arktype-validation

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Translated

ArkType runtime validation with TypeScript-native syntax. Type-safe schemas using string expressions, morphs, scopes, and generics. Use when defining schemas, validating data, transforming input, or building type-safe APIs with ArkType.

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Sourceoakoss/agent-skills

Added on2026-02-21

NPX Install

npx skill4agent add oakoss/agent-skills arktype-validation

SKILL.md Content

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ArkType Validation

Overview

ArkType is a TypeScript-native runtime validation library that defines schemas using string expressions mirroring TypeScript syntax, providing editor autocomplete, syntax highlighting, and optimized validators. Use when building type-safe APIs, validating JSON payloads, or replacing Zod with a more TypeScript-idiomatic approach. Not suitable for projects that need Zod ecosystem compatibility or JSON Schema output.

Package:

arktype

Quick Reference

Pattern	Usage
`type({ key: "string" })`	Define object schema
`type("string")`	Primitive type
`"string.email"` , `"string.url"`	Built-in string validators
`"string.trim"` , `"string.lower"`	Built-in string morphs (transforms)
`"string.json.parse"`	Parse JSON string to validated object
`"number > 0"` , `"string >= 1"`	Inline constraints
`"string \| number"`	Union types
`"'a' \| 'b' \| 'c'"`	String literal unions
`"string[]"`	Array types
`"key?": "string"`	Optional properties
`"key = 'default'"`	Default values
`.pipe()` , `.to()`	Transform output (morphs)
`.narrow()`	Custom validation (like Zod refine)
`.pick()` , `.omit()`	Object property selection
`.merge()`	Combine object types
`scope({...}).export()`	Named type scopes with cross-references
`type("<t>", { box: "t" })`	Generic type definitions
`type.errors`	Error handling (check `instanceof type.errors` )
`configure()`	Global defaults (from `arktype/config` )
`match()`	Type-safe pattern matching (2.1)
`"+" : "reject"`	Inline undeclared key handling

Common Mistakes

Mistake	Fix
`type("string.email()")` with parens	`type("string.email")` (no parens)
Checking errors with `=== null`	Use `instanceof type.errors`
`{ key: "string?" }` for optional	`{ "key?": "string" }` (question mark on key)
Importing from `arktype/types`	Import `type` and `scope` from `"arktype"`
Nested `type()` in string expressions	Use `scope()` for cross-referencing types
Raw `.pipe()` without error handling	Use `.pipe.try()` for operations that can throw
`"string.lowercase"` for case morph	`"string.lower"` (also `"string.upper"` )
Configuring after importing `arktype`	Import `arktype/config` before `arktype`

Delegation

Use this skill for ArkType schema definitions, runtime validation, morphs/transforms, scopes, and type inference. For Zod-based validation, delegate to the zod-validation skill.

References

Schema Types — primitives, string keywords, number constraints, objects, arrays, tuples, unions, optional, defaults
Morphs and Scopes — pipe, morph transforms, narrow validation, scopes, recursive types, generics, global configuration, pattern matching
Common Patterns — JSON parsing, form validation, API responses, error handling, comparison with Zod