TypeScript Type Transformation with Schema Encoding and Decoding

const transformRarity = <
  A extends {
    readonly rarity: {
      readonly color: string;
      readonly name: string;
    };
  },
  I,
  R
>(
  schema: S.Schema<A, I, R>
) => {

  const ast = schema.pipe(S.typeSchema, S.omit("rarity")).ast

  const Transformed = S.Struct({
    ...ast,
    rarity: S.String,
    color: S.String,
  });

  return S.transform(
    schema,
    Transformed,
    {
      decode: ({ rarity, ...data }) => ({
        ...data,
        rarity: rarity.name,
        color: rarity.color,
      }),
      encode: ({ rarity, color, ...rest }) => {
        const encoded: A = {
          ...rest,
          rarity: {
            name: rarity,
            color,
          },
        };
        return encoded;
      },
      strict: true,
    }
  ).pipe(S.asSchema);
};