orchestration: example dapp contract that can swap on osmosis

[0xpatrickdev]

What is the Problem Being Solved?

As a zoe smart contract, I'd like to be able to swap assets on an external chain. A user offers me ATOM* and wants an equivalent amount of BLD** in return. I will use the Osmosis DEX to complete the swap.

• for simplicity, we may want to start with an Osmosis-native asset like OSMO so we do not need to unwrap ATOM (ibc transfer to gaia -> ibc transfer to osmosis with hook)
  ** tangential to the above, a non-Agoric asset will need to be unwrapped going back to Agoric so we may want to test with a different scenario here as we progress.

Description of the Design

Use vat-transfer (#8624) to make a Transfer Account and execute a Swap on Osmosis using cosmwasm IBC-Hooks.

To start, the goal is to create working zoe contract that using the listed APIs. The author may want to consider future reuse of the contract and how we can expose functionality for this to become a reusable component for other dapps, a la postSvc.

Security Considerations

Scaling Considerations

Test Plan

Possible test cases to cover

• Swap BLD against OSMO, receiver on Agoric
• Swap BLD against OSMO, receiver on CosmosHub
• Swap OSMO against BLD, receiver on Agoric
• Swap output sent to an unknown address, swap should fail
  • Not sure what's the default XCS behavior is here
  • In case assets are stuck at localchain account's bank, the user should be able to withdraw that
• Verify osmosis xcs state

Upgrade Considerations

[otoole-brendan]

Open question: Should Agoric token for example code change from IST to BLD in light of imminent Inter Protocol plans?

Update: Yes. I've updated description to reflect IST to BLD change (for Agoric token)

[0xpatrickdev]

Here are scenarios I would suggest covering in tests:

• BLD on Agoric for OSMO (no PFM necessary)
• BLD on Agoric for ATOM (PFM transfer after swap to unwrap)
• ATOM on Agoric for BLD (PFM transfer before swap to unwrap)