Dev-Backend — Production-Grade Backend Engineering

Ownership boundary: This skill owns API design, app architecture, database optimization, error handling, middleware, queues, long-lived connections, and app-level observability/health hooks. Deployment strategy, rollback proof, rollout shape, SLOs, alert routing, incident response, and operational readiness gates are owned by dev-devops. Backend exposes the app-level hooks that DevOps operational gates consume.

Build reliable, secure, and maintainable server-side applications. This skill is a routing role that activates by change-surface: whenever the work primarily touches APIs, servers, services, jobs, data access, schemas, migrations, or operational backend behavior, use this skill and then read the relevant references.

Before backend work, read dev for classification, fast paths, rule authority, family invariants, verification, and safety; current/public evidence follows its Conditional Routes.

Modular References

Condition	Reference
C2 ordinary CRUD/resource slice	CRUD API alone suffices
New/changed API style or C3+ API work	API design
Versioning, deprecation, or API migration	API lifecycle
Stack detection, ambiguous technology, or architecture/protocol selection	Setup; C3+: Architecture
New endpoints, classes, or modules	Anti-slop
SSE/WebSocket, runtime timeouts/drain/request IDs, or async queues	Connections and queues
Layer placement, error mapping/Result, middleware order, or response contracts	Request contracts
Caching, observability, template evaluation, performance, SEO, handoff, or delivery checklist	Production delivery
Production/long-lived services	Observability, health checks
CPU-bound/untrusted work	Process isolation
Cache optimization	Caching patterns
Node/TypeScript, Python, or database work	Node, Python, database, respectively
ML deployment, RAG/LLM integration, or mobile APIs	ML serving, LLM integration, mobile API, respectively
Auth/input/security policy	cxc-dev-security
Deployment, analytics, frontend contracts, testing, RCA, or scaffolding	Handoff owners

Read api-design.md + anti-slop-backend.md first, then the relevant stack file. For C2 ordinary slices, crud-api.md alone suffices; read api-design.md/architecture.md for new API styles or C3+ work.

3. Error Handling

For error mapping and the conditional Result pattern, read Error handling.