Zod

This is a comprehensive reference for Zod v4, focused on the breaking changes from v3 that will trip you up: string formats moved to dedicated methods like z.email(), nativeEnum is gone, and the error API changed completely. It's organized by priority, so the critical parsing and schema design rules come first. The bundled references cover everything from basic validation to architecture patterns for API boundaries, and there's specific guidance on where Zod actually belongs (API handlers, form validation, env parsing) versus where plain TypeScript is enough. The anti-patterns doc alone will save you from the classic mistakes like throwing in refinements or using z.coerce.boolean() on form data.