Mimlet's ArkType adapter

Introduced in the coordinated toolkit 0.1.0-alpha.1 train.

Native builders for ArkType 2.2.5. fromArkType(schema, options) generates encoded input through ArkType's Standard JSON Schema projection and validates through the original Type. Input/output inference, morphs, brands, defaults, scoped recursion and native error paths are retained.

See the executable Zod and ArkType guide for tested recipes and the compatibility matrix for version bounds.

Builders and factories

.build() creates input; .buildValidated() returns native transformed output. Use complete .replace() values to switch object-union variants. The ordinary Mimlet configuration, clone policy, list budgets and fluent operations apply.

fromArkTypeFactory(schema, factory, options) bypasses JSON conversion and retains the factory's argument tuple. Known async factories expose async build methods. Native Date/bigint values and opaque predicates can therefore use explicit factories while keeping ArkType validation. This does not add asynchronous morph semantics or a reverse encoder to ArkType.

Native operations and generation

arkTypeAdapter(schema, options) exposes the original source and standard handle. checkInput(value) delegates to native allows() without applying morphs or output predicates. decode(input) delegates to assert(). Validated builder failures retain native issues inside BuilderValidationError; thrown callback errors propagate without retries. Native undeclared-key and cloning policies stay under the schema's control.

generation() prepares and caches the input JSON Schema generator on demand, and create(session?) generates input. Profiles, offline references, budgets and versioned custom providers use the shared JSON Schema contract. Automatic builders prepare generation immediately. Unsupported conversion or exhausted sampling raises an error; a factory supplies data for constraints that cannot be synthesized.

Use generation().session(seed) for generator-owned replay identity and keep application schema/morph versions in the identity when output depends on opaque functions. The core remains free of vendor dependencies. Native declarations need DOM and Node types; the schema-free core does not inherit those requirements.