Zod4

Zod 4 is a major breaking release with real performance wins and faster TypeScript compilation, but you'll need to update your code. The biggest gotchas are z.record() now requiring two arguments instead of one, strict objects moving from .strict() to z.strictObject(), and .default() behavior changing in ways that'll bite you if you're using transforms. This guide walks through the migration with a quick reference table, covers new features like z.file() and z.templateLiteral(), and includes find-replace patterns for the common breaks. If you're maintaining a Zod 3 codebase or starting fresh with v4, this gives you the specifics without having to dig through changelog noise.

Install to Claude Code

npx -y skills add kastalien-research/thoughtbox-dot-claude --skill zod4 --agent claude-code