How to correctly use Alchemy provider with transport function in createWalletClient

[tx-nikola]

When trying to use the Alchemy RPC, we tried creating the wallet client like this:

const [account] = await window.ethereum!.request({ method: "eth_requestAccounts" });

const walletClient = createWalletClient({
  account,
  chain: zkSync,
  transport: fallback
  ([ 
    http('https://zksync-mainnet.g.alchemy.com/v2/<API_KEY>'), 
    http('https://eth-mainnet.g.alchemy.com/v2/<API_KEY>'),
  ]),
}).extend(eip712WalletActions());

Initially we just tested with zkSync network, but later added the eth fallback as well, but didn't help.

The issue might also be with how Alchemy designed the API - here is one example where we can see that eth_accounts method exists on eth mainnet, but not on zksync.

This means that if we use the Alchemy RPC for zkSync, and we try to call some methods like

const [account] = await this.wallet.getAddresses();

it will fail, as the getAddresses method is calling an unsupported RPC method under the hood.

Is there something we're not understanding correctly, or if we're doing something wrong?

Our main use case is that we need to call the writeContract method on the zkSync network, but the same issue happens.
When I try to use writeContract, it tries to call the "eth_signTypedData_v4" RPC method and sends the request to the alchemy endpoint, which doesn't have this method, thus the request fails (returns 400).

[jordaniza]

We also ran into this problem at Aragon, solution for now was to directly use window.ethereum but it would be nice to use our existing RPC infra