| name | arktype-validation |
| description | ArkType runtime validation with TypeScript-native syntax. Type-safe schemas using string expressions, morphs, scopes, and generics. Includes ArkEnv for typesafe environment variable validation with auto-coercion and Vite plugin. Use when defining schemas, validating data, transforming input, building type-safe APIs with ArkType, or validating environment variables with ArkEnv. |
| license | MIT |
| metadata | {"author":"oakoss","version":"1.2"} |
| user-invocable | false |
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) |
.assert(data) | Throws on invalid input instead of returning |
"(number % 2)#even" | Branding — type-only validated marker |
"0 <= number <= 100" | Compact range constraints |
configure() | Global defaults (from arktype/config) |
match() | Type-safe pattern matching (2.1) |
"+" : "reject" | Inline undeclared key handling |
arkenv({ PORT: "number" }) | Typesafe env var validation (ArkEnv) |
arkenvVitePlugin(Env) | Build-time env validation for Vite |
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 |
Manual process.env parsing | Use arkenv() for auto-coercion and validation |
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, ArkEnv environment variables, Vite plugin, comparison with Zod
