Zod has been a great boon to a project I've been working on. I get data from multiple sources where strong types cannot be generated and checking the schema of the response has caught a great number of errors early.
Another feature that I use intensively is transforming the response to parse JSON into more complex data types, e.g. dates but also project-specific types. In some situations, I also need to serialize these data types back into JSON. This is where Zod lacks most for my use-case. I cannot easily specify bidirectional transforms, instead I need to define two schemas (one for parsing, one for serializing) and only change the transforms. I have added type assertions that should catch any mistakes in this manual process, but it'd be great if I didn't have to keep these two schemas in sync.
Another comment mentioned @effect/schema [0], which apparently supports these encode/decode relationships. I'm excited to try it out.