diff --git a/src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAlarmSource.cs b/src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAlarmSource.cs
index 1d763c7c..51671cde 100644
--- a/src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAlarmSource.cs
+++ b/src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAlarmSource.cs
@@ -3,7 +3,8 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 /// <summary>
 ///     Driver capability for alarm events. Optional — only drivers whose backends expose
 ///     alarm conditions implement this. Currently: Galaxy (MxAccess alarms), FOCAS
-///     (CNC alarms), OPC UA Client (A&amp;C events from upstream server).
+///     (CNC alarms), OPC UA Client (A&amp;C events from upstream server), MTConnect
+///     (CONDITION data items, Gitea #626).
 /// </summary>
 public interface IAlarmSource
 {
@@ -85,6 +86,22 @@ public sealed record AlarmAcknowledgeRequest(
 ///     other fields. <see cref="AlarmTransitionKind.Unspecified"/> when the upstream
 ///     path doesn't surface a distinct kind.
 /// </param>
+/// <param name="OpcUaSeverity">
+///     Optional exact OPC UA severity (1..1000) for a source whose own scale is finer than the four
+///     <see cref="AlarmSeverity"/> buckets (Gitea #626: MTConnect Warning = 500, Fault = 800). When set it
+///     supersedes the bucket on the projected Part 9 condition (clamped to 1..1000); <c>null</c> — every
+///     pre-#626 source — keeps the bucket mapping. <see cref="Severity"/> must still carry the nearest
+///     bucket for consumers that only read the bucket.
+/// </param>
+/// <param name="QualityStatusCode">
+///     Optional status code of the condition's SOURCE data (Part 9 <c>ConditionType.Quality</c>), for a
+///     source that can report "no value for this condition" per alarm rather than per connection (Gitea
+///     #626: MTConnect <c>Unavailable</c>). <c>null</c> keeps the pre-#626 behaviour (projected Good;
+///     driver-wide comms loss is annotated separately by the host). An event whose <see cref="Kind"/> is
+///     <see cref="AlarmTransitionKind.Unspecified"/> and which carries a quality is a
+///     <b>quality-only annotation</b> (<see cref="IsQualityOnly"/>): the host updates the condition's
+///     Quality without touching its Active/Acked state and publishes no <c>alerts</c> row for it.
+/// </param>
 public sealed record AlarmEventArgs(
     IAlarmSubscriptionHandle SubscriptionHandle,
     string SourceNodeId,
@@ -96,7 +113,17 @@ public sealed record AlarmEventArgs(
     string? OperatorComment = null,
     DateTime? OriginalRaiseTimestampUtc = null,
     string? AlarmCategory = null,
-    AlarmTransitionKind Kind = AlarmTransitionKind.Unspecified);
+    AlarmTransitionKind Kind = AlarmTransitionKind.Unspecified,
+    int? OpcUaSeverity = null,
+    uint? QualityStatusCode = null)
+{
+    /// <summary>
+    ///     True when this event only re-annotates the condition's source-data quality — a
+    ///     <see cref="QualityStatusCode"/> with an <see cref="AlarmTransitionKind.Unspecified"/> kind. No
+    ///     alarm-state change happened, so the host must not publish it as an alarm transition.
+    /// </summary>
+    public bool IsQualityOnly => Kind == AlarmTransitionKind.Unspecified && QualityStatusCode is not null;
+}
 
 /// <summary>Mirrors the <c>NodePermissions</c> alarm-severity enum in <c>docs/v2/acl-design.md</c>.</summary>
 public enum AlarmSeverity { Low, Medium, High, Critical }
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs
index d3e974e0..ac0cfbdd 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs
@@ -1811,8 +1811,11 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers, IWithUnboundedS
             _opcUaPublishActor.Tell(new ZB.MOM.WW.OtOpcUa.Runtime.OpcUa.OpcUaPublishActor.AlarmStateUpdate(
                 nodeId, snapshot, msg.Args.SourceTimestampUtc, n.Realm));
 
-            // Only the Primary publishes the cluster-wide alerts transition (see the gate above).
-            if (!serviceAlertsAsPrimary) continue;
+            // Only the Primary publishes the cluster-wide alerts transition (see the gate above). A quality-only
+            // annotation (#626: e.g. an MTConnect condition gone Unavailable while already Normal) is not an
+            // alarm transition at all — the condition write above carries it; an alerts row would read as
+            // "Activated" for something that never activated.
+            if (!serviceAlertsAsPrimary || msg.Args.IsQualityOnly) continue;
 
             var meta = _alarmMetaByNodeId.TryGetValue(nodeId, out var m)
                 ? m : (EquipmentId: nodeId, Name: nodeId, AlarmType: "AlarmCondition", HistorizeToAveva: (bool?)null,
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/NativeAlarmProjector.cs b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/NativeAlarmProjector.cs
index a7e2b75e..4e52cf90 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/NativeAlarmProjector.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/NativeAlarmProjector.cs
@@ -21,7 +21,8 @@ public sealed class NativeAlarmProjector
     public AlarmConditionSnapshot Project(string nodeId, AlarmEventArgs e)
     {
         var prev = _prior.TryGetValue(nodeId, out var p) ? p : (Active: false, Acked: true);
-        var sev = MapSeverity(e.Severity);
+        // #626: a source with a finer scale than the four buckets supplies the exact Part 9 severity.
+        var sev = e.OpcUaSeverity is { } exact ? (ushort)Math.Clamp(exact, 1, 1000) : MapSeverity(e.Severity);
         var (active, acked) = e.Kind switch
         {
             AlarmTransitionKind.Raise or AlarmTransitionKind.Retrigger => (true, false),
@@ -32,7 +33,11 @@ public sealed class NativeAlarmProjector
         _prior[nodeId] = (active, acked);
         return new AlarmConditionSnapshot(
             Active: active, Acknowledged: acked, Confirmed: true, Enabled: true,
-            Shelving: AlarmShelvingKind.Unshelved, Severity: sev, Message: e.Message);
+            Shelving: AlarmShelvingKind.Unshelved, Severity: sev, Message: e.Message,
+            // #626: a per-condition source quality (MTConnect Unavailable) when the driver reports one. Absent
+            // (every pre-#626 source) ⇒ Good, as before — driver-wide comms loss stays the host's
+            // out-of-band WriteAlarmQuality annotation (#477), not something the projector infers.
+            StatusCode: e.QualityStatusCode ?? OpcUaStatus.Good);
     }
 
     /// <summary>Clears all tracked per-node state (call on address-space rebuild).</summary>
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs
index e14b57aa..0a99914d 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs
@@ -271,6 +271,62 @@ public sealed class DriverHostActorNativeAlarmTests : RuntimeActorTestBase
         evt.User.ShouldBe("device");
     }
 
+    /// <summary>Gitea #626 — a QUALITY-ONLY native event (an <see cref="AlarmTransitionKind.Unspecified"/> kind
+    /// carrying <see cref="AlarmEventArgs.QualityStatusCode"/>, e.g. an MTConnect condition gone Unavailable while
+    /// already Normal) re-annotates the condition's Quality through the ordinary state update, and publishes NO
+    /// <c>alerts</c> row — it is not an alarm transition. The positive control is the Raise that follows: it
+    /// MUST publish, and it must be the FIRST alerts message, so the absence is proven rather than timed.</summary>
+    [Fact]
+    public void Quality_only_native_event_updates_the_condition_but_publishes_no_alerts_row()
+    {
+        var db = NewInMemoryDbFactory();
+        var deploymentId = SeedV3AlarmDeployment(db, RevA, Driver: "drv-1", Tag: "temp_hi");
+
+        var alerts = CreateTestProbe();
+        SubscribeToAlerts(alerts);
+
+        var (actor, publish) = SpawnHostAndApply(db, deploymentId);
+
+        actor.Tell(new DriverInstanceActor.AttributeAlarmPublished("drv-1", new AlarmEventArgs(
+            new StubAlarmHandle(),
+            SourceNodeId: "Temp",
+            ConditionId: AlarmRawPath,
+            AlarmType: "SYSTEM",
+            Message: "SYSTEM UNAVAILABLE",
+            Severity: AlarmSeverity.Low,
+            SourceTimestampUtc: Ts,
+            Kind: AlarmTransitionKind.Unspecified,
+            QualityStatusCode: OpcUaStatus.BadNoCommunication)));
+
+        var annotated = publish.ExpectMsg<OpcUaPublishActor.AlarmStateUpdate>(TimeSpan.FromSeconds(5));
+        annotated.AlarmNodeId.ShouldBe(AlarmRawPath);
+        annotated.State.Active.ShouldBeFalse();
+        annotated.State.StatusCode.ShouldBe(OpcUaStatus.BadNoCommunication);
+
+        // Positive control: a real transition after it DOES publish, and is the first thing on the topic.
+        actor.Tell(new DriverInstanceActor.AttributeAlarmPublished("drv-1", new AlarmEventArgs(
+            new StubAlarmHandle(),
+            SourceNodeId: "Temp",
+            ConditionId: AlarmRawPath,
+            AlarmType: "SYSTEM",
+            Message: "spindle fault",
+            Severity: AlarmSeverity.High,
+            SourceTimestampUtc: Ts,
+            Kind: AlarmTransitionKind.Raise,
+            OpcUaSeverity: 800,
+            QualityStatusCode: OpcUaStatus.Good)));
+
+        var raised = publish.ExpectMsg<OpcUaPublishActor.AlarmStateUpdate>(TimeSpan.FromSeconds(5));
+        raised.State.Active.ShouldBeTrue();
+        raised.State.Severity.ShouldBe((ushort)800);
+        raised.State.StatusCode.ShouldBe(OpcUaStatus.Good);
+
+        var evt = alerts.ExpectMsg<AlarmTransitionEvent>(TimeSpan.FromSeconds(5));
+        evt.Message.ShouldBe("spindle fault", "the quality-only annotation must not have published an alerts row");
+        evt.TransitionKind.ShouldBe("Activated");
+        evt.Severity.ShouldBe(800);
+    }
+
     /// <summary>#477 Layer 2 — a driver <see cref="DriverInstanceActor.ConnectivityChanged"/> annotates the
     /// Quality of the driver's native conditions via <see cref="OpcUaPublishActor.AlarmQualityUpdate"/>: comms
     /// lost → Bad, restored → Good, at the raw condition NodeId + realm. No alarm transition is involved — this
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/NativeAlarmProjectorTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/NativeAlarmProjectorTests.cs
index b7df4648..eaee1d77 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/NativeAlarmProjectorTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/NativeAlarmProjectorTests.cs
@@ -166,6 +166,49 @@ public class NativeAlarmProjectorTests
         snap.StatusCode.ShouldBe(OpcUaStatus.Good);
     }
 
+    // Gitea #626 — a source with a finer severity scale than the four buckets (MTConnect Fault = 800) sets
+    // OpcUaSeverity, which supersedes the bucket on the projected condition. Clamped to the Part 9 1..1000.
+    [Theory]
+    [InlineData(800, 800)]
+    [InlineData(500, 500)]
+    [InlineData(0, 1)]
+    [InlineData(5000, 1000)]
+    public void Explicit_opcua_severity_supersedes_the_bucket(int requested, int projected)
+    {
+        var sut = new NativeAlarmProjector();
+
+        var snap = sut.Project("n1", Evt(AlarmTransitionKind.Raise, AlarmSeverity.High) with { OpcUaSeverity = requested });
+
+        snap.Severity.ShouldBe((ushort)projected);
+    }
+
+    // Gitea #626 — a per-condition source quality (MTConnect Unavailable) rides the snapshot's StatusCode, the
+    // same Quality child #477's connectivity annotation writes.
+    [Fact]
+    public void Supplied_quality_is_projected_onto_the_snapshot()
+    {
+        var sut = new NativeAlarmProjector();
+
+        var snap = sut.Project("n1", Evt(AlarmTransitionKind.Clear) with { QualityStatusCode = OpcUaStatus.BadNoCommunication });
+
+        snap.StatusCode.ShouldBe(OpcUaStatus.BadNoCommunication);
+    }
+
+    // Gitea #626 — a quality-only annotation (Unspecified kind + quality) must not move Active/Acked: an
+    // active, unacknowledged condition stays exactly that while only its Quality changes.
+    [Fact]
+    public void Quality_only_annotation_keeps_the_prior_alarm_state()
+    {
+        var sut = new NativeAlarmProjector();
+        sut.Project("n1", Evt(AlarmTransitionKind.Raise));
+
+        var snap = sut.Project("n1", Evt(AlarmTransitionKind.Unspecified) with { QualityStatusCode = OpcUaStatus.BadNoCommunication });
+
+        snap.Active.ShouldBeTrue();
+        snap.Acknowledged.ShouldBeFalse();
+        snap.StatusCode.ShouldBe(OpcUaStatus.BadNoCommunication);
+    }
+
     private static AlarmEventArgs Evt(
         AlarmTransitionKind kind,
         AlarmSeverity sev = AlarmSeverity.High,