Merge pull request 'feat(alarms): condition Quality tracks source connectivity (#477)' (#479) from fix/alarm-condition-quality-477 into master

docs/AlarmTracking.md

@@ -68,6 +68,7 @@ are set explicitly. Leaving them unset shipped them as **null** on every event
 | `ConditionName` | the leaf / display name (e.g. `HR200`) | Where the short human-readable name lives |
 | `ConditionClassId` | always **`BaseConditionClassType`** | Part 9's "no condition class modelled" value. Unset shipped `NodeId.Null` (#475) |
 | `ConditionClassName` | always **`"BaseConditionClass"`** | Matches `ConditionClassId`. Unset shipped empty text (#475) |
+| `Quality` | the condition's **source-data quality** — tracks the native source's connectivity (`Good` / `Bad`) | A pure annotation; never alters Active/Acked/Retain. Unset shipped the accidentally-Good default (#477) — see below |
 
 **Why `BaseConditionClassType` and not `ProcessConditionClassType`.** We hold no per-alarm
 classification at the materialize seam, and `ConditionClassId` is a wire contract clients bucket on.
@@ -111,6 +112,43 @@ that `ConditionClassId` / `ConditionClassName` do too. The two class fields are
 > a live↔history join key. Correlate on `ConditionId` / the RawPath instead. (Pre-existing; the
 > live-path fix above does not change the history path.)
 
+### Condition source-data Quality (#477)
+
+`ConditionType.Quality` reports the quality of the condition's source data. It was never assigned, and
+because `StatusCodes.Good == 0x00000000` an unassigned `StatusCode` **is** `Good` — so every condition
+reported `Good` unconditionally (a wrong *value*, not a null like #473/#475). A native alarm whose device
+went offline still read `Good`, so an operator could not tell *"genuinely inactive"* from *"we have lost
+contact and do not know"*.
+
+**How it is driven now (native alarms).** An alarm-bearing raw tag materializes a condition with **no
+sibling value variable**, so the value/quality path (`WriteValue`) never touches it, and a comms-lost
+driver emits **no alarm transitions** (the feed goes silent). The quality therefore comes from the
+**driver's connectivity**, out of band from alarm transitions:
+
+- `DriverInstanceActor` Tells its host `ConnectivityChanged(driverInstanceId, connected)` on every
+  transition into `Connected` (`true`) / `Reconnecting` (`false`).
+- `DriverHostActor.OnDriverConnectivityChanged` fans that out to **every** native condition the driver
+  owns as an `OpcUaPublishActor.AlarmQualityUpdate` (`Good` on connect, `Bad` on disconnect).
+- `OtOpcUaNodeManager.WriteAlarmQuality` sets **only** the condition's `Quality` and fires a Part 9
+  event **only on a quality-bucket change** — it never touches Active/Acked/Severity/Retain (an active
+  alarm that loses comms stays active). This is a dedicated path, *not* a full-snapshot re-projection, so
+  it cannot clobber a condition's severity/message and works for a condition that never fired a transition.
+- A freshly materialized native condition starts `BadWaitingForInitialData` (the "no driver data yet"
+  convention value variables use); the first `Connected` confirms it `Good`.
+- The connectivity annotation is **ungated by redundancy role** (a Secondary keeps its condition quality
+  warm for failover) and publishes **no `/alerts` row** — driver comms health already has its own status
+  surface (`IDriverHealthPublisher`); a row per condition would be alarm-fatigue.
+
+**Scripted alarms** are script-computed and always live in this scope, so they materialize `Good` and are
+not connectivity-driven. Deriving a scripted condition's quality from the worst of its input tags'
+qualities is a deferred follow-up (Layer 3).
+
+Wire-level guard: `NativeAlarmEventIdentityFieldDeliveryTests.Condition_event_Quality_tracks_source_connectivity_on_the_wire`
+subscribes with a `[Quality, Message]` clause (Quality is declared on `ConditionType`) and asserts a
+healthy source reports `Good`, a comms-lost source reports non-`Good`, and recovery returns to `Good` — on
+a real client subscription. `NodeManagerAlarmSourceFieldsTests` guards the node itself + the no-clobber /
+unknown-node-no-op invariants.
+
 ## Galaxy driver path (driver-native)
 
 Restored in PR B.2 of the epic. `GalaxyDriver` implements

docs/plans/2026-07-17-alarm-condition-quality-477-design.md

@@ -0,0 +1,127 @@
+# Alarm condition Quality (issue #477) — design
+
+**Status:** implemented (L1+L2) · **Date:** 2026-07-17 · **Issue:** #477 (follow-up chain #473 → #475 → #477)
+**Scope decision:** Layer 1 + Layer 2, Bad-direct, annotate-only. Layer 3 (scripted worst-of-input) deferred → **#478**.
+
+## Problem
+
+`AlarmConditionState.Quality` is never assigned anywhere in `src/` — neither by
+`OtOpcUaNodeManager.MaterialiseAlarmCondition` nor by the `WriteAlarmCondition` transition path.
+Because `StatusCodes.Good == 0x00000000`, `default(StatusCode)` **is** `Good`, so the field is
+*accidentally valid* — clients parse it, but it reports **`Good` unconditionally regardless of the
+backing tag's real quality**.
+
+This is a wrong-*value* bug, not the null-value bug class of #473/#475. Part 9 defines
+`ConditionType.Quality` as "the quality of the Condition's source data". OT impact: when a native
+alarm's device goes offline (comms lost) the condition still reports `Quality = Good`, so an operator
+(or an HMI bucketing on `IsGood`) cannot distinguish *"genuinely not active"* from *"we have lost
+contact and do not know"*.
+
+## Why it isn't a 2-line default (confirmed by code)
+
+1. **Alarm-bearing raw tags have no value variable.** `AddressSpaceApplier` materialises a raw tag as
+   *either* a condition node (`tag.Alarm is not null`) *or* a value variable (`else`) — never both,
+   since they'd share the same `s=<RawPath>` NodeId. So `WriteValue` (the only path carrying
+   `OpcUaQuality`) is never invoked for an alarm node. Quality has nowhere to land today.
+2. **The alarm channel is quality-blind.** `AlarmEventArgs` (driver → host) and `AlarmConditionSnapshot`
+   (host → SDK sink) both carry no quality field.
+3. **On comms-loss the alarm feed goes silent.** `DriverInstanceActor` on `DisconnectObserved` detaches
+   the alarm subscription and re-enters `Reconnecting` — no transition event ever arrives to carry Bad.
+   So the "device offline" signal must come from **driver connectivity**, independently of alarm
+   transitions.
+
+## Decisions (the issue's open questions)
+
+| # | Question | Decision | Rationale |
+|---|----------|----------|-----------|
+| 1 | Does an alarm tag get quality today? | No | Confirmed above — new plumbing required. |
+| 2 | Direct status code vs. policy map | **Direct Bad** on comms-loss; Good on reconnect | Matches how a value variable would read; unambiguous for `IsGood` bucketing. |
+| 3 | Does Bad also suppress transitions / touch Retain? | **No — annotate only** | A comms-lost *active* condition must stay active + retained. Silently clearing an active alarm on comms-loss is the unsafe direction. Quality is a pure annotation; the Active/Ack/Retain state machine is untouched. |
+| 4 | Scripted alarms: worst-of-inputs quality? | **Deferred (Layer 3)** | Scripted conditions stay `Good`. Filed as a follow-up issue. |
+
+## Architecture — reuse the existing publish path, add no sink method
+
+The key move: **do not add a new `IOpcUaAddressSpaceSink` method.** A new sink-interface surface would
+have to be forwarded through `DeferredAddressSpaceSink` or it is inert on driver hosts (the F10b
+prod-inertness trap). Instead the `NativeAlarmProjector` becomes the single owner of per-condition
+state *and* quality, and a connectivity change re-projects the *last* snapshot with a swapped quality
+through the **existing** `AlarmStateUpdate → OpcUaPublishActor → WriteAlarmCondition` path.
+
+### Layer 1 — make Quality a real, plumbed field
+
+- `AlarmConditionSnapshot` (Commons) gains `OpcUaQuality Quality` (last positional param, default
+  `OpcUaQuality.Good` so scripted callers and existing tests keep compiling; Commons already knows
+  `OpcUaQuality` via `IOpcUaAddressSpaceSink`).
+- `MaterialiseAlarmCondition` sets `alarm.Quality.Value` at build time:
+  **native → `BadWaitingForInitialData`** (honest until connectivity confirms Good, matching the
+  value-variable "waiting for initial data" convention), **scripted → `Good`** (script-computed, always
+  live in this scope).
+- `WriteAlarmCondition` projects `StatusFromQuality(state.Quality)` onto `condition.Quality.Value`
+  (+ `SourceTimestamp`).
+- The delta-gate (`AlarmConditionDelta` / `ReadConditionDelta` / `ToConditionDelta`) gains a `Quality`
+  member, so a Good→Bad bucket change is a genuine delta and **fires a Part 9 condition event**.
+
+### Layer 2 — drive native quality from driver connectivity
+
+- `DriverInstanceActor`: new `public sealed record ConnectivityChanged(string DriverInstanceId, bool Connected)`.
+  `Context.Parent.Tell` it on `Become(Connected)` entry (`true`) and on the transitions into
+  `Reconnecting` (`DisconnectObserved` / `ForceReconnect`) (`false`). Fire-and-forget, mirrors
+  `DeltaApplied`.
+- `NativeAlarmProjector`: per-node state becomes `(bool Active, bool Acked, OpcUaQuality Quality)`.
+  `Project(transition)` preserves the current quality; new `ProjectQuality(nodeId, quality)` preserves
+  Active/Acked and swaps only the quality, returning a full snapshot.
+- `DriverHostActor`: `Receive<ConnectivityChanged>` iterates `_alarmNodeIdByDriverRef` for that driver
+  instance and Tells one `AlarmStateUpdate` per condition with the re-projected snapshot
+  (`connected ? Good : Bad`). **Ungated** — both redundancy nodes track their own driver's comms, matching
+  the existing "condition write stays ungated (Secondary keeps its address space warm)" rule.
+  **No `/alerts` row** for a quality-only change — driver health already has its own status/alerts surface
+  via `IDriverHealthPublisher`; a row here would be alarm-fatigue.
+
+Scripted alarms are unaffected: they are not driver instances, receive no `ConnectivityChanged`, and
+their snapshot quality stays `Good`.
+
+## Files
+
+**Layer 1**
+- `src/Core/ZB.MOM.WW.OtOpcUa.Commons/OpcUa/AlarmConditionSnapshot.cs`
+- `src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs` (`MaterialiseAlarmCondition`,
+  `WriteAlarmCondition`, `AlarmConditionDelta`/`ReadConditionDelta`/`ToConditionDelta`)
+- `src/Server/ZB.MOM.WW.OtOpcUa.Runtime/ScriptedAlarms/ScriptedAlarmHostActor.cs` (`ToSnapshot` — Quality=Good, or rely on default)
+
+**Layer 2**
+- `src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverInstanceActor.cs`
+- `src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/NativeAlarmProjector.cs`
+- `src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs`
+
+## Tests (TDD, RED-first)
+
+1. **Wire-level (the issue's suggested guard)** — extend `NativeAlarmEventIdentityFieldDeliveryTests`
+   (OpcUaServer.IntegrationTests): active alarm → event `Quality.IsGood`; driver disconnect → condition
+   event `Quality.IsGood == false`; reconnect → Good. Verify RED against pre-fix.
+2. **Node-level** — `NodeManagerAlarmSourceFieldsTests`: materialise sets Quality (native
+   `BadWaitingForInitialData`, scripted `Good`); `WriteAlarmCondition` projects snapshot quality and
+   fires on a quality-bucket change only.
+3. **`NativeAlarmProjector`** unit: `ProjectQuality` keeps Active/Acked + swaps quality; `Project`
+   preserves quality.
+4. **`DriverInstanceActor`**: `Connected` entry Tells `ConnectivityChanged(true)`; `DisconnectObserved`
+   Tells `ConnectivityChanged(false)`.
+5. **`DriverHostActor`**: `ConnectivityChanged(false)` pushes a Bad-quality `AlarmStateUpdate` to every
+   condition of that driver instance.
+
+## Deferred / notes
+
+- **Layer 3** (scripted worst-of-input quality) → **Gitea #478**.
+- **Implementation note:** L2 uses a **dedicated `IOpcUaAddressSpaceSink.WriteAlarmQuality`** path (not a
+  full-snapshot re-projection). Rationale: a connectivity change must set *only* Quality; re-projecting a full
+  snapshot would clobber a cold condition's severity/message and can't annotate a condition that never fired a
+  transition. The new sink method is forwarded through `DeferredAddressSpaceSink` (the F10b inertness trap) —
+  auto-verified by `DeferredSinkForwardingReflectionTests` (reflection guard) + its realm-discriminator guard.
+- **Test-harness note:** the new `DriverInstanceActor → parent` `ConnectivityChanged` Tell polluted existing
+  parent-`TestProbe` assertions in 3 `DriverInstanceActor*Tests` files; those tests now
+  `parent.IgnoreMessages(m => m is ConnectivityChanged)` since they assert on data/alarm/discovery forwards,
+  not connectivity.
+- `Bad_NoCommunication` vs generic `Bad`: v1 maps `OpcUaQuality.Bad → StatusCodes.Bad`; refining
+  `StatusFromQuality` to emit `BadNoCommunication` for the comms-loss case is a one-line nicety, noted in
+  the issue.
+- `docs/AlarmTracking.md` §"Condition event identity fields" gains a Quality subsection (Good/Bad
+  semantics, annotation-not-state-change, quality-bucket change fires an event).

src/Core/ZB.MOM.WW.OtOpcUa.Commons/OpcUa/AlarmConditionSnapshot.cs

@@ -16,6 +16,12 @@ namespace ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
 /// <param name="Shelving">The shelving mode (ShelvingState): unshelved, one-shot, or timed.</param>
 /// <param name="Severity">OPC UA severity on the 1..1000 scale (the SDK <c>SetSeverity</c> input).</param>
 /// <param name="Message">The human-readable condition message (LocalizedText payload).</param>
+/// <param name="Quality">
+///     Quality of the condition's source data (Part 9 <c>ConditionType.Quality</c>). Carried so a
+///     comms-lost native source can report a non-<c>Good</c> condition instead of the accidentally-Good
+///     default (issue #477). It is a pure annotation — it never alters Active/Acked/Retain. Defaults to
+///     <see cref="OpcUaQuality.Good"/> so scripted-alarm callers (which stay Good in v1) need not supply it.
+/// </param>
 public sealed record AlarmConditionSnapshot(
     bool Active,
     bool Acknowledged,
@@ -23,7 +29,8 @@ public sealed record AlarmConditionSnapshot(
     bool Enabled,
     AlarmShelvingKind Shelving,
     ushort Severity,
-    string Message);
+    string Message,
+    OpcUaQuality Quality = OpcUaQuality.Good);
 
 /// <summary>
 ///     Commons-local mirror of the Core <c>ShelvingKind</c> enum so this assembly carries no

src/Core/ZB.MOM.WW.OtOpcUa.Commons/OpcUa/DeferredAddressSpaceSink.cs

@@ -30,6 +30,9 @@ public sealed class DeferredAddressSpaceSink : IOpcUaAddressSpaceSink, ISurgical
     public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm)
         => _inner.WriteAlarmCondition(alarmNodeId, state, sourceTimestampUtc, realm);
 
+    public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm)
+        => _inner.WriteAlarmQuality(alarmNodeId, quality, sourceTimestampUtc, realm);
+
     /// <inheritdoc />
     public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false)
         => _inner.MaterialiseAlarmCondition(alarmNodeId, equipmentNodeId, displayName, alarmType, severity, realm, isNative);

src/Core/ZB.MOM.WW.OtOpcUa.Commons/OpcUa/IOpcUaAddressSpaceSink.cs

@@ -33,6 +33,17 @@ public interface IOpcUaAddressSpaceSink
     /// the condition was materialised under).</param>
     void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm);
 
+    /// <summary>#477 — annotate a materialised condition's source-data quality OUT OF BAND from any alarm
+    /// transition (used by the driver-connectivity path: comms lost → <see cref="OpcUaQuality.Bad"/>,
+    /// restored → <see cref="OpcUaQuality.Good"/>). Sets ONLY the condition's Quality — never
+    /// Active/Acked/Severity/Retain (a comms-lost active alarm stays active) — and fires one Part 9 event
+    /// only on a quality-bucket change. A no-op for an unmaterialised / non-condition node.</summary>
+    /// <param name="alarmNodeId">The condition node id (RawPath for a native alarm).</param>
+    /// <param name="quality">The source-data quality to annotate.</param>
+    /// <param name="sourceTimestampUtc">The connectivity transition timestamp in UTC.</param>
+    /// <param name="realm">The namespace realm the condition was materialised under.</param>
+    void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm);
+
     /// <summary>
     ///     Materialise a real OPC UA Part 9 alarm-condition node under its equipment folder so clients
     ///     can browse it as a proper condition (with basic Active/Ack state). The node id equals the
@@ -165,6 +176,7 @@ public sealed class NullOpcUaAddressSpaceSink : IOpcUaAddressSpaceSink
 
     /// <inheritdoc />
     public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
+    public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
 
     /// <inheritdoc />
     public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false) { }

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs

@@ -497,6 +497,16 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
                 condition.SetSeverity(SystemContext, MapSeverity(state.Severity));
                 condition.Message.Value = new LocalizedText(state.Message);
 
+                // #477 — project the source-data quality. A Good→Bad bucket change is a genuine condition
+                // change (it's in the delta-gate above), so it fires a Part 9 event carrying the new Quality;
+                // it never touches Active/Acked/Retain (annotation only). Quality is an optional Part 9 child —
+                // null-guard it like Confirmed/Shelving in case a leaner SDK child set omits it.
+                if (condition.Quality is not null)
+                {
+                    condition.Quality.Value = StatusFromQuality(state.Quality);
+                    if (condition.Quality.SourceTimestamp is not null) condition.Quality.SourceTimestamp.Value = sourceTimestampUtc;
+                }
+
                 // Part 9: retain the condition while it is active OR unacknowledged so a client's
                 // ConditionRefresh replays it. The event firing below also depends on this Retain being
                 // correct (a non-retained inactive+acked condition still fires its transition event, but
@@ -535,6 +545,50 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         }
     }
 
+    /// <summary>
+    ///     #477 Layer 2 — apply a source-data quality annotation to a materialised condition, OUT OF BAND
+    ///     from any alarm transition. Used by the driver-connectivity path (comms lost → Bad, restored →
+    ///     Good) so a native condition whose device is unreachable stops reporting the accidentally-Good
+    ///     default. This sets ONLY <see cref="ConditionState.Quality"/> — it never touches
+    ///     Active / Acked / Severity / Retain (a comms-lost active alarm must stay active). A change in the
+    ///     quality bucket is a genuine Part 9 condition change, so it fires one condition event carrying the
+    ///     new Quality; an unchanged bucket suppresses (no spurious event). Unknown / unmaterialised node ⇒
+    ///     safe no-op (a mid-rebuild race must not fault a connectivity update), mirroring the other writes.
+    /// </summary>
+    /// <param name="alarmNodeId">The condition node id (RawPath for a native alarm).</param>
+    /// <param name="quality">The source-data quality to annotate.</param>
+    /// <param name="sourceTimestampUtc">Timestamp of the connectivity transition in UTC.</param>
+    /// <param name="realm">The condition's address-space realm.</param>
+    public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm)
+    {
+        ArgumentException.ThrowIfNullOrEmpty(alarmNodeId);
+        EnsureAddressSpaceCreated();
+
+        var key = MapKey(realm, alarmNodeId);
+        lock (Lock)
+        {
+            // Only materialised conditions carry a Quality child; a bare value variable or a missing node is
+            // a no-op (the connectivity fan-out visits every condition the driver owns, some of which a
+            // concurrent rebuild may have just cleared).
+            if (!_alarmConditions.TryGetValue(key, out var condition) || condition.Quality is null)
+                return;
+
+            var newCode = StatusFromQuality(quality);
+            var changed = condition.Quality.Value.Code != newCode.Code;
+
+            condition.Quality.Value = newCode;
+            if (condition.Quality.SourceTimestamp is not null) condition.Quality.SourceTimestamp.Value = sourceTimestampUtc;
+
+            // Fire ONLY on a real bucket change so a steady-state connectivity re-assert doesn't spam events.
+            if (changed)
+            {
+                condition.Time.Value = sourceTimestampUtc;
+                condition.ReceiveTime.Value = sourceTimestampUtc;
+                ReportConditionEvent(condition, sourceTimestampUtc);
+            }
+        }
+    }
+
     /// <summary>
     ///     Fire a real OPC UA Part 9 condition event for one engine-driven state transition on a
     ///     materialised <see cref="AlarmConditionState"/>. The caller MUST already hold <c>Lock</c> and
@@ -650,7 +704,11 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         bool Enabled,
         AlarmShelvingKind Shelving,
         ushort MappedSeverity,
-        string Message);
+        string Message,
+        // #477 — the source-data quality bucket. Included so a quality-only transition (e.g. a device
+        // going comms-lost: Good→Bad with no state change) is a genuine delta and fires a Part 9 event.
+        // StatusCode has value equality, so the record struct's == still holds.
+        StatusCode Quality);
 
     /// <summary>Decide whether a <see cref="WriteAlarmCondition"/> projection is a genuine state change
     /// (and so should fire a Part 9 condition event) by comparing the node's pre-projection state to the
@@ -676,7 +734,10 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         Enabled: condition.EnabledState?.Id?.Value ?? true,
         Shelving: ReadShelvingKind(condition),
         MappedSeverity: condition.Severity?.Value ?? (ushort)0,
-        Message: condition.Message?.Value?.Text ?? string.Empty);
+        Message: condition.Message?.Value?.Text ?? string.Empty,
+        // Optional Part 9 child; a node without it reads as Good (matching the accidentally-Good default
+        // and ToConditionDelta's fold), so a snapshot Quality can't create a phantom delta against it.
+        Quality: condition.Quality?.Value ?? StatusCodes.Good);
 
     /// <summary>Build the gate-relevant slice from the incoming snapshot, normalising the two fields that
     /// the node stores in a derived form: Severity is run through <see cref="MapSeverity"/> so it matches
@@ -694,7 +755,10 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         // node's read-back default (Unshelved).
         Shelving: condition.ShelvingState is not null ? state.Shelving : AlarmShelvingKind.Unshelved,
         MappedSeverity: (ushort)MapSeverity(state.Severity),
-        Message: state.Message ?? string.Empty);
+        Message: state.Message ?? string.Empty,
+        // If the node has no Quality child, WriteAlarmCondition's projection is a no-op there; fold to the
+        // node's read-back default (Good) so a snapshot Quality can't register a spurious delta.
+        Quality: condition.Quality is not null ? StatusFromQuality(state.Quality) : StatusCodes.Good);
 
     /// <summary>Map the live shelving state machine's CurrentState back to our 3-way
     /// <see cref="AlarmShelvingKind"/> by matching its well-known Part 9 state object id. Any node without
@@ -827,6 +891,20 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
             if (alarm.ConditionClassId is not null) alarm.ConditionClassId.Value = ObjectTypeIds.BaseConditionClassType;
             if (alarm.ConditionClassName is not null) alarm.ConditionClassName.Value = new LocalizedText("BaseConditionClass");
 
+            // #477 — ConditionType.Quality (the quality of the condition's source data). Create() leaves it
+            // UNSET, and default(StatusCode) == StatusCodes.Good (0x0), so an unassigned Quality reports Good
+            // unconditionally — a wrong VALUE (not a null), which hides a comms-lost source. A NATIVE condition
+            // has no data yet at materialise (its driver hasn't confirmed connectivity), so it starts
+            // BadWaitingForInitialData — the same "no driver data yet" convention value variables use — and is
+            // driven Good by the driver-connectivity path (DriverHostActor → ProjectQuality) once Connected. A
+            // SCRIPTED condition is script-computed and always live in v1, so it starts Good. Quality is a pure
+            // annotation: it NEVER alters Active/Acked/Retain (a comms-lost active alarm must stay active).
+            if (alarm.Quality is not null)
+            {
+                alarm.Quality.Value = isNative ? StatusCodes.BadWaitingForInitialData : StatusCodes.Good;
+                if (alarm.Quality.SourceTimestamp is not null) alarm.Quality.SourceTimestamp.Value = DateTime.UtcNow;
+            }
+
             // Initial state via the SDK setters (T14: basic state only, NO event firing).
             alarm.SetEnableState(SystemContext, true);
             alarm.SetActiveState(SystemContext, false);

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/SdkAddressSpaceSink.cs

@@ -28,6 +28,9 @@ public sealed class SdkAddressSpaceSink : IOpcUaAddressSpaceSink, ISurgicalAddre
     public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm)
         => _nodeManager.WriteAlarmCondition(alarmNodeId, state, sourceTimestampUtc, realm);
 
+    public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm)
+        => _nodeManager.WriteAlarmQuality(alarmNodeId, quality, sourceTimestampUtc, realm);
+
     /// <inheritdoc />
     public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false)
         => _nodeManager.MaterialiseAlarmCondition(alarmNodeId, equipmentNodeId, displayName, alarmType, severity, realm, isNative);

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs

@@ -570,6 +570,7 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
         Receive<GetDiagnostics>(HandleGetDiagnostics);
         Receive<DriverInstanceActor.AttributeValuePublished>(ForwardToMux);
         Receive<DriverInstanceActor.AttributeAlarmPublished>(ForwardNativeAlarm);
+        Receive<DriverInstanceActor.ConnectivityChanged>(OnDriverConnectivityChanged);
         Receive<DriverInstanceActor.DiscoveredNodesReady>(HandleDiscoveredNodes);
         Receive<DriverInstanceActor.DeltaApplied>(HandleDeltaApplied);
         Receive<RestartDriver>(HandleRestartDriver);
@@ -600,6 +601,7 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
         Receive<GetDiagnostics>(HandleGetDiagnostics);
         Receive<DriverInstanceActor.AttributeValuePublished>(ForwardToMux);
         Receive<DriverInstanceActor.AttributeAlarmPublished>(ForwardNativeAlarm);
+        Receive<DriverInstanceActor.ConnectivityChanged>(OnDriverConnectivityChanged);
         Receive<DriverInstanceActor.DiscoveredNodesReady>(HandleDiscoveredNodes);
         Receive<DriverInstanceActor.DeltaApplied>(HandleDeltaApplied);
         Receive<RestartDriver>(HandleRestartDriver);
@@ -1010,6 +1012,46 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
     ///         signal the inbound-write gate uses — only the Primary publishes the single fleet-wide copy.
     ///     </para>
     /// </summary>
+    /// <summary>
+    ///     #477 — a child driver's connectivity transition. Annotates the source-data Quality of EVERY native
+    ///     alarm condition the driver owns: comms lost → <see cref="OpcUaQuality.Bad"/>, restored →
+    ///     <see cref="OpcUaQuality.Good"/>. This is the ONLY signal for a comms-lost native source, because a
+    ///     disconnected driver emits no alarm transitions — the alarm feed goes silent, so without this a
+    ///     comms-lost condition would keep reporting the accidentally-Good default forever.
+    ///     <para>
+    ///         UNGATED by redundancy role (like the condition write in <see cref="ForwardNativeAlarm"/>): a
+    ///         Secondary keeps its address space — including condition quality — warm for failover. Quality is
+    ///         a pure annotation: <c>WriteAlarmQuality</c> touches ONLY the condition's Quality, never its
+    ///         Active/Acked/Retain, and fires a Part 9 event only on a real quality-bucket change. No cluster
+    ///         <c>alerts</c> row is published here — driver comms health has its own status surface
+    ///         (<see cref="IDriverHealthPublisher"/>); a row per condition would be alarm-fatigue.
+    ///     </para>
+    /// </summary>
+    private void OnDriverConnectivityChanged(DriverInstanceActor.ConnectivityChanged msg)
+    {
+        if (_opcUaPublishActor is null) return;
+
+        var quality = msg.Connected ? OpcUaQuality.Good : OpcUaQuality.Bad;
+        var ts = DateTime.UtcNow;
+        var annotated = 0;
+        // Fan out to every condition this driver owns. _alarmNodeIdByDriverRef is keyed by
+        // (DriverInstanceId, RawPath); one driver ref can back several condition NodeIds (identical machines).
+        foreach (var ((driverId, _), nodeIds) in _alarmNodeIdByDriverRef)
+        {
+            if (driverId != msg.DriverInstanceId) continue;
+            foreach (var n in nodeIds)
+            {
+                _opcUaPublishActor.Tell(new ZB.MOM.WW.OtOpcUa.Runtime.OpcUa.OpcUaPublishActor.AlarmQualityUpdate(
+                    n.NodeId, quality, ts, n.Realm));
+                annotated++;
+            }
+        }
+
+        if (annotated > 0)
+            _log.Debug("DriverHost {Node}: driver {Driver} {State} — annotated {Count} native condition(s) {Quality}",
+                _localNode, msg.DriverInstanceId, msg.Connected ? "connected" : "disconnected", annotated, quality);
+    }
+
     private void ForwardNativeAlarm(DriverInstanceActor.AttributeAlarmPublished msg)
     {
         if (_opcUaPublishActor is null) return;
@@ -1326,6 +1368,9 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
         // applied yet, so the equipment can't be resolved). Drop it — the re-discovery loop re-sends it
         // and the post-recovery re-apply self-heals it once an apply runs (matches the no-op drops above).
         Receive<DriverInstanceActor.DiscoveredNodesReady>(_ => { });
+        // A child connectivity transition while the host is Stale has no live address space to annotate — drop
+        // it (the post-recovery rebuild re-materialises conditions, and the child re-announces on its next entry).
+        Receive<DriverInstanceActor.ConnectivityChanged>(_ => { });
         // A late DeltaApplied (an apply completed just before the DB went Stale) — re-register the driver's
         // mux adapter anyway; it simply re-reads the driver's current refs (harmless, no DB access).
         Receive<DriverInstanceActor.DeltaApplied>(HandleDeltaApplied);

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverInstanceActor.cs

@@ -46,6 +46,12 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
     public sealed record InitializeSucceeded(int Generation);
     public sealed record InitializeFailed(string Reason, int Generation);
     public sealed record DisconnectObserved(string Reason);
+    /// <summary>#477 — sent to the parent (<see cref="DriverHostActor"/>) on every connectivity transition:
+    /// <c>Connected=true</c> on entering the Connected state, <c>false</c> on entering Reconnecting. The host
+    /// annotates this driver's native alarm conditions' source-data Quality from it (comms lost → Bad,
+    /// restored → Good) — independently of alarm transitions, since a comms-lost driver emits no alarm
+    /// events. Fire-and-forget, mirroring <see cref="DeltaApplied"/>.</summary>
+    public sealed record ConnectivityChanged(string DriverInstanceId, bool Connected);
     public sealed record ApplyDelta(string DriverConfigJson, CorrelationId Correlation);
     public sealed record ApplyResult(bool Success, string? Reason, CorrelationId Correlation);
     /// <summary>
@@ -413,6 +419,11 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
 
     private void Connected()
     {
+        // #477 — announce connectivity to the host so it can clear any comms-lost Quality annotation on this
+        // driver's native alarm conditions (Bad → Good). Fire-and-forget; the host defaults conditions to a
+        // non-Good "waiting for initial data" quality at materialise, and this is what confirms them Good.
+        Context.Parent.Tell(new ConnectivityChanged(_driverInstanceId, Connected: true));
+
         ReceiveAsync<ApplyDelta>(HandleApplyDeltaAsync);
         Receive<DisconnectObserved>(msg =>
         {
@@ -483,6 +494,10 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
 
     private void Reconnecting()
     {
+        // #477 — announce comms loss to the host so it annotates this driver's native alarm conditions Bad
+        // (a comms-lost driver emits no alarm events, so this is the ONLY signal that the source is unreachable).
+        Context.Parent.Tell(new ConnectivityChanged(_driverInstanceId, Connected: false));
+
         Receive<RetryConnect>(_ => InitializeAsync(_currentConfigJson ?? "{}"));
         // Fast-fail writes while reconnecting (same reason as Connecting — avoids the 8s host Ask
         // timeout on an inbound write to a transiently-down driver). Synchronous Receive.

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/OpcUa/OpcUaPublishActor.cs

@@ -58,6 +58,15 @@ public sealed class OpcUaPublishActor : ReceiveActor, IWithTimers
     /// <param name="Realm">The namespace realm the condition lives in — <see cref="AddressSpaceRealm.Uns"/> for
     /// scripted alarms (default), <see cref="AddressSpaceRealm.Raw"/> for v3 native raw conditions.</param>
     public sealed record AlarmStateUpdate(string AlarmNodeId, AlarmConditionSnapshot State, DateTime TimestampUtc, AddressSpaceRealm Realm);
+    /// <summary>#477 — annotate a materialised condition's source-data Quality out of band from any alarm
+    /// transition (the driver-connectivity path: comms lost → <see cref="OpcUaQuality.Bad"/>, restored →
+    /// <see cref="OpcUaQuality.Good"/>). Routed to <see cref="IOpcUaAddressSpaceSink.WriteAlarmQuality"/>,
+    /// which sets ONLY Quality and fires one Part 9 event on a quality-bucket change.</summary>
+    /// <param name="AlarmNodeId">The condition node id (RawPath for a native alarm).</param>
+    /// <param name="Quality">The source-data quality to annotate.</param>
+    /// <param name="TimestampUtc">The connectivity transition timestamp in UTC.</param>
+    /// <param name="Realm">The namespace realm the condition lives in (<see cref="AddressSpaceRealm.Raw"/> for native).</param>
+    public sealed record AlarmQualityUpdate(string AlarmNodeId, OpcUaQuality Quality, DateTime TimestampUtc, AddressSpaceRealm Realm);
     /// <summary>
     ///     Triggers an address-space rebuild. <paramref name="DeploymentId"/> is the deployment
     ///     just applied by the host; the rebuild loads THAT artifact so materialisation matches the
@@ -239,6 +248,7 @@ public sealed class OpcUaPublishActor : ReceiveActor, IWithTimers
 
         Receive<AttributeValueUpdate>(HandleAttributeUpdate);
         Receive<AlarmStateUpdate>(HandleAlarmUpdate);
+        Receive<AlarmQualityUpdate>(HandleAlarmQualityUpdate);
         Receive<RebuildAddressSpace>(HandleRebuild);
         Receive<MaterialiseDiscoveredNodes>(HandleMaterialiseDiscovered);
         Receive<ServiceLevelChanged>(HandleServiceLevelChanged);
@@ -296,6 +306,20 @@ public sealed class OpcUaPublishActor : ReceiveActor, IWithTimers
         }
     }
 
+    private void HandleAlarmQualityUpdate(AlarmQualityUpdate msg)
+    {
+        try
+        {
+            _sink.WriteAlarmQuality(msg.AlarmNodeId, msg.Quality, msg.TimestampUtc, msg.Realm);
+            Interlocked.Increment(ref _writes);
+            OtOpcUaTelemetry.OpcUaSinkWrite.Add(1, new KeyValuePair<string, object?>("kind", "alarm-quality"));
+        }
+        catch (Exception ex)
+        {
+            _log.Warning(ex, "OpcUaPublish: sink.WriteAlarmQuality threw for {Node}", msg.AlarmNodeId);
+        }
+    }
+
     private void HandleRebuild(RebuildAddressSpace msg)
     {
         using var span = OtOpcUaTelemetry.StartAddressSpaceRebuildSpan();

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/ScriptedAlarms/ScriptedAlarmHostActor.cs

@@ -539,7 +539,10 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
         Enabled: e.Condition.Enabled == AlarmEnabledState.Enabled,
         Shelving: MapShelving(e.Condition.Shelving.Kind),
         Severity: (ushort)SeverityToInt(e.Severity),
-        Message: e.Message);
+        Message: e.Message,
+        // #477 — scripted conditions are script-computed and always live in this scope, so they report Good.
+        // Deriving quality from the worst of a script's input-tag qualities is a deferred follow-up (Layer 3).
+        Quality: OpcUaQuality.Good);
 
     /// <summary>Maps the Core <see cref="ShelvingKind"/> onto the Commons <see cref="AlarmShelvingKind"/>
     /// mirror (the Commons assembly can't see the Core enum).</summary>

tests/Core/ZB.MOM.WW.OtOpcUa.Commons.Tests/OpcUa/DeferredAddressSpaceSinkTests.cs

@@ -209,6 +209,8 @@ public class DeferredAddressSpaceSinkTests
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns)
             => WriteValueCalled = true;
 
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
+
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false) { }
         public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
@@ -226,6 +228,7 @@ public class DeferredAddressSpaceSinkTests
         public bool FolderRenameCalled { get; private set; }
 
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false) { }
         public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.IntegrationTests/NativeAlarmEventIdentityFieldDeliveryTests.cs

@@ -31,6 +31,7 @@ public sealed class NativeAlarmEventIdentityFieldDeliveryTests
 {
     private const string ServerUri = "urn:OtOpcUa.AlarmEventIdentityFields";
     private const string ConditionClassServerUri = "urn:OtOpcUa.AlarmEventConditionClassFields";
+    private const string QualityServerUri = "urn:OtOpcUa.AlarmEventQualityField";
 
     private const string RawDeviceFolder = "pymodbus/plc";
     private const string RawAlarmPath = "pymodbus/plc/HR200";
@@ -53,6 +54,11 @@ public sealed class NativeAlarmEventIdentityFieldDeliveryTests
     private const int ConditionClassNameIndex = 1;
     private const int ConditionClassMessageIndex = 2;
 
+    // #477 — indices in BuildQualityEventFilter's clause [Quality, Message]. Again SEPARATE from the load-bearing
+    // ScadaBridge clause so its indices don't shift.
+    private const int QualityIndex = 0;
+    private const int QualityMessageIndex = 1;
+
     /// <summary>A live native condition event delivers a populated EventType / SourceNode / SourceName to a
     /// Server-object subscriber using the standard BaseEventType select clause.</summary>
     [Fact]
@@ -172,6 +178,63 @@ public sealed class NativeAlarmEventIdentityFieldDeliveryTests
         }
     }
 
+    /// <summary>Issue #477 — the over-the-wire proof that a native condition's source-data Quality tracks its
+    /// driver's connectivity. A comms-lost source (<c>WriteAlarmQuality(Bad)</c>) delivers a condition event
+    /// whose <c>Quality</c> is non-Good, and recovery (<c>WriteAlarmQuality(Good)</c>) delivers Good again — so a
+    /// client can distinguish "genuinely inactive" from "we have lost contact". Before the fix the field was the
+    /// accidentally-Good default (<c>default(StatusCode) == Good</c>) on every event regardless of the source.</summary>
+    [Fact]
+    public async Task Condition_event_Quality_tracks_source_connectivity_on_the_wire()
+    {
+        var pkiRoot = Path.Combine(Path.GetTempPath(), $"otopcua-alarm-quality-{Guid.NewGuid():N}");
+        var port = AllocateFreePort();
+        var ct = TestContext.Current.CancellationToken;
+        try
+        {
+            var (server, host) = await BootServerAsync(port, pkiRoot + "-srv", QualityServerUri, ct);
+            await using var _ = host;
+
+            var sink = new SdkAddressSpaceSink(server.NodeManager!);
+            WireCondition(sink);
+
+            using var session = await OpenSessionAsync($"opc.tcp://127.0.0.1:{port}/OtOpcUa", ct);
+
+            var collector = new EventCollector(QualityMessageIndex);
+            var subscription = new Subscription(session.DefaultSubscription) { PublishingInterval = 100 };
+            subscription.FastEventCallback = collector.OnEvents;
+            session.AddSubscription(subscription);
+            await subscription.CreateAsync(ct);
+
+            AddEventItem(subscription, ObjectIds.Server, BuildQualityEventFilter());
+            await subscription.ApplyChangesAsync(ct);
+
+            // Raise the alarm while the source is healthy → Quality Good.
+            sink.WriteAlarmCondition(RawAlarmPath, ActiveSnapshot(), DateTime.UtcNow, AddressSpaceRealm.Raw);
+            await WaitUntilAsync(() => collector.Fields.Count >= 1, TimeSpan.FromSeconds(5));
+            StatusCode.IsGood((StatusCode)collector.Fields[^1][QualityIndex].Value)
+                .ShouldBeTrue("a healthy source's condition reports Good quality");
+
+            // Device goes comms-lost (connectivity path) → the next condition event carries a Bad Quality, while
+            // the alarm stays active (annotation only — not asserted here, covered by the node-level test).
+            sink.WriteAlarmQuality(RawAlarmPath, OpcUaQuality.Bad, DateTime.UtcNow, AddressSpaceRealm.Raw);
+            await WaitUntilAsync(() => collector.Fields.Count >= 2, TimeSpan.FromSeconds(5));
+            StatusCode.IsBad((StatusCode)collector.Fields[^1][QualityIndex].Value)
+                .ShouldBeTrue("a comms-lost source's condition must report non-Good quality on the wire");
+
+            // Device recovers → Quality returns to Good.
+            sink.WriteAlarmQuality(RawAlarmPath, OpcUaQuality.Good, DateTime.UtcNow, AddressSpaceRealm.Raw);
+            await WaitUntilAsync(() => collector.Fields.Count >= 3, TimeSpan.FromSeconds(5));
+            StatusCode.IsGood((StatusCode)collector.Fields[^1][QualityIndex].Value)
+                .ShouldBeTrue("a recovered source's condition reports Good quality again");
+
+            await subscription.DeleteAsync(true, ct);
+        }
+        finally
+        {
+            SafeDelete(pkiRoot + "-srv");
+        }
+    }
+
     /// <summary>Materialise the raw device folder + the native condition at its RawPath, plus one referencing
     /// equipment folder wired as a notifier (the production topology).</summary>
     private static void WireCondition(SdkAddressSpaceSink sink)
@@ -225,6 +288,17 @@ public sealed class NativeAlarmEventIdentityFieldDeliveryTests
         return filter;
     }
 
+    /// <summary>#477's clause: [Quality, Message]. Quality is declared on <c>ConditionType</c>, so it must be
+    /// selected against that type. Message rides along as the collector's filter key (a quality-only change still
+    /// snapshots the unchanged Message).</summary>
+    private static EventFilter BuildQualityEventFilter()
+    {
+        var filter = new EventFilter();
+        filter.AddSelectClause(ObjectTypes.ConditionType, BrowseNames.Quality);
+        filter.AddSelectClause(ObjectTypes.BaseEventType, BrowseNames.Message);
+        return filter;
+    }
+
     /// <summary>Captures the delivered event field lists, filtered to our unique alarm Message so unrelated
     /// server events / refresh brackets never count.</summary>
     /// <param name="messageIndex">Position of the Message field in the select clause this collector is paired

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/AddressSpaceApplierFailureSurfaceTests.cs

@@ -163,6 +163,8 @@ public sealed class AddressSpaceApplierFailureSurfaceTests
 
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
 
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
+
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns)
         {
             if (ThrowOnAlarmWrite) throw new InvalidOperationException("simulated WriteAlarmCondition fault");

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/AddressSpaceApplierHierarchyTests.cs

@@ -312,6 +312,7 @@ public sealed class AddressSpaceApplierHierarchyTests : IDisposable
         /// <param name="alarmNodeId">The node ID of the alarm condition.</param>
         /// <param name="state">The full condition state snapshot.</param>
         /// <param name="sourceTimestampUtc">The source timestamp in UTC.</param>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         /// <summary>Materialises an alarm condition (stub implementation for testing).</summary>
         /// <param name="alarmNodeId">The alarm node ID (== ScriptedAlarmId).</param>

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/AddressSpaceApplierRawUnsTests.cs

@@ -301,6 +301,7 @@ public sealed class AddressSpaceApplierRawUnsTests
             => References.Add((sourceNodeId, sourceRealm, targetNodeId, targetRealm, referenceType));
 
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void RebuildAddressSpace() { }
         public void RaiseNodesAddedModelChange(string affectedNodeId, AddressSpaceRealm realm) { }

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/AddressSpaceApplierTests.cs

@@ -2268,6 +2268,7 @@ public sealed class AddressSpaceApplierTests
         /// <param name="alarmNodeId">The alarm node ID.</param>
         /// <param name="state">The full condition state snapshot.</param>
         /// <param name="sourceTimestampUtc">The source timestamp in UTC.</param>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns)
             => AlarmQueue.Enqueue((alarmNodeId, state));
         /// <summary>Records an alarm-condition materialise call.</summary>
@@ -2322,6 +2323,7 @@ public sealed class AddressSpaceApplierTests
         /// <summary>Records a value write (no-op in this sink).</summary>
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         /// <summary>No-op alarm condition write call.</summary>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         /// <summary>No-op alarm-condition materialise call.</summary>
         public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false) { }
@@ -2355,6 +2357,7 @@ public sealed class AddressSpaceApplierTests
         /// <param name="state">The full condition state snapshot.</param>
         /// <param name="sourceTimestampUtc">The source timestamp in UTC.</param>
         /// <exception cref="InvalidOperationException">Thrown when configured to throw on alarm write.</exception>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns)
         {
             if (_throwOnAlarmWrite) throw new InvalidOperationException("simulated sink fault");

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/DeferredAddressSpaceSinkTests.cs

@@ -231,6 +231,7 @@ public sealed class DeferredAddressSpaceSinkTests
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns)
             => CallQueue.Enqueue($"WV:{nodeId}");
         /// <inheritdoc />
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns)
             => CallQueue.Enqueue($"WA:{alarmNodeId}");
         /// <inheritdoc />
@@ -289,6 +290,7 @@ public sealed class DeferredAddressSpaceSinkTests
         /// <inheritdoc />
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         /// <inheritdoc />
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         /// <inheritdoc />
         public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false) { }

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerAlarmSourceFieldsTests.cs

@@ -196,6 +196,120 @@ public sealed class NodeManagerAlarmSourceFieldsTests : IDisposable
         condition.ConditionClassName!.Value.Text.ShouldBe("BaseConditionClass");
     }
 
+    /// <summary>#477 — a freshly materialised NATIVE condition reports BadWaitingForInitialData quality (not the
+    /// accidentally-Good default), matching the value-variable "no driver data yet" convention. Its quality only
+    /// becomes Good once its driver's connectivity confirms it (Layer 2).</summary>
+    [Trait("Category", "Unit")]
+    [Fact]
+    public async Task Native_condition_materialises_with_waiting_for_initial_data_quality()
+    {
+        await using var host = await BootAsync();
+        var nm = host.Nm;
+
+        nm.EnsureFolder(RawDeviceFolder, parentNodeId: null, displayName: "dev1", realm: AddressSpaceRealm.Raw);
+        nm.MaterialiseAlarmCondition(RawAlarmPath, RawDeviceFolder, "HR200", "OffNormalAlarm", 700,
+            realm: AddressSpaceRealm.Raw, isNative: true);
+
+        var condition = nm.TryGetAlarmCondition(RawAlarmPath, AddressSpaceRealm.Raw);
+        condition.ShouldNotBeNull();
+        condition.Quality.ShouldNotBeNull();
+        condition.Quality.Value.ShouldBe((StatusCode)StatusCodes.BadWaitingForInitialData);
+        StatusCode.IsGood(condition.Quality.Value).ShouldBeFalse();
+    }
+
+    /// <summary>#477 — a SCRIPTED condition is script-computed and always "live" in v1, so it materialises Good.
+    /// (Scripted worst-of-input quality is deferred to Layer 3.)</summary>
+    [Trait("Category", "Unit")]
+    [Fact]
+    public async Task Scripted_condition_materialises_with_good_quality()
+    {
+        await using var host = await BootAsync();
+        var nm = host.Nm;
+
+        nm.EnsureFolder("eq-q1", parentNodeId: null, displayName: "Station Q1", realm: AddressSpaceRealm.Uns);
+        nm.MaterialiseAlarmCondition("scripted-q", "eq-q1", "Scripted Q", "OffNormalAlarm", 700,
+            realm: AddressSpaceRealm.Uns, isNative: false);
+
+        var condition = nm.TryGetAlarmCondition("scripted-q", AddressSpaceRealm.Uns);
+        condition.ShouldNotBeNull();
+        condition.Quality.ShouldNotBeNull();
+        StatusCode.IsGood(condition.Quality.Value).ShouldBeTrue();
+    }
+
+    /// <summary>#477 — WriteAlarmCondition projects the snapshot's Quality onto the live condition node, so a
+    /// Bad-quality snapshot (comms-lost source) makes the condition report non-Good.</summary>
+    [Trait("Category", "Unit")]
+    [Fact]
+    public async Task WriteAlarmCondition_projects_snapshot_quality_onto_the_condition()
+    {
+        await using var host = await BootAsync();
+        var nm = host.Nm;
+
+        nm.EnsureFolder(RawDeviceFolder, parentNodeId: null, displayName: "dev1", realm: AddressSpaceRealm.Raw);
+        nm.MaterialiseAlarmCondition(RawAlarmPath, RawDeviceFolder, "HR200", "OffNormalAlarm", 700,
+            realm: AddressSpaceRealm.Raw, isNative: true);
+
+        // A comms-lost snapshot: the alarm state is unchanged but Quality is Bad.
+        var badSnapshot = new AlarmConditionSnapshot(
+            Active: false, Acknowledged: true, Confirmed: true, Enabled: true,
+            Shelving: AlarmShelvingKind.Unshelved, Severity: 700, Message: "HR200",
+            Quality: OpcUaQuality.Bad);
+        nm.WriteAlarmCondition(RawAlarmPath, badSnapshot, DateTime.UtcNow, AddressSpaceRealm.Raw);
+
+        var condition = nm.TryGetAlarmCondition(RawAlarmPath, AddressSpaceRealm.Raw);
+        condition.ShouldNotBeNull();
+        StatusCode.IsBad(condition.Quality.Value).ShouldBeTrue();
+
+        // Recover: a Good snapshot restores Good quality.
+        var goodSnapshot = badSnapshot with { Quality = OpcUaQuality.Good };
+        nm.WriteAlarmCondition(RawAlarmPath, goodSnapshot, DateTime.UtcNow, AddressSpaceRealm.Raw);
+        StatusCode.IsGood(condition.Quality.Value).ShouldBeTrue();
+    }
+
+    /// <summary>#477 Layer 2 — the dedicated connectivity-quality path sets ONLY the condition's Quality
+    /// (comms lost → Bad, restored → Good) and never clobbers the node's severity / message / alarm state:
+    /// it is a pure annotation applied out-of-band from any alarm transition.</summary>
+    [Trait("Category", "Unit")]
+    [Fact]
+    public async Task WriteAlarmQuality_sets_only_quality_without_touching_state_or_severity()
+    {
+        await using var host = await BootAsync();
+        var nm = host.Nm;
+
+        nm.EnsureFolder(RawDeviceFolder, parentNodeId: null, displayName: "dev1", realm: AddressSpaceRealm.Raw);
+        nm.MaterialiseAlarmCondition(RawAlarmPath, RawDeviceFolder, "HR200", "OffNormalAlarm", 700,
+            realm: AddressSpaceRealm.Raw, isNative: true);
+
+        var condition = nm.TryGetAlarmCondition(RawAlarmPath, AddressSpaceRealm.Raw);
+        condition.ShouldNotBeNull();
+        var severityBefore = condition.Severity!.Value;
+        var messageBefore = condition.Message!.Value?.Text;
+
+        // Device comes online → Good.
+        nm.WriteAlarmQuality(RawAlarmPath, OpcUaQuality.Good, DateTime.UtcNow, AddressSpaceRealm.Raw);
+        StatusCode.IsGood(condition.Quality!.Value).ShouldBeTrue();
+
+        // Device goes comms-lost → Bad, but severity / message / active-ack state are untouched.
+        nm.WriteAlarmQuality(RawAlarmPath, OpcUaQuality.Bad, DateTime.UtcNow, AddressSpaceRealm.Raw);
+        StatusCode.IsBad(condition.Quality.Value).ShouldBeTrue();
+        condition.Severity.Value.ShouldBe(severityBefore);
+        condition.Message.Value?.Text.ShouldBe(messageBefore);
+        condition.ActiveState!.Id!.Value.ShouldBeFalse(); // unchanged: annotation only
+    }
+
+    /// <summary>#477 Layer 2 — WriteAlarmQuality on an unknown / unmaterialised node is a safe no-op (never
+    /// throws), mirroring the other write paths: a mid-rebuild race must not fault a connectivity update.</summary>
+    [Trait("Category", "Unit")]
+    [Fact]
+    public async Task WriteAlarmQuality_is_a_noop_for_an_unknown_condition()
+    {
+        await using var host = await BootAsync();
+        var nm = host.Nm;
+
+        Should.NotThrow(() =>
+            nm.WriteAlarmQuality("no/such/node", OpcUaQuality.Bad, DateTime.UtcNow, AddressSpaceRealm.Raw));
+    }
+
     /// <summary>A booted server + its node manager, disposed via <c>await using</c> so an assertion failure
     /// cannot leak a live server (and its bound port) into the rest of the test run.</summary>
     private sealed class BootedServer(OpcUaApplicationHost host, OtOpcUaNodeManager nm) : IAsyncDisposable

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/SdkAddressSpaceSinkTests.cs

@@ -523,7 +523,8 @@ public sealed class SdkAddressSpaceSinkTests : IDisposable
     {
         var baseState = new OtOpcUaNodeManager.AlarmConditionDelta(
             Active: true, Acknowledged: false, Confirmed: true, Enabled: true,
-            Shelving: AlarmShelvingKind.Unshelved, MappedSeverity: 100, Message: "m");
+            Shelving: AlarmShelvingKind.Unshelved, MappedSeverity: 100, Message: "m",
+            Quality: StatusCodes.Good);
 
         // Equal ⇒ suppress (this is the inbound double-emit case in pure form).
         OtOpcUaNodeManager.ShouldFireConditionEvent(baseState, baseState).ShouldBeFalse();
@@ -537,6 +538,8 @@ public sealed class SdkAddressSpaceSinkTests : IDisposable
         OtOpcUaNodeManager.ShouldFireConditionEvent(baseState, baseState with { Shelving = AlarmShelvingKind.Timed }).ShouldBeTrue();
         OtOpcUaNodeManager.ShouldFireConditionEvent(baseState, baseState with { MappedSeverity = 900 }).ShouldBeTrue();
         OtOpcUaNodeManager.ShouldFireConditionEvent(baseState, baseState with { Message = "other" }).ShouldBeTrue();
+        // #477 — a quality-only change (e.g. source going comms-lost, no state change) is a genuine delta.
+        OtOpcUaNodeManager.ShouldFireConditionEvent(baseState, baseState with { Quality = StatusCodes.Bad }).ShouldBeTrue();
     }
 
     /// <summary>T20 — null-vs-empty Message normalization. Both snapshot.Message = null and a live node
@@ -552,7 +555,8 @@ public sealed class SdkAddressSpaceSinkTests : IDisposable
         // Both null and "" collapse to string.Empty in AlarmConditionDelta — they are the same delta value.
         var withNull = new OtOpcUaNodeManager.AlarmConditionDelta(
             Active: false, Acknowledged: true, Confirmed: true, Enabled: true,
-            Shelving: AlarmShelvingKind.Unshelved, MappedSeverity: 100, Message: string.Empty);
+            Shelving: AlarmShelvingKind.Unshelved, MappedSeverity: 100, Message: string.Empty,
+            Quality: StatusCodes.Good);
 
         var withEmpty = withNull with { Message = string.Empty };
 

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DiscoveryInjectionEndToEndTests.cs

@@ -328,6 +328,7 @@ public sealed class DiscoveryInjectionEndToEndTests : RuntimeActorTestBase
             => _values.Enqueue((nodeId, value, quality, sourceTimestampUtc));
 
         /// <summary>No-op: alarm writes are not exercised by this suite.</summary>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
 
         /// <summary>No-op: alarm materialise is not exercised by this suite.</summary>

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverHostActorNativeAlarmTests.cs

@@ -271,6 +271,46 @@ public sealed class DriverHostActorNativeAlarmTests : RuntimeActorTestBase
         evt.User.ShouldBe("device");
     }
 
+    /// <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
+    /// is the ONLY signal for a comms-lost native source.</summary>
+    [Fact]
+    public void Driver_disconnect_and_reconnect_annotate_native_condition_quality()
+    {
+        var db = NewInMemoryDbFactory();
+        var deploymentId = SeedV3AlarmDeployment(db, RevA, Driver: "drv-1", Tag: "temp_hi");
+
+        var (actor, publish) = SpawnHostAndApply(db, deploymentId);
+
+        // Comms lost → the raw condition is annotated Bad.
+        actor.Tell(new DriverInstanceActor.ConnectivityChanged("drv-1", Connected: false));
+        var bad = publish.ExpectMsg<OpcUaPublishActor.AlarmQualityUpdate>(TimeSpan.FromSeconds(5));
+        bad.AlarmNodeId.ShouldBe(AlarmRawPath);
+        bad.Realm.ShouldBe(AddressSpaceRealm.Raw);
+        bad.Quality.ShouldBe(OpcUaQuality.Bad);
+
+        // Comms restored → annotated Good.
+        actor.Tell(new DriverInstanceActor.ConnectivityChanged("drv-1", Connected: true));
+        var good = publish.ExpectMsg<OpcUaPublishActor.AlarmQualityUpdate>(TimeSpan.FromSeconds(5));
+        good.AlarmNodeId.ShouldBe(AlarmRawPath);
+        good.Quality.ShouldBe(OpcUaQuality.Good);
+    }
+
+    /// <summary>#477 Layer 2 — connectivity for a DIFFERENT driver instance annotates none of this driver's
+    /// conditions (the fan-out is scoped by DriverInstanceId).</summary>
+    [Fact]
+    public void Connectivity_for_another_driver_annotates_nothing()
+    {
+        var db = NewInMemoryDbFactory();
+        var deploymentId = SeedV3AlarmDeployment(db, RevA, Driver: "drv-1", Tag: "temp_hi");
+
+        var (actor, publish) = SpawnHostAndApply(db, deploymentId);
+
+        actor.Tell(new DriverInstanceActor.ConnectivityChanged("drv-OTHER", Connected: false));
+        publish.ExpectNoMsg(TimeSpan.FromMilliseconds(500));
+    }
+
     /// <summary>Subscribe <paramref name="probe"/> to the <c>alerts</c> DPS topic and wait for the ack.</summary>
     private void SubscribeToAlerts(TestProbe probe)
     {

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverInstanceActorDiscoveryTests.cs

@@ -30,6 +30,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new DiscoverableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         // Tiny interval so the bounded retry runs in well under a second (no real-time waits).
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20)));
@@ -68,6 +71,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new SubscribableStubDriver(); // IDriver + ISubscribable, NOT ITagDiscovery
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20)));
 
@@ -92,6 +98,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new DiscoverableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         // Tiny reconnect + rediscover intervals so the whole reconnect-then-rediscover cycle runs fast.
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver,
@@ -133,6 +142,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new YieldingDiscoverableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20)));
 
@@ -167,6 +179,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
             driverType: "Stub");
         var driver = new YieldingDiscoverableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20), invoker: invoker));
 
@@ -187,6 +202,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new GrowingDiscoverableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20), rediscoverMaxAttempts: 3));
 
@@ -215,6 +233,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new DiscoverableStubDriver(DiscoveryRediscoverPolicy.Never);
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20)));
 
@@ -239,6 +260,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new GrowingDiscoverableStubDriver(DiscoveryRediscoverPolicy.Once);
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20)));
 
@@ -269,6 +293,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new GrowingDiscoverableStubDriver(DiscoveryRediscoverPolicy.Once);
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         // Small reconnect + rediscover intervals so the cycle runs fast; cap 3 so a (wrong) full loop is
         // visibly more than the one pass Once must run per (re)connect.
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
@@ -314,6 +341,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
         // Props must accept the new optional parameter — no throw and actor starts normally.
         var driver = new DiscoverableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver,
             rediscoverInterval: TimeSpan.FromMilliseconds(20),
@@ -340,6 +370,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
         // (no second settling pass to drain, and no stale-tick double pass alongside the fresh one).
         var driver = new GrowingDiscoverableStubDriver(DiscoveryRediscoverPolicy.Once);
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20)));
 
@@ -373,6 +406,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
     {
         var driver = new DiscoverableStubDriver(DiscoveryRediscoverPolicy.Never);
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver, rediscoverInterval: TimeSpan.FromMilliseconds(20)));
 
@@ -400,6 +436,9 @@ public sealed class DriverInstanceActorDiscoveryTests : RuntimeActorTestBase
         // a long reconnect interval so the actor parks in Reconnecting deterministically within the test window.
         var driver = new GrowingDiscoverableStubDriver(DiscoveryRediscoverPolicy.Once);
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(
             driver,
             reconnectInterval: TimeSpan.FromSeconds(30),

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverInstanceActorNativeAlarmTests.cs

@@ -30,6 +30,9 @@ public sealed class DriverInstanceActorNativeAlarmTests : RuntimeActorTestBase
     {
         var driver = new AlarmSourceStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -77,6 +80,9 @@ public sealed class DriverInstanceActorNativeAlarmTests : RuntimeActorTestBase
     {
         var driver = new AlarmSourceStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -110,6 +116,9 @@ public sealed class DriverInstanceActorNativeAlarmTests : RuntimeActorTestBase
     {
         var driver = new SubscribableOnlyStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -170,6 +179,9 @@ public sealed class DriverInstanceActorNativeAlarmTests : RuntimeActorTestBase
         // Long reconnect interval (default 10 s) so the retry doesn't fire during the assertion window.
         var driver = new AlarmSourceStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));
 
         // Drive to Connected; confirm the alarm handler is attached.
@@ -217,6 +229,9 @@ public sealed class DriverInstanceActorNativeAlarmTests : RuntimeActorTestBase
     {
         var driver = new AlarmSourceStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromMilliseconds(50)));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -245,6 +260,33 @@ public sealed class DriverInstanceActorNativeAlarmTests : RuntimeActorTestBase
         parent.ExpectNoMsg(TimeSpan.FromMilliseconds(300));
     }
 
+    /// <summary>#477 Layer 2 — the actor announces connectivity to its parent (the host): Connected on
+    /// reaching the Connected state, then Connected=false on a <see cref="DriverInstanceActor.DisconnectObserved"/>,
+    /// then Connected=true again on the reconnect. This is the signal the host uses to annotate the driver's
+    /// native alarm conditions' Quality (comms lost → Bad, restored → Good).</summary>
+    [Fact]
+    public void ConnectivityChanged_is_announced_to_parent_on_connect_disconnect_and_reconnect()
+    {
+        var driver = new AlarmSourceStubDriver();
+        var parent = CreateTestProbe(); // deliberately does NOT ignore ConnectivityChanged — it's the subject.
+        var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromMilliseconds(50)));
+
+        actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
+
+        // Initial connect → Connected=true.
+        parent.FishForMessage<DriverInstanceActor.ConnectivityChanged>(m => true, TimeSpan.FromSeconds(3))
+            .Connected.ShouldBeTrue();
+
+        // Disconnect → Connected=false (this is what drives the conditions Bad).
+        actor.Tell(new DriverInstanceActor.DisconnectObserved("backend blip"));
+        parent.FishForMessage<DriverInstanceActor.ConnectivityChanged>(m => true, TimeSpan.FromSeconds(3))
+            .Connected.ShouldBeFalse();
+
+        // Reconnect → Connected=true again (drives them back Good).
+        parent.FishForMessage<DriverInstanceActor.ConnectivityChanged>(m => true, TimeSpan.FromSeconds(3))
+            .Connected.ShouldBeTrue();
+    }
+
     // --- stub drivers ----------------------------------------------------------------------------
 
     private class StubDriver : IDriver

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/DriverInstanceActorTests.cs

@@ -109,6 +109,9 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
     {
         var driver = new SubscribableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -134,6 +137,9 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
     {
         var driver = new SubscribableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -162,6 +168,9 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
     {
         var driver = new SubscribableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromMilliseconds(50)));
 
         // Desired set arrives BEFORE connect — retained, not yet applied.
@@ -197,6 +206,9 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
         // is used — the exact condition that throws NotSupportedException on the subsequent Sender read.
         var driver = new SubscribableStubDriver { UnsubscribeYields = true };
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -242,6 +254,9 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
     {
         var driver = new SubscribableStubDriver();
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromSeconds(30)));
 
         actor.Tell(new DriverInstanceActor.InitializeRequested("{}"));
@@ -271,6 +286,9 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
             InitBehavior = cfg => cfg == good ? Task.CompletedTask : throw new InvalidOperationException("bad-cfg"),
         };
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromMilliseconds(50)));
 
         actor.Tell(new DriverInstanceActor.SetDesiredSubscriptions(new[] { "tag-a" }, TimeSpan.FromMilliseconds(100)));
@@ -304,6 +322,9 @@ public sealed class DriverInstanceActorTests : RuntimeActorTestBase
             InitBehavior = cfg => cfg == v1 ? gate1.Task : gate2.Task,
         };
         var parent = CreateTestProbe();
+        // #477: DriverInstanceActor now Tells the parent ConnectivityChanged on each connect/
+        // disconnect; these tests assert on the data/alarm/discovery forwards, so ignore it.
+        parent.IgnoreMessages(m => m is DriverInstanceActor.ConnectivityChanged);
         var actor = parent.ChildActorOf(DriverInstanceActor.Props(driver, reconnectInterval: TimeSpan.FromSeconds(30)));
         actor.Tell(new DriverInstanceActor.SetDesiredSubscriptions(new[] { "tag-a" }, TimeSpan.FromMilliseconds(100)));
 

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/NativeAlarmProjectorTests.cs

@@ -153,6 +153,19 @@ public class NativeAlarmProjectorTests
         snap.Acknowledged.ShouldBeTrue();
     }
 
+    // #477 — native transitions carry Good quality; comms-loss quality is applied out-of-band via the
+    // dedicated WriteAlarmQuality path (connectivity → DriverHostActor), NOT through the projector, so the
+    // projector stays quality-agnostic and its transition snapshots default to Good.
+    [Fact]
+    public void Transition_projection_defaults_to_good_quality()
+    {
+        var sut = new NativeAlarmProjector();
+
+        var snap = sut.Project("n1", Evt(AlarmTransitionKind.Raise));
+
+        snap.Quality.ShouldBe(OpcUaQuality.Good);
+    }
+
     private static AlarmEventArgs Evt(
         AlarmTransitionKind kind,
         AlarmSeverity sev = AlarmSeverity.High,

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Observability/OtOpcUaTelemetryHookTests.cs

@@ -199,6 +199,7 @@ public sealed class OtOpcUaTelemetryHookTests : RuntimeActorTestBase
         /// <param name="alarmNodeId">The alarm node identifier.</param>
         /// <param name="state">The full condition state snapshot.</param>
         /// <param name="occurredUtc">The time the alarm occurred in UTC.</param>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime occurredUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) => Writes++;
         /// <summary>Materialises an alarm condition (stub implementation).</summary>
         /// <param name="alarmNodeId">The alarm node identifier.</param>

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/OpcUa/OpcUaPublishActorApplyFailureTests.cs

@@ -119,6 +119,7 @@ public sealed class OpcUaPublishActorApplyFailureTests : RuntimeActorTestBase
     private sealed class ThrowOnRebuildSink : IOpcUaAddressSpaceSink
     {
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime occurredUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false) { }
         public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
@@ -133,6 +134,7 @@ public sealed class OpcUaPublishActorApplyFailureTests : RuntimeActorTestBase
     private sealed class NoopSink : IOpcUaAddressSpaceSink
     {
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime occurredUtc, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }
         public void MaterialiseAlarmCondition(string alarmNodeId, string equipmentNodeId, string displayName, string alarmType, int severity, AddressSpaceRealm realm, bool isNative = false) { }
         public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName, AddressSpaceRealm realm = AddressSpaceRealm.Uns) { }

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/OpcUa/OpcUaPublishActorRebuildTests.cs

@@ -443,6 +443,7 @@ public sealed class OpcUaPublishActorRebuildTests : RuntimeActorTestBase
         /// <param name="alarmNodeId">The alarm node ID.</param>
         /// <param name="state">The full condition state snapshot.</param>
         /// <param name="ts">The timestamp of the state change.</param>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime sourceTimestampUtc, AddressSpaceRealm realm) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime ts, AddressSpaceRealm realm = AddressSpaceRealm.Uns)
             => Calls.Enqueue($"WA:{alarmNodeId}");
         /// <summary>Records a materialise-alarm-condition call.</summary>

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/OpcUa/OpcUaPublishActorTests.cs

@@ -76,6 +76,26 @@ public sealed class OpcUaPublishActorTests : RuntimeActorTestBase
         }, duration: TimeSpan.FromMilliseconds(500));
     }
 
+    /// <summary>#477 — AlarmQualityUpdate routes to sink.WriteAlarmQuality with the quality + realm.</summary>
+    [Fact]
+    public void AlarmQualityUpdate_routes_to_sink_WriteAlarmQuality()
+    {
+        var sink = new RecordingSink();
+        var actor = Sys.ActorOf(OpcUaPublishActor.PropsForTests(sink: sink));
+
+        actor.Tell(new OpcUaPublishActor.AlarmQualityUpdate(
+            "Plant/Modbus/dev1/temp_hi", OpcUaQuality.Bad, DateTime.UtcNow, Realm: AddressSpaceRealm.Raw));
+
+        AwaitAssert(() =>
+        {
+            sink.AlarmQualityQueue.Count.ShouldBe(1);
+            sink.AlarmQualityQueue.TryPeek(out var q).ShouldBeTrue();
+            q.AlarmNodeId.ShouldBe("Plant/Modbus/dev1/temp_hi");
+            q.Quality.ShouldBe(OpcUaQuality.Bad);
+            q.Realm.ShouldBe(AddressSpaceRealm.Raw);
+        }, duration: TimeSpan.FromMilliseconds(500));
+    }
+
     /// <summary>Builds a test <see cref="AlarmConditionSnapshot"/> with sensible defaults so each test
     /// only specifies the fields it cares about.</summary>
     private static AlarmConditionSnapshot Snapshot(
@@ -577,6 +597,8 @@ public sealed class OpcUaPublishActorTests : RuntimeActorTestBase
         public ConcurrentQueue<(string NodeId, object? Value, OpcUaQuality Quality, DateTime Ts)> ValueQueue { get; } = new();
         /// <summary>Gets the queue of recorded alarm condition updates.</summary>
         public ConcurrentQueue<(string AlarmNodeId, AlarmConditionSnapshot State, DateTime Ts)> AlarmQueue { get; } = new();
+        /// <summary>Gets the queue of recorded alarm-quality annotations (#477).</summary>
+        public ConcurrentQueue<(string AlarmNodeId, OpcUaQuality Quality, DateTime Ts, AddressSpaceRealm Realm)> AlarmQualityQueue { get; } = new();
         /// <summary>Count of rebuild calls.</summary>
         public int RebuildCalls;
         /// <summary>Gets the queue of recorded EnsureFolder calls.</summary>
@@ -616,6 +638,10 @@ public sealed class OpcUaPublishActorTests : RuntimeActorTestBase
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime ts, AddressSpaceRealm realm = AddressSpaceRealm.Uns) =>
             AlarmQueue.Enqueue((alarmNodeId, state, ts));
 
+        /// <summary>Records an alarm-quality annotation (#477).</summary>
+        public void WriteAlarmQuality(string alarmNodeId, OpcUaQuality quality, DateTime ts, AddressSpaceRealm realm = AddressSpaceRealm.Uns) =>
+            AlarmQualityQueue.Enqueue((alarmNodeId, quality, ts, realm));
+
         /// <summary>Materialises an alarm condition (no-op in test).</summary>
         /// <param name="alarmNodeId">The alarm node ID.</param>
         /// <param name="equipmentNodeId">The equipment folder node ID.</param>