zodv4 output produces unknown for optional nested input fields with exactOptionalPropertyTypes: true #1494

(Note this is an AI-generated summary from troubleshooting session).

I’m seeing a TypeScript assignability error in generated zod.ts when using graphql-codegen-typescript-validation-schema with:

• schema: 'zodv4'
• imported generated types via importFrom
• TypeScript exactOptionalPropertyTypes: true

In this setup, nested optional input fields can be emitted with unknown in Zod output typing, which then fails assignment to the generated GraphQL input types.

Possibly related to #1460 (similar need for manual type correction), but this report is specifically about zodv4 + exactOptionalPropertyTypes: true producing unknown in nested optional input output types.

Environment

• graphql-codegen-typescript-validation-schema: 0.19.0
• @graphql-codegen/cli: 7.1.2
• @graphql-codegen/typescript: 6.0.2
• TypeScript: strict mode with exactOptionalPropertyTypes: true
• Zod: 4.x

Codegen config (relevant parts)

// codegen.ts
generates: {
  'src/magento/__generated__/types.ts': {
    plugins: ['typescript'],
    config: {
      inputMaybeValue: 'T | null | undefined',
      useTypeImports: true,
    },
  },
  'src/magento/__generated__/zod.ts': {
    plugins: ['typescript-validation-schema'],
    config: {
      schema: 'zodv4',
      importFrom: './types',
      schemaNamespacedImportName: 'types',
    },
  },
}

TS config (relevant parts)

{
  "compilerOptions": {
    "strict": true,
    "exactOptionalPropertyTypes": true
  }
}

Observed behaviour

Type '{ ... customizable_options?: unknown; ... } | null' is not assignable to type 'InputMaybe<BundleProductCartItemInput>'.
Types of property 'customizable_options' are incompatible.
Type 'unknown' is not assignable to type 'InputMaybe<InputMaybe<CustomizableOptionInput>[]>'.

Expected behaviour

Generated Zod schemas should typecheck with exactOptionalPropertyTypes: true, without degrading nested optional field types to unknown.

Additional notes

• inputMaybeValue: 'T | null | undefined' is already set on TypeScript generation.
• The issue appears specific to the zodv4 emitter path.
• Behaviour is reproducible on nested optional input arrays/objects.

Workaround

Switch the validation schema emitter to zod while keeping Zod v4 runtime import:

'src/magento/__generated__/zod.ts': {
  plugins: ['typescript-validation-schema'],
  config: {
    schema: 'zod',
    zodImportPath: 'zod/v4',
    importFrom: './types',
    schemaNamespacedImportName: 'types',
  },
},

This avoids the unknown typing issue in our case while still using Zod v4.