Custom tx: Fetch implementation abi when contract is proxy

[scottrepreneur]

What is the feature about

When using the custom tx builder and attempting to interact with a proxied contract the Abi is fetched for the proxy contract.

Rather we should detect that the contract is a proxy and additionally fetch the abi for the proxy's implementation.

The list of requirements

• detect that input contract is a proxy via interface
• fetch implementation abi
• Parse functions from the implementation abi

Designs/sketches

Should largely happen behind the scenes. Show a message that we've detected a proxy and fetched the implementation abi.

This would greatly enhance usability for proxy contracts via the custom transaction builder.

[katspaugh]

Isn’t that how it already works? If it detects a proxy, it offers to use the implementation ABI.

[scottrepreneur]

It has not worked in my testing with the Base (Optimism) Portal contract. I've been needing to add the implementation ABI manually.
https://etherscan.io/address/0x49048044d57e1c92a77f79988d21fa8faf74e97e#writeProxyContract