fix(opcua): #855 perf review 4 — registry sweep threshold capped; re-sweep at the cap

- The sweep threshold never rises above the 4096 cap (a threshold the count
  could not reach stopped sweeping, and sharing, for good); at the cap a
  sweep for dead shapes runs after every 256 refusals.
- The per-report "queued" mark is taken after the filter group resolves,
  so a failure there leaves the item unmarked.
- The bucket key also carries TypeDefinitionId and IndexRange.

Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk

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

@@ -199,6 +199,10 @@ internal static class ProjectedEventDelivery
     private static readonly Dictionary<string, List<WeakReference<FilterGroup>>> s_registry = new(StringComparer.Ordinal);
     private static int s_registered;
     private static int s_sweepAt = 1024;
+    private static int s_unsharedSinceSweep;
+
+    /// <summary>At the cap, refusals between two sweeps for dead shapes.</summary>
+    private const int UnsharedResweepInterval = 256;
 
     /// <summary>Live distinct filter shapes kept for sharing; past this a new filter gets a group of its own (no sharing).</summary>
     internal const int MaxSharedFilterGroups = 4096;
@@ -225,10 +229,9 @@ internal static class ProjectedEventDelivery
             var handler = s_eventQueue!(item);
             if (s_filterToUse!(item) is not EventFilter filter) return false;
             if (handler is null) return true; // Disabled: the SDK queues nothing (no handler)
-            if (!cache.TryMarkQueued(item)) return true; // the SDK's duplicate check (see EventDeliveryCache)
-
             var locales = item.Session?.PreferredLocales; // string[]?, exactly what the SDK hands its FilterContext and TranslateValue
             var group = GroupOf(filter, server);
+            if (!cache.TryMarkQueued(item)) return true; // the SDK's duplicate check (see EventDeliveryCache)
             var projection = cache.ProjectionFor(group, LocalesKey(locales), () => new EventDeliveryCache.Projection(
                 () => Passes(server, group, locales, e), () => Project(server, group, locales, e)));
             if (!projection.Passes || handler.SetQueueOverflowIfFull()) return true;
@@ -313,9 +316,21 @@ internal static class ProjectedEventDelivery
                 var created = new FilterGroup(f, server);
                 if (s_registered >= MaxSharedFilterGroups)
                 {
-                    OtOpcUaTelemetry.ConditionEventFilterGroupsUnshared.Add(1);
-                    Interlocked.Increment(ref s_unsharedGroups);
-                    return created;
+                    // Full: re-check for dead shapes after every UnsharedResweepInterval refusals, so a registry that filled
+                    // once does not refuse sharing for good, and one that is genuinely full of live shapes is not swept on
+                    // every new filter.
+                    if (++s_unsharedSinceSweep >= UnsharedResweepInterval)
+                    {
+                        s_unsharedSinceSweep = 0;
+                        SweepRegistry();
+                    }
+
+                    if (s_registered >= MaxSharedFilterGroups)
+                    {
+                        OtOpcUaTelemetry.ConditionEventFilterGroupsUnshared.Add(1);
+                        Interlocked.Increment(ref s_unsharedGroups);
+                        return created;
+                    }
                 }
 
                 s_registered++;
@@ -337,8 +352,9 @@ internal static class ProjectedEventDelivery
         }
 
         s_registered = live;
-        // Amortised: the next sweep only once as many shapes again have been registered (never more often than every 1024).
-        s_sweepAt = Math.Max(1024, live * 2);
+        // Amortised: the next sweep only once as many shapes again have been registered (never more often than every 1024),
+        // and never above the cap — a threshold the count can no longer reach would stop sweeping, and sharing, for good.
+        s_sweepAt = Math.Min(MaxSharedFilterGroups, Math.Max(1024, live * 2));
     }
 
     private static long s_unsharedGroups;
@@ -361,7 +377,7 @@ internal static class ProjectedEventDelivery
 
             var path = new List<string>();
             foreach (var name in clause.BrowsePath) path.Add(name.ToString());
-            parts.Add(string.Join("/", path) + "@" + clause.AttributeId);
+            parts.Add(clause.TypeDefinitionId + ":" + string.Join("/", path) + "@" + clause.AttributeId + "[" + clause.IndexRange + "]");
         }
 
         return string.Join("|", parts);