Zod 4 / Standard Schema support

[oxc]

Is your feature request related to a problem? Please describe.
I am now using Zod 4 in my project, and I get peer dependency mismatch warnings for command-zod and event-type-zod

The code works still fine, but it would be good to have official support and get rid of the warnings.

Note

While investigating potential breakage, I was surprised to learn that ZodCommand does not use the schemas in any way to validate the input. While I can figure out some good reasons behind this decision, it's really unexpected, and IMHO deserves a mention in the README.
EDIT: Just found #136 and #175

Describe the solution you'd like
The naive solution would be to just bump the peer dependencies. However, while reading Zod migration guides and notes for library authors, I noticed this section:

If you're building a library that accepts user-defined schemas to perform black-box validation, you may not need to integrate with Zod specifically. Instead look into Standard Schema. It's a shared interface implemented by most popular validation libraries in the TypeScript ecosystem (see the full list), including Zod.

This sounds like a very reasonable choice for castore types, regardless of whether they do validation or not. This way, a event-type-standard-schema and command-standard-schema could support all kinds of typed validators, not just zod.

I would like to get your input, on how to best move forward with this. I would be happy to prepare a PR for either way, but I would like to avoid wasted work.

[ThomasAribart]

Hi @oxc !

I'm ok with bumping the Zod peer-dependency to "^3.0.0 || ^4.0.0". which would be a quick win regarding your issue (Castore seems to be compatible w. both versions).

I'm also fully onboard with creating event-type-standard-schema and command-standard-schema packages 👍 This definitely is the future.

[oxc]

The standard-schema ones might even go into the default package, since the schema types can just be copy&pasted into the code base (this seems to be what several libraries are doing and is explicitly "supported" by standard-schema). I understand if you prefer a separate package though.

[oxc]

Please see #200 for a proposed solution. It requires a typescript update though.