# Backend API

> Design and implement reliable local or network APIs with validation, streaming, cancellation, observability, and stable contracts.

- Skill: `nafeeur/backend-api` (Agent Skill)
- Install (CLI): `npx skillmds@latest add nafeeur/backend-api`
- Raw SKILL.md: https://api.skillmd.com/api/skills/nafeeur/backend-api/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: nafeeur (https://skillmd.com/u/nafeeur)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/nafeeur/backend-api

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# Backend API

- Define request, response, error, and streaming event contracts before implementation.
- Validate at the boundary and return actionable status codes without leaking secrets.
- Propagate cancellation and deadlines through subprocess, model, database, and network calls.
- Make retries explicit and idempotent where possible.
- Emit structured logs and correlation identifiers for sessions, runs, and tool calls.
- Add contract tests for success, malformed input, missing resources, conflict, timeout, and cancellation.