Type inference errors when writing wrappers around Viem functions

[deodad]

We are trying to write a transaction broadcasting system that has a similar interface to the Viem wallet actions. Internally it could perform multiple operations like building a serialized view of the transactions (prepareTransactionRequest), simulating it (simulateContract), writing it (writeContract), along with application specific error handling, data persistence, error handling, etc.

We've run into troubles trying to get type checking to work. The simplified example below demonstrates the basic problem. We don't necessarily care about gasPrice rather it just served as a simple example demonstrating the issue we hit.

I'm hoping this discussion can uncover:

• alternative / better ways to accomplish the general problem of writing generic extensions like this
• short-term work arounds
• potential long-term improvements to type inference

TSPlayground

We would expect the addition of the gasPrice property to type check correctly in transactionBroadcasterB, but it doesn't.

import { type Abi, WriteContractParameters, Chain, WalletClient, Account, Transport, parseGwei } from 'viem';

export const transactionBroadcasterA = <
  transport extends Transport = Transport,
  chain extends Chain | undefined = Chain | undefined,
  account extends Account | undefined = Account | undefined
>(
  client: WalletClient<transport, chain, account>
) => {
  return {
    broadcastTransaction: <
      const TAbi extends Abi | readonly unknown[],
      TFunctionName extends string,
      TChainOverride extends Chain | undefined
    >(
      args: WriteContractParameters<TAbi, TFunctionName, chain, account, TChainOverride>
    ) => {
      void client.writeContract({
        ...args,
      });
    },
  };
};

export const transactionBroadcasterB = <
  transport extends Transport = Transport,
  chain extends Chain | undefined = Chain | undefined,
  account extends Account | undefined = Account | undefined
>(
  client: WalletClient<transport, chain, account>
) => {
  return {
    broadcastTransaction: <
      const TAbi extends Abi | readonly unknown[],
      TFunctionName extends string,
      TChainOverride extends Chain | undefined
    >(
      args: WriteContractParameters<TAbi, TFunctionName, chain, account, TChainOverride>
    ) => {
     // this fails to typecheck
      void client.writeContract({
        ...args,
        gasPrice: parseGwei('20'),
      });
    },
  };
};

Related:
#238
#586