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Why no type checking? Generate an Open API client for target languages. Done. Assuming you need an API. I'll never build an app that way again, it's not worth my hands. I'd rather use Hotwire, or LiveViews, or Django's Unicorn for the web part. Zod looks nice too.
The problem isn't so much with checking as it is with what kinds of things you can check. OpenAPI offers a very powerless type system. So bad, it's almost not worth using. Not only that, it's designed for JSON, which is an awfully bad format -- so, even if you could check that somehow, you'd still be very limited by what you can actually send. Also, yeah, all kind of hot garbage you listed will work on Web, because t…