rft: risk premium cap -> risk premium threshold (#961)

Co-authored-by: DhairyaSethi <[email protected]>
Co-authored-by: YBM <[email protected]>

Author: 3 people

.prettierignore

@@ -6,3 +6,4 @@ snapshots
 report
 src/dependencies
 tests/mocks/JsonBindings.sol
+tests/misc/prototype

src/hub/Hub.sol

@@ -37,7 +37,7 @@ contract Hub is IHub, AccessManaged {
   uint40 public constant MAX_ALLOWED_SPOKE_CAP = type(uint40).max;
 
   /// @inheritdoc IHub
-  uint24 public constant MAX_ALLOWED_RISK_PREMIUM_CAP = type(uint24).max;
+  uint24 public constant MAX_RISK_PREMIUM_THRESHOLD = type(uint24).max;
 
   uint256 internal _assetCount;
   mapping(uint256 assetId => Asset) internal _assets;
@@ -144,7 +144,7 @@ contract Hub is IHub, AccessManaged {
       _updateSpokeConfig(
         assetId,
         asset.feeReceiver,
-        SpokeConfig({addCap: 0, drawCap: 0, riskPremiumCap: 0, active: true, paused: false})
+        SpokeConfig({addCap: 0, drawCap: 0, riskPremiumThreshold: 0, active: true, paused: false})
       );
       asset.feeReceiver = config.feeReceiver;
       _addFeeReceiver(assetId, config.feeReceiver);
@@ -632,7 +632,7 @@ contract Hub is IHub, AccessManaged {
       SpokeConfig({
         addCap: spokeData.addCap,
         drawCap: spokeData.drawCap,
-        riskPremiumCap: spokeData.riskPremiumCap,
+        riskPremiumThreshold: spokeData.riskPremiumThreshold,
         active: spokeData.active,
         paused: spokeData.paused
       });
@@ -647,7 +647,7 @@ contract Hub is IHub, AccessManaged {
       SpokeConfig({
         addCap: MAX_ALLOWED_SPOKE_CAP,
         drawCap: 0,
-        riskPremiumCap: 0,
+        riskPremiumThreshold: 0,
         active: true,
         paused: false
       })
@@ -665,7 +665,7 @@ contract Hub is IHub, AccessManaged {
     SpokeData storage spokeData = _spokes[assetId][spoke];
     spokeData.addCap = config.addCap;
     spokeData.drawCap = config.drawCap;
-    spokeData.riskPremiumCap = config.riskPremiumCap;
+    spokeData.riskPremiumThreshold = config.riskPremiumThreshold;
     spokeData.active = config.active;
     spokeData.paused = config.paused;
     emit UpdateSpokeConfig(assetId, spoke, config);
@@ -682,9 +682,8 @@ contract Hub is IHub, AccessManaged {
   }
 
   /// @dev Applies premium deltas on asset & spoke premium owed.
-  /// @dev Checks premium owed does not increase by more than `premiumAmount`.
-  /// @dev Checks updated risk premium is within allowed limit.
-  /// @dev Can increase premium by 2 wei due to opposite rounding on premium shares and offset.
+  /// @dev Checks premium owed does not increase by more than `premiumAmount` + 2 wei (due to opposite rounding on premium shares and offset); reverts with `InvalidPremiumChange()` otherwise.
+  /// @dev Checks updated risk premium is within allowed threshold; reverts with `InvalidPremiumChange()` otherwise (even if risk premium decreases).
   function _applyPremiumDelta(
     Asset storage asset,
     SpokeData storage spoke,
@@ -713,10 +712,10 @@ contract Hub is IHub, AccessManaged {
       premiumAmount
     );
 
-    uint24 riskPremiumCap = spoke.riskPremiumCap;
+    uint24 riskPremiumThreshold = spoke.riskPremiumThreshold;
     require(
-      riskPremiumCap == MAX_ALLOWED_RISK_PREMIUM_CAP ||
-        spoke.premiumShares <= spoke.drawnShares.percentMulUp(riskPremiumCap),
+      riskPremiumThreshold == MAX_RISK_PREMIUM_THRESHOLD ||
+        spoke.premiumShares <= spoke.drawnShares.percentMulUp(riskPremiumThreshold),
       InvalidPremiumChange()
     );
   }

src/hub/HubConfigurator.sol

@@ -227,15 +227,15 @@ contract HubConfigurator is Ownable2Step, IHubConfigurator {
   }
 
   /// @inheritdoc IHubConfigurator
-  function updateSpokeRiskPremiumCap(
+  function updateSpokeRiskPremiumThreshold(
     address hub,
     uint256 assetId,
     address spoke,
-    uint256 riskPremiumCap
+    uint256 riskPremiumThreshold
   ) external onlyOwner {
     IHub targetHub = IHub(hub);
     IHub.SpokeConfig memory config = targetHub.getSpokeConfig(assetId, spoke);
-    config.riskPremiumCap = riskPremiumCap.toUint24();
+    config.riskPremiumThreshold = riskPremiumThreshold.toUint24();
     targetHub.updateSpokeConfig(assetId, spoke, config);
   }
 
@@ -245,10 +245,9 @@ contract HubConfigurator is Ownable2Step, IHubConfigurator {
     uint256 assetId,
     address spoke,
     uint256 addCap,
-    uint256 drawCap,
-    uint256 riskPremiumCap
+    uint256 drawCap
   ) external onlyOwner {
-    _updateSpokeCaps(IHub(hub), assetId, spoke, addCap, drawCap, riskPremiumCap);
+    _updateSpokeCaps(IHub(hub), assetId, spoke, addCap, drawCap);
   }
 
   /// @inheritdoc IHubConfigurator
@@ -306,13 +305,11 @@ contract HubConfigurator is Ownable2Step, IHubConfigurator {
     uint256 assetId,
     address spoke,
     uint256 addCap,
-    uint256 drawCap,
-    uint256 riskPremiumCap
+    uint256 drawCap
   ) internal {
     IHub.SpokeConfig memory config = hub.getSpokeConfig(assetId, spoke);
     config.addCap = addCap.toUint40();
     config.drawCap = drawCap.toUint40();
-    config.riskPremiumCap = riskPremiumCap.toUint24();
     hub.updateSpokeConfig(assetId, spoke, config);
   }
 

src/hub/interfaces/IHub.sol

@@ -71,7 +71,7 @@ interface IHub is IHubBase, IAccessManaged {
   /// @dev addedShares The added shares of a spoke for a given asset.
   /// @dev addCap The maximum amount that can be added by a spoke, expressed in whole assets (not scaled by decimals). A value of `MAX_ALLOWED_SPOKE_CAP` indicates no cap.
   /// @dev drawCap The maximum amount that can be drawn by a spoke, expressed in whole assets (not scaled by decimals). A value of `MAX_ALLOWED_SPOKE_CAP` indicates no cap.
-  /// @dev riskPremiumCap The maximum proportion of drawn shares that a spoke can update, expressed in BPS. A value of `MAX_ALLOWED_RISK_PREMIUM_CAP` indicates no cap.
+  /// @dev riskPremiumThreshold The maximum ratio of premium to drawn shares a spoke can have, expressed in BPS. A value of `MAX_RISK_PREMIUM_THRESHOLD` indicates no threshold.
   /// @dev active True if the spoke is prevented from performing any actions.
   /// @dev paused True if the spoke is prevented from performing actions that instantly update the liquidity.
   /// @dev deficit The deficit reported by a spoke for a given asset, expressed in asset units.
@@ -85,7 +85,7 @@ interface IHub is IHubBase, IAccessManaged {
     uint128 addedShares;
     uint40 addCap;
     uint40 drawCap;
-    uint24 riskPremiumCap;
+    uint24 riskPremiumThreshold;
     bool active;
     bool paused;
     //
@@ -96,7 +96,7 @@ interface IHub is IHubBase, IAccessManaged {
   struct SpokeConfig {
     uint40 addCap;
     uint40 drawCap;
-    uint24 riskPremiumCap;
+    uint24 riskPremiumThreshold;
     bool active;
     bool paused;
   }
@@ -372,5 +372,8 @@ interface IHub is IHubBase, IAccessManaged {
   /// @return The maximum cap value, expressed in asset units.
   function MAX_ALLOWED_SPOKE_CAP() external view returns (uint40);
 
-  function MAX_ALLOWED_RISK_PREMIUM_CAP() external view returns (uint24);
+  /// @notice Returns the maximum value for any spoke risk premium threshold.
+  /// @dev The value is not inclusive; using the maximum value indicates no threshold.
+  /// @return The maximum risk premium threshold, expressed in BPS.
+  function MAX_RISK_PREMIUM_THRESHOLD() external view returns (uint24);
 }

src/hub/interfaces/IHubConfigurator.sol

@@ -177,16 +177,16 @@ interface IHubConfigurator {
     uint256 drawCap
   ) external;
 
-  /// @notice Updates the risk premium cap of an asset's spoke.
+  /// @notice Updates the risk premium threshold of an asset's spoke.
   /// @param hub The address of the Hub contract.
   /// @param assetId The identifier of the asset.
   /// @param spoke The address of the spoke.
-  /// @param riskPremiumCap The new risk premium cap.
-  function updateSpokeRiskPremiumCap(
+  /// @param riskPremiumThreshold The new risk premium threshold.
+  function updateSpokeRiskPremiumThreshold(
     address hub,
     uint256 assetId,
     address spoke,
-    uint256 riskPremiumCap
+    uint256 riskPremiumThreshold
   ) external;
 
   /// @notice Updates the caps of an asset's spoke.
@@ -195,14 +195,12 @@ interface IHubConfigurator {
   /// @param spoke The address of the spoke.
   /// @param addCap The new supply cap.
   /// @param drawCap The new draw cap.
-  /// @param riskPremiumCap The new risk premium cap.
   function updateSpokeCaps(
     address hub,
     uint256 assetId,
     address spoke,
     uint256 addCap,
-    uint256 drawCap,
-    uint256 riskPremiumCap
+    uint256 drawCap
   ) external;
 
   /// @notice Deactivates all assets of a spoke on a specified hub by setting the active flag to false.

src/spoke/interfaces/ISpokeBase.sol

@@ -59,19 +59,19 @@ interface ISpokeBase {
   );
 
   /// @dev Emitted when a borrower is liquidated.
-  /// @param collateralAssetId The identifier of the asset used as collateral, to receive as result of the liquidation.
-  /// @param debtAssetId The identifier of the asset to be repaid with the liquidation.
+  /// @param collateralReserveId The identifier of the reserve used as collateral, to receive as a result of the liquidation.
+  /// @param debtReserveId The identifier of the reserve to be repaid with the liquidation.
   /// @param user The address of the borrower getting liquidated.
-  /// @param liquidatedDebt The debt amount of borrowed asset to be liquidated.
-  /// @param liquidatedCollateral The amount of collateral received by the liquidator.
+  /// @param debtToLiquidate The debt amount of borrowed reserve to be liquidated.
+  /// @param collateralToLiquidate The total amount of collateral asset to be liquidated, inclusive of liquidation fee.
   /// @param liquidator The address of the liquidator.
-  /// @param receiveShares Whether the liquidator receives collateral in supplied shares or in underlying assets.
+  /// @param receiveShares True if the liquidator receives collateral in supplied shares rather than underlying assets.
   event LiquidationCall(
-    uint256 indexed collateralAssetId,
-    uint256 indexed debtAssetId,
+    uint256 indexed collateralReserveId,
+    uint256 indexed debtReserveId,
     address indexed user,
-    uint256 liquidatedDebt,
-    uint256 liquidatedCollateral,
+    uint256 debtToLiquidate,
+    uint256 collateralToLiquidate,
     address liquidator,
     bool receiveShares
   );

tests/Base.t.sol

@@ -428,7 +428,7 @@ abstract contract Base is Test {
       paused: false,
       addCap: Constants.MAX_ALLOWED_SPOKE_CAP,
       drawCap: Constants.MAX_ALLOWED_SPOKE_CAP,
-      riskPremiumCap: Constants.MAX_ALLOWED_COLLATERAL_RISK
+      riskPremiumThreshold: Constants.MAX_ALLOWED_COLLATERAL_RISK
     });
 
     bytes memory encodedIrData = abi.encode(
@@ -1264,14 +1264,14 @@ abstract contract Base is Test {
     assertEq(hub.getSpokeConfig(assetId, spoke), spokeConfig);
   }
 
-  function _updateSpokeRiskPremiumCap(
+  function _updateSpokeRiskPremiumThreshold(
     IHub hub,
     uint256 assetId,
     address spoke,
-    uint24 newRiskPremiumCap
+    uint24 newRiskPremiumThreshold
   ) internal pausePrank {
     IHub.SpokeConfig memory spokeConfig = hub.getSpokeConfig(assetId, spoke);
-    spokeConfig.riskPremiumCap = newRiskPremiumCap;
+    spokeConfig.riskPremiumThreshold = newRiskPremiumThreshold;
     vm.prank(HUB_ADMIN);
     hub.updateSpokeConfig(assetId, spoke, spokeConfig);
 
@@ -2077,7 +2077,7 @@ abstract contract Base is Test {
   function assertEq(IHub.SpokeConfig memory a, IHub.SpokeConfig memory b) internal pure {
     assertEq(a.addCap, b.addCap, 'addCap');
     assertEq(a.drawCap, b.drawCap, 'drawCap');
-    assertEq(a.riskPremiumCap, b.riskPremiumCap, 'riskPremiumCap');
+    assertEq(a.riskPremiumThreshold, b.riskPremiumThreshold, 'riskPremiumThreshold');
     assertEq(a.active, b.active, 'active');
     assertEq(a.paused, b.paused, 'paused');
     assertEq(abi.encode(a), abi.encode(b));

tests/Constants.sol

@@ -7,7 +7,7 @@ library Constants {
   uint8 public constant MAX_ALLOWED_UNDERLYING_DECIMALS = 18;
   uint8 public constant MIN_ALLOWED_UNDERLYING_DECIMALS = 6;
   uint40 public constant MAX_ALLOWED_SPOKE_CAP = type(uint40).max;
-  uint24 public constant MAX_ALLOWED_RISK_PREMIUM_CAP = type(uint24).max; // 167772.15%
+  uint24 public constant MAX_RISK_PREMIUM_THRESHOLD = type(uint24).max; // 167772.15%
 
   /// @dev Spoke Constants
   uint8 public constant ORACLE_DECIMALS = 8;