name: backend-design description: Design robust backend systems and APIs. Use when users ask to plan or implement services, data models, or integrations. allowed-tools:

• Read
• Grep
• Glob
• Bash

Backend Design Skill

This skill guides the design of reliable backend systems, APIs, and data models with clear trade-offs, strong correctness guarantees, and operational readiness.

Design Thinking

• Scope: Identify core use cases, data flows, and integration points.
• Constraints: Latency, throughput, availability, compliance, and deployment limits.
• Data: Define entities, relationships, invariants, and lifecycle.
• Reliability: Error handling, retries, idempotency, and consistency model.

Architecture Guidelines

• API Design: Explicit contracts, versioning, validation, and error shape.
• Storage: Choose stores based on access patterns and durability needs.
• Performance: Indexing, caching, batching, and async processing.
• Security: AuthN/AuthZ, least privilege, secrets handling, auditability.
• Observability: Logging, metrics, tracing, and alerting signals.
• Scalability: Stateless services where possible, clear scaling boundaries.

Output Requirements

Provide a clear backend plan or implementation that includes:

• Data model and key invariants
• API endpoints or service interfaces
• Failure modes and recovery strategy
• Performance and scaling considerations
• Security and observability notes

Response Checklist

Backend Design Checklist

- [ ] Confirm requirements and constraints
- [ ] Define data model and invariants
- [ ] Specify API contracts and error shape
- [ ] Address failure modes and consistency
- [ ] Cover performance, scaling, and caching
- [ ] Include security and observability plans