fix(abcip): ALMA review round 2 - IsRestatement contract docs, ALMD no-InAlarm warning, un-ack retrigger

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipAlarmProjection.cs

@@ -38,6 +38,7 @@ internal sealed class AbCipAlarmProjection : IAsyncDisposable
     private readonly Dictionary<long, Subscription> _subs = new();
     private readonly Lock _subsLock = new();
     private long _nextId;
+    private readonly HashSet<string> _warnedNoInAlarm = new(StringComparer.Ordinal);
 
     /// <summary>Initializes a new instance of the <see cref="AbCipAlarmProjection"/> class.</summary>
     /// <param name="driver">The AB CIP driver instance.</param>
@@ -285,6 +286,8 @@ internal sealed class AbCipAlarmProjection : IAsyncDisposable
         }
     }
 
+    private bool WarnOnce(string id) { lock (_warnedNoInAlarm) return _warnedNoInAlarm.Add(id); }
+
     private List<NodePlan> BuildPlans(IReadOnlyList<string> nodeIds)
     {
         var plans = new List<NodePlan>(nodeIds.Count);
@@ -293,6 +296,16 @@ internal sealed class AbCipAlarmProjection : IAsyncDisposable
             AlmaPlan? alma = null;
             if (_driver.TryGetTagDefinition(id, out var def) && AbCipAlarmDetector.IsAlma(def))
                 alma = AlmaPlan.From(def);
+            else if (def is { DataType: AbCipDataType.Structure, Members: { } members }
+                && !members.Any(m => string.Equals(m.Name, "InAlarm", StringComparison.OrdinalIgnoreCase))
+                && WarnOnce(id))
+            {
+                // ALMD's active bit is InAlarm; a tag that declared members without it (e.g. a pre-hw4 config that
+                // declared InFaulted) reads BadNodeIdUnknown every tick and would stay silent forever.
+                _logger.LogWarning(
+                    "AbCip alarm ref {Ref} declares members but no 'InAlarm'; the ALMD projection polls InAlarm + Severity, " +
+                    "so this alarm will never raise. Add InAlarm (InFaulted is the input-health flag, not the alarm).", id);
+            }
             plans.Add(new NodePlan(alma));
         }
         return plans;
@@ -307,6 +320,8 @@ internal sealed class AbCipAlarmProjection : IAsyncDisposable
     ///       <item>a limit NEWLY entering: Retrigger (a new unacknowledged occurrence) — or ActiveAcknowledged when
     ///         nothing is pending ack (AckRequired false), never Retrigger-then-Acknowledge (#656).</item>
     ///       <item>no new limit, every declared limit now acked while the condition was unacked: Acknowledge.</item>
+    ///       <item>no new limit, the condition was fully acked and a declared <c>*Acked</c> read (Good) is now false:
+    ///         Retrigger — an occurrence the poll missed.</item>
     ///       <item>no new limit, the governing limit or its severity changed (a drop-out): an
     ///         <c>Unspecified</c> + <c>IsRestatement</c> state update — the projector keeps active/acked and writes
     ///         NO alerts row; anything else here would render a false "Activated".</item>
@@ -386,6 +401,14 @@ internal sealed class AbCipAlarmProjection : IAsyncDisposable
         }
 
         _driver.AlarmAnalogRecord.Set(nodeId, mask, nowAcked, topId, topSev);
+        if (ackKnown && prior.Acked && !allAcked)
+        {
+            // Every limit was acked and now one is not, with the same limits active: an occurrence the poll missed (a
+            // limit left and re-entered inside one interval) or one a Bad *Acked read hid on the tick it entered.
+            // Either way the PLC says unacknowledged, so tell it — a new unacknowledged occurrence.
+            _driver.InvokeAlarmEvent(Build(AlarmTransitionKind.Retrigger, message, topSev));
+            return;
+        }
         if (nowAcked && !prior.Acked)
             _driver.InvokeAlarmEvent(Build(AlarmTransitionKind.Acknowledge, message, topSev));
         else if (topId != prior.Top || topSev != prior.TopSeverity)