diff --git a/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/IMxGatewayClient.cs b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/IMxGatewayClient.cs
index db9eefca..da59744c 100644
--- a/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/IMxGatewayClient.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/IMxGatewayClient.cs
@@ -1,4 +1,5 @@
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Protocol;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.Alarms;
 
 namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;
 
@@ -69,6 +70,17 @@ public interface IMxGatewayClient : IAsyncDisposable
     /// <param name="onUpdate">Callback invoked per advised-tag value change.</param>
     /// <param name="ct">Cancellation token; ends the loop when cancelled.</param>
     Task RunEventLoopAsync(Action<MxValueUpdate> onUpdate, CancellationToken ct = default);
+
+    /// <summary>
+    /// Long-running consumer of the gateway's session-less StreamAlarms feed. Emits a
+    /// Snapshot…SnapshotComplete replay of active alarms then live transitions. Re-opens
+    /// the stream internally on transport faults (the source replays a fresh snapshot).
+    /// Completes only when <paramref name="ct"/> is cancelled.
+    /// </summary>
+    /// <param name="alarmFilterPrefix">Optional source-reference prefix to scope the feed; null = gateway-wide.</param>
+    /// <param name="onTransition">Callback invoked per native alarm transition.</param>
+    /// <param name="ct">Cancellation token; ends the loop when cancelled.</param>
+    Task RunAlarmStreamAsync(string? alarmFilterPrefix, Action<NativeAlarmTransition> onTransition, CancellationToken ct = default);
 }
 
 /// <summary>Builds <see cref="IMxGatewayClient"/> instances.</summary>
diff --git a/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayAlarmMapper.cs b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayAlarmMapper.cs
new file mode 100644
index 00000000..17e8ade8
--- /dev/null
+++ b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayAlarmMapper.cs
@@ -0,0 +1,102 @@
+using ZB.MOM.WW.MxGateway.Contracts.Proto;
+using ProtoConditionState = ZB.MOM.WW.MxGateway.Contracts.Proto.AlarmConditionState;
+using ProtoTransitionKind = ZB.MOM.WW.MxGateway.Contracts.Proto.AlarmTransitionKind;
+// Alias the Commons alarm types so their simple names bind here, unambiguous
+// against the colliding gateway proto enums above.
+using NativeAlarmTransition = ZB.MOM.WW.ScadaBridge.Commons.Types.Alarms.NativeAlarmTransition;
+using AlarmConditionState = ZB.MOM.WW.ScadaBridge.Commons.Types.Alarms.AlarmConditionState;
+using AlarmTransitionKind = ZB.MOM.WW.ScadaBridge.Commons.Types.Enums.AlarmTransitionKind;
+using AlarmShelveState = ZB.MOM.WW.ScadaBridge.Commons.Types.Enums.AlarmShelveState;
+
+namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;
+
+/// <summary>
+/// Pure mapping from MxAccess Gateway alarm-feed proto messages to the
+/// protocol-neutral <see cref="NativeAlarmTransition"/> shape. The gateway proto
+/// enums (AlarmConditionState / AlarmTransitionKind) collide with the Commons
+/// alarm enums, so they are aliased here. Unit-tested without a live gateway.
+/// </summary>
+public static class MxGatewayAlarmMapper
+{
+    /// <summary>Clamps the gateway severity onto the unified 0–1000 scale.</summary>
+    public static int NormalizeSeverity(int severity) => Math.Clamp(severity, 0, 1000);
+
+    /// <summary>Maps a gateway condition-state + severity to the unified condition.</summary>
+    public static AlarmConditionState MapConditionState(ProtoConditionState state, int severity)
+    {
+        var (active, acked) = state switch
+        {
+            ProtoConditionState.Active => (true, false),
+            ProtoConditionState.ActiveAcked => (true, true),
+            ProtoConditionState.Inactive => (false, true),
+            _ => (false, true)
+        };
+        return new AlarmConditionState(active, acked, Confirmed: null,
+            Shelve: AlarmShelveState.Unshelved, Suppressed: false, Severity: NormalizeSeverity(severity));
+    }
+
+    /// <summary>Maps a gateway transition kind to the unified transition kind.</summary>
+    public static AlarmTransitionKind MapKind(ProtoTransitionKind kind) => kind switch
+    {
+        ProtoTransitionKind.Raise => AlarmTransitionKind.Raise,
+        ProtoTransitionKind.Acknowledge => AlarmTransitionKind.Acknowledge,
+        ProtoTransitionKind.Clear => AlarmTransitionKind.Clear,
+        ProtoTransitionKind.Retrigger => AlarmTransitionKind.Retrigger,
+        _ => AlarmTransitionKind.StateChange
+    };
+
+    /// <summary>Derives the mirrored condition from a transition kind + severity.</summary>
+    private static AlarmConditionState ConditionFromKind(ProtoTransitionKind kind, int severity)
+    {
+        var (active, acked) = kind switch
+        {
+            ProtoTransitionKind.Raise => (true, false),
+            ProtoTransitionKind.Acknowledge => (true, true),
+            ProtoTransitionKind.Retrigger => (true, false),
+            ProtoTransitionKind.Clear => (false, true),
+            _ => (false, true)
+        };
+        return new AlarmConditionState(active, acked, Confirmed: null,
+            Shelve: AlarmShelveState.Unshelved, Suppressed: false, Severity: NormalizeSeverity(severity));
+    }
+
+    /// <summary>Maps a live <see cref="OnAlarmTransitionEvent"/> to a transition.</summary>
+    public static NativeAlarmTransition MapTransition(OnAlarmTransitionEvent body) => new(
+        SourceReference: body.AlarmFullReference,
+        SourceObjectReference: body.SourceObjectReference,
+        AlarmTypeName: body.AlarmTypeName,
+        Kind: MapKind(body.TransitionKind),
+        Condition: ConditionFromKind(body.TransitionKind, body.Severity),
+        Category: body.Category,
+        Description: body.Description,
+        Message: body.Description,
+        OperatorUser: body.OperatorUser,
+        OperatorComment: body.OperatorComment,
+        OriginalRaiseTime: body.OriginalRaiseTimestamp?.ToDateTimeOffset(),
+        TransitionTime: body.TransitionTimestamp?.ToDateTimeOffset() ?? DateTimeOffset.UtcNow,
+        CurrentValue: "",
+        LimitValue: "");
+
+    /// <summary>The end-of-snapshot sentinel transition (no condition payload).</summary>
+    public static NativeAlarmTransition SnapshotComplete() => new(
+        "", "", "", AlarmTransitionKind.SnapshotComplete,
+        new AlarmConditionState(false, true, null, AlarmShelveState.Unshelved, false, 0),
+        "", "", "", "", "", null, DateTimeOffset.UtcNow, "", "");
+
+    /// <summary>Maps one initial-snapshot <see cref="ActiveAlarmSnapshot"/> entry to a Snapshot transition.</summary>
+    public static NativeAlarmTransition MapSnapshot(ActiveAlarmSnapshot snapshot) => new(
+        SourceReference: snapshot.AlarmFullReference,
+        SourceObjectReference: snapshot.SourceObjectReference,
+        AlarmTypeName: snapshot.AlarmTypeName,
+        Kind: AlarmTransitionKind.Snapshot,
+        Condition: MapConditionState(snapshot.CurrentState, snapshot.Severity),
+        Category: snapshot.Category,
+        Description: snapshot.Description,
+        Message: snapshot.Description,
+        OperatorUser: snapshot.OperatorUser,
+        OperatorComment: snapshot.OperatorComment,
+        OriginalRaiseTime: snapshot.OriginalRaiseTimestamp?.ToDateTimeOffset(),
+        TransitionTime: snapshot.LastTransitionTimestamp?.ToDateTimeOffset() ?? DateTimeOffset.UtcNow,
+        CurrentValue: "",
+        LimitValue: "");
+}
diff --git a/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayDataConnection.cs b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayDataConnection.cs
index 79d9b8e2..8a5f501c 100644
--- a/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayDataConnection.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayDataConnection.cs
@@ -20,7 +20,7 @@ namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;
 /// <see cref="Disconnected"/>, the actor disposes this adapter, creates a fresh one,
 /// reconnects and re-subscribes all tags.
 /// </summary>
-public class MxGatewayDataConnection : IDataConnection, IBrowsableDataConnection
+public class MxGatewayDataConnection : IDataConnection, IBrowsableDataConnection, IAlarmSubscribableConnection
 {
     private readonly IMxGatewayClientFactory _clientFactory;
     private readonly ILogger<MxGatewayDataConnection> _logger;
@@ -28,6 +28,15 @@ public class MxGatewayDataConnection : IDataConnection, IBrowsableDataConnection
     private ConnectionHealth _status = ConnectionHealth.Disconnected;
     private CancellationTokenSource? _eventLoopCts;
 
+    // Native alarm feed: the gateway StreamAlarms RPC is session-less and
+    // gateway-wide, so one shared feed serves the whole connection. The
+    // DataConnectionActor routes transitions to instances by source reference,
+    // so a single shared callback (the first registered) suffices; subscriptions
+    // are ref-counted so the feed stops when the last one is removed.
+    private CancellationTokenSource? _alarmCts;
+    private int _alarmSubCount;
+    private readonly object _alarmLock = new();
+
     // subscriptionId → (tagPath, callback) so the event loop can route updates by tag,
     // plus tagPath → subscriptionId for reverse lookup. Concurrent because the event
     // loop reads from a background thread while Subscribe/Unsubscribe mutate.
@@ -112,6 +121,13 @@ public class MxGatewayDataConnection : IDataConnection, IBrowsableDataConnection
     public async Task DisconnectAsync(CancellationToken cancellationToken = default)
     {
         _eventLoopCts?.Cancel();
+        lock (_alarmLock)
+        {
+            _alarmCts?.Cancel();
+            _alarmCts?.Dispose();
+            _alarmCts = null;
+            _alarmSubCount = 0;
+        }
         if (_client is not null)
             await _client.DisconnectAsync(cancellationToken);
         _status = ConnectionHealth.Disconnected;
@@ -134,6 +150,43 @@ public class MxGatewayDataConnection : IDataConnection, IBrowsableDataConnection
         await _client!.UnsubscribeAsync(subscriptionId, cancellationToken);
     }
 
+    /// <inheritdoc />
+    public Task<string> SubscribeAlarmsAsync(
+        string sourceReference, string? conditionFilter,
+        AlarmTransitionCallback callback, CancellationToken cancellationToken = default)
+    {
+        lock (_alarmLock)
+        {
+            _alarmSubCount++;
+            if (_alarmCts == null)
+            {
+                _alarmCts = new CancellationTokenSource();
+                var token = _alarmCts.Token;
+                var client = _client!;
+                // Gateway-wide feed (null prefix); the actor filters per source reference.
+                _ = Task.Run(() => client.RunAlarmStreamAsync(null, t => callback(t), token), token);
+            }
+        }
+        return Task.FromResult(Guid.NewGuid().ToString());
+    }
+
+    /// <inheritdoc />
+    public Task UnsubscribeAlarmsAsync(string subscriptionId, CancellationToken cancellationToken = default)
+    {
+        lock (_alarmLock)
+        {
+            if (_alarmSubCount > 0)
+                _alarmSubCount--;
+            if (_alarmSubCount == 0)
+            {
+                _alarmCts?.Cancel();
+                _alarmCts?.Dispose();
+                _alarmCts = null;
+            }
+        }
+        return Task.CompletedTask;
+    }
+
     /// <inheritdoc />
     public async Task<ReadResult> ReadAsync(string tagPath, CancellationToken cancellationToken = default)
     {
diff --git a/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/RealMxGatewayClient.cs b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/RealMxGatewayClient.cs
index d208f6ee..e38caa0b 100644
--- a/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/RealMxGatewayClient.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/RealMxGatewayClient.cs
@@ -246,6 +246,61 @@ public sealed class RealMxGatewayClient : IMxGatewayClient
         }
     }
 
+    /// <inheritdoc />
+    public async Task RunAlarmStreamAsync(
+        string? alarmFilterPrefix, Action<Commons.Types.Alarms.NativeAlarmTransition> onTransition,
+        CancellationToken ct = default)
+    {
+        var reconnectDelay = TimeSpan.FromSeconds(5);
+        while (!ct.IsCancellationRequested)
+        {
+            try
+            {
+                var request = new StreamAlarmsRequest
+                {
+                    ClientCorrelationId = Guid.NewGuid().ToString("N"),
+                    AlarmFilterPrefix = alarmFilterPrefix ?? string.Empty,
+                };
+
+                await foreach (var message in _client!.StreamAlarmsAsync(request, ct)
+                    .WithCancellation(ct).ConfigureAwait(false))
+                {
+                    if (ct.IsCancellationRequested) break;
+                    switch (message.PayloadCase)
+                    {
+                        case AlarmFeedMessage.PayloadOneofCase.ActiveAlarm:
+                            onTransition(MxGatewayAlarmMapper.MapSnapshot(message.ActiveAlarm));
+                            break;
+                        case AlarmFeedMessage.PayloadOneofCase.Transition:
+                            onTransition(MxGatewayAlarmMapper.MapTransition(message.Transition));
+                            break;
+                        case AlarmFeedMessage.PayloadOneofCase.SnapshotComplete:
+                            onTransition(MxGatewayAlarmMapper.SnapshotComplete());
+                            break;
+                    }
+                }
+            }
+            catch (OperationCanceledException) when (ct.IsCancellationRequested)
+            {
+                return; // clean shutdown
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex,
+                    "MxGateway alarm stream faulted; reopening in {DelaySeconds}s", reconnectDelay.TotalSeconds);
+            }
+
+            try
+            {
+                await Task.Delay(reconnectDelay, ct).ConfigureAwait(false);
+            }
+            catch (OperationCanceledException) when (ct.IsCancellationRequested)
+            {
+                return;
+            }
+        }
+    }
+
     /// <inheritdoc />
     public async ValueTask DisposeAsync()
     {
diff --git a/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/FakeMxGatewayClient.cs b/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/FakeMxGatewayClient.cs
index 1118dedc..b1d1982e 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/FakeMxGatewayClient.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/FakeMxGatewayClient.cs
@@ -58,6 +58,12 @@ public sealed class FakeMxGatewayClient : IMxGatewayClient, IMxGatewayClientFact
         ct.ThrowIfCancellationRequested(); // …or FaultEventLoop() faults it to simulate a stream break
     }
 
+    public Task RunAlarmStreamAsync(
+        string? alarmFilterPrefix,
+        Action<ZB.MOM.WW.ScadaBridge.Commons.Types.Alarms.NativeAlarmTransition> onTransition,
+        CancellationToken ct = default)
+        => Task.CompletedTask; // no alarm feed in the fake
+
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
 
     /// <summary>Simulate a stream break so the adapter raises Disconnected.</summary>
diff --git a/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/MxGatewayAlarmMapperTests.cs b/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/MxGatewayAlarmMapperTests.cs
new file mode 100644
index 00000000..74c117af
--- /dev/null
+++ b/tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/MxGatewayAlarmMapperTests.cs
@@ -0,0 +1,66 @@
+using ZB.MOM.WW.MxGateway.Contracts.Proto;
+using ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;
+using CommonsTransitionKind = ZB.MOM.WW.ScadaBridge.Commons.Types.Enums.AlarmTransitionKind;
+using ProtoConditionState = ZB.MOM.WW.MxGateway.Contracts.Proto.AlarmConditionState;
+using ProtoTransitionKind = ZB.MOM.WW.MxGateway.Contracts.Proto.AlarmTransitionKind;
+
+namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests;
+
+/// <summary>Task-12: pure MxGateway alarm-feed proto → NativeAlarmTransition mapping.</summary>
+public class MxGatewayAlarmMapperTests
+{
+    [Fact]
+    public void MapTransition_AckTransition_IsAcknowledgedWithOperator()
+    {
+        var ev = new OnAlarmTransitionEvent
+        {
+            AlarmFullReference = "Tank01.Level.HiHi",
+            SourceObjectReference = "Tank01",
+            AlarmTypeName = "AnalogLimitAlarm.HiHi",
+            TransitionKind = ProtoTransitionKind.Acknowledge,
+            Severity = 600,
+            OperatorUser = "operator1",
+            OperatorComment = "ack",
+            Category = "Process",
+            Description = "hi"
+        };
+
+        var t = MxGatewayAlarmMapper.MapTransition(ev);
+
+        Assert.Equal(CommonsTransitionKind.Acknowledge, t.Kind);
+        Assert.True(t.Condition.Active);
+        Assert.True(t.Condition.Acknowledged);
+        Assert.Equal(600, t.Condition.Severity);
+        Assert.Equal("operator1", t.OperatorUser);
+        Assert.Equal("Tank01", t.SourceObjectReference);
+    }
+
+    [Fact]
+    public void MapConditionState_ActiveAcked_To_ActiveTrue_AckTrue()
+    {
+        var c = MxGatewayAlarmMapper.MapConditionState(ProtoConditionState.ActiveAcked, severity: 600);
+        Assert.True(c.Active);
+        Assert.True(c.Acknowledged);
+        Assert.Equal(600, c.Severity);
+    }
+
+    [Fact]
+    public void MapSnapshot_ActiveUnacked_IsSnapshotKind()
+    {
+        var snap = new ActiveAlarmSnapshot
+        {
+            AlarmFullReference = "Tank01.Level.Hi",
+            SourceObjectReference = "Tank01",
+            AlarmTypeName = "AnalogLimitAlarm.Hi",
+            CurrentState = ProtoConditionState.Active,
+            Severity = 1500 // out of range — must clamp
+        };
+
+        var t = MxGatewayAlarmMapper.MapSnapshot(snap);
+
+        Assert.Equal(CommonsTransitionKind.Snapshot, t.Kind);
+        Assert.True(t.Condition.Active);
+        Assert.False(t.Condition.Acknowledged);
+        Assert.Equal(1000, t.Condition.Severity);
+    }
+}