Adding runtime-aware assembly loading strategy

BHoM_UI/Global/AssemblyResolver.cs

@@ -84,7 +84,7 @@ public bool MakeSureAssemblyIsLoadedForType(string type)
             {
                 if (!BH.Engine.Base.Query.IsAssemblyLoaded(assemblyName))
                 {
-                    string assemblyPath = Path.Combine(BH.Engine.Base.Query.BHoMFolder(), assemblyName + ".dll");
+                    string assemblyPath = BH.Engine.UI.Query.AssemblyPath(assemblyName);
                     if (!File.Exists(assemblyPath))
                     {
                         BH.Engine.Base.Compute.RecordError($"Assembly file not found when trying to load assemblies for type {type}: {assemblyPath}");
@@ -162,7 +162,7 @@ public bool MakeSureAssemblyIsLoadedForExtensionMethod(string methodName, Type t
             {
                 if (!BH.Engine.Base.Query.IsAssemblyLoaded(assemblyName))
                 {
-                    string assemblyPath = Path.Combine(BH.Engine.Base.Query.BHoMFolder(), assemblyName + ".dll");
+                    string assemblyPath = BH.Engine.UI.Query.AssemblyPath(assemblyName);
                     if (!File.Exists(assemblyPath))
                     {
                         BH.Engine.Base.Compute.RecordNote($"Assembly not found for extension method {methodName}: {assemblyPath}");

BHoM_UI/Global/Initialisation.cs

@@ -68,9 +68,9 @@ public static bool Activate()
 
             success &= LoadCodeElements();
             success &= CreateAssemblyResolver();
+            success &= LoadToolkitSettings();
             success &= LoadNewAssemblies();
             success &= CreateSearchItems(CodeElements);
-            success &= LoadToolkitSettings(); 
 
             CompletionTime = DateTime.UtcNow;
 
@@ -127,7 +127,10 @@ private static bool InitialiseToolkit(IInitialisationSettings settings)
 
             // Make sure the assembly is loaded for that method
             if (!string.IsNullOrEmpty(settings.InitialisationAssembly) && !BH.Engine.Base.Query.IsAssemblyLoaded(settings.InitialisationAssembly))
-                BH.Engine.Base.Compute.LoadAssembly(Path.Combine(BH.Engine.Base.Query.BHoMFolder(), settings.InitialisationAssembly + ".dll"));
+            {
+                string initAssemblyPath = BH.Engine.UI.Query.AssemblyPath(settings.InitialisationAssembly);
+                BH.Engine.Base.Compute.LoadAssembly(initAssemblyPath);
+            }
 
             // Get method declaring type
             List<Type> typeCandidates = Engine.Base.Create.AllTypes(typeName).Where(x => x.FullName == typeName).ToList();

UI_Engine/Compute/LoadNewAssemblies.cs

@@ -55,31 +55,62 @@ public static List<string> LoadNewAssemblies(Dictionary<string, DateTime> lastAs
 
             // Make sure the keys for the assemblies are in lower case to avoid casing mismatching
             Dictionary<string, DateTime> lastUpdateTimes = lastAssemblyUpdateTimes.ToDictionary(x => x.Key.ToLower(), x => x.Value);
+            HashSet<string> loadedAssemblies = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+            HashSet<string> visitedAssemblies = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
 
-            List<string> loadedAssemblies = new List<string>();
+            // Pass 1: runtime-specific subdirectory (preferred over flat folder when present)
+            string bhomFolder = BH.Engine.Base.Query.BHoMFolder();
+            foreach (string subFolder in BH.Engine.UI.Query.SubFoldersForRuntime())
+            {
+                string runtimeFolder = Path.Combine(bhomFolder, subFolder);
+                LoadNewAssembliesForFolder(runtimeFolder, lastUpdateTimes, loadedAssemblies, visitedAssemblies);
+            }
+
+            // Pass 2: flat folder, skipping any assembly already handled by the runtime subdir pass
+            LoadNewAssembliesForFolder(bhomFolder, lastUpdateTimes, loadedAssemblies, visitedAssemblies);
+
+            return loadedAssemblies.ToList();
+        }
 
-            Regex regex = new Regex(@"oM$|_Engine$|_Adapter$");
-            foreach (string file in Directory.GetFiles(BH.Engine.Base.Query.BHoMFolder(), "*.dll", SearchOption.TopDirectoryOnly))
+
+        /*************************************/
+        /**** Private Methods             ****/
+        /*************************************/
+
+        private static void LoadNewAssembliesForFolder(string folderPath, Dictionary<string, DateTime> lastUpdateTimes, HashSet<string> loadedAssemblies, HashSet<string> visitedAssemblies)
+        {
+            if (!Directory.Exists(folderPath))
+                return;
+
+            foreach (string file in Directory.GetFiles(folderPath, "*.dll", SearchOption.TopDirectoryOnly))
             {
                 string name = Path.GetFileNameWithoutExtension(file);
-                if (regex.IsMatch(name))
+
+                if (m_AssemblyNameFilter.IsMatch(name) && !visitedAssemblies.Contains(name))
                 {
+                    visitedAssemblies.Add(name);
                     string key = name.ToLower();
+
                     if (!lastUpdateTimes.ContainsKey(key) || lastUpdateTimes[key] < File.GetLastWriteTimeUtc(file))
                     {
                         Assembly assembly = BH.Engine.Base.Compute.LoadAssembly(file);
                         if (assembly != null)
                         {
                             BH.Engine.Base.Compute.RecordNote($"Assembly {name} loaded as it was newer than its last recorded update time.");
                             loadedAssemblies.Add(name);
-                        }   
-                    }  
+                        }
+                    }
                 }
             }
-
-            return loadedAssemblies;
         }
 
+
+        /*************************************/
+        /**** Private Fields              ****/
+        /*************************************/
+
+        private static readonly Regex m_AssemblyNameFilter = new Regex(@"oM$|_Engine$|_Adapter$");
+
         /*************************************/
 
     }

UI_Engine/Query/AssemblyPath.cs

@@ -0,0 +1,70 @@
+/*
+ * This file is part of the Buildings and Habitats object Model (BHoM)
+ * Copyright (c) 2015 - 2026, the respective contributors. All rights reserved.
+ *
+ * Each contributor holds copyright over their respective contributions.
+ * The project versioning (Git) records all such contribution source information.
+ *                                           
+ *                                                                              
+ * The BHoM is free software: you can redistribute it and/or modify         
+ * it under the terms of the GNU Lesser General Public License as published by  
+ * the Free Software Foundation, either version 3.0 of the License, or          
+ * (at your option) any later version.                                          
+ *                                                                              
+ * The BHoM is distributed in the hope that it will be useful,              
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of               
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                 
+ * GNU Lesser General Public License for more details.                          
+ *                                                                            
+ * You should have received a copy of the GNU Lesser General Public License     
+ * along with this code. If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.      
+ */
+
+using BH.Engine.Base;
+using BH.oM.Base.Attributes;
+using BH.oM.UI;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace BH.Engine.UI
+{
+    public static partial class Query
+    {
+        /*************************************/
+        /**** Public Methods              ****/
+        /*************************************/
+
+        [Description("Returns the best on-disk path for a BHoM assembly, preferring the runtime-specific subdirectory (netX.0\\ or netfx\\) over the flat folder.")]
+        [Input("assemblyName", "Assembly name without extension, e.g. 'SQL_Adapter'")]
+        [Output("path", "Full path to the .dll file; the file may or may not exist.")]
+        public static string AssemblyPath(string assemblyName)
+        {
+            string bhomFolder = BH.Engine.Base.Query.BHoMFolder();
+
+            // First try to return an assembly from a runtime-specific folder 
+            foreach (string subFolder in BH.Engine.UI.Query.SubFoldersForRuntime())
+            {
+                string runtimePath = Path.Combine(bhomFolder, subFolder, assemblyName + ".dll");
+                if (File.Exists(runtimePath))
+                    return runtimePath;
+            }
+
+            //Then  fallback to returning the assembly from the default rool folder
+            return Path.Combine(bhomFolder, assemblyName + ".dll");
+        }
+
+        /*************************************/
+    }
+}
+
+
+
+
+
+
+

UI_Engine/Query/SubFoldersForRuntime.cs

@@ -0,0 +1,85 @@
+/*
+ * This file is part of the Buildings and Habitats object Model (BHoM)
+ * Copyright (c) 2015 - 2026, the respective contributors. All rights reserved.
+ *
+ * Each contributor holds copyright over their respective contributions.
+ * The project versioning (Git) records all such contribution source information.
+ *                                           
+ *                                                                              
+ * The BHoM is free software: you can redistribute it and/or modify         
+ * it under the terms of the GNU Lesser General Public License as published by  
+ * the Free Software Foundation, either version 3.0 of the License, or          
+ * (at your option) any later version.                                          
+ *                                                                              
+ * The BHoM is distributed in the hope that it will be useful,              
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of               
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                 
+ * GNU Lesser General Public License for more details.                          
+ *                                                                            
+ * You should have received a copy of the GNU Lesser General Public License     
+ * along with this code. If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.      
+ */
+
+using BH.Engine.Base;
+using BH.oM.Base.Attributes;
+using BH.oM.UI;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace BH.Engine.UI
+{
+    public static partial class Query
+    {
+        /*************************************/
+        /**** Public Methods              ****/
+        /*************************************/
+
+        [Description("Returns the runtime-specific subdirectories of the BHoM Assemblies folder where assemblies compatible with the current .NET runtime can be found. " +
+             "Returns '.../Assemblies/netfx/' on .NET Framework and '.../Assemblies/netX.0/' on CoreCLR (.NET X).")]
+        [Output("subFolders", "runtime-specific subdirectories for the BHoM assemblies sorted in the order they should be traversed.")]
+        public static List<string> SubFoldersForRuntime()
+        {
+            if (m_SubFoldersForRuntime != null) 
+                return m_SubFoldersForRuntime;
+
+
+            var desc = RuntimeInformation.FrameworkDescription;
+            if (desc.StartsWith(".NET Framework", StringComparison.OrdinalIgnoreCase))
+            {
+                // Return 'netfx' if the framework is a .NET Framework
+                m_SubFoldersForRuntime = new List<string> { "netfx" };
+            }
+            else
+            {
+                // For .NET Core, return exact TFM first, then descend to lower versions as fallback
+                m_SubFoldersForRuntime = new List<string>();
+                int major = Environment.Version.Major;
+                for (int v = major; v >= 5; v--)
+                    m_SubFoldersForRuntime.Add($"net{v}.0");
+            }
+
+            return m_SubFoldersForRuntime;
+        }
+
+
+        /*************************************/
+        /**** Private Fields              ****/
+        /*************************************/
+
+        private static List<string> m_SubFoldersForRuntime = null;
+
+        /*************************************/
+    }
+}
+
+
+
+
+
+
+