From 4504ed930c33d0a3062e351cae2260b92fb6962e Mon Sep 17 00:00:00 2001
From: Joseph Doherty <dohejw01@gmail.com>
Date: Mon, 13 Jul 2026 12:12:09 -0400
Subject: [PATCH] feat(opcua): surgical RemoveEquipmentSubtree with notifier
 demotion (R2-07 T10)

---
 ...2-07-surgical-pure-adds-plan.md.tasks.json |  2 +-
 .../OtOpcUaNodeManager.cs                     | 68 ++++++++++++++++++-
 2 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/archreview/plans/R2-07-surgical-pure-adds-plan.md.tasks.json b/archreview/plans/R2-07-surgical-pure-adds-plan.md.tasks.json
index df9b97d7..6e179a63 100644
--- a/archreview/plans/R2-07-surgical-pure-adds-plan.md.tasks.json
+++ b/archreview/plans/R2-07-surgical-pure-adds-plan.md.tasks.json
@@ -87,7 +87,7 @@
     {
       "id": "T10",
       "subject": "Phase 2: OtOpcUaNodeManager.RemoveEquipmentSubtree (descendants + notifier demotion) + SdkAddressSpaceSink forwards (high-risk)",
-      "status": "pending",
+      "status": "completed",
       "blockedBy": [
         "T8",
         "T9"
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
index cbcb0de2..27919037 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
@@ -1847,7 +1847,73 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     }
 
     /// <inheritdoc cref="ISurgicalAddressSpaceSink.RemoveEquipmentSubtree"/>
-    public bool RemoveEquipmentSubtree(string equipmentNodeId) => false;
+    public bool RemoveEquipmentSubtree(string equipmentNodeId)
+    {
+        ArgumentException.ThrowIfNullOrEmpty(equipmentNodeId);
+        EnsureAddressSpaceCreated();
+
+        GeneralModelChangeEventState e;
+        lock (Lock)
+        {
+            // Unknown equipment id ⇒ map drift ⇒ false (caller rebuilds).
+            if (!_folders.ContainsKey(equipmentNodeId)) return false;
+
+            // Folder-scoped NodeIds mean every descendant's id is the equipment id itself or begins with
+            // "<equipmentId>/" (sub-folders, variables, condition nodes). Snapshot each map's in-scope keys
+            // first (ToList) so we don't mutate while enumerating.
+            var prefix = equipmentNodeId + "/";
+            bool InScope(string id) => id == equipmentNodeId || id.StartsWith(prefix, StringComparison.Ordinal);
+
+            // Value variables (+ their historized-tagname registrations).
+            foreach (var id in _variables.Keys.Where(InScope).ToList())
+            {
+                if (_variables.TryRemove(id, out var v))
+                {
+                    v.Parent?.RemoveChild(v);
+                    PredefinedNodes?.Remove(v.NodeId);
+                }
+                _historizedTagnames.TryRemove(id, out _);
+            }
+
+            // Part 9 condition nodes (+ their native flags).
+            foreach (var id in _alarmConditions.Keys.Where(InScope).ToList())
+            {
+                if (_alarmConditions.TryRemove(id, out var c))
+                {
+                    c.Parent?.RemoveChild(c);
+                    PredefinedNodes?.Remove(c.NodeId);
+                }
+                _nativeAlarmNodeIds.Remove(id);
+            }
+
+            // Notifier demotion BEFORE dropping the folders: sever the Server↔folder HasNotifier ref for
+            // every promoted folder in the subtree (an equipment folder, or a sub-folder that hosted an
+            // alarm), else the removal leaks an orphaned root-notifier reference on the Server object.
+            // _notifierFolders is keyed by the folder's NodeId; match on its string identifier.
+            foreach (var kvp in _notifierFolders.Where(kv => InScope(kv.Key.Identifier?.ToString() ?? string.Empty)).ToList())
+            {
+                RemoveRootNotifier(kvp.Value);
+                _notifierFolders.Remove(kvp.Key);
+            }
+            // Drop the event-history source registrations for the subtree (keyed by the folder id string).
+            foreach (var src in _eventNotifierSources.Keys.Where(InScope).ToList())
+                _eventNotifierSources.TryRemove(src, out _);
+
+            // Sub-folders + the equipment folder itself (children already detached above).
+            foreach (var id in _folders.Keys.Where(InScope).ToList())
+            {
+                if (_folders.TryRemove(id, out var f))
+                {
+                    f.Parent?.RemoveChild(f);
+                    PredefinedNodes?.Remove(f.NodeId);
+                }
+            }
+
+            e = BuildNodesRemovedModelChange(equipmentNodeId);
+        }
+        ReportModelChangeOutsideLock(e, equipmentNodeId);
+        return true;
+    }
 
     private FolderState ResolveParentFolder(string? parentNodeId)
     {