[Core Protocol] Can I bridge multiple tokens in the same TX?

[efecarranza]

Issue Description

Hello,

I am looking to bridge some tokens from Optimism to Mainnet.
is it possible to do multiple in one TX (let's say if i did a contract call).
How does proveMessage and finalizeTransfer work then?

Thank you

Additional Information

No response

[sbvegan]

Hey @efecarranza,

I took a look a look a the Optimism Portal Contract and it looks like it only processes one withdrawal transaction at a time. I'm not sure if there is a higher level way to do this. Let me ask around and see!

[efecarranza]

hey @sbvegan I took a look at that code as well, and it expects one TX, but what if the TX has multiple withdrawals/burns is what's not clear to me. thanks

[sbvegan]

I need to ask someone with more domain knowledge. I have a meeting with some client engineers tomorrow, so I'll bring it up then and see what I can find out.

[sbvegan]

Yes you can. You can use our sdk to accomplish this.

You just need to supply the messageIndex parameter to the SDK when proving/retreiving things https://github.com/ethereum-optimism/optimism/blob/2b289da4984ce358c92b655900783513bfa12d29/packages/sdk/src/cross-chain-messenger.ts#L1599

and use multicall to initiate it

[efecarranza]

hey, thanks for getting back to me but, HOW can i get the proofs etc? The relevant data to call prove()

[sbvegan]

Hey @efecarranza sorry for the delayed response, I'm out of office this week so I need to check in with someone early next week. You can take a look SDK source code to see how its done internally. I will note if you roll your own solution and something goes wrong; we cannot provide support.

You might also be able to craft and sign the transaction with your hardware wallet. Then send it off with the SDK or a tool like op-viem. I need to check with someone with more domain experience to confirm that.

[efecarranza]

hey @sbvegan i know you're out but if you're back, i don't wanna roll out my own, but rather want to get the proof without the SDK if possible.

[roninjin10]

If you want to do it with foundry it's certainly possible. It is very tedious though as you will have to reimplement a good amount of code in solidity to do it with a foundry script alone.

op-viem since it doesn't have the tech debt of handling pre bedrock tx is the best reference code for how to do withdrawals and also how to prove/finalize them https://github.com/base-org/op-viem. Check out the code for proving claiming and initiating withdrawals as a reference implementation of how to do this.

If you run into any issues or questions implementing this in foundry let me know

[sbvegan]

Hey @efecarranza, just checking back in. Are you okay with me marking this as the answer? You can always open a new discussion if you have different questions.

[efecarranza]

hey @roninjin10 and @sbvegan i haven't had the chance to try this out, just saw this reponse. my bad! i'll take a look and if anything i'll report back monday

[efecarranza]

@roninjin10 can you point me to the right files on proving? is it this API request to get a proof for a tx?
https://github.com/base-org/op-viem/blob/main/src/actions/public/getProof.ts#L25

[sbvegan]

Hey @efecarranza, following back up. This type of implementation is off the path that we can support. We've implemented the sdk so folks can more easily accomplish the cross domain transactions. If you have questions on how to do it with op-viem I'd suggest opening a detailed issue in that repository. I'm pretty sure @roninjin10 is a maintainer there, but there are also other folks who can probably offer help.

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