How to pass your own fetch to the SDK (deps.fetch)

Pass deps: { fetch: yourFetch } to createKernelClient or createVerifyClient. The SDK uses it for every request. Without it, the SDK uses the fetch built into Node.js 18.

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Steps

  1. Pass it in

    const client = createKernelClient({
  deps: { fetch: myFetch },
});

  2. Use it to simulate API errors in tests

    const errorFetch = async () => ({
  ok: false,
  status: 429,
  json: async () => ({ error: 'Rate limit exceeded' }),
});
// errorFetch answers locally, so this key is never sent anywhere.
const client = createKernelClient({ hosted: { apiKey: 'not-sent' }, deps: { fetch: errorFetch } });

When you need it

  • Tests that should not call the network but need a hosted-shaped error.
  • A proxy or logging wrapper around fetch.
  • Older runtimes with no global fetch.