A note on getting the chain ID for transaction insights

[Montoya]

If you are building transaction insights Snaps and relying on the chain ID to generate insights, please make sure you are using the chainId parameter passed in the transaction handler like so:

export const onTransaction: OnTransactionHandler = async ({
  transaction,
  chainId,
  transactionOrigin,
}) => {
  const networkName = getNetworkName(chainId);
  return {
    content: panel([
      text(`The network name is ${networkName}`),
    ]),
  };
};

If you are requesting the chain ID from the ethereum provider instead, this is not guaranteed to match the chain ID of the transaction. This is because in future updates of MetaMask, each site can have its own selected network independently of other sites and of the globally selected network in MetaMask. Thus, the following code will give unreliable outcomes:

export const onTransaction: OnTransactionHandler = async ({
  transaction,
  transactionOrigin,
}) => {
  const chainId = await ethereum.request({ method: 'eth_chainId' }); 
  // this may not match the chain ID of the transaction!
  return {
    content: panel([
      text(`The chain Id is ${chainId}`),
    ]),
  };
};

Other requests using the ethereum provider will also give unreliable behavior. In general, you should check the current chainId before making any requests such as for reading token balances or contract data.