What

Fixes #3661 (v4).

A nullable schema inside an allOf produced invalid Zod output:

export const getHealth200Schema = z.lazy(() => nullableStringSchema).and(.nullable())

The .and(.nullable()) is a syntax error.

Why

When a single nullable allOf member is merged into the intersection, its nullable keyword ends up as a sibling of the real members. The and handler in parser.ts only filtered out optional and describe, so nullable (and nullish/default) were parsed as intersection members — producing the broken .and(.nullable()).

How

Modifier keywords (nullable, nullish, optional, default, describe) are now separated from the intersection members. The real members build the .and() chain and the modifiers wrap the whole result:

// single nullable member
export const nullableAllOf = z.lazy(() => nullableString).nullable()

// multi-member allOf with a nullable member
export const nullableAllOfMulti = z.lazy(() => base).and(z.lazy(() => nullableString)).nullable()

Mini mode wraps the result with the functional modifiers (z.nullable(...)).

Tests

• New regression test packages/plugin-zod/src/generators/nullableAllOf.test.tsx covering single/multi-member allOf and mini mode.
• Full @kubb/plugin-zod suite (198) and the 3.0.x e2e suite (9) pass; no snapshot churn.

Note: v5 (main) already flattens single-member allOf and propagates nullable in @kubb/adapter-oas, so it emits valid output. A regression test for v5 is added separately in kubb-labs/plugins.

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