Yes, both are writing code. But nearly all the time, the constraints you want to express can be expressed with zod, and in that case using zod means you write less code, and the code you do write is more correct.

> Of course, you hope zod is robust, tested, supported, extensible, and has docs so you can understand how to express your domain in terms it can help you with. And you hope you don’t have to spend too much time migrating as zod’s api changes.

Yes, judgement is required to make depending on zod (or any library) worthwhile. This is not different in principle from trusting those same things hold for TypeScript, or Node, or V8, or the C++ compiler V8 was compiled with, or the x86_64 chip it's running on, or the laws of physics.

Sure... the laws of physics last broke backwards compatibility at the Big Bang, Zod last broke backwards compatibility a few months ago.