add start checkpoint but to the interface, but don't use in implementation

Author: ggonzalez94

src/protocol/CheckpointTracker.sol

@@ -35,7 +35,13 @@ contract CheckpointTracker is ICheckpointTracker {
     }
 
     /// @inheritdoc ICheckpointTracker
-    function proveTransition(Checkpoint calldata end, uint256 numPublications, bytes calldata proof) external {
+    /// @dev This function does not use the `start` checkpoint since we don't support parallel transitions.
+    function proveTransition(
+        Checkpoint calldata,
+        Checkpoint calldata end,
+        uint256 numPublications,
+        bytes calldata proof
+    ) external {
         require(
             proverManager == address(0) || msg.sender == proverManager, "Only the prover manager can call this function"
         );

src/protocol/ICheckpointTracker.sol

@@ -15,10 +15,16 @@ interface ICheckpointTracker {
     function getProvenCheckpoint() external view returns (Checkpoint memory);
 
     /// @notice Verifies a transition between two checkpoints. Update the latest `provenCheckpoint` if possible
+    /// @param start The initial checkpoint before the transition
     /// @param end The final checkpoint after the transition
     /// @param numPublications The number of publications that need to be processed between the two checkpoints.
     /// Note that this is not necessarily (end.publicationId - start.publicationId) because there could be irrelevant
     /// publications.
     /// @param proof Arbitrary data passed to the `verifier` contract to confirm the transition validity
-    function proveTransition(Checkpoint calldata end, uint256 numPublications, bytes calldata proof) external;
+    function proveTransition(
+        Checkpoint calldata start,
+        Checkpoint calldata end,
+        uint256 numPublications,
+        bytes calldata proof
+    ) external;
 }

src/protocol/taiko_alethia/ProverManager.sol

@@ -238,7 +238,7 @@ contract ProverManager is IProposerFees, IProverManager {
         require(start.publicationId + 1 == firstPub.id, "First publication not immediately after start checkpoint");
         require(firstPub.timestamp > previousPeriodEnd, "First publication is before the period");
 
-        checkpointTracker.proveTransition(end, numPublications, proof);
+        checkpointTracker.proveTransition(start, end, numPublications, proof);
 
         bool isPastDeadline = block.timestamp > period.deadline && period.deadline != 0;
         if (isPastDeadline) {

test/CheckpointTracker.t.sol

@@ -65,7 +65,11 @@ contract CheckpointTrackerTest is Test {
 
         vm.expectEmit();
         emit ICheckpointTracker.CheckpointUpdated(end);
-        tracker.proveTransition(end, numRelevantPublications, proof);
+
+        // Empty checkpoint needed to comply with the interface, but not used in `CheckpointTracker`
+        ICheckpointTracker.Checkpoint memory emptyCheckpoint =
+            ICheckpointTracker.Checkpoint({publicationId: 0, commitment: bytes32(0)});
+        tracker.proveTransition(emptyCheckpoint, end, numRelevantPublications, proof);
 
         ICheckpointTracker.Checkpoint memory provenCheckpoint = tracker.getProvenCheckpoint();
         assertEq(provenCheckpoint.publicationId, end.publicationId);
@@ -78,7 +82,10 @@ contract CheckpointTrackerTest is Test {
         uint256 numRelevantPublications = 2;
 
         vm.expectRevert("Checkpoint commitment cannot be 0");
-        tracker.proveTransition(end, numRelevantPublications, proof);
+        // Empty checkpoint needed to comply with the interface, but not used in `CheckpointTracker`
+        ICheckpointTracker.Checkpoint memory emptyCheckpoint =
+            ICheckpointTracker.Checkpoint({publicationId: 0, commitment: bytes32(0)});
+        tracker.proveTransition(emptyCheckpoint, end, numRelevantPublications, proof);
     }
 
     function createSampleFeed() private {

test/mocks/MockCheckpointTracker.sol

@@ -13,7 +13,12 @@ contract MockCheckpointTracker is ICheckpointTracker {
     }
 
     /// @notice Do nothing. All checkpoints and proofs are accepted.
-    function proveTransition(Checkpoint calldata end, uint256 numPublications, bytes calldata proof) external {}
+    function proveTransition(
+        Checkpoint calldata,
+        Checkpoint calldata end,
+        uint256 numPublications,
+        bytes calldata proof
+    ) external {}
 
     /// @notice Helper to set the proven hash for easier testing
     /// @param checkpoint the checkpoint to set as proven, that will be hashed and stored as the proven hash