# FAQ

**Does `add` modify my `package.json`?**
No. It copies source files. The only thing it writes outside the refiners
folder is `zod-refiners.json`.

**Do the copied files import from `zod-refiners`?**
Never. That is the point. The only import a copied refiner has is
`./types`; your application imports it alongside `zod` and nothing else.

**What happens when I run `add` and the file is already there?**
You get a per-file confirmation defaulting to *No*. Nothing is ever
overwritten silently, which makes re-running `add` a safe way to see what
changed upstream.

**How do I get updates to a refiner I already installed?**
Run `add` again and accept the overwrite. You will lose local edits to
that file — read the new copy first if you have customized it.

**Can I edit the copied files?**
Yes, they are yours now. The only consequence is that upstream updates
will conflict with your edits, and the overwrite prompt is where you
decide which version wins.

**`Unknown refiner "x"` — what now?**
The name is not in the manifest. Run `npx zod-refiners list`, and check
for typos. Names are case-sensitive.

**Does it work with Zod v4?**
Yes. The `RefineTuple` shape — a predicate plus `{ message, path }` — is
accepted by Zod 3 and Zod 4, and the examples were run against Zod 4.

**Windows?**
The CLI uses `node:path` throughout, so paths behave correctly on
Windows, Linux, and macOS.

**Why is there no plugin/runtime API?**
Because a runtime API would reintroduce the dependency this project
exists to remove. The registry is data, the CLI is a copier, and your
code stays yours.

## Writing your own refiner

A refiner is a factory: it takes the configuration a call site needs and
returns a `RefineTuple`. The full template, the `registry/index.json`
manifest fields, and the refiner checklist live in the repository:
[Writing your own refiner](https://github.com/usefmahmud/zod-refiners#writing-your-own-refiner).

Contributions are welcome — new refiners especially. See
[Contributing](https://github.com/usefmahmud/zod-refiners#contributing).