fix: round up for burn

contracts/PointTokenVault.sol

@@ -12,6 +12,7 @@ import {ERC20} from "solmate/tokens/ERC20.sol";
 import {SafeTransferLib} from "solmate/utils/SafeTransferLib.sol";
 
 import {LibString} from "solady/utils/LibString.sol";
+import {FixedPointMathLib} from "solmate/utils/FixedPointMathLib.sol";
 
 import {PToken} from "./PToken.sol";
 
@@ -146,8 +147,8 @@ contract PointTokenVault is UUPSUpgradeable, AccessControlUpgradeable, Multicall
             _verifyClaimAndUpdateClaimed(_claim, claimHash, msg.sender, claimedRedemptionRights);
         }
 
-        // Will fail if the user doesn't also have enough point tokens.
-        pTokens[pointsId].burn(msg.sender, amountToClaim * 1e18 / rewardsPerPToken);
+        // Will fail if the user doesn't also have enough point tokens. Assume rewardsPerPToken is 18 decimals.
+        pTokens[pointsId].burn(msg.sender, FixedPointMathLib.mulWadUp(amountToClaim, rewardsPerPToken)); // Round up for burn.
         rewardToken.safeTransfer(_receiver, amountToClaim);
         emit RewardsClaimed(msg.sender, _receiver, pointsId, amountToClaim);
     }

contracts/test/PointTokenVault.t.sol

@@ -362,6 +362,31 @@ contract PointTokenVaultTest is Test {
         assertEq(rewardToken.balanceOf(vitalik), 2e18);
     }
 
+    function test_RedeemRounding() public {
+        bytes32 root = 0x4e40a10ce33f33a4786960a8bb843fe0e170b651acd83da27abc97176c4bed3c;
+
+        bytes32[] memory proof = new bytes32[](1);
+        proof[0] = 0x6d0fcb8de12b1f57f81e49fa18b641487b932cdba4f064409fde3b05d3824ca2;
+
+        vm.prank(merkleUpdater);
+        pointTokenVault.updateRoot(root);
+
+        vm.prank(vitalik);
+        pointTokenVault.claimPTokens(PointTokenVault.Claim(eigenPointsId, 1e18, 1e18, proof), vitalik);
+
+        rewardToken.mint(address(pointTokenVault), 3e18);
+
+        vm.prank(operator);
+        pointTokenVault.setRedemption(eigenPointsId, rewardToken, 2e18, false);
+
+        bytes32[] memory empty = new bytes32[](0);
+        vm.prank(vitalik);
+        pointTokenVault.redeemRewards(PointTokenVault.Claim(eigenPointsId, 2e18, 1, empty), vitalik);
+
+        assertEq(rewardToken.balanceOf(vitalik), 1);
+        assertEq(pointTokenVault.pTokens(eigenPointsId).balanceOf(vitalik), 1e18 - 2); // round up for burn.
+    }
+
     event RewardsClaimed(address indexed owner, address indexed receiver, bytes32 indexed pointsId, uint256 amount);
 
     function test_MerkleBasedRedemption() public {