Function finalize

packages/zod/src/v4/core/to-json-schema.ts:359–524

(
  ctx: ToJSONSchemaContext,
  schema: T
)

}

export function finalize<T extends schemas.$ZodType>(
  ctx: ToJSONSchemaContext,
  schema: T
): ZodStandardJSONSchemaPayload<T> {
  const root = ctx.seen.get(schema);
  if (!root) throw new Error("Unprocessed schema. This is a bug in Zod.");

  // flatten refs - inherit properties from parent schemas
  const flattenRef = (zodSchema: schemas.$ZodType) => {
    const seen = ctx.seen.get(zodSchema)!;

    // already processed
    if (seen.ref === null) return;

    const schema = seen.def ?? seen.schema;
    const _cached = { ...schema };

    const ref = seen.ref;
    seen.ref = null; // prevent infinite recursion

    if (ref) {
      flattenRef(ref);

      const refSeen = ctx.seen.get(ref)!;
      const refSchema = refSeen.schema;

      // merge referenced schema into current
      if (refSchema.$ref && (ctx.target === "draft-07" || ctx.target === "draft-04" || ctx.target === "openapi-3.0")) {
        // older drafts can't combine $ref with other properties
        schema.allOf = schema.allOf ?? [];
        schema.allOf.push(refSchema);
      } else {
        Object.assign(schema, refSchema);
      }
      // restore child's own properties (child wins)
      Object.assign(schema, _cached);

      const isParentRef = zodSchema._zod.parent === ref;

      // For parent chain, child is a refinement - remove parent-only properties
      if (isParentRef) {
        for (const key in schema) {
          if (key === "$ref" || key === "allOf") continue;
          if (!(key in _cached)) {
            delete schema[key];
          }
        }
      }

      // When ref was extracted to $defs, remove properties that match the definition
      if (refSchema.$ref && refSeen.def) {
        for (const key in schema) {
          if (key === "$ref" || key === "allOf") continue;
          if (key in refSeen.def && JSON.stringify(schema[key]) === JSON.stringify(refSeen.def[key])) {
            delete schema[key];
          }
        }
      }