Add Asset Hub Flow

[TorstenStueber]

For offramping Asset Hub USDC, we need to implement a new flow structure that starts with the Asset Hub.

Different flow structures will also imply that other parts of the code are more generic, e.g., the OfframpingState type.

Proposal

• for simplicity, we can just reuse the current definition of OfframpingState for the new flow
  • squidRouterApproveHash, squidRouterSwapHash, moonbeamXcmTransactionHash will not be required but they are defined as optional anyway
  • squidRouterReceiverId and squidRouterReceiverHash are determined in constructInitialState but we can keep this logic as we can use it to show a unique id to the user (https://github.com/pendulum-chain/vortex/issues/193)
• add a new field to OfframpingState that describes the type of flow (e.g., "type": "evmMoonbeam" | "assetHub")
• add a new phase assetHubXcm and a handler
  • the handler will create an XCM transfer transaction the way it is defined [in this comment] (https://github.com/pendulum-chain/tasks/issues/427#issuecomment-2472873799) – i.e., leave WeightLimit: Unlimited
  • the handler will then use the Polkadot wallet integration to sign and submit this transaction
  • the handler will finally switch to the phase subsidizePreSwap
• remove the initial wait for the squidRouterSwapHash evm transaction from the pendulumFundEphemeral phase handler
• in prepareTransactions phase handler proceed to
  • phase squidRouter if state.type === "evmMoonbeam"
  • phase pendulumFundEphemeral if state.type === "assetHub"
• in pendulumFundEphemeral phase handler proceed to
  • phase executeXCM if state.type === "evmMoonbeam"
  • phase assetHubXcm if state.type === "assetHub"

Note

The new flow structure is not explicitly defined in the file src/services/offrampingFlow.ts but implicitly defined by the successor phase returned in every phase handler.

Whereas the initial structure of the evm-moonbeam flow is:

• prepareTransactions
• squidRouter
• pendulumFundEphemeral
• executeXCM
• subsidizePreSwap

the structure for the Asset Hub flow is:

• prepareTransactions
• pendulumFundEphemeral
• assetHubXcm
• subsidizePreSwap

[TorstenStueber]

Hey team! Please add your planning poker estimate with Zenhub @ebma @gianfra-t @Sharqiewicz

[TorstenStueber]

To be discussed: how identify the Asset Hub user and derive the memo for sep10 (https://github.com/pendulum-chain/vortex/pull/257)

[ebma]

We can use the same function @gianfra-t implemented for the EVM accounts and just pass the Polkadot address. We need to make sure that we pass the addresses using the same ss58 encoding and we don't mix it up ending with different memos for the same account.

[TorstenStueber]

That makes sense, but I also meant the signing part. Do Polkadot wallets also have a standardized API to sign arbitrary messages? (I guess so, this happens on Polkassembly for example).

[gianfra-t]

I think so, we will use also the talisman package as in the portal right? In the only example of the package they show a message sign.

[TorstenStueber]

I am not familiar with the Talisman package. That works with every Polkadot wallet, not just with Talisman?

[gianfra-t]

If I understand correctly, yes, it's our wagmi for Polkadot on the Portal.

[ebma]

Polkadot.js supports signing arbitrary messages, see the docs here. As we can't do const alice = keyring.addFromUri('//Alice'); but instead need to access the signer from the wallet, we can use talisman for that. But this is quite straightforward so once #271 is added and a polkadot signer is available, it's just a simple function call.