Let there be docs! Generating an OpenAPI schema across the Rails stack

In API development, documentation is often treated as an afterthought—something tackled once the code’s written and tested. But there’s a growing movement advocating for a documentation-first approach, where API specifications are crafted before a single line of code. Let there be docs! A documentation-first approach to Rails API development The other post in this series presented compelling arguments for this, but I’d like to share our experience with the opposing approach: using existing implementation to generate documentation while maintaining the benefits of schema validation—and making sure that it reflects the reality of your implementation.