fix(contracts): owner vault metadata compatibility (#4566)

### Description

- Added PRECISION and rateUpdateNonce to ensure compatibility of
HypERC4626 (even though this is not a useful warp route bc exchangeRate
will stay at 1e10)

### Drive-by changes

None

### Related issues

- closes https://github.com/chainlight-io/2024-08-hyperlane/issues/9

### Backward compatibility

No

### Testing

Unit test

.changeset/sweet-humans-argue.md

@@ -0,0 +1,5 @@
+---
+'@hyperlane-xyz/core': minor
+---
+
+Added PRECISION and rateUpdateNonce to ensure compatibility of HypERC4626

solidity/contracts/token/extensions/HypERC4626.sol

@@ -1,13 +1,28 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 pragma solidity >=0.8.0;
 
+/*@@@@@@@       @@@@@@@@@
+ @@@@@@@@@       @@@@@@@@@
+  @@@@@@@@@       @@@@@@@@@
+   @@@@@@@@@       @@@@@@@@@
+    @@@@@@@@@@@@@@@@@@@@@@@@@
+     @@@@@  HYPERLANE  @@@@@@@
+    @@@@@@@@@@@@@@@@@@@@@@@@@
+   @@@@@@@@@       @@@@@@@@@
+  @@@@@@@@@       @@@@@@@@@
+ @@@@@@@@@       @@@@@@@@@
+@@@@@@@@@       @@@@@@@@*/
+
+// ============ Internal Imports ============
 import {IXERC20} from "../interfaces/IXERC20.sol";
 import {HypERC20} from "../HypERC20.sol";
-import {Math} from "@openzeppelin/contracts/utils/math/Math.sol";
 import {Message} from "../../libs/Message.sol";
 import {TokenMessage} from "../libs/TokenMessage.sol";
 import {TokenRouter} from "../libs/TokenRouter.sol";
 
+// ============ External Imports ============
+import {Math} from "@openzeppelin/contracts/utils/math/Math.sol";
+
 /**
  * @title Hyperlane ERC20 Rebasing Token
  * @author Abacus Works

solidity/contracts/token/extensions/HypERC4626Collateral.sol

@@ -1,11 +1,26 @@
 // SPDX-License-Identifier: Apache-2.0
 pragma solidity >=0.8.0;
 
-import "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
+/*@@@@@@@       @@@@@@@@@
+ @@@@@@@@@       @@@@@@@@@
+  @@@@@@@@@       @@@@@@@@@
+   @@@@@@@@@       @@@@@@@@@
+    @@@@@@@@@@@@@@@@@@@@@@@@@
+     @@@@@  HYPERLANE  @@@@@@@
+    @@@@@@@@@@@@@@@@@@@@@@@@@
+   @@@@@@@@@       @@@@@@@@@
+  @@@@@@@@@       @@@@@@@@@
+ @@@@@@@@@       @@@@@@@@@
+@@@@@@@@@       @@@@@@@@*/
+
+// ============ Internal Imports ============
 import {TokenMessage} from "../libs/TokenMessage.sol";
 import {HypERC20Collateral} from "../HypERC20Collateral.sol";
 import {TypeCasts} from "../../libs/TypeCasts.sol";
 
+// ============ External Imports ============
+import "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
+
 /**
  * @title Hyperlane ERC4626 Token Collateral with deposits collateral to a vault
  * @author Abacus Works
@@ -17,7 +32,9 @@ contract HypERC4626Collateral is HypERC20Collateral {
 
     // Address of the ERC4626 compatible vault
     ERC4626 public immutable vault;
+    // Precision for the exchange rate
     uint256 public constant PRECISION = 1e10;
+    // Null recipient for rebase transfer
     bytes32 public constant NULL_RECIPIENT =
         0x0000000000000000000000000000000000000000000000000000000000000001;
     // Nonce for the rate update, to ensure sequential updates

solidity/contracts/token/extensions/HypERC4626OwnerCollateral.sol

@@ -1,9 +1,24 @@
 // SPDX-License-Identifier: Apache-2.0
 pragma solidity >=0.8.0;
 
-import "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
+/*@@@@@@@       @@@@@@@@@
+ @@@@@@@@@       @@@@@@@@@
+  @@@@@@@@@       @@@@@@@@@
+   @@@@@@@@@       @@@@@@@@@
+    @@@@@@@@@@@@@@@@@@@@@@@@@
+     @@@@@  HYPERLANE  @@@@@@@
+    @@@@@@@@@@@@@@@@@@@@@@@@@
+   @@@@@@@@@       @@@@@@@@@
+  @@@@@@@@@       @@@@@@@@@
+ @@@@@@@@@       @@@@@@@@@
+@@@@@@@@@       @@@@@@@@*/
+
+// ============ Internal Imports ============
 import {HypERC20Collateral} from "../HypERC20Collateral.sol";
 
+// ============ External Imports ============
+import {ERC4626} from "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
+
 /**
  * @title Hyperlane ERC20 Token Collateral with deposits collateral to a vault, the yield goes to the owner
  * @author ltyu
@@ -11,9 +26,12 @@ import {HypERC20Collateral} from "../HypERC20Collateral.sol";
 contract HypERC4626OwnerCollateral is HypERC20Collateral {
     // Address of the ERC4626 compatible vault
     ERC4626 public immutable vault;
-
+    // standby precision for exchange rate
+    uint256 public constant PRECISION = 1e10;
     // Internal balance of total asset deposited
     uint256 public assetDeposited;
+    // Nonce for the rate update, to ensure sequential updates (not necessary for Owner variant but for compatibility with HypERC4626)
+    uint32 public rateUpdateNonce;
 
     event ExcessSharesSwept(uint256 amount, uint256 assetsRedeemed);
 
@@ -40,8 +58,11 @@ contract HypERC4626OwnerCollateral is HypERC20Collateral {
     function _transferFromSender(
         uint256 _amount
     ) internal override returns (bytes memory metadata) {
-        metadata = super._transferFromSender(_amount);
+        super._transferFromSender(_amount);
         _depositIntoVault(_amount);
+        rateUpdateNonce++;
+
+        return abi.encode(PRECISION, rateUpdateNonce);
     }
 
     /**

solidity/test/token/HypERC20CollateralVaultDeposit.t.sol

@@ -16,8 +16,11 @@ pragma solidity ^0.8.13;
 import "forge-std/Test.sol";
 import {TransparentUpgradeableProxy} from "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";
 
+import {HypERC4626} from "../../contracts/token/extensions/HypERC4626.sol";
+
 import {ERC4626Test} from "../../contracts/test/ERC4626/ERC4626Test.sol";
 import {TypeCasts} from "../../contracts/libs/TypeCasts.sol";
+import {TokenMessage} from "../../contracts/token/libs/TokenMessage.sol";
 import {HypTokenTest} from "./HypERC20.t.sol";
 
 import {HypERC4626OwnerCollateral} from "../../contracts/token/extensions/HypERC4626OwnerCollateral.sol";
@@ -227,6 +230,20 @@ contract HypERC4626OwnerCollateralTest is HypTokenTest {
         );
     }
 
+    function testERC4626VaultDeposit_TransferFromSender_CorrectMetadata()
+        public
+    {
+        remoteToken = new HypERC4626(18, address(remoteMailbox), ORIGIN);
+        _enrollRemoteTokenRouter();
+        vm.prank(ALICE);
+
+        primaryToken.approve(address(localToken), TRANSFER_AMT);
+        _performRemoteTransfer(0, TRANSFER_AMT, 1);
+
+        assertEq(HypERC4626(address(remoteToken)).exchangeRate(), 1e10);
+        assertEq(HypERC4626(address(remoteToken)).previousNonce(), 1);
+    }
+
     function testBenchmark_overheadGasUsage() public override {
         vm.prank(ALICE);
         primaryToken.approve(address(localToken), TRANSFER_AMT);
@@ -243,4 +260,34 @@ contract HypERC4626OwnerCollateralTest is HypTokenTest {
         uint256 gasAfter = gasleft();
         console.log("Overhead gas usage: %d", gasBefore - gasAfter);
     }
+
+    function _performRemoteTransfer(
+        uint256 _msgValue,
+        uint256 _amount,
+        uint32 _nonce
+    ) internal {
+        vm.prank(ALICE);
+        localToken.transferRemote{value: _msgValue}(
+            DESTINATION,
+            BOB.addressToBytes32(),
+            _amount
+        );
+
+        vm.expectEmit(true, true, false, true);
+        emit ReceivedTransferRemote(ORIGIN, BOB.addressToBytes32(), _amount);
+        bytes memory _tokenMessage = TokenMessage.format(
+            BOB.addressToBytes32(),
+            _amount,
+            abi.encode(uint256(1e10), _nonce)
+        );
+
+        vm.prank(address(remoteMailbox));
+        remoteToken.handle(
+            ORIGIN,
+            address(localToken).addressToBytes32(),
+            _tokenMessage
+        );
+
+        assertEq(remoteToken.balanceOf(BOB), _amount);
+    }
 }