fix(template-engine): repeated composition no longer drops nested members — cycle guard keyed on recursion path, not global template id

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Flattening/FlatteningService.cs

@@ -262,7 +262,7 @@ public class FlatteningService
         IReadOnlyDictionary<int, IReadOnlyList<TemplateComposition>> compositionMap,
         IReadOnlyDictionary<int, IReadOnlyList<Template>> composedTemplateChains,
         Dictionary<string, ResolvedAttribute> attributes,
-        HashSet<int> visited)
+        HashSet<int> path)
     {
         if (!composedTemplateChains.TryGetValue(composition.ComposedTemplateId, out var composedChain))
             return;
@@ -283,17 +283,27 @@ public class FlatteningService
         }
 
         // Descend into nested compositions of every template in the chain.
+        // Guard on the recursion PATH, not globally: composition is by-slot, so a
+        // template legitimately appears twice under different prefixes; only a
+        // template already on the CURRENT path is a cycle.
         foreach (var composedTemplate in composedChain)
         {
-            if (!visited.Add(composedTemplate.Id))
-                continue;
-            if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+            if (!path.Add(composedTemplate.Id))
                 continue;
+            try
+            {
+                if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+                    continue;
 
-            foreach (var nested in nestedCompositions)
-                ResolveComposedAttributesRecursive(
-                    nested, $"{prefix}.{nested.InstanceName}",
-                    compositionMap, composedTemplateChains, attributes, visited);
+                foreach (var nested in nestedCompositions)
+                    ResolveComposedAttributesRecursive(
+                        nested, $"{prefix}.{nested.InstanceName}",
+                        compositionMap, composedTemplateChains, attributes, path);
+            }
+            finally
+            {
+                path.Remove(composedTemplate.Id);
+            }
         }
     }
 
@@ -625,7 +635,7 @@ public class FlatteningService
         IReadOnlyDictionary<int, IReadOnlyList<Template>> composedTemplateChains,
         Dictionary<string, ResolvedAlarm> alarms,
         Dictionary<string, int> alarmScriptIds,
-        HashSet<int> visited)
+        HashSet<int> path)
     {
         if (!composedTemplateChains.TryGetValue(composition.ComposedTemplateId, out var composedChain))
             return;
@@ -646,17 +656,27 @@ public class FlatteningService
         }
 
         // Descend into nested compositions of every template in the chain.
+        // Guard on the recursion PATH, not globally: composition is by-slot, so a
+        // template legitimately appears twice under different prefixes; only a
+        // template already on the CURRENT path is a cycle.
         foreach (var composedTemplate in composedChain)
         {
-            if (!visited.Add(composedTemplate.Id))
-                continue;
-            if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+            if (!path.Add(composedTemplate.Id))
                 continue;
+            try
+            {
+                if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+                    continue;
 
-            foreach (var nested in nestedCompositions)
-                ResolveComposedAlarmsRecursive(
-                    nested, $"{prefix}.{nested.InstanceName}",
-                    compositionMap, composedTemplateChains, alarms, alarmScriptIds, visited);
+                foreach (var nested in nestedCompositions)
+                    ResolveComposedAlarmsRecursive(
+                        nested, $"{prefix}.{nested.InstanceName}",
+                        compositionMap, composedTemplateChains, alarms, alarmScriptIds, path);
+            }
+            finally
+            {
+                path.Remove(composedTemplate.Id);
+            }
         }
     }
 
@@ -739,7 +759,7 @@ public class FlatteningService
         IReadOnlyDictionary<int, IReadOnlyList<TemplateComposition>> compositionMap,
         IReadOnlyDictionary<int, IReadOnlyList<Template>> composedTemplateChains,
         Dictionary<string, ResolvedNativeAlarmSource> sources,
-        HashSet<int> visited)
+        HashSet<int> path)
     {
         if (!composedTemplateChains.TryGetValue(composition.ComposedTemplateId, out var composedChain))
             return;
@@ -758,17 +778,27 @@ public class FlatteningService
             }
         }
 
+        // Guard on the recursion PATH, not globally: composition is by-slot, so a
+        // template legitimately appears twice under different prefixes; only a
+        // template already on the CURRENT path is a cycle.
         foreach (var composedTemplate in composedChain)
         {
-            if (!visited.Add(composedTemplate.Id))
-                continue;
-            if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+            if (!path.Add(composedTemplate.Id))
                 continue;
+            try
+            {
+                if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+                    continue;
 
-            foreach (var nested in nestedCompositions)
-                ResolveComposedNativeAlarmSourcesRecursive(
-                    nested, $"{prefix}.{nested.InstanceName}",
-                    compositionMap, composedTemplateChains, sources, visited);
+                foreach (var nested in nestedCompositions)
+                    ResolveComposedNativeAlarmSourcesRecursive(
+                        nested, $"{prefix}.{nested.InstanceName}",
+                        compositionMap, composedTemplateChains, sources, path);
+            }
+            finally
+            {
+                path.Remove(composedTemplate.Id);
+            }
         }
     }
 
@@ -889,7 +919,7 @@ public class FlatteningService
         IReadOnlyDictionary<int, IReadOnlyList<Template>> composedTemplateChains,
         Dictionary<string, ResolvedScript> scripts,
         Dictionary<int, string> scriptCanonicalById,
-        HashSet<int> visited)
+        HashSet<int> path)
     {
         if (!composedTemplateChains.TryGetValue(composition.ComposedTemplateId, out var composedChain))
             return;
@@ -910,17 +940,27 @@ public class FlatteningService
         }
 
         // Descend into nested compositions of every template in the chain.
+        // Guard on the recursion PATH, not globally: composition is by-slot, so a
+        // template legitimately appears twice under different prefixes; only a
+        // template already on the CURRENT path is a cycle.
         foreach (var composedTemplate in composedChain)
         {
-            if (!visited.Add(composedTemplate.Id))
-                continue;
-            if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+            if (!path.Add(composedTemplate.Id))
                 continue;
+            try
+            {
+                if (!compositionMap.TryGetValue(composedTemplate.Id, out var nestedCompositions))
+                    continue;
 
-            foreach (var nested in nestedCompositions)
-                ResolveComposedScriptsRecursive(
-                    nested, $"{prefix}.{nested.InstanceName}", parentPath: prefix,
-                    compositionMap, composedTemplateChains, scripts, scriptCanonicalById, visited);
+                foreach (var nested in nestedCompositions)
+                    ResolveComposedScriptsRecursive(
+                        nested, $"{prefix}.{nested.InstanceName}", parentPath: prefix,
+                        compositionMap, composedTemplateChains, scripts, scriptCanonicalById, path);
+            }
+            finally
+            {
+                path.Remove(composedTemplate.Id);
+            }
         }
     }