Discussion about merging changes to @sanity-typed/types into Sanity.io and improving dev story for custom types.

// From sanity's docs: <https://www.sanity.io/docs/schema-field-types#e5642a3e8506>
// import { defineField, defineType } from "sanity";
import { defineField, defineType } from "@sanity-typed/types";
// This is where the magic happens
import { InferValue } from "@sanity-typed/types";

// Import this into sanity's createSchema, as usual.
export const product = defineType({
  name: "product",
  type: "document",
  title: "Product",
  fields: [
    defineField({
      name: "productName",
      type: "string",
      title: "Product name",
    }),
    defineField({
      name: "tags",
      type: "array",
      title: "Tags for item",
      of: [
        defineArrayMember({
          type: "object",
          name: "tag",
          fields: [
            { type: "string", name: "label" },
            { type: "string", name: "value" },
          ],
        }),
      ],
    }),
  ],
});

// Import this into your application!
export type Product = InferValue<typeof product>;

/**
 *  Product === {
 *    _createdAt: string;
 *    _id: string;
 *    _rev: string;
 *    _type: string;
 *    _updatedAt: string;
 *    productName?: string;
 *    tags?: ({
 *      label?: string;
 *      value: string;
 *    })[];
 *  };
 **/

InferValue<typeof schema, { [type]: typeof customSchema }>

type MyInferValue<Value> = MakeInferValue<Value, { [type]: typeof customSchema }>

{ name: 'customName', type: 'object', fields: [...] }

{ name: 'somewhereElse, type: 'object', fields: [..., { name: 'foo', type: 'customName' }] }

const customName = { name: 'customName', type: 'object', fields: [...] };

{ name: 'somewhereElse, type: 'object', fields: [..., customName] }

ExpandNamedTypes<TypeToExpand, NamedTypes | PluginTypes | Etc>