# `react-doctor/zod-v4-prefer-top-level-string-formats`

Replace z.string().<format>() with the Zod 4 top-level format API, e.g. z.email() or z.uuid()

- **Status:** Active
- **Category:** Architecture
- **Assessment:** Evidence-required risk
- **Required evidence:** source code, repository context
- **Default configuration:** Enabled
- **Default severity:** warn
- **Scope:** All supported frameworks
- **Active when:** always
- **Requirements:** zod:4
- **Tags:** migration-hint
- **Priority:** 34 (P3)
- **Source:** oxlint-plugin-react-doctor
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://zod.dev/v4/changelog)

## Validation prompt

Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.

Fires on a CallExpression that is a direct method call on a z.string() factory call where the method is one of the deprecated string-format names base64, base64url, cidr, cidrv4, cidrv6, cuid, cuid2, date, datetime, duration, email, emoji, ip, ipv4, ipv6, jwt, nanoid, time, ulid, url, or uuid: isDirectMethodCallOnZodFactory requires the receiver to itself be a CallExpression to the zod string factory, resolved through the actual import binding: z.string().email(), zod.string().ip(), schema.string().uuid() (aliased import), string().ulid() (named string import), z.string().url() (default import), and static computed access z.string()['email'](). Parens and TS as-casts are stripped, so ((z as typeof z)).string().uuid() still fires.

Suppress when: a same-named non-Zod builder where z is not imported from zod, e.g. const z = createValidator(); z.string().email(): must NOT fire because the binding does not resolve to a zod import. Also do not flag a parameter or local that shadows the zod import (function build(z){ return z.string().email() }), a dynamic computed method name (z.string()[method]() where method is a variable), or a format method invoked on a stored intermediate schema rather than the inline factory call (const s = z.string(); s.email()): the rule only matches when .format() is chained directly on z.string().

## Evidence boundary

The diagnostic proves only that the detector's modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.

Establish the environment, explicit repository policy, relevant exceptions, and required rendered or runtime evidence before deciding the occurrence. This page’s Assessment and Required evidence fields define the review contract.

Default severity is registry metadata. Use the occurrence's JSON severity after repository configuration when ordering real findings.

Record one outcome:

- **Confirmed failure:** The required evidence establishes the violation.
- **Rejected:** A documented exception or false-positive predicate applies.
- **Needs evidence:** Named evidence can still be collected.
- **Unavailable:** Required evidence cannot be collected in this run.
- **Waived with evidence:** An authorized, scoped exception applies to an established failure.
- **Observation:** The review records an optional tradeoff without claiming a defect.

A waiver records its scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

## Fix prompt

Apply this candidate correction only after the required evidence confirms the risk.

Collapse the chained format call onto the Zod 4 top-level factory: rewrite z.string().email() as z.email(), z.string().uuid() as z.uuid(), z.string().datetime() as z.iso.datetime(), z.string().date() as z.iso.date(), and z.string().time() as z.iso.time(); the removed z.string().ip() and z.string().cidr() helpers split by version, so pick z.ipv4()/z.ipv6() (or z.ipv4().or(z.ipv6())) and z.cidrv4()/z.cidrv6() to match the data. Carry over any chained refinements/messages by passing options to the new factory, e.g. z.email({ message: '...' }), and keep the named import shape you already use. See https://zod.dev/v4/changelog

## Repository-wide copy prompt

Use this only for a repository-wide pass after validating each occurrence. For one occurrence, use the occurrence-level guidance above.

````text
Fix every confirmed `react-doctor/zod-v4-prefer-top-level-string-formats` diagnostic in the current repository.

Required change:
- Collapse the chained format call onto the Zod 4 top-level factory: rewrite z.string().email() as z.email(), z.string().uuid() as z.uuid(), z.string().datetime() as z.iso.datetime(), z.string().date() as z.iso.date(), and z.string().time() as z.iso.time(); the removed z.string().ip() and z.string().cidr() helpers split by version, so pick z.ipv4()/z.ipv6() (or z.ipv4().or(z.ipv6())) and z.cidrv4()/z.cidrv6() to match the data. Carry over any chained refinements/messages by passing options to the new factory, e.g. z.email({ message: '...' }), and keep the named import shape you already use. See https://zod.dev/v4/changelog.

Validation before editing:
Fires on a CallExpression that is a direct method call on a z.string() factory call where the method is one of the deprecated string-format names base64, base64url, cidr, cidrv4, cidrv6, cuid, cuid2, date, datetime, duration, email, emoji, ip, ipv4, ipv6, jwt, nanoid, time, ulid, url, or uuid: isDirectMethodCallOnZodFactory requires the receiver to itself be a CallExpression to the zod string factory, resolved through the actual import binding: z.string().email(), zod.string().ip(), schema.string().uuid() (aliased import), string().ulid() (named string import), z.string().url() (default import), and static computed access z.string()['email'](). Parens and TS as-casts are stripped, so ((z as typeof z)).string().uuid() still fires.

Suppress when: a same-named non-Zod builder where z is not imported from zod, e.g. const z = createValidator(); z.string().email(): must NOT fire because the binding does not resolve to a zod import. Also do not flag a parameter or local that shadows the zod import (function build(z){ return z.string().email() }), a dynamic computed method name (z.string()[method]() where method is a variable), or a format method invoked on a stored intermediate schema rather than the inline factory call (const s = z.string(); s.email()): the rule only matches when .format() is chained directly on z.string().

Constraints:
- Make the smallest change that fixes the root cause.
- Preserve behavior and interfaces unrelated to this diagnostic.
- Reuse existing project components, utilities, and conventions.
- Adapt identifiers and framework details instead of copying blindly.
- Do not disable the rule or suppress matching code.

Assessment:
- Record detector evidence, applicability facts, assumptions, missing evidence, and the rule class for this occurrence.
- Return one outcome: Confirmed failure, Rejected, Needs evidence, Unavailable, Waived with evidence, or Observation.
- A waiver records the established failure, scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

Verification:
- Run focused tests for the changed behavior.
- Run React Doctor and confirm this diagnostic no longer appears from changed code.
- Run an unfiltered scan of the affected scope before claiming no cross-category regression.
- Report the files changed and any checks you could not run.
````