Koa 2 Middleware for Swagger 2.0 Validation

swagger2-koa is a Koa 2 middleware package designed for loading, parsing, and validating incoming HTTP requests and outgoing responses against a Swagger 2.0 document. As of version 5.1.0, it targets Node.js version 22 or higher and is an ESM-only package. The library offers two primary modes of operation: a comprehensive `router` utility that sets up a full Koa server with pre-configured middleware (including `@koa/cors`, `@koa/router`, and `koa-bodyparser`), or a standalone `validate` middleware for integration into existing Koa applications. It strictly enforces schema validation, returning HTTP 400 for invalid requests and HTTP 500 for invalid responses, providing detailed validation errors. The release cadence is driven by dependency updates and major refactors, such as the recent transition to ESM. Its key differentiator lies in its specific focus on Koa 2 and Swagger 2.0, providing robust API contract enforcement.