`deepPartial` throws ".partial() cannot be used on object schemas containing refinements" with zod ≥ 4.3.0

[gak10100]

Summary

deepPartial from @traversable/zod throws on any schema whose tree contains a refined object (.refine() / .superRefine()), because it internally calls zod's .partial() — which zod has rejected on object schemas containing refinements since v4.3.0.

Reproduction

import { z } from 'zod'
import { deepPartial } from '@traversable/zod/deep-partial'

// ❌ Error: .partial() cannot be used on object schemas containing refinements
deepPartial(z.object({ a: z.string() }).refine(() => true))

// ❌ Same error when the refinement is nested anywhere in the tree:
deepPartial(z.object({ inner: z.object({ a: z.string() }).refine(() => true) }))

// ✅ Works without a refinement:
deepPartial(z.object({ a: z.string() }))

Standalone:

mkdir repro && cd repro && npm init -y && npm pkg set type=module
npm install zod@4.4.3 @traversable/zod@0.0.57
# put the snippet above in repro.mjs
node repro.mjs

Actual

Error: .partial() cannot be used on object schemas containing refinements
    at Module.partial (zod/v4/core/util.js)
    at @traversable/zod/src/deep-partial.ts:91

Expected

deepPartial should produce a deep-partial schema for trees that contain refined objects — e.g. by partialing the underlying object shape and dropping the refinement (a .refine() predicate can't be preserved through a structural partial anyway), instead of calling .partial() directly on the refined wrapper.

This shows up for any nested refined field — in our case a shared LocalizedString = z.object({...}).refine(...) used across many models, so deepPartial(SomeModel) fails at module-load for every model that embeds it.

Root cause / zod version boundary

zod introduced the .partial()-on-refinements restriction in 4.3.0:

zod	z.object({...}).refine(...).partial()
≤ 4.2.1	✅ allowed
4.3.0 → 4.4.3 (latest)	❌ throws

@traversable/zod's peer is zod: 4, so any consumer on current zod (4.3+/4.4) hits this.

Environment

• @traversable/zod 0.0.57 (latest)
• zod 4.4.3 (also reproduces on 4.3.0)
• node v24.12.0

Possible fix

In deep-partial.ts, when a node is an object schema carrying refinements, partial the inner shape / unwrap to the underlying ZodObject def and rebuild, rather than calling .partial() on the refined wrapper.