Remove fees (borrow and redeem) and SP logic for LQTY and front ends

contracts/src/BoldToken.sol

@@ -46,6 +46,8 @@ contract BoldToken is CheckContract, IBoldToken {
 
     mapping (address => uint256) private _nonces;
 
+    uint256 public deploymentStartTime;
+
     // User data for Bold token
     mapping (address => uint256) private _balances;
     mapping (address => mapping (address => uint256)) private _allowances;  
@@ -88,6 +90,8 @@ contract BoldToken is CheckContract, IBoldToken {
         _HASHED_VERSION = hashedVersion;
         _CACHED_CHAIN_ID = _chainID();
         _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(_TYPE_HASH, hashedName, hashedVersion);
+
+        deploymentStartTime = block.timestamp;
     }
 
     // --- Functions for intra-Liquity calls ---

contracts/src/BorrowerOperations.sol

@@ -165,8 +165,7 @@ contract BorrowerOperations is LiquityBase, Ownable, CheckContract, IBorrowerOpe
         vars.netDebt = _boldAmount;
 
         if (!isRecoveryMode) {
-            vars.BoldFee = _triggerBorrowingFee(contractsCache.troveManager, contractsCache.boldToken, _boldAmount, _maxFeePercentage);
-            vars.netDebt = vars.netDebt + vars.BoldFee;
+            // TODO: implement interest rate charges
         }
         _requireAtLeastMinNetDebt(vars.netDebt);
 
@@ -271,8 +270,7 @@ contract BorrowerOperations is LiquityBase, Ownable, CheckContract, IBorrowerOpe
 
         // If the adjustment incorporates a debt increase and system is in Normal Mode, then trigger a borrowing fee
         if (_isDebtIncrease && !isRecoveryMode) { 
-            vars.BoldFee = _triggerBorrowingFee(contractsCache.troveManager, contractsCache.boldToken, _boldChange, _maxFeePercentage);
-            vars.netDebtChange = vars.netDebtChange + vars.BoldFee; // The raw debt change includes the fee
+            // TODO: implement interest rate charges
         }
 
         vars.debt = contractsCache.troveManager.getTroveDebt(_borrower);
@@ -358,19 +356,6 @@ contract BorrowerOperations is LiquityBase, Ownable, CheckContract, IBorrowerOpe
 
     // --- Helper functions ---
 
-    function _triggerBorrowingFee(ITroveManager _troveManager, IBoldToken _boldToken, uint _boldAmount, uint _maxFeePercentage) internal returns (uint) {
-        _troveManager.decayBaseRateFromBorrowing(); // decay the baseRate state variable
-        uint BoldFee = _troveManager.getBorrowingFee(_boldAmount);
-
-        _requireUserAcceptsFee(BoldFee, _boldAmount, _maxFeePercentage);
-
-        // Send fee to LQTY staking contract
-        lqtyStaking.increaseF_bold(BoldFee);
-        _boldToken.mint(lqtyStakingAddress, BoldFee);
-
-        return BoldFee;
-    }
-
     function _getUSDValue(uint _coll, uint _price) internal pure returns (uint) {
         uint usdValue = _price * _coll / DECIMAL_PRECISION;
 

contracts/src/Interfaces/IBoldToken.sol

@@ -6,6 +6,8 @@ import "../Dependencies/IERC20.sol";
 import "../Dependencies/IERC2612.sol";
 
 interface IBoldToken is IERC20, IERC2612 { 
+    function deploymentStartTime() external view returns (uint256);
+
     function mint(address _account, uint256 _amount) external;
 
     function burn(address _account, uint256 _amount) external;

contracts/src/Interfaces/IStabilityPool.sol

@@ -27,18 +27,7 @@ import "./ITroveManager.sol";
  * Please see the implementation spec in the proof document, which closely follows on from the compounded deposit / ETH gain derivations:
  * https://github.com/liquity/liquity/blob/master/papers/Scalable_Reward_Distribution_with_Compounding_Stakes.pdf
  *
- * --- LQTY ISSUANCE TO STABILITY POOL DEPOSITORS ---
- *
- * An LQTY issuance event occurs at every deposit operation, and every liquidation.
- *
- * Each deposit is tagged with the address of the front end through which it was made.
- *
- * All deposits earn a share of the issued LQTY in proportion to the deposit as a share of total deposits. The LQTY earned
- * by a given deposit, is split between the depositor and the front end through which the deposit was made, based on the front end's kickbackRate.
- *
- * Please see the system Readme for an overview:
- * https://github.com/liquity/dev/blob/main/README.md#lqty-issuance-to-stability-providers
- */
+*/
 interface IStabilityPool is ILiquityBase {
     function borrowerOperations() external view returns (IBorrowerOperations);
     function boldToken() external view returns (IBoldToken);
@@ -54,64 +43,34 @@ interface IStabilityPool is ILiquityBase {
         address _activePoolAddress,
         address _boldTokenAddress,
         address _sortedTrovesAddress,
-        address _priceFeedAddress,
-        address _communityIssuanceAddress
+        address _priceFeedAddress
     ) external;
-
-    /*
-     * Initial checks:
-     * - Frontend is registered or zero address
-     * - Sender is not a registered frontend
-     * - _amount is not zero
-     * ---
-     * - Triggers a LQTY issuance, based on time passed since the last issuance. The LQTY issuance is shared between *all* depositors and front ends
-     * - Tags the deposit with the provided front end tag param, if it's a new deposit
-     * - Sends depositor's accumulated gains (LQTY, ETH) to depositor
-     * - Sends the tagged front end's accumulated LQTY gains to the tagged front end
-     * - Increases deposit and tagged front end's stake, and takes new snapshots for each.
-     */
-    function provideToSP(uint _amount, address _frontEndTag) external;
-
-    /*
-     * Initial checks:
-     * - _amount is zero or there are no under collateralized troves left in the system
-     * - User has a non zero deposit
-     * ---
-     * - Triggers a LQTY issuance, based on time passed since the last issuance. The LQTY issuance is shared between *all* depositors and front ends
-     * - Removes the deposit's front end tag if it is a full withdrawal
-     * - Sends all depositor's accumulated gains (LQTY, ETH) to depositor
-     * - Sends the tagged front end's accumulated LQTY gains to the tagged front end
-     * - Decreases deposit and tagged front end's stake, and takes new snapshots for each.
-     *
-     * If _amount > userDeposit, the user withdraws all of their compounded deposit.
-     */
+
+    /*  provideToSP():
+    * - Calculates depositor's ETH gain
+    * - Calculates the compounded deposit
+    * - Increases deposit, and takes new snapshots of accumulators P and S
+    * - Sends depositor's accumulated ETH gains to depositor
+    */
+    function provideToSP(uint _amount) external;
+
+
+    /*  withdrawFromSP():
+    * - Calculates depositor's ETH gain
+    * - Calculates the compounded deposit
+    * - Sends the requested BOLD withdrawal to depositor 
+    * - (If _amount > userDeposit, the user withdraws all of their compounded deposit)
+    * - Decreases deposit by withdrawn amount and takes new snapshots of accumulators P and S
+    */
     function withdrawFromSP(uint _amount) external;
 
-    /*
-     * Initial checks:
-     * - User has a non zero deposit
-     * - User has an open trove
-     * - User has some ETH gain
-     * ---
-     * - Triggers a LQTY issuance, based on time passed since the last issuance. The LQTY issuance is shared between *all* depositors and front ends
-     * - Sends all depositor's LQTY gain to  depositor
-     * - Sends all tagged front end's LQTY gain to the tagged front end
-     * - Transfers the depositor's entire ETH gain from the Stability Pool to the caller's trove
-     * - Leaves their compounded deposit in the Stability Pool
-     * - Updates snapshots for deposit and tagged front end stake
-     */
+    /* withdrawETHGainToTrove():
+    * - Transfers the depositor's entire ETH gain from the Stability Pool to the caller's trove
+    * - Leaves their compounded deposit in the Stability Pool
+    * - Takes new snapshots of accumulators P and S 
+    */
     function withdrawETHGainToTrove(address _upperHint, address _lowerHint) external;
 
-    /*
-     * Initial checks:
-     * - Frontend (sender) not already registered
-     * - User (sender) has no deposit
-     * - _kickbackRate is in the range [0, 100%]
-     * ---
-     * Front end makes a one-time selection of kickback rate upon registering
-     */
-    function registerFrontEnd(uint _kickbackRate) external;
-
     /*
      * Initial checks:
      * - Caller is TroveManager
@@ -138,31 +97,11 @@ interface IStabilityPool is ILiquityBase {
      */
     function getDepositorETHGain(address _depositor) external view returns (uint);
 
-    /*
-     * Calculate the LQTY gain earned by a deposit since its last snapshots were taken.
-     * If not tagged with a front end, the depositor gets a 100% cut of what their deposit earned.
-     * Otherwise, their cut of the deposit's earnings is equal to the kickbackRate, set by the front end through
-     * which they made their deposit.
-     */
-    function getDepositorLQTYGain(address _depositor) external view returns (uint);
-
-    /*
-     * Return the LQTY gain earned by the front end.
-     */
-    function getFrontEndLQTYGain(address _frontEnd) external view returns (uint);
-
     /*
      * Return the user's compounded deposit.
      */
     function getCompoundedBoldDeposit(address _depositor) external view returns (uint);
 
-    /*
-     * Return the front end's compounded stake.
-     *
-     * The front end's compounded stake is equal to the sum of its depositors' compounded deposits.
-     */
-    function getCompoundedFrontEndStake(address _frontEnd) external view returns (uint);
-
     /*
      * Fallback function
      * Only callable by Active Pool, it just accounts for ETH received

contracts/src/Interfaces/ITroveManager.sol

@@ -33,6 +33,8 @@ interface ITroveManager is ILiquityBase {
     function sortedTroves() external view returns(ISortedTroves);
     function borrowerOperationsAddress() external view returns (address);
 
+    function BOOTSTRAP_PERIOD() external view returns (uint256);
+
     function getTroveOwnersCount() external view returns (uint);
 
     function getTroveFromTroveOwnersArray(uint _index) external view returns (address);