zod

I have a zod object that is handed to me from elsewhere, and I do not have the ability to change it. However, I do know what items it contains. For example, it has a "firstName" string with a min length of 3 and a max length of 24. I believe at present there is no way to do something like: Could support be added for such a feature?

Since 4.6.0, emits , and for , and . None of those are JSON Schema formats, so ajv warns about them. Chained after a real format, the later check also overwrote it: exported in place of , which lets accept input Zod rejects. These three checks now contribute only their , as in 4.5.x. A format set by , or similar is kept in either chain order, and / still emit their own format. The converter tells them apart by the trait rather than a list of names. Output matches across 24 schemas on , and , apart from the email regex text, which changed independently. Bundle: +12 B gzip classic, +9 B gzip mini ( fixtures). Runtime: no measurable change in (interleaved, load ~60, indicative); parse paths are untouched. Memory: no new properties or closures. Closes #6648 Thanks to @MFA-G for the original fix and test.

Since zod 4.6.0 (#6554, "derive JSON Schema constraints by folding checks in the converter"), copies every check's name into the JSON Schema keyword. For , , and that name is not a JSON Schema format, so validators such as ajv report . Reproduction on zod 4.6.5 (bun 1.4): Output: On 4.5.4 the same schemas emit only the . Expected: the alone, since it already carries the constraint, and only for names JSON Schema (or zod's documented format set) defines. Where it comes from: copies from every check, and // construct their checks with and the internal names above. Fix Branch, ready to open as a PR by a collaborator (this repository refuses PR creation from my account): https://github.com/colinhacks/zod/compare/main...Vivswan:zod:fix/json-schema-string-format-trait One change in : a check contributes a only if it carries the trait. Why that works: , and are built with , not . That is why they never wrote on 4.5.x. Test: fails on with received, passes on the branch. Full suite green. Bundle: unchanged unless is used, then +31 gzip bytes classic, +30 mini. Trait read, not :** pulls into mini bundles that never build a format check (+89 bytes).