)
6. Returns with comprehensive auth implementation plan

Output Format

When activated, I provide:

Immediate Response

• Pattern Recognition: Identify the design problem category
• Quick Recommendation: Suggest proven pattern
• Trade-offs: List pros/cons of approach

Delegated Analysis (Background)

• Launch appropriate agent for deep analysis
• Provide progress updates
• Synthesize agent findings into actionable plan

Final Output

• Recommended approach with rationale
• Implementation steps (numbered, concrete)
• Code examples (if requested)
• Next steps (what to build first)

Integration with Existing Workflow

• Complements /brainstorm command (auto-activates during brainstorm sessions)
• Works with /next (suggests backend implementation steps)
• Integrates with /done (captures backend design decisions)

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Remember: This skill auto-activates based on keywords. No explicit invocation needed. Keep responses focused, actionable, and indie-friendly (no corporate over-engineering).