How to work extension api for VSF (magento)

integrations: {
    magento: {
      location: '@vue-storefront/magento-api/server',
      extensions: (extensions) => [
        ...extensions,
        {
          name: 'extension-name',
          extendApiMethods: {
            customMethod: async (context, params) => {
              const response = await context.client.mutate({
                mutation: gql${CUSTOMER_METHOD},
                variables,
                fetchPolicy: 'no-cache', 
                context: {
                  req: context.req,
                  res: context.res
                }
              });
            }
          }
        }
      ],
    },
  },

import { useVSFContext, onSSR } from '@vue-storefront/core';
xport default {
  setup() {
    const { $magento} = useVSFContext();

    onSSR(async () => {
      await $magento.api.customMethod({
        query: 'test',
        limit: 20
      })
    });
  }
}