perf(adminui): pooled DbContext factory; role-grants reads per-call, not per-circuit

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ContinuousHistorizationRecorder.cs

@@ -240,6 +240,7 @@ public sealed class ContinuousHistorizationRecorder : ReceiveActor, IWithTimers
         _maxWriteAttempts = maxWriteAttempts > 0 ? maxWriteAttempts : 1;
 
         ReceiveAsync<VirtualTagActor.DependencyValueChanged>(OnValueChangedAsync);
+        ReceiveAsync<VirtualTagActor.DependencyValueBatch>(OnValueBatchAsync);
         Receive<UpdateHistorizedRefs>(OnUpdateHistorizedRefs);
         Receive<DrainTick>(_ => OnDrainTick());
         Receive<DrainResult>(OnDrainResult);
@@ -275,6 +276,30 @@ public sealed class ContinuousHistorizationRecorder : ReceiveActor, IWithTimers
         base.PostStop();
     }
 
+    /// <summary>
+    ///     The mux's batched delivery: one message carrying this recorder's whole matched slice of a driver
+    ///     burst. Each item is appended by the existing per-value handler, in order — the saving here is the
+    ///     mailbox hop, not the append (a genuinely batched append is a later change).
+    ///     <para>
+    ///         ⚠️ The await below deliberately does NOT use <c>ConfigureAwait(false)</c>. <see
+    ///         cref="OnValueChangedAsync"/> reads <c>Self</c> before its own first await, so it must start
+    ///         each item ON the actor thread; a context-dropping await here would leave item 2 onward with
+    ///         no ActorContext and throw <c>NotSupportedException</c> — the Gitea #491 failure, which
+    ///         supervision turns into a restart that silently discards every historized ref. A plain await
+    ///         resumes on Akka's ActorTaskScheduler context, so the context is restored before the next
+    ///         iteration.
+    ///     </para>
+    /// </summary>
+    /// <param name="msg">The batch of matched dependency values.</param>
+    private async Task OnValueBatchAsync(VirtualTagActor.DependencyValueBatch msg)
+    {
+        IReadOnlyList<VirtualTagActor.DependencyValueChanged> items = msg.Items;
+        for (int i = 0; i < items.Count; i++)
+        {
+            await OnValueChangedAsync(items[i]);
+        }
+    }
+
     private async Task OnValueChangedAsync(VirtualTagActor.DependencyValueChanged msg)
     {
         // The mux fans values keyed by the driver ref (msg.TagId == the mux ref). Only historize refs we

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

@@ -201,6 +201,10 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
         Receive<ApplyScriptedAlarms>(OnApply);
         Receive<AlarmsLoaded>(OnAlarmsLoaded);
         Receive<VirtualTagActor.DependencyValueChanged>(OnDependencyChanged);
+        // The mux's batched delivery: one message carrying this host's whole matched slice of a driver
+        // burst. The engine upstream is fed per value, so push each item in order — the saving is the
+        // mailbox hop, not the push.
+        Receive<VirtualTagActor.DependencyValueBatch>(OnDependencyBatch);
         Receive<EngineEmission>(OnEngineEmission);
         // Cluster redundancy snapshots (published on the `redundancy-state` topic, subscribed in PreStart)
         // cache this node's role so OnEngineEmission can gate the cluster-wide alerts publish to the Primary.
@@ -395,6 +399,17 @@ public sealed class ScriptedAlarmHostActor : ReceiveActor
             new DataValueSnapshot(msg.Value, msg.StatusCode, msg.TimestampUtc, msg.TimestampUtc));
     }
 
+    /// <summary>One batched mux delivery — every item already matched this host's registered interest.
+    /// Loops the per-value handler, preserving in-burst order.</summary>
+    private void OnDependencyBatch(VirtualTagActor.DependencyValueBatch msg)
+    {
+        var items = msg.Items;
+        for (var i = 0; i < items.Count; i++)
+        {
+            OnDependencyChanged(items[i]);
+        }
+    }
+
     private void OnEngineEmission(EngineEmission msg)
     {
         var e = msg.Event;

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/VirtualTags/DependencyConsumerMuxAdapter.cs

@@ -45,6 +45,7 @@ public sealed class DependencyConsumerMuxAdapter : ReceiveActor
         _mux = mux ?? throw new ArgumentNullException(nameof(mux));
 
         Receive<VirtualTagActor.DependencyValueChanged>(OnDependencyValueChanged);
+        Receive<VirtualTagActor.DependencyValueBatch>(OnDependencyValueBatch);
         Receive<ReRegister>(_ => RegisterInterest());
     }
 
@@ -68,4 +69,16 @@ public sealed class DependencyConsumerMuxAdapter : ReceiveActor
         // Quality is stripped at the mux boundary (value + timestamp only), so forward Good (0).
         _consumer.OnDependencyValue(msg.TagId, msg.Value, statusCode: 0u, msg.TimestampUtc);
     }
+
+    /// <summary>The mux's batched delivery: one message carrying this adapter's whole matched slice of a
+    /// driver burst. The consumer contract is per value, so dispatch each item in order — the saving is the
+    /// mailbox hop, not the consumer call.</summary>
+    private void OnDependencyValueBatch(VirtualTagActor.DependencyValueBatch msg)
+    {
+        var items = msg.Items;
+        for (var i = 0; i < items.Count; i++)
+        {
+            OnDependencyValueChanged(items[i]);
+        }
+    }
 }

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/VirtualTags/DependencyMuxActor.cs

@@ -8,9 +8,9 @@ namespace ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;
 ///     Per-node fan-out router from <see cref="DriverInstanceActor.AttributeValuePublished"/>
 ///     to interested <see cref="VirtualTagActor"/> instances. VirtualTagActor sends
 ///     <see cref="RegisterInterest"/> on start-up listing the tag refs it depends on; the mux
-///     keeps a map of <c>tagRef → Set&lt;IActorRef&gt;</c> and on every AttributeValuePublished
-///     forwards a <see cref="VirtualTagActor.DependencyValueChanged"/> to each interested
-///     subscriber.
+///     keeps a map of <c>tagRef → Set&lt;IActorRef&gt;</c> and on every ingress forwards each
+///     interested subscriber ONE <see cref="VirtualTagActor.DependencyValueBatch"/> carrying that
+///     subscriber's matched slice of the burst.
 ///
 ///     DriverHostActor forwards driver-child value publishes to this mux (one mux per driver-role
 ///     node). The ONLY driver ingress is the batched
@@ -18,8 +18,11 @@ namespace ZB.MOM.WW.OtOpcUa.Runtime.VirtualTags;
 ///     production burst, which the mux filters per item. The per-value
 ///     <see cref="DriverInstanceActor.AttributeValuePublished"/> receive stays for the comms-loss fan
 ///     ALONE: <c>DriverHostActor.FanCommsLossToDependencyMux</c> fabricates that message and Tells this
-///     mux directly, never through the host's own receive. Both
-///     produce the same <see cref="VirtualTagActor.DependencyValueChanged"/> per interested subscriber.
+///     mux directly, never through the host's own receive.
+///
+///     <b>The mux emits ONLY batches</b> (the comms-loss fan as a single-item one), so a subscriber's
+///     batch receive is its complete hot path. Every subscriber keeps a per-value
+///     <see cref="VirtualTagActor.DependencyValueChanged"/> receive as well, for direct senders and tests.
 ///     The mux is deliberately not a DPS subscriber — virtual-tag evaluation is local to each node and
 ///     would over-emit if it spanned the cluster.
 /// </summary>
@@ -110,14 +113,20 @@ public sealed class DependencyMuxActor : ReceiveActor
         var dep = new VirtualTagActor.DependencyValueChanged(msg.FullReference, msg.Value, msg.TimestampUtc, msg.StatusCode);
         foreach (var sub in subscribers)
         {
-            sub.Tell(dep);
+            // A single-item batch, so the mux emits exactly ONE message shape and every subscriber needs
+            // only the batch receive on its hot path. One list per subscriber: batch ownership transfers
+            // to the receiver, so a shared list must never cross mailboxes. This is the comms-loss fan
+            // (one ref, on a driver disconnect), not the steady value path — the extra allocation is noise.
+            sub.Tell(new VirtualTagActor.DependencyValueBatch(new[] { dep }));
         }
     }
 
-    /// <summary>Filters one batched driver production burst per item — the batched analogue of
-    /// <see cref="OnAttributeValuePublished"/>. Items nobody registered for are dropped (the common case:
-    /// only a fraction of an address space feeds virtual-tag expressions), so a burst of N values costs one
-    /// message plus one DependencyValueChanged per genuinely interested (item, subscriber) pair.
+    /// <summary>Filters one batched driver production burst per item and delivers each subscriber's matched
+    /// slice as ONE <see cref="VirtualTagActor.DependencyValueBatch"/>. Items nobody registered for are
+    /// dropped (the common case: only a fraction of an address space feeds virtual-tag expressions), so a
+    /// burst of N values costs one inbound message plus one outbound message per genuinely interested
+    /// SUBSCRIBER — not per (item, subscriber) pair as it did when this fanned out per value. That is what
+    /// lets <see cref="VirtualTagActor"/> evaluate its script once per burst instead of once per input.
     /// <para>The registered set is NOT just virtual-tag inputs: <c>ContinuousHistorizationRecorder</c>
     /// registers interest in every historized ref, so on a historizing node <see cref="_byRef"/> can be
     /// large and a sizeable fraction of each burst resolves.</para></summary>
@@ -126,6 +135,10 @@ public sealed class DependencyMuxActor : ReceiveActor
         // Nobody has registered anything — skip the whole burst rather than probing an empty map per item.
         if (_byRef.Count == 0) return;
 
+        // Allocated lazily on the first matched item: a burst in which nothing is registered for — still
+        // the common case on a node with a handful of virtual tags — allocates nothing at all.
+        Dictionary<IActorRef, List<VirtualTagActor.DependencyValueChanged>>? perSubscriber = null;
+
         // Indexed for-loop, not foreach: this is the hot value ingress and an IReadOnlyList<T> enumerator
         // would allocate once per burst.
         var count = msg.Items.Count;
@@ -134,7 +147,25 @@ public sealed class DependencyMuxActor : ReceiveActor
             var item = msg.Items[i];
             if (!_byRef.TryGetValue(item.FullReference, out var subscribers) || subscribers.Count == 0) continue;
             var dep = new VirtualTagActor.DependencyValueChanged(item.FullReference, item.Value, item.TimestampUtc, item.StatusCode);
-            foreach (var sub in subscribers) sub.Tell(dep);
+            perSubscriber ??= new Dictionary<IActorRef, List<VirtualTagActor.DependencyValueChanged>>();
+            foreach (var sub in subscribers)
+            {
+                if (!perSubscriber.TryGetValue(sub, out var list))
+                {
+                    list = new List<VirtualTagActor.DependencyValueChanged>();
+                    perSubscriber[sub] = list;
+                }
+                list.Add(dep);
+            }
+        }
+
+        if (perSubscriber is null) return;
+
+        // One message per subscriber, carrying that subscriber's own list. The lists are built here and
+        // never touched again, so handing ownership to the receiver is safe.
+        foreach (var (sub, list) in perSubscriber)
+        {
+            sub.Tell(new VirtualTagActor.DependencyValueBatch(list));
         }
     }
 }

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/VirtualTags/VirtualTagActor.cs

@@ -37,6 +37,13 @@ public sealed class VirtualTagActor : ReceiveActor
     public sealed record DependencyValueChanged(
         string TagId, object? Value, DateTime TimestampUtc, uint StatusCode = OpcUaStatus.Good);
 
+    /// <summary>
+    ///     One subscriber's slice of one upstream burst: every item in this batch matched
+    ///     this subscriber's registered interest set. Never empty. List ownership transfers
+    ///     to the receiver (the mux allocates a fresh list per subscriber per burst).
+    /// </summary>
+    public sealed record DependencyValueBatch(IReadOnlyList<DependencyValueChanged> Items);
+
     /// <summary>Re-assert the last emitted value/quality to the parent bridge, bypassing the value dedup.
     /// Sent by <see cref="VirtualTagHostActor"/> on every apply (deploy) to a surviving child: a deploy
     /// re-materialises the child's published UNS node to <c>BadWaitingForInitialData</c>, but an
@@ -132,6 +139,7 @@ public sealed class VirtualTagActor : ReceiveActor
         _telemetryHub = telemetryHub;
 
         Receive<DependencyValueChanged>(OnDependencyChanged);
+        Receive<DependencyValueBatch>(OnDependencyBatch);
         Receive<ReassertValue>(_ => OnReassertValue());
     }
 
@@ -179,7 +187,41 @@ public sealed class VirtualTagActor : ReceiveActor
     private void OnDependencyChanged(DependencyValueChanged msg)
     {
         _dependencies[msg.TagId] = msg.Value;
+        Evaluate(msg.TimestampUtc);
+    }
 
+    /// <summary>Applies EVERY item in the batch to the dependency map first, then evaluates the script
+    /// ONCE. This is the whole point of the batched mux delivery: a burst that moves K of this tag's inputs
+    /// used to arrive as K messages and cost K script evaluations, K-1 of them against a half-updated input
+    /// set whose intermediate results nobody wants (and which the value dedup could not suppress, since each
+    /// intermediate value usually differs). Deliberately NOT a loop over
+    /// <see cref="OnDependencyChanged"/>.
+    /// <para>The single evaluation is stamped with the LAST item's timestamp — the newest sample in the
+    /// burst, and the same stamp the final evaluation of the old per-item fan-out carried.</para></summary>
+    private void OnDependencyBatch(DependencyValueBatch msg)
+    {
+        var items = msg.Items;
+        var count = items.Count;
+        // The mux never sends an empty batch; guard anyway rather than evaluate on no new input.
+        if (count == 0) return;
+
+        // Indexed for-loop, not foreach: this is the hot value ingress and an IReadOnlyList<T> enumerator
+        // would allocate once per burst.
+        for (var i = 0; i < count; i++)
+        {
+            var item = items[i];
+            _dependencies[item.TagId] = item.Value;
+        }
+
+        Evaluate(items[count - 1].TimestampUtc);
+    }
+
+    /// <summary>Recomputes the expression against the current dependency map and emits/dedups the result.
+    /// Shared by the single-value and batched dependency handlers — the only difference between them is how
+    /// many inputs were applied before this runs.</summary>
+    /// <param name="timestampUtc">The triggering dependency change's timestamp, stamped on the result.</param>
+    private void Evaluate(DateTime timestampUtc)
+    {
         VirtualTagEvalResult result;
         try
         {
@@ -188,13 +230,13 @@ public sealed class VirtualTagActor : ReceiveActor
         catch (Exception ex)
         {
             _log.Warning(ex, "VirtualTag {Id}: evaluator threw", _virtualTagId);
-            OnEvaluationFailed($"evaluator threw: {ex.Message}", "Error", msg.TimestampUtc);
+            OnEvaluationFailed($"evaluator threw: {ex.Message}", "Error", timestampUtc);
             return;
         }
 
         if (!result.Success)
         {
-            OnEvaluationFailed(result.Reason ?? "evaluator failure", "Warning", msg.TimestampUtc);
+            OnEvaluationFailed(result.Reason ?? "evaluator failure", "Warning", timestampUtc);
             return;
         }
 
@@ -219,7 +261,7 @@ public sealed class VirtualTagActor : ReceiveActor
         _lastValue = result.Value;
         _lastPublishedBad = false;
         OtOpcUaTelemetry.VirtualTagEval.Add(1, new KeyValuePair<string, object?>("outcome", "ok"));
-        var evalResult = new EvaluationResult(_virtualTagId, result.Value, msg.TimestampUtc, CorrelationId.NewId());
+        var evalResult = new EvaluationResult(_virtualTagId, result.Value, timestampUtc, CorrelationId.NewId());
         Context.Parent.Tell(evalResult);
     }