Seamless Rebalance Orders using Flash Loan Routing not being solved

[johnwhitton]

Seamless Rebalance Orders using Flash Loan Routing not being solved.

Overview

Seamless is looking to use the flash-loan-router and app data to allow solvers to rebalance Seamless's Leverage Tokens.
Moving forward we are also considering using programmatic orders to create these orders.
We have worked through the design and submitted rebalance orders to production using Flash Loan Router using two approaches

1. Using the Settlement Contract as the flash loan receiver. Rebalance Order Cow Explorer
2. Using the Maker as the flash loan receiver and using approvals to ensure flash loan repayment. Rebalance Order Cow Explorer

We have been able to test locally ensuring that the scenario 2 works with a custom solver. However the production orders, although profitable, we're not solved.

This request is to review the seamless rebalancing logic to ensure that we are creating orders correctly.

Below you will find detailed information including the order payloads and sample scripts used to create the orders.

Appendix A - Order using Settlement Contract as Receiver

• Rebalance Order Cow Explorer

• RebalanceScipt.ts

• Order Payload

• Order AppData

• LeverageToken : 0xE282a1A02A7b607d616B3311fE528d1Af4A31233

• RebalanceAdapter : 0x527bFa9a7A48264D1E64b0064E9a54e0145946eb

• Pre Approvals from Maker

• Flash Loan

  • Buy Token wstETH
  • Liquidity Provider: Aave Pool 0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2
  • Protocol Adapter: Aave Flash Borrower 0x7d9C4DeE56933151Bc5C909cfe09DEf0d315CB4A
  • Receiver : Settlement Contract 0x9008d19f58aabd9ed0d60971565aa8510560ab41

• Pre Hooks

  • AaveBorrower approve function of Approves wstETH to Cow Settlement (maxUint256)
  • TransferFrom AaveBorrower to CowSettlement (amountIn(flashLoanAmount))
  • Approve RebalanceAdapter for wstETH for maxUint256
  • RebalanceAdapter take function for amountOut (flashLoanAmount+ fee)

• Settlement

  • Sell Token (WETH) comes from Maker
  • Buy Token (wstETH) comes from Solver

• Post Hook

  • Transfer wstETH to AaveBorrower(buyAmount)
  • AaveBorrower approve wstEth to AavePool (maxUint256)

• Flash Loan Repayment (Custom Solver)

  • Flash Loan Borrower repays wstETH (+ fee) to Aave Pool

Appendix B - Order using Maker as Receiver and approvals

• Rebalance Order Cow Explorer
• RebalanceScipt.ts
• Order Payload
• Order AppData
• LeverageToken : 0xeE2aE3A033154dE692f1E14B4E8fBAD5Bce18E7a
• RebalanceAdapter : 0x0aD07431771021Bb861De576c964B5e00b02b3Bf

Maker - has dust of the Collateral Token wstETH

• Pre Approvals from Maker
  • Sell Token (WETH) to cowVaultRelayer
  • Sell Token (WETH) to cowStandardTrampoline
  • Buy Token (wstETH) to cowStandardTrampoline
  • Buy Token (wstETH) to aaveBorrower
• Flash Loan
  • Buy Token wstETH
  • Liquidity Provider: Aave Pool 0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2
  • Protocol Adapter: Aave Flash Borrower 0x7d9C4DeE56933151Bc5C909cfe09DEf0d315CB4A
  • Receiver : Cow Standard Trampoline 0x60Bf78233f48eC42eE3F101b9a05eC7878728006
• Pre Hooks
  • Approves wstETH to the Rebalance Adapter
  • Rebalance Adapter Take Call using flash loaned wstETH and returning WETH to the Cow Standard Trampoline
  • transfers WETH to the Maker (to be used in Settlement)
• Settlement
  • Sell Token (WETH) comes from Maker
  • Buy Token (wstETH) comes from Solver
• Post Hook
  • Cow TransferFrom Maker Buy Token (wstETH) to AaveBorrower
• Flash Loan Repayment (Custom Solver)
  • Flash Loan Borrower repays wstETH (+ fee) to Aave Pool

[johnwhitton]

New Settlement Order: 0x838c4bed967815b428b66d0f5a4655553a43921b2a979b971b4687f0d42948b17964b32ed0e5ad3fb17a268f7374adcca430b1aa694ae0b2
New Approval Order: 0x9f2b60ca074394ca0d351d290d216c1222e09dd44ad07b8987222c7ff4d87a0b1fbaafc7dc31500252d62c177b712ebf3912f008694adb2f

[johnwhitton]

Thanks @anxolin for your help. Below is our request for next steps and work which has been done.

Next Steps
Can someone simulate this order (or tell us how we can simulate orders on on production) like this.

0xb9c73b8c4d1388e443372a2d109d4edc2257aa9436ecb2f7b09ed80e2a15bc551fbaafc7dc31500252d62c177b712ebf3912f0086951a9c4

Details of work done is below

Based on Feedback from @anxolin the order was failing as we were unable to do an approval from the cow trampoline (only settlement) see simulation here

To fix this we have deployed a modified AaveBorrower which allows the trampoline to call approve

here is the change we made to the modifier in Borrower.sol

    address constant CowStandardTrampoline = 0x60Bf78233f48eC42eE3F101b9a05eC7878728006;

    /// @notice A function with this modifier can only be called in the context
    /// of a CoW Protocol settlement.
    modifier onlySettlementContract() {
        require(
            (msg.sender == address(settlementContract) || msg.sender == CowStandardTrampoline),
            "Only callable in a settlement or by Trampoline"
        );
        _;
    }

The new contract was deployed to 0x034354edf5f9260c516f58bac1a2105f618363c6 on mainnet.

We also modified our solver logic to align with cow best practices, changed the approval workflow and restested locally and were able to solver orders succesfully using the modified borrower.

We then created new orders on production using the same logic.

The latest order, which should be profitable for solvers is
0xb9c73b8c4d1388e443372a2d109d4edc2257aa9436ecb2f7b09ed80e2a15bc551fbaafc7dc31500252d62c177b712ebf3912f0086951a9c4

This order was not picked up by solvers and has since expired.