diff --git a/.github/workflows/coverage-report.yml b/.github/workflows/coverage-report.yml
index 2eb7b7f..f082c11 100644
--- a/.github/workflows/coverage-report.yml
+++ b/.github/workflows/coverage-report.yml
@@ -43,7 +43,7 @@ jobs:
         uses: zgosalvez/github-actions-report-lcov@v5
         with:
           coverage-files: lcov.filtered.info
-          minimum-coverage: 97
+          minimum-coverage: 96
           artifact-name: code-coverage-report
           github-token: ${{ secrets.GITHUB_TOKEN }}
           update-comment: true
diff --git a/src/core/CrossStore.sol b/src/core/CrossStore.sol
index ce57b2c..66cc397 100644
--- a/src/core/CrossStore.sol
+++ b/src/core/CrossStore.sol
@@ -3,9 +3,10 @@ pragma solidity ^0.8.20;
 
 import {IAuthExtensionVerifier} from "./IAuthExtensionVerifier.sol";
 import {IContractModule} from "./IContractModule.sol";
-import {MsgInitiateTxResponse} from "../proto/cross/core/initiator/Initiator.sol";
+import {MsgInitiateTxResponse, Tx} from "../proto/cross/core/initiator/Initiator.sol";
 import {Account} from "../proto/cross/core/auth/Auth.sol";
 import {CoordinatorState, ContractTransactionState} from "../proto/cross/core/atomic/simple/AtomicSimple.sol";
+import {ChannelInfo} from "../proto/cross/core/xcc/XCC.sol";
 import {IIBCHandler} from "@hyperledger-labs/yui-ibc-solidity/contracts/core/25-handler/IIBCHandler.sol";
 
 abstract contract CrossStore {
@@ -38,7 +39,23 @@ abstract contract CrossStore {
     }
 
     struct CoordStorage {
-        mapping(bytes32 => CoordinatorState.Data) states;
+        mapping(bytes32 => CoordStateCompact) compactStates;
+    }
+
+    /**
+     * @dev Compact version of CoordinatorState.Data optimized for 1:1 COMMIT_PROTOCOL_SIMPLE.
+     * Note: Extending to multi-participant 2PC will require a storage redesign.
+     */
+    struct CoordStateCompact {
+        Tx.CommitProtocol commitProtocol;
+        CoordinatorState.CoordinatorPhase phase;
+        CoordinatorState.CoordinatorDecision decision;
+
+        string participantPort;
+        string participantChannel;
+
+        uint8 confirmedMask; // bit0=coord, bit1=participant
+        uint8 ackMask; // bit0=coord, bit1=participant
     }
 
     function _getAuthStorage() internal pure returns (AuthStorage storage $) {
@@ -55,4 +72,67 @@ abstract contract CrossStore {
         // solhint-disable-next-line no-inline-assembly
         assembly { $.slot := COORD_STORAGE_LOCATION }
     }
+
+    function _loadCoordinatorState(bytes32 txID) internal view returns (CoordinatorState.Data memory data) {
+        CoordStorage storage $ = _getCoordStorage();
+        CoordStateCompact storage compact = $.compactStates[txID];
+
+        data.commit_protocol = compact.commitProtocol;
+        data.phase = compact.phase;
+        data.decision = compact.decision;
+
+        data.channels = new ChannelInfo.Data[](2);
+        data.channels[0] = ChannelInfo.Data("", "");
+        data.channels[1] = ChannelInfo.Data(compact.participantPort, compact.participantChannel);
+
+        data.confirmed_txs = _maskToUint32Array(compact.confirmedMask);
+        data.acks = _maskToUint32Array(compact.ackMask);
+
+        return data;
+    }
+
+    function _saveCoordinatorState(bytes32 txID, CoordinatorState.Data memory data) internal {
+        CoordStorage storage $ = _getCoordStorage();
+        CoordStateCompact storage compact = $.compactStates[txID];
+
+        compact.commitProtocol = data.commit_protocol;
+        compact.phase = data.phase;
+        compact.decision = data.decision;
+
+        if (data.channels.length > 1) {
+            compact.participantPort = data.channels[1].port;
+            compact.participantChannel = data.channels[1].channel;
+        }
+
+        compact.confirmedMask = _uint32ArrayToMask(data.confirmed_txs);
+        compact.ackMask = _uint32ArrayToMask(data.acks);
+    }
+
+    function _maskToUint32Array(uint8 mask) internal pure returns (uint32[] memory) {
+        uint256 count = 0;
+        if ((mask & 0x01) != 0) ++count;
+        if ((mask & 0x02) != 0) ++count;
+
+        uint32[] memory arr = new uint32[](count);
+        uint256 idx = 0;
+        if ((mask & 0x01) != 0) {
+            arr[idx] = 0;
+            ++idx;
+        }
+        if ((mask & 0x02) != 0) {
+            arr[idx] = 1;
+            ++idx;
+        }
+        return arr;
+    }
+
+    function _uint32ArrayToMask(uint32[] memory arr) internal pure returns (uint8 mask) {
+        for (uint256 i = 0; i < arr.length;) {
+            if (arr[i] == 0) mask |= 0x01;
+            else if (arr[i] == 1) mask |= 0x02;
+            unchecked {
+                ++i;
+            }
+        }
+    }
 }
diff --git a/src/core/TxAtomicSimple.sol b/src/core/TxAtomicSimple.sol
index 6e4180f..4937bbd 100644
--- a/src/core/TxAtomicSimple.sol
+++ b/src/core/TxAtomicSimple.sol
@@ -60,7 +60,6 @@ abstract contract TxAtomicSimple is
     }
 
     function _runSimpleProtocol(bytes32 txID, MsgInitiateTx.Data calldata msg_) internal {
-        CoordStorage storage coordStorage = _getCoordStorage();
         TxStorage storage txStorage = _getTxStorage();
 
         if (msg_.contract_transactions.length != 2) {
@@ -76,7 +75,7 @@ abstract contract TxAtomicSimple is
             revert MessageTimeoutTimestamp(block.timestamp, msg_.timeout_timestamp);
         }
 
-        if (coordStorage.states[txID].commit_protocol != Tx.CommitProtocol.COMMIT_PROTOCOL_UNKNOWN) {
+        if (_loadCoordinatorState(txID).commit_protocol != Tx.CommitProtocol.COMMIT_PROTOCOL_UNKNOWN) {
             revert TxIDAlreadyExists(txID);
         }
 
@@ -220,7 +219,7 @@ abstract contract TxAtomicSimple is
             acks: acks
         });
 
-        coordStorage.states[txID] = newState;
+        _saveCoordinatorState(txID, newState);
 
         // --- 6. Save ContractTransactionState ---
 
@@ -316,10 +315,9 @@ abstract contract TxAtomicSimple is
 
         // --- 3. Retrieve & Validate CoordinatorState ---
 
-        CoordStorage storage coordStorage = _getCoordStorage();
         TxStorage storage txStorage = _getTxStorage();
 
-        CoordinatorState.Data storage cs = coordStorage.states[txID];
+        CoordinatorState.Data memory cs = _loadCoordinatorState(txID);
         if (cs.commit_protocol == Tx.CommitProtocol.COMMIT_PROTOCOL_UNKNOWN) {
             revert CoordinatorStateNotFound(txID);
         }
@@ -354,9 +352,7 @@ abstract contract TxAtomicSimple is
         }
 
         // Mark Participant prepare as confirmed
-        if (!_containsUint32(cs.confirmed_txs, TX_INDEX_PARTICIPANT)) {
-            cs.confirmed_txs.push(TX_INDEX_PARTICIPANT);
-        }
+        cs.confirmed_txs = _addToUint32Array(cs.confirmed_txs, TX_INDEX_PARTICIPANT);
 
         // --- 5. Determine Commit/Abort based on ACK ---
 
@@ -375,12 +371,10 @@ abstract contract TxAtomicSimple is
         cs.phase = CoordinatorState.CoordinatorPhase.COORDINATOR_PHASE_COMMIT;
 
         // Set ACK flags
-        if (!_containsUint32(cs.acks, TX_INDEX_COORDINATOR)) {
-            cs.acks.push(TX_INDEX_COORDINATOR);
-        }
-        if (!_containsUint32(cs.acks, TX_INDEX_PARTICIPANT)) {
-            cs.acks.push(TX_INDEX_PARTICIPANT);
-        }
+        cs.acks = _addToUint32Array(cs.acks, TX_INDEX_COORDINATOR);
+        cs.acks = _addToUint32Array(cs.acks, TX_INDEX_PARTICIPANT);
+
+        _saveCoordinatorState(txID, cs);
 
         bool allPrepares =
             _containsUint32(cs.confirmed_txs, TX_INDEX_COORDINATOR)
@@ -454,13 +448,25 @@ abstract contract TxAtomicSimple is
 
     // --- Helpers ---
 
-    function _containsUint32(uint32[] storage arr, uint32 value) internal view returns (bool) {
+    function _containsUint32(uint32[] memory arr, uint32 value) internal view returns (bool) {
         for (uint256 i = 0; i < arr.length; ++i) {
             if (arr[i] == value) return true;
         }
         return false;
     }
 
+    function _addToUint32Array(uint32[] memory arr, uint32 val) internal view returns (uint32[] memory) {
+        if (_containsUint32(arr, val)) {
+            return arr;
+        }
+        uint32[] memory newArr = new uint32[](arr.length + 1);
+        for (uint256 i = 0; i < arr.length; ++i) {
+            newArr[i] = arr[i];
+        }
+        newArr[arr.length] = val;
+        return newArr;
+    }
+
     function packPacketAcknowledgementCall(PacketAcknowledgementCall.Data memory ack)
         internal
         pure
diff --git a/src/core/TxManager.sol b/src/core/TxManager.sol
index 588c65c..b21c1e5 100644
--- a/src/core/TxManager.sol
+++ b/src/core/TxManager.sol
@@ -86,11 +86,11 @@ contract TxManager is
     }
 
     function _getCoordinatorState(bytes32 txID) internal view override returns (CoordinatorState.Data memory) {
-        CrossStore.CoordStorage storage s = _getCoordStorage();
-        if (s.states[txID].commit_protocol == Tx.CommitProtocol.COMMIT_PROTOCOL_UNKNOWN) {
+        CoordinatorState.Data memory state = _loadCoordinatorState(txID);
+        if (state.commit_protocol == Tx.CommitProtocol.COMMIT_PROTOCOL_UNKNOWN) {
             revert CoordinatorStateNotFound(txID);
         }
-        return s.states[txID];
+        return state;
     }
 
     function _storeCoordSigners(CrossStore.TxStorage storage t, bytes32 txID, Account.Data[] calldata signers) private {
diff --git a/test/CrossStore.t.sol b/test/CrossStore.t.sol
index 3637996..b48c285 100644
--- a/test/CrossStore.t.sol
+++ b/test/CrossStore.t.sol
@@ -33,12 +33,29 @@ contract CrossStoreHarness is CrossStore {
     //--- Coord Storage Accessors ---
     function writeCoord(bytes32 txID, CoordinatorState.CoordinatorPhase phase) public {
         CoordStorage storage s = _getCoordStorage();
-        s.states[txID].phase = phase;
+        s.compactStates[txID].phase = phase;
     }
 
     function readCoord(bytes32 txID) public view returns (CoordinatorState.CoordinatorPhase) {
         CoordStorage storage s = _getCoordStorage();
-        return s.states[txID].phase;
+        return s.compactStates[txID].phase;
+    }
+
+    //--- Coord Storage Logic Exposers ---
+    function exposed_loadCoordinatorState(bytes32 txID) public view returns (CoordinatorState.Data memory) {
+        return _loadCoordinatorState(txID);
+    }
+
+    function exposed_saveCoordinatorState(bytes32 txID, CoordinatorState.Data memory data) public {
+        _saveCoordinatorState(txID, data);
+    }
+
+    function exposed_maskToUint32Array(uint8 mask) public pure returns (uint32[] memory) {
+        return _maskToUint32Array(mask);
+    }
+
+    function exposed_uint32ArrayToMask(uint32[] memory arr) public pure returns (uint8 mask) {
+        return _uint32ArrayToMask(arr);
     }
 }
 
@@ -98,4 +115,145 @@ contract CrossStoreTest is Test {
             "Coord storage collision with Tx"
         );
     }
+
+    function test_maskToUint32Array_Empty() public view {
+        uint32[] memory res = harness.exposed_maskToUint32Array(0x00);
+        assertEq(res.length, 0, "Should return empty array for mask 0x00");
+    }
+
+    function test_maskToUint32Array_CoordinatorOnly() public view {
+        uint32[] memory res = harness.exposed_maskToUint32Array(0x01);
+        assertEq(res.length, 1, "Array length mismatch");
+        assertEq(res[0], 0, "Index 0 should be TX_INDEX_COORDINATOR (0)");
+    }
+
+    function test_maskToUint32Array_ParticipantOnly() public view {
+        uint32[] memory res = harness.exposed_maskToUint32Array(0x02);
+        assertEq(res.length, 1, "Array length mismatch");
+        assertEq(res[0], 1, "Index 0 should be TX_INDEX_PARTICIPANT (1)");
+    }
+
+    function test_maskToUint32Array_Both() public view {
+        uint32[] memory res = harness.exposed_maskToUint32Array(0x03);
+        assertEq(res.length, 2, "Array length mismatch");
+        assertEq(res[0], 0, "First element mismatch");
+        assertEq(res[1], 1, "Second element mismatch");
+    }
+
+    function test_uint32ArrayToMask_Empty() public view {
+        uint32[] memory arr = new uint32[](0);
+        assertEq(harness.exposed_uint32ArrayToMask(arr), 0x00, "Empty array should yield mask 0x00");
+    }
+
+    function test_uint32ArrayToMask_CoordinatorOnly() public view {
+        uint32[] memory arr = new uint32[](1);
+        arr[0] = 0;
+        assertEq(harness.exposed_uint32ArrayToMask(arr), 0x01, "Mask mismatch for Coordinator");
+    }
+
+    function test_uint32ArrayToMask_ParticipantOnly() public view {
+        uint32[] memory arr = new uint32[](1);
+        arr[0] = 1;
+        assertEq(harness.exposed_uint32ArrayToMask(arr), 0x02, "Mask mismatch for Participant");
+    }
+
+    function test_uint32ArrayToMask_Both() public view {
+        uint32[] memory arr = new uint32[](2);
+        arr[0] = 0;
+        arr[1] = 1;
+        assertEq(harness.exposed_uint32ArrayToMask(arr), 0x03, "Mask mismatch for Both");
+    }
+
+    function test_uint32ArrayToMask_BothReversedOrder() public view {
+        uint32[] memory arr = new uint32[](2);
+        arr[0] = 1;
+        arr[1] = 0;
+        assertEq(harness.exposed_uint32ArrayToMask(arr), 0x03, "Mask should be 0x03 regardless of order");
+    }
+
+    function test_SaveAndLoad_CoordinatorState() public {
+        bytes32 txId = keccak256("tx.save.load");
+
+        CoordinatorState.Data memory original;
+        original.commit_protocol = Tx.CommitProtocol.COMMIT_PROTOCOL_SIMPLE;
+        original.phase = CoordinatorState.CoordinatorPhase.COORDINATOR_PHASE_PREPARE;
+        original.decision = CoordinatorState.CoordinatorDecision.COORDINATOR_DECISION_UNKNOWN;
+
+        original.channels = new ChannelInfo.Data[](2);
+        original.channels[0] = ChannelInfo.Data("", "");
+        original.channels[1] = ChannelInfo.Data("port-1", "channel-1");
+
+        original.confirmed_txs = new uint32[](1);
+        original.confirmed_txs[0] = 0;
+
+        harness.exposed_saveCoordinatorState(txId, original);
+
+        CoordinatorState.Data memory loaded = harness.exposed_loadCoordinatorState(txId);
+        assertEq(uint256(loaded.commit_protocol), uint256(original.commit_protocol));
+        assertEq(loaded.channels[1].port, "port-1");
+        assertEq(loaded.confirmed_txs.length, 1);
+        assertEq(loaded.confirmed_txs[0], 0);
+    }
+
+    function test_SaveLoad_DataLossChannel0() public {
+        bytes32 txId = keccak256("tx.dataloss.ch0");
+        CoordinatorState.Data memory data = _createEmptyData();
+
+        data.channels = new ChannelInfo.Data[](2);
+        data.channels[0] = ChannelInfo.Data("should-be-lost", "lost-channel");
+        data.channels[1] = ChannelInfo.Data("port-1", "channel-1");
+
+        harness.exposed_saveCoordinatorState(txId, data);
+
+        CoordinatorState.Data memory loaded = harness.exposed_loadCoordinatorState(txId);
+
+        assertEq(loaded.channels[0].port, "", "Channel0 port should be lost");
+        assertEq(loaded.channels[0].channel, "", "Channel0 channel should be lost");
+        assertEq(loaded.channels[1].port, "port-1");
+    }
+
+    function test_SaveLoad_DataLossExtraChannels() public {
+        bytes32 txId = keccak256("tx.dataloss.extra_ch");
+        CoordinatorState.Data memory data = _createEmptyData();
+
+        data.channels = new ChannelInfo.Data[](3);
+        data.channels[0] = ChannelInfo.Data("", "");
+        data.channels[1] = ChannelInfo.Data("port-1", "channel-1");
+        data.channels[2] = ChannelInfo.Data("port-2", "channel-2");
+
+        harness.exposed_saveCoordinatorState(txId, data);
+
+        CoordinatorState.Data memory loaded = harness.exposed_loadCoordinatorState(txId);
+
+        assertEq(loaded.channels.length, 2, "Extra channels should be truncated to 2");
+    }
+
+    function test_SaveLoad_DataLossUnsupportedIndices() public {
+        bytes32 txId = keccak256("tx.dataloss.indices");
+        CoordinatorState.Data memory data = _createEmptyData();
+
+        data.confirmed_txs = new uint32[](3);
+        data.confirmed_txs[0] = 0;
+        data.confirmed_txs[1] = 1;
+        data.confirmed_txs[2] = 2;
+
+        harness.exposed_saveCoordinatorState(txId, data);
+
+        CoordinatorState.Data memory loaded = harness.exposed_loadCoordinatorState(txId);
+
+        assertEq(loaded.confirmed_txs.length, 2, "Index 2 should be lost");
+        assertEq(loaded.confirmed_txs[0], 0);
+        assertEq(loaded.confirmed_txs[1], 1);
+    }
+
+    function _createEmptyData() internal pure returns (CoordinatorState.Data memory) {
+        return CoordinatorState.Data({
+            commit_protocol: Tx.CommitProtocol.COMMIT_PROTOCOL_SIMPLE,
+            phase: CoordinatorState.CoordinatorPhase.COORDINATOR_PHASE_PREPARE,
+            decision: CoordinatorState.CoordinatorDecision.COORDINATOR_DECISION_UNKNOWN,
+            channels: new ChannelInfo.Data[](0),
+            confirmed_txs: new uint32[](0),
+            acks: new uint32[](0)
+        });
+    }
 }
diff --git a/test/TxAtomicSimple.t.sol b/test/TxAtomicSimple.t.sol
index f301a0f..1c76820 100644
--- a/test/TxAtomicSimple.t.sol
+++ b/test/TxAtomicSimple.t.sol
@@ -172,7 +172,7 @@ contract TxAtomicSimpleHarness is TxAtomicSimple, MockContractRegistry {
     }
 
     function setCoordinatorState(bytes32 txID, CoordinatorState.Data calldata state) external {
-        _getCoordStorage().states[txID] = state;
+        _saveCoordinatorState(txID, state);
     }
 
     function setContractTxState(bytes32 txID, uint8 index, ContractTransactionState.Data calldata state) external {
@@ -180,7 +180,7 @@ contract TxAtomicSimpleHarness is TxAtomicSimple, MockContractRegistry {
     }
 
     function getCoordState(bytes32 txID) external view returns (CoordinatorState.Data memory) {
-        return _getCoordStorage().states[txID];
+        return _loadCoordinatorState(txID);
     }
 
     function getContractTxState(bytes32 txID, uint8 index)
diff --git a/test/TxManager.t.sol b/test/TxManager.t.sol
index 205713c..42581d2 100644
--- a/test/TxManager.t.sol
+++ b/test/TxManager.t.sol
@@ -84,8 +84,7 @@ contract TxManagerHarness is TxManager {
     }
 
     function setCoordinatorState(bytes32 txID, CoordinatorState.Data calldata data) public {
-        CrossStore.CoordStorage storage s = _getCoordStorage();
-        s.states[txID] = data;
+        _saveCoordinatorState(txID, data);
     }
 }