Update _assertAuction to check borrower t0ReserveSettleAmount and add invariant A10

src/PoolInfoUtils.sol

@@ -83,7 +83,7 @@ contract PoolInfoUtils is Multicall {
             kickTime_,
             referencePrice_,
             neutralPrice_,
-            debtToCollateral_, , , ) = IPool(ajnaPool_).auctionInfo(borrower_);
+            debtToCollateral_, , , , ) = IPool(ajnaPool_).auctionInfo(borrower_);
 
         if (kickTime_ != 0) {
             (debtToCover_, collateral_, , ) = this.borrowerInfo(ajnaPool_, borrower_);
@@ -99,18 +99,19 @@ contract PoolInfoUtils is Multicall {
     /**
      *  @notice Returns details of an auction for a given borrower address.
      *  @dev    Calls and returns all values from pool.auctionInfo().
-     *  @param  ajnaPool_         Address of `Ajna` pool.
-     *  @param  borrower_         Address of the borrower that is liquidated.
-     *  @return kicker_           Address of the kicker that is kicking the auction.
-     *  @return bondFactor_       The factor used for calculating bond size.
-     *  @return bondSize_         The bond amount in quote token terms.
-     *  @return kickTime_         Time the liquidation was initiated.
-     *  @return referencePrice_   Price used to determine auction start price.
-     *  @return neutralPrice_     `Neutral Price` of auction.
-     *  @return debtToCollateral_ Borrower debt to collateral at time of kick, which is used in BPF for kicker's reward calculation.
-     *  @return head_             Address of the head auction.
-     *  @return next_             Address of the next auction in queue.
-     *  @return prev_             Address of the prev auction in queue.
+     *  @param  ajnaPool_              Address of `Ajna` pool.
+     *  @param  borrower_              Address of the borrower that is liquidated.
+     *  @return kicker_                Address of the kicker that is kicking the auction.
+     *  @return bondFactor_            The factor used for calculating bond size.
+     *  @return bondSize_              The bond amount in quote token terms.
+     *  @return kickTime_              Time the liquidation was initiated.
+     *  @return referencePrice_        Price used to determine auction start price.
+     *  @return neutralPrice_          `Neutral Price` of auction.
+     *  @return debtToCollateral_      Borrower debt to collateral at time of kick, which is used in BPF for kicker's reward calculation.
+     *  @return t0ReserveSettleAmount_ Amount of t0Debt that could be settled via reserves in this auction
+     *  @return head_                  Address of the head auction.
+     *  @return next_                  Address of the next auction in queue.
+     *  @return prev_                  Address of the prev auction in queue.
      */
     function auctionInfo(address ajnaPool_, address borrower_) external view returns (
         address kicker_,
@@ -120,6 +121,7 @@ contract PoolInfoUtils is Multicall {
         uint256 referencePrice_,
         uint256 neutralPrice_,
         uint256 debtToCollateral_,
+        uint256 t0ReserveSettleAmount_,
         address head_,
         address next_,
         address prev_

src/base/Pool.sol

@@ -741,6 +741,7 @@ abstract contract Pool is Clone, ReentrancyGuard, Multicall, IPool {
         uint256 referencePrice_,
         uint256 neutralPrice_,
         uint256 debtToCollateral_,
+        uint256 t0ReserveSettleAmount_,
         address head_,
         address next_,
         address prev_
@@ -754,6 +755,7 @@ abstract contract Pool is Clone, ReentrancyGuard, Multicall, IPool {
             liquidation.referencePrice,
             liquidation.neutralPrice,
             liquidation.debtToCollateral,
+            liquidation.t0ReserveSettleAmount,
             auctions.head,
             liquidation.next,
             liquidation.prev

src/interfaces/pool/commons/IPoolState.sol

@@ -9,17 +9,18 @@ interface IPoolState {
 
     /**
      *  @notice Returns details of an auction for a given borrower address.
-     *  @param  borrower_         Address of the borrower that is liquidated.
-     *  @return kicker_           Address of the kicker that is kicking the auction.
-     *  @return bondFactor_       The factor used for calculating bond size.
-     *  @return bondSize_         The bond amount in quote token terms.
-     *  @return kickTime_         Time the liquidation was initiated.
-     *  @return referencePrice_   Price used to determine auction start price.
-     *  @return neutralPrice_     `Neutral Price` of auction.
-     *  @return debtToCollateral_ Borrower debt to collateral, which is used in BPF for kicker's reward calculation.
-     *  @return head_             Address of the head auction.
-     *  @return next_             Address of the next auction in queue.
-     *  @return prev_             Address of the prev auction in queue.
+     *  @param  borrower_              Address of the borrower that is liquidated.
+     *  @return kicker_                Address of the kicker that is kicking the auction.
+     *  @return bondFactor_            The factor used for calculating bond size.
+     *  @return bondSize_              The bond amount in quote token terms.
+     *  @return kickTime_              Time the liquidation was initiated.
+     *  @return referencePrice_        Price used to determine auction start price.
+     *  @return neutralPrice_          `Neutral Price` of auction.
+     *  @return debtToCollateral_      Borrower debt to collateral, which is used in BPF for kicker's reward calculation.
+     *  @return t0ReserveSettleAmount_ Amount of t0Debt that could be settled via reserves in this auction
+     *  @return head_                  Address of the head auction.
+     *  @return next_                  Address of the next auction in queue.
+     *  @return prev_                  Address of the prev auction in queue.
      */
     function auctionInfo(address borrower_)
         external
@@ -32,6 +33,7 @@ interface IPoolState {
             uint256 referencePrice_,
             uint256 neutralPrice_,
             uint256 debtToCollateral_,
+            uint256 t0ReserveSettleAmount_,
             address head_,
             address next_,
             address prev_

tests/INVARIANTS.md

@@ -26,6 +26,7 @@
 - **A7**: total bond escrowed accumulator (`AuctionsState.totalBondEscrowed`) should increase when auction is kicked with the difference needed to cover the bond and should decrease only when kicker bonds withdrawn (`Pool.withdrawBonds`). Claimable bonds should be available for withdrawal from pool at any time.  
 - **A8**: Upon a take/arbtake/deposittake the kicker reward <= borrower penalty
 - **A9**: reference prices in liquidation queue shall not decrease
+- **A10**: Upon kick `t0ReserveSettleAmount` should be set to `BorrowerT0Debt * borrowFeeRate / 2` for the kicked borrower.
 
 ## Loans
 - **L1**: for each `Loan` in loans array (`LoansState.loans`) starting from index 1, the corresponding address (`Loan.borrower`) is not `0x`, the borrower t0 debt to collateral (`Loan.t0DebtToCollateral`) is different than 0 and the id mapped in indices mapping (`LoansState.indices`) equals index of loan in loans array.

tests/forge/interactions/PurchaseQuoteWithExternalLiquidity.t.sol

@@ -21,7 +21,7 @@ contract PurchaseQuoteWithExternalLiquidityTest is Test {
     address   internal _lender;
 
     function setUp() external {
-        vm.createSelectFork(vm.envString("ETH_RPC_URL"));
+        vm.createSelectFork(vm.envString("ETH_RPC_URL"), 18800000);
         _ajnaPool = ERC20Pool(new ERC20PoolFactory(AJNA).deployPool(WETH, USDC, 0.05 * 10**18));
         _lender   = makeAddr("lender");
 

tests/forge/invariants/PositionManager/handlers/ERC20PoolPositionHandler.sol

@@ -24,7 +24,7 @@ contract ERC20PoolPositionHandler is PositionPoolHandler, BaseERC20PoolHandler,
     address[] internal _borrowers;
 
     uint16 internal constant LENDERS = 200;
-    uint16 internal constant LOANS_COUNT = 500;
+    uint16 internal constant LOANS_COUNT = 320;
     uint16 nonce;
     uint256 numberOfBuckets;
 
@@ -117,7 +117,7 @@ contract ERC20PoolPositionHandler is PositionPoolHandler, BaseERC20PoolHandler,
     ) external useTimestamps useRandomActor(takerIndex_) skipTime(skippedTime_) writeLogs {
         address borrower = _borrowers[constrictToRange(borrowerIndex_, 0, _borrowers.length - 1)];
 
-        (, , , uint256 kickTime, , , , , , ) = _pool.auctionInfo(borrower);
+        (, , , uint256 kickTime, , , , , , , ) = _pool.auctionInfo(borrower);
 
         // Kick borrower if not already kicked
         if (kickTime == 0) {

tests/forge/invariants/base/BasicInvariants.t.sol

@@ -321,7 +321,7 @@ abstract contract BasicInvariants is BaseInvariants {
         for (uint256 i = 0; i < actorCount; i++) {
             address borrower = IBaseHandler(_handler).actors(i);
 
-            (, , , uint256 kickTime, , , , , , ) = _pool.auctionInfo(borrower);
+            (, , , uint256 kickTime, , , , , , , ) = _pool.auctionInfo(borrower);
 
             if (kickTime == 0) {
                 (uint256 borrowerT0Debt, uint256 borrowerCollateral, ) = _pool.borrowerInfo(borrower);

tests/forge/invariants/base/LiquidationInvariants.t.sol

@@ -22,6 +22,7 @@ abstract contract LiquidationInvariants is BasicInvariants {
         _invariant_A7();
         _invariant_A8();
         _invariant_A9();
+        _invariant_A10();
     }
 
     /// @dev checks sum of all borrower's t0debt is equals to total pool t0debtInAuction
@@ -31,7 +32,7 @@ abstract contract LiquidationInvariants is BasicInvariants {
 
         for (uint256 i = 0; i < actorCount; i++) {
             address borrower = IBaseHandler(_handler).actors(i);
-            (, , , uint256 kickTime, , , , , , ) = _pool.auctionInfo(borrower);
+            (, , , uint256 kickTime, , , , , , , ) = _pool.auctionInfo(borrower);
 
             if (kickTime != 0) {
                 (uint256 t0debt, , ) = _pool.borrowerInfo(borrower);
@@ -63,7 +64,7 @@ abstract contract LiquidationInvariants is BasicInvariants {
         uint256 lockedBonds;
         for (uint256 i = 0; i < actorCount; i++) {
             address borrower = IBaseHandler(_handler).actors(i);
-            (, , uint256 bond, , , , , , , ) = _pool.auctionInfo(borrower);
+            (, , uint256 bond, , , , , , , , ) = _pool.auctionInfo(borrower);
             lockedBonds += bond;
         }
         require(lockedBonds == kickerLockedBond, "A2: bonds in auctions != than kicker locked bonds");
@@ -95,7 +96,7 @@ abstract contract LiquidationInvariants is BasicInvariants {
         for (uint256 i = 0; i < actorCount; i++) {
             address borrower = IBaseHandler(_handler).actors(i);
 
-            (, , , uint256 kickTime, , , , , , ) = _pool.auctionInfo(borrower);
+            (, , , uint256 kickTime, , , , , , , ) = _pool.auctionInfo(borrower);
 
             if (kickTime != 0) borrowersKicked += 1;
         }
@@ -109,7 +110,7 @@ abstract contract LiquidationInvariants is BasicInvariants {
 
         for (uint256 i = 0; i < actorCount; i++) {
             address borrower = IBaseHandler(_handler).actors(i);
-            (address kicker, , uint256 bondSize, , , , , , , ) = _pool.auctionInfo(borrower);
+            (address kicker, , uint256 bondSize, , , , , , , , ) = _pool.auctionInfo(borrower);
             (, uint256 lockedAmount) = _pool.kickerInfo(kicker);
 
             require(lockedAmount >= bondSize, "Auction Invariant A5");
@@ -145,13 +146,26 @@ abstract contract LiquidationInvariants is BasicInvariants {
     /// @dev reference prices in liquidation queue shall not decrease
     function _invariant_A9() internal view {
         uint256 referencePrice;
-        (,,,, uint256 lastReferencePrice,,, address nextBorrower,,) = _pool.auctionInfo(address(0));
+        (,,,, uint256 lastReferencePrice,,,, address nextBorrower,,) = _pool.auctionInfo(address(0));
         while (nextBorrower != address(0)) {
-            (,,,, referencePrice,,,, nextBorrower,) = _pool.auctionInfo(nextBorrower);
+            (,,,, referencePrice,,,,, nextBorrower,) = _pool.auctionInfo(nextBorrower);
             require(lastReferencePrice <= referencePrice, "Auction Invariant A9");
             lastReferencePrice = referencePrice;
         }
     }
+
+    /// @dev borrower t0 reserve settle amount should be set borrowerT0debt * borrowFeeRate / 2.
+    function _invariant_A10() internal view {
+        uint256 actorCount = IBaseHandler(_handler).getActorsCount();
+
+        for (uint256 i = 0; i < actorCount; i++) {
+            address borrower = IBaseHandler(_handler).actors(i);
+            uint256 borrowerT0ReserveSettleAmount = IBaseHandler(_handler).borrowerT0ReserveSettleAmount(borrower);
+            (,,,,,,,uint256 requiredT0ReserveSettleAmount,,,) = _pool.auctionInfo(borrower);
+
+            require(borrowerT0ReserveSettleAmount == requiredT0ReserveSettleAmount, "Auction Invariant A10");
+        }
+    }
 
     function invariant_call_summary() public virtual override useCurrentTimestamp {
         console.log("\nCall Summary\n");

tests/forge/invariants/base/handlers/unbounded/BaseHandler.sol

@@ -50,12 +50,11 @@ abstract contract BaseHandler is Test {
 
     struct AuctionInfo {
         address kicker;
-        uint256 bondFactor;
-        uint256 bondSize;
         uint256 kickTime;
         uint256 referencePrice;
         uint256 neutralPrice;
         uint256 debtToCollateral;
+        uint256 t0ReserveSettleAmount;
         uint256 auctionPrice;
         uint256 auctionPriceIndex;
         address head;
@@ -144,6 +143,9 @@ abstract contract BaseHandler is Test {
     uint256 public borrowerPenalty; // Borrower penalty on take
     uint256 public kickerReward;    // Kicker reward on take
 
+    // Borrower reserve settlement state
+    mapping(address => uint256) public borrowerT0ReserveSettleAmount;
+
     // All Buckets used in invariant testing that also includes Buckets where collateral is added when a borrower is in auction and has partial NFT
     EnumerableSet.UintSet internal buckets;
 
@@ -331,12 +333,13 @@ abstract contract BaseHandler is Test {
     function _getAuctionInfo(address borrower_) internal view returns (AuctionInfo memory auctionInfo_) {
         (
             auctionInfo_.kicker,
-            auctionInfo_.bondFactor,
-            auctionInfo_.bondSize,
+            ,
+            ,
             auctionInfo_.kickTime,
             auctionInfo_.referencePrice,
             auctionInfo_.neutralPrice,
             auctionInfo_.debtToCollateral,
+            auctionInfo_.t0ReserveSettleAmount,
             auctionInfo_.head,
             ,
         ) = _pool.auctionInfo(borrower_);
@@ -527,6 +530,12 @@ abstract contract BaseHandler is Test {
         decreaseInBonds = 0;
         // record totalBondEscrowed before each action
         (previousTotalBonds, , , , ) = _pool.reservesInfo();
+
+        // Record borrower reserve settle amount
+        for(uint256 i = 0; i < actors.length; i++) {
+            address borrower = actors[i];
+            borrowerT0ReserveSettleAmount[borrower] = _getAuctionInfo(borrower).t0ReserveSettleAmount;
+        }
     }
 
     /********************************/
@@ -662,7 +671,7 @@ abstract contract BaseHandler is Test {
         ) = _poolInfo.poolLoansInfo(address(_pool));
 
         (
-            , , , , , , ,
+            , , , , , , , ,
             address headAuction, ,
         ) = _pool.auctionInfo(address(0));
 
@@ -778,11 +787,11 @@ abstract contract BaseHandler is Test {
         uint256 bondFactor;
         uint256 bondSize;
         uint256 neutralPrice;
-        (,,,,,,, nextBorrower,,) = _pool.auctionInfo(address(0));
+        (,,,,,,,, nextBorrower,,) = _pool.auctionInfo(address(0));
         while (nextBorrower != address(0)) {
             data = string(abi.encodePacked("Borrower ", Strings.toHexString(uint160(nextBorrower), 20), " Auction Details :"));
             printInNextLine(data);
-            (, bondFactor, bondSize, kickTime, referencePrice, neutralPrice,,, nextBorrower,) = _pool.auctionInfo(nextBorrower);
+            (, bondFactor, bondSize, kickTime, referencePrice, neutralPrice,,,, nextBorrower,) = _pool.auctionInfo(nextBorrower);
 
             printLog("Bond Factor     = ", bondFactor);
             printLog("Bond Size       = ", bondSize);