CS Note 8.3: Delegations Are Deleted on Liquidation

[bingen]

Liquidations return surplus collateral to the trove owner. However, only the owner of the trove can reclaim the surplus. Delegated accounts cannot.

Note that liquidations trigger the BorrowerOperations.onLiquidateTrove hook, so all delegations for that trove ID are deleted on liquidation.

If the trove owner is a smart contract, it must implement the function to claim collateral. It cannot rely on another contract via delegation. Not having the ability to call claimCollateral() risks losing access to the surplus collateral in case of liquidation.

[bingen]

It’s true, but it’s the same for all other borrower operations. It would be even worse if the contract didn’t implement things like adjustTrove or closeTrove. A contract owning a trove must make sure to implement all those functions for proper functioning.
For reference, in v1 we didn’t have managers, and the process for claiming collateral was the same.

To fix this, we should also change CollSurplusPool as even if delegations were not deleted, the claim of collateral is done per account, not per trove.