perf(comms): alarms-only seed, capped buffers, at-least-once audit pull

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/InstanceActor.cs

@@ -1372,13 +1372,21 @@ public class InstanceActor : ReceiveActor
     private void HandleDebugSnapshot(DebugSnapshotRequest request)
     {
         var now = DateTimeOffset.UtcNow;
-        var attributeValues = _attributes.Select(kvp => new AttributeValueChanged(
-            _instanceUniqueName,
-            kvp.Key,
-            kvp.Key,
-            kvp.Value,
-            _attributeQualities.GetValueOrDefault(kvp.Key, "Good"),
-            _attributeTimestamps.GetValueOrDefault(kvp.Key, now))).ToList();
+
+        // Alarms-only projection (WP2.3): the central live-alarm cache seeds/reconciles
+        // through this same query surface and throws every attribute row away. Building
+        // and shipping them is pure waste — one instance with a few hundred attributes
+        // costs more on the wire than the whole alarm set of the site. The flag is
+        // additive and defaults false, so the Debug View is untouched.
+        var attributeValues = request.AlarmsOnly
+            ? new List<AttributeValueChanged>()
+            : _attributes.Select(kvp => new AttributeValueChanged(
+                _instanceUniqueName,
+                kvp.Key,
+                kvp.Key,
+                kvp.Value,
+                _attributeQualities.GetValueOrDefault(kvp.Key, "Good"),
+                _attributeTimestamps.GetValueOrDefault(kvp.Key, now))).ToList();
 
         var snapshot = new DebugViewSnapshot(
             _instanceUniqueName,