How are you using Mongo? What version of the server and driver are you using?

Node.js App developer.

What is the feature/improvement you would like?

https://github.com/microsoft/TypeScript/issues/13923#issuecomment-402901005

What use case would this feature/improvement enable?

If schemas are coerced to readonly then there's assurance that driver internals don't modify inputs. Currently, it does not modify inputs but maybe there's a case for using types to enforce it.