handling-api-errors_skill

Overview

This skill implements standardized API error handling with clear HTTP status codes and consistent JSON error responses. It provides patterns, middleware hooks, and response schemas so services return predictable errors for clients and automated tests. The goal is safer, debuggable APIs and easier integration across services.

How this skill works

The skill inspects API specs and route handlers, then adds centralized error middleware and typed error classes. It enforces status codes, error codes, user-friendly messages, and optional debug details based on environment. It can scaffold handlers, validation layers, and OpenAPI error responses to keep documentation and runtime behavior aligned.

When to use it

• Adding error handling to new APIs
• Standardizing responses across microservices
• Improving client-side error parsing and retries
• Ensuring compliance with API contracts and OpenAPI specs
• Adding observability and structured error logs

Best practices

• Use a small set of canonical error types (e.g., ValidationError, NotFoundError, AuthError, ServerError) with numeric codes and stable strings
• Return proper HTTP status codes (4xx for client errors, 5xx for server errors) and avoid leaking internal details in production
• Include an error id or request id in responses for tracing and correlate with logs
• Keep error schema consistent: {code, message, details?, request_id?} and document it in OpenAPI
• Validate input early and translate validation failures into structured errors rather than stack traces
• Write integration tests that assert status codes and error payload shapes

Example use cases

• Add middleware that converts exceptions into JSON responses and maps exceptions to status codes
• Standardize validation failures across endpoints with a common ValidationError response shape
• Implement an error id header and include it in logs to speed debugging across services
• Update OpenAPI docs to include standardized error responses for every endpoint
• Create a CLI scaffold command to add error handling boilerplate to new endpoints