Zod and ArkType builders

The dedicated @mimlet/zod and @mimlet/arktype packages are published in 0.1.0-alpha.2 on npm's next channel. Existing Standard Schema and Standard JSON Schema entry points remain supported. Install the adapter you use, with its tested peer:

# Zod, including Zod Mini
npm install --save-dev @mimlet/zod@0.1.0-alpha.2 zod@4.4.3

# ArkType
npm install --save-dev @mimlet/arktype@0.1.0-alpha.2 arktype@2.2.5

Zod: typed input, native output

import { z } from 'zod';
import { fromZod } from '@mimlet/zod';

const User = z.object({
  name: z.string(),
  age: z.string().transform(Number),
});

const users = fromZod(User).with({ name: 'Ada', age: '42' });
export const input = users.build(); // age: string
export const user = users.buildValidated(); // age: number

The encoded age is a string. Native validation produces a number. The original schema keeps control over coercion, defaults, object stripping and codec behavior. Zod Mini is supported through the same native Zod core API.

For async refinements or codecs, choose fromZodAsync or fromZodFactoryAsync. They go directly through native async parsing; the pinned Standard Schema implementation's sync probe is not repeated. Their builders expose async methods only. Ordinary async input factories with synchronous schemas can also use fromZodFactory.

Use zodAdapter(schema) when you need direct decode/encode operations or access to the generation engine. One-way transforms keep Zod's native encoding failure. See the Zod package contract.

ArkType: preserve morphs and scopes

import { type } from 'arktype';
import { fromArkType } from '@mimlet/arktype';

const User = type({ name: 'string', age: 'string' }).pipe(({ name, age }) => ({
  name,
  age: Number(age),
}));

const users = fromArkType(User).with({ name: 'Ada', age: '42' });
export const input = users.build(); // age: string
export const user = users.buildValidated(); // age: number

ArkType's original Type remains the validator. Its allows() input check does not execute morphs; validated builds do. Scoped and recursive Types retain their input and output types. Undeclared keys follow the schema's own ignore/reject/delete policy.

fromArkTypeFactory retains factory arguments and supports asynchronous input production. It does not invent inverse morphs or a native asynchronous parser. See the ArkType package contract.

Use factories for native values and domain constraints

Automatic generation is bounded sampling of converted input metadata. It can handle the shared generator's supported profiles and constraints; it does not solve every refinement. Native validation remains authoritative when a refinement cannot be represented. Conversion and sampling failures stay visible.

Factories do not require conversion, so schemas involving Date, bigint, custom predicates or application-owned objects can retain their native behavior. Keep the schema and supply meaningful input through fromZodFactory, fromZodFactoryAsync or fromArkTypeFactory.

For replay, preserve the generator identity and the application's schema/codec version. The existing scenario, replay and property-testing contracts work with these builders.

The examples above are compiled and executed against isolated package tarballs by pnpm test:examples; pnpm test:optional also runs native conformance, negative type checks and coverage for both adapters.