So what problem does this solve? Protobuf + grpc already provide types for tons of languages. As in, messages are generated to models/structs/classes what have you, depending on the language…

OpenAPI already exists and anyone can write a spec today and have code generated (servers, clients, models) today. Same principle as protobuf but the message and service description is much more verbose.

> tRPC to OpenAPI generator

So, … another level of indirection? Why would I ever pick this up when I can just use OpenAPI directly?