Support multi-chain wallets in a nicer way

[arilotter]

Hey! I've been using wagmi + RainbowKit for an upgrade to Vaportrade
Vaportrade's primary userbase is users of the Sequence wallet, which supports being connected to multiple chains at once.
I'd like to propose that wagmi support multi-chain wallets better, such that devs can request a signer or a provider for a specific chain without setting "the current chain" of the wallet.

Motivation

To provide a seamless integration with multichain wallets, devs need to be able to access things like a Signer without requesting that a wallet change its "current chain", since not all multichain wallets care about a "current chain".

Prior Art and API inspiration

Vaportrade needs this functionality, and so I've built a small version myself.
In my current version, I manually type-cast a connector to (Connector | (Connector & MultiChainConnector)), so if isMultiChain is true, I can access the getProvider & getSigner's additional arguments.

interface MultiChainConnector<Provider = any> {
  getProvider(create?: boolean, chainId?: number): Provider;
  getSigner(chainId?: number): Promise<Signer>;
  isMultiChain: true;
}

If this were to be integrated into wagmi I would imagine a MultiChainConnector subclass that multichain wallets could extend, and we could get rid of isMultiChain in favor of an instanceof call that would show you the extra chainId parameters.

abstract class MultiChainConnector<Provider = any, Options = any> extends Connector<Provider, Options> {
  abstract getProvider(create?: boolean, chainId?: number): Provider;
  abstract getSigner(chainId?: number): Promise<Signer>;
}

and it would be used like

const chainId = ...;
let signer;
if (connector instanceof MultiChainConnector) {
  signer = await connector.getSigner(chainId);
} else {
  const { data, error } = await switchNetwork(chainId);
  if(error) {
    throw error;
  }
  if (data.chain.id === chainId) {
    throw new Error("Failed to switch network");  
  }
  signer = connector.getSigner();
}

The switchChain method could become a no-op for MultiChainConnector instances.

What else?

Any thoughts? Would love to upstream something like this :)

[jmrossy]

I'm also curious about how libs like wagmi can better support multi-chain apps.

As far as I can tell, all popular libs are built around the assumption that they're connected to one chain at a time. As bridging solutions become more mature, it'll be more common for apps to need live connections to multiple chains simultaneously.

Your proposal for a MultiChainConnector can work but having its methods not match the Connector methods' signatures is maybe not ideal.

[Ding-Fan]

I'm using https://docs.family.co/connectkit , looks good to me

[kombos]

I'm using docs.family.co/connectkit , looks good to me

do you mean that multichain connectedness works with ConnectKit ? how do we perform write operations (send transactions) to multiple chains without the need to switch network , in connectKit ?