Hello, I think we should make all the Pydantic models that are used towards FastAPI response models frozen. I ask for this feature primarily because I would like the static typechecker to stop me from mutating response models, and to make the response models hashable.

I actually would benefit quite heavily from the hashability as I put some model instances into set HashSet.

An alternative solution is for me to make my own class implementations frozen=True, this is currently impossible without pyright complaining (which is fine).