Caretaker Module

Global shutdown

The Caretaker module is responsible for deprecating the entire protocol, and particularly the Shrine, in a graceful manner by allowing yin holders to claim collateral backing their yin. Note that, in the future, other modules may have their own shutdown mechanisms that fall outside the purview of the Caretaker.

Description of key functions

• shut: permanently disables user actions for the Shrine and transfers a percentage of the collateral backing the prevailing total troves' debt to the Caretaker

• release: allow trove owners to withdraw all collateral from their trove after shut has occurred

• reclaim: allow yin holders to burn yin and receive a percentage of the collateral in the Caretaker, up to the total troves' debt, after shut has occurred.

Shutdown

Once shut is executed, all troves' debt cannot be repaid, and all collateral that is needed to back the value of the total amount of debt forged by troves is transferred from the Shrine to the Caretaker. Anyone may then subsequently burn yin to claim a proportional percentage of this collateral, up to the total amount of the troves' debt that the Caretaker is supposed to back. The total troves' debt at the time of shutdown is stored in the Caretaker, and is gradually decremented as users call reclaim.

The transfer of collateral at the time of shutdown acts as a final system-wide redistribution on all trove owners because the same percentage of all yangs are transferred to the Caretaker.

• This also means that if the total value of yangs in the Shrine is less than the total amount of troves' debt, then there would be no collateral remaining for trove owners to withdraw because the entire amount of yangs will be used to back the circulating yin representing the total amount of troves' debt.

At the time of shut, there may be troves with unaccrued interest. This means that for each trove, the Trove.debt value in storage will be taken to be the amount of debt for that Trove , and collectively the prevailing total troves' debt in Shrine would similarly exclude all unaccrued interest. This may result in a permanent loss of income for the allocated recipients because they would otherwise have been minted as debt surpluses via the Equalizer. This design is intended as the alternative to charge interest on all troves may be too expensive.

In addition, the protocol owned yang amounts are rebased to zero to the benefit of all trove owners. Note that in the initial transfer of collateral to the Caretaker, the total backing is calculated with the protocol owned yang amounts included, which means that a proportional amount of the underlying assets of the protocol owned yang amounts were also transferred to the Caretaker, to the benefit of yin holders. Therefore, this subsequent rebasing ensures that both yin holders and trove owners are treated fairly.

Redeeming `yin` for assets

After shut, yin holders may exchange their yin for a percentage of the collateral assets in the Caretaker. The amount of assets a yin holder is entitled to is proportional to the remaining amount of yin that is reclaimable. Users may rely on preview_reclaim to determine the amount of assets they are entitled to for a given yin amount.

Withdrawing remaining collateral from troves

After shut, trove holders may withdraw all remaining collateral in their troves. Due to the system-wide redistribution during shut, the amount of collateral remaining for withdrawal will likely be a fraction of what was deposited in the trove prior to shut. Trove owners may rely on preview_release to determine the amount of assets they are entitled to withdraw from their trove.