C4 S-106 IntentAlreadyUsed validation will never fail (#68)

* S-106 Remove IntentAlreadyUsed validation that will never be hit

* Remove usedIntents entirely

* Update snapshot

* Update gas snapshot for TrailsIntentEntrypoint tests with new gas usage metrics and adjustments to ensure accuracy.

* Remove unused error 'IntentAlreadyUsed' from TrailsIntentEntrypoint contract

---------

Co-authored-by: Shun Kakinoki <39187513+shunkakinoki@users.noreply.github.com>
Co-authored-by: Shun Kakinoki <shunkakinoki@gmail.com>

Author: ScreamingHawk

.gas-snapshot

@@ -6,48 +6,47 @@ DelegatecallGuardTest:test_direct_call_reverts_NotDelegateCall() (gas: 8420)
 DelegatecallGuardTest:test_multiple_delegatecall_guards() (gas: 298825)
 DelegatecallGuardTest:test_onlyDelegatecall_modifier_usage() (gas: 98867)
 DelegatecallGuardTest:test_self_address_immutable() (gas: 2877)
-TrailsIntentEntrypointDeploymentTest:test_DeployIntentEntrypoint_SameAddress() (gas: 886036)
-TrailsIntentEntrypointDeploymentTest:test_DeployIntentEntrypoint_Success() (gas: 878447)
-TrailsIntentEntrypointDeploymentTest:test_DeployedIntentEntrypoint_HasCorrectConfiguration() (gas: 884342)
-TrailsIntentEntrypointTest:testAssemblyCodeExecution() (gas: 112699)
-TrailsIntentEntrypointTest:testConstructor() (gas: 3309)
-TrailsIntentEntrypointTest:testConstructorAndDomainSeparator() (gas: 7706)
-TrailsIntentEntrypointTest:testDepositToIntentAlreadyUsed() (gas: 136588)
-TrailsIntentEntrypointTest:testDepositToIntentCannotReuseDigest() (gas: 117228)
-TrailsIntentEntrypointTest:testDepositToIntentExpiredDeadline() (gas: 56096)
-TrailsIntentEntrypointTest:testDepositToIntentReentrancyProtection() (gas: 136566)
-TrailsIntentEntrypointTest:testDepositToIntentRequiresNonZeroAmount() (gas: 27416)
-TrailsIntentEntrypointTest:testDepositToIntentRequiresValidToken() (gas: 30799)
-TrailsIntentEntrypointTest:testDepositToIntentTransferFromFails() (gas: 80879)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitAlreadyUsed() (gas: 155215)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitExpiredDeadline() (gas: 36526)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitReentrancyProtection() (gas: 146586)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitRequiresNonZeroAmount() (gas: 35240)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitRequiresPermitAmount() (gas: 83234)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitRequiresValidToken() (gas: 35966)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitTransferFromFails() (gas: 82463)
-TrailsIntentEntrypointTest:testDepositToIntentWithPermitWrongSigner() (gas: 40524)
-TrailsIntentEntrypointTest:testDepositToIntentWithoutPermit_RequiresIntentAddress() (gas: 31508)
-TrailsIntentEntrypointTest:testDepositToIntentWrongSigner() (gas: 57349)
-TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20AndFee_Success() (gas: 831960)
-TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20_InsufficientAllowance_Reverts() (gas: 794757)
-TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20_InsufficientBalance_Reverts() (gas: 794716)
-TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20_Success() (gas: 802824)
-TrailsIntentEntrypointTest:testExactApprovalFlow() (gas: 192796)
-TrailsIntentEntrypointTest:testExecuteIntentWithFee() (gas: 176076)
-TrailsIntentEntrypointTest:testExecuteIntentWithPermit() (gas: 145698)
-TrailsIntentEntrypointTest:testExecuteIntentWithPermitExpired() (gas: 36445)
-TrailsIntentEntrypointTest:testExecuteIntentWithPermitInvalidSignature() (gas: 37768)
-TrailsIntentEntrypointTest:testFeeCollectorReceivesFees() (gas: 170228)
-TrailsIntentEntrypointTest:testFeeCollectorReceivesFeesWithoutPermit() (gas: 139856)
-TrailsIntentEntrypointTest:testInfiniteApprovalFlow() (gas: 185611)
-TrailsIntentEntrypointTest:testIntentTypehashConstant() (gas: 5707)
-TrailsIntentEntrypointTest:testInvalidNonceReverts() (gas: 54701)
-TrailsIntentEntrypointTest:testNonceIncrementsOnDeposit() (gas: 112900)
-TrailsIntentEntrypointTest:testPermitAmountExcessiveWithFee() (gas: 83027)
-TrailsIntentEntrypointTest:testPermitAmountInsufficientWithFee() (gas: 82059)
-TrailsIntentEntrypointTest:testUsedIntentsMapping() (gas: 113770)
-TrailsIntentEntrypointTest:testVersionConstant() (gas: 10381)
+TrailsIntentEntrypointDeploymentTest:test_DeployIntentEntrypoint_SameAddress() (gas: 839567)
+TrailsIntentEntrypointDeploymentTest:test_DeployIntentEntrypoint_Success() (gas: 832067)
+TrailsIntentEntrypointDeploymentTest:test_DeployedIntentEntrypoint_HasCorrectConfiguration() (gas: 834866)
+TrailsIntentEntrypointTest:testAssemblyCodeExecution() (gas: 89228)
+TrailsIntentEntrypointTest:testConstructor() (gas: 3287)
+TrailsIntentEntrypointTest:testConstructorAndDomainSeparator() (gas: 7684)
+TrailsIntentEntrypointTest:testDepositToIntentAlreadyUsed() (gas: 114117)
+TrailsIntentEntrypointTest:testDepositToIntentCannotReuseDigest() (gas: 94757)
+TrailsIntentEntrypointTest:testDepositToIntentExpiredDeadline() (gas: 56029)
+TrailsIntentEntrypointTest:testDepositToIntentReentrancyProtection() (gas: 114095)
+TrailsIntentEntrypointTest:testDepositToIntentRequiresNonZeroAmount() (gas: 27371)
+TrailsIntentEntrypointTest:testDepositToIntentRequiresValidToken() (gas: 30754)
+TrailsIntentEntrypointTest:testDepositToIntentTransferFromFails() (gas: 58387)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitAlreadyUsed() (gas: 132693)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitExpiredDeadline() (gas: 36459)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitReentrancyProtection() (gas: 124115)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitRequiresNonZeroAmount() (gas: 35173)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitRequiresPermitAmount() (gas: 60742)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitRequiresValidToken() (gas: 35899)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitTransferFromFails() (gas: 59993)
+TrailsIntentEntrypointTest:testDepositToIntentWithPermitWrongSigner() (gas: 40450)
+TrailsIntentEntrypointTest:testDepositToIntentWithoutPermit_RequiresIntentAddress() (gas: 31441)
+TrailsIntentEntrypointTest:testDepositToIntentWrongSigner() (gas: 57297)
+TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20AndFee_Success() (gas: 809490)
+TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20_InsufficientAllowance_Reverts() (gas: 772287)
+TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20_InsufficientBalance_Reverts() (gas: 772224)
+TrailsIntentEntrypointTest:testDepositToIntent_WithNonStandardERC20_Success() (gas: 780332)
+TrailsIntentEntrypointTest:testExactApprovalFlow() (gas: 150375)
+TrailsIntentEntrypointTest:testExecuteIntentWithFee() (gas: 153584)
+TrailsIntentEntrypointTest:testExecuteIntentWithPermit() (gas: 123206)
+TrailsIntentEntrypointTest:testExecuteIntentWithPermitExpired() (gas: 36378)
+TrailsIntentEntrypointTest:testExecuteIntentWithPermitInvalidSignature() (gas: 37716)
+TrailsIntentEntrypointTest:testFeeCollectorReceivesFees() (gas: 147736)
+TrailsIntentEntrypointTest:testFeeCollectorReceivesFeesWithoutPermit() (gas: 117386)
+TrailsIntentEntrypointTest:testInfiniteApprovalFlow() (gas: 144644)
+TrailsIntentEntrypointTest:testIntentTypehashConstant() (gas: 5685)
+TrailsIntentEntrypointTest:testInvalidNonceReverts() (gas: 54678)
+TrailsIntentEntrypointTest:testNonceIncrementsOnDeposit() (gas: 90407)
+TrailsIntentEntrypointTest:testPermitAmountExcessiveWithFee() (gas: 60535)
+TrailsIntentEntrypointTest:testPermitAmountInsufficientWithFee() (gas: 59589)
+TrailsIntentEntrypointTest:testVersionConstant() (gas: 10337)
 TrailsRouterDeploymentTest:test_DeployTrailsRouter_SameAddress() (gas: 1722289)
 TrailsRouterDeploymentTest:test_DeployTrailsRouter_Success() (gas: 1712948)
 TrailsRouterDeploymentTest:test_DeployedRouter_HasCorrectConfiguration() (gas: 1712744)

src/TrailsIntentEntrypoint.sol

@@ -36,7 +36,6 @@ contract TrailsIntentEntrypoint is ReentrancyGuard, ITrailsIntentEntrypoint {
     error InvalidIntentAddress();
     error IntentExpired();
     error InvalidIntentSignature();
-    error IntentAlreadyUsed();
     error InvalidNonce();
     error PermitAmountMismatch();
 
@@ -51,9 +50,6 @@ contract TrailsIntentEntrypoint is ReentrancyGuard, ITrailsIntentEntrypoint {
     // State Variables
     // -------------------------------------------------------------------------
 
-    /// @notice Tracks whether an intent digest has been consumed to prevent replays.
-    mapping(bytes32 => bool) public usedIntents;
-
     /// @notice Tracks nonce for each user to prevent replay attacks.
     mapping(address => uint256) public nonces;
 
@@ -203,9 +199,6 @@ contract TrailsIntentEntrypoint is ReentrancyGuard, ITrailsIntentEntrypoint {
         address recovered = ECDSA.recover(digest, sigV, sigR, sigS);
         if (recovered != user) revert InvalidIntentSignature();
 
-        if (usedIntents[digest]) revert IntentAlreadyUsed();
-        usedIntents[digest] = true;
-
         // Increment nonce for the user
         nonces[user]++;
     }

src/interfaces/ITrailsIntentEntrypoint.sol

@@ -37,10 +37,6 @@ interface ITrailsIntentEntrypoint {
     /// forge-lint: disable-next-line(mixed-case-function)
     function VERSION() external view returns (string memory);
 
-    /// @notice Returns whether an intent digest has already been consumed.
-    /// @param digest The EIP-712 digest of the intent message.
-    function usedIntents(bytes32 digest) external view returns (bool);
-
     /// @notice Returns the current nonce for a given user.
     /// @param user The user address to query.
     function nonces(address user) external view returns (uint256);

test/TrailsIntentEntrypoint.t.sol

@@ -1655,49 +1655,6 @@ contract TrailsIntentEntrypointTest is Test {
         vm.stopPrank();
     }
 
-    function testUsedIntentsMapping() public {
-        vm.startPrank(user);
-
-        address intentAddress = address(0x5678);
-        uint256 amount = 50 * 10 ** token.decimals();
-        uint256 deadline = block.timestamp + 3600;
-        uint256 nonce = entrypoint.nonces(user);
-
-        bytes32 intentHash = keccak256(
-            abi.encode(
-                entrypoint.TRAILS_INTENT_TYPEHASH(),
-                user,
-                address(token),
-                amount,
-                intentAddress,
-                deadline,
-                block.chainid,
-                nonce,
-                0, // feeAmount
-                address(0) // feeCollector
-            )
-        );
-
-        bytes32 intentDigest = keccak256(abi.encodePacked("\x19\x01", entrypoint.DOMAIN_SEPARATOR(), intentHash));
-
-        (uint8 sigV, bytes32 sigR, bytes32 sigS) = vm.sign(userPrivateKey, intentDigest);
-
-        token.approve(address(entrypoint), amount);
-
-        // Check that intent is not used initially
-        assertFalse(entrypoint.usedIntents(intentDigest));
-
-        // Execute intent
-        entrypoint.depositToIntent(
-            user, address(token), amount, intentAddress, deadline, nonce, 0, address(0), sigV, sigR, sigS
-        );
-
-        // Check that intent is now marked as used
-        assertTrue(entrypoint.usedIntents(intentDigest));
-
-        vm.stopPrank();
-    }
-
     function testAssemblyCodeExecution() public {
         vm.startPrank(user);
 
@@ -1732,9 +1689,6 @@ contract TrailsIntentEntrypointTest is Test {
             user, address(token), amount, intentAddress, deadline, nonce, 0, address(0), sigV, sigR, sigS
         );
 
-        // Verify the intent was processed correctly
-        assertTrue(entrypoint.usedIntents(intentDigest));
-
         vm.stopPrank();
     }
 

test/script/TrailsIntentEntrypoint.s.t.sol

@@ -108,10 +108,5 @@ contract TrailsIntentEntrypointDeploymentTest is Test {
         // Verify constants are set correctly
         assertEq(entrypoint.VERSION(), "1", "Version should be 1");
         assertTrue(entrypoint.TRAILS_INTENT_TYPEHASH() != bytes32(0), "Intent typehash should be set");
-
-        // Verify contract has expected storage layout by checking usedIntents mapping
-        // This is a smoke test that the contract is properly initialized
-        bytes32 testIntentHash = keccak256("test");
-        assertEq(entrypoint.usedIntents(testIntentHash), false, "usedIntents should be false for unused intent");
     }
 }