LT-22822: Don't display autogenerated Natural Classes

DistFiles/Language Explorer/Configuration/Grammar/areaConfiguration.xml

@@ -426,7 +426,11 @@
 					<recordList owner="MorphologicalData" property="Phonemes"/>
 		</clerk>
 				<clerk id="naturalClasses">
-					<recordList owner="MorphologicalData" property="NaturalClasses"/>
+					<dynamicloaderinfo assemblyPath="MorphologyEditorDll.dll"
+						class="SIL.FieldWorks.XWorks.MorphologyEditor.NaturalClassRecordClerk"/>
+					<recordList owner="MorphologicalData" property="NaturalClasses">
+					  <dynamicloaderinfo assemblyPath="MorphologyEditorDll.dll" class="SIL.FieldWorks.XWorks.MorphologyEditor.NaturalClassRecordList"/>
+					</recordList>
 				</clerk>
 				<clerk id="environments">
 					<recordList owner="MorphologicalData" property="Environments"/>

Src/LexText/Morphology/AffixRuleFormulaControl.cs

@@ -841,7 +841,9 @@ public override void SetMappingNaturalClass(SelectionHelper sel = null)
 			var natClasses = new HashSet<ICmObject>();
 			foreach (var nc in m_cache.LangProject.PhonologicalDataOA.NaturalClassesOS)
 			{
-				if (nc.ClassID == PhNCFeaturesTags.kClassId)
+				// Rule mappings only allow feature-based, user-defined natural classes
+				// to be selected.
+				if (nc is IPhNCFeatures featNC && IsFeatureBasedNCUserDefined(featNC))
 					natClasses.Add(nc);
 			}
 			var selectedNc = DisplayChooser(MEStrings.ksRuleNCOpt, MEStrings.ksRuleNCChooserLink,

Src/LexText/Morphology/AffixRuleFormulaSlice.cs

@@ -62,7 +62,11 @@ public bool OnMappingSetNaturalClass(object args)
 		public bool OnDisplayMappingJumpToNaturalClass(object commandObject, ref XCore.UIItemDisplayProperties display)
 		{
 			CheckDisposed();
-			bool enable = AffixRuleFormulaControl.IsNCIndexCurrent;
+			// Note that a mapping's Natural Class is always feature-based.
+			// For feature-based NCs, we only want to allow jumping to the NC
+			// if it is user-defined.
+			var mapping = AffixRuleFormulaControl.CurrentObject as IMoModifyFromInput;
+			bool enable = mapping != null && RuleFormulaControl.IsFeatureBasedNCUserDefined(mapping.ModificationRA);
 			display.Enabled = enable;
 			display.Visible = enable;
 			return true;

Src/LexText/Morphology/MEStrings.resx

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <root>
   <!-- 
     Microsoft ResX Schema 
@@ -239,6 +239,9 @@
   <data name="ksRuleNCFeatsName" xml:space="preserve">
     <value>Created automatically for rule "{0}"</value>
   </data>
+  <data name="ksRuleNCSharedNameFormat" xml:space="preserve">
+    <value>Shared: {0}</value>
+  </data>
   <data name="ksRuleRedoInsert" xml:space="preserve">
     <value>Redo Insert {0}</value>
   </data>

Src/LexText/Morphology/MorphologyEditorDllTests/NaturalClassRecordListTests.cs

@@ -0,0 +1,109 @@
+// Copyright (c) 2026 SIL International
+// This software is licensed under the LGPL, version 2.1 or later
+// (http://www.gnu.org/licenses/lgpl-2.1.html)
+
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using SIL.LCModel;
+
+namespace SIL.FieldWorks.XWorks.MorphologyEditor
+{
+	/// <summary>
+	/// Tests to confirm that <see cref="NaturalClassRecordList"/> includes every
+	/// natural class except a feature-based one generated automatically for a rule.
+	/// </summary>
+	[TestFixture]
+	public class NaturalClassRecordListTests : RuleFormulaVcTestBase
+	{
+		private IEnumerable<int> NCRecordList(params ICmObject[] natClasses)
+		{
+			return NaturalClassRecordList.ExcludeAutoGenerated(
+				natClasses.Select(nc => nc.Hvo), Cache);
+		}
+		[Test]
+		public void AutoGeneratedClass_IsExcluded()
+		{
+			IPhNCFeatures natClass = AddAutoGeneratedFeatureNaturalClass("s to n",
+				new Dictionary<string, string> { { "vd", "+" } });
+
+			// Since the only NC is autogenerated, the NC record list should be empty
+			Assert.That(NCRecordList(natClass), Is.Empty);
+		}
+
+		[Test]
+		public void NamedFeatureClass_IsIncluded()
+		{
+			IPhNCFeatures natClass = AddFeatureNaturalClass("Voiced", "Vd",
+				new Dictionary<string, string> { { "vd", "+" } });
+
+			Assert.That(NCRecordList(natClass), Is.EqualTo(new[] { natClass.Hvo }));
+		}
+
+		/// <summary>
+		/// A feature-based class the user creates starts with no name, so an unnamed class must
+		/// be included for the user to be able to name it.
+		/// </summary>
+		[Test]
+		public void UnnamedFeatureClass_IsIncluded()
+		{
+			IPhNCFeatures natClass = AddFeatureNaturalClass(null, null,
+				new Dictionary<string, string> { { "vd", "+" } });
+
+			Assert.That(NCRecordList(natClass), Is.EqualTo(new[] { natClass.Hvo }));
+		}
+
+		[Test]
+		public void SegmentClass_IsIncluded()
+		{
+			IPhNCSegments natClass = AddSegmentNaturalClass("Vowels", "V");
+
+			Assert.That(NCRecordList(natClass), Is.EqualTo(new[] { natClass.Hvo }));
+		}
+
+		/// <summary>
+		/// A class given an abbreviation by the user is considered user defined,
+		/// so it should display in the NC list.
+		/// </summary>
+		[Test]
+		public void AbbreviatedGeneratedClass_IsIncluded()
+		{
+			IPhNCFeatures natClass = AddAutoGeneratedFeatureNaturalClass("s to n",
+				new Dictionary<string, string> { { "vd", "+" } });
+			natClass.Abbreviation.SetAnalysisDefaultWritingSystem("Vd");
+
+			Assert.That(NCRecordList(natClass), Is.EqualTo(new[] { natClass.Hvo }));
+		}
+
+		/// <summary>
+		/// A class with the "shared" prefix is not considered user defined if it is used
+		/// by at most one rule, so it should not display in the NC list.
+		/// </summary>
+		[Test]
+		public void PrefixedClassUsedByOneRule_IsExcluded()
+		{
+			IPhNCFeatures natClass = AddAutoGeneratedFeatureNaturalClass("s to n",
+				new Dictionary<string, string> { { "vd", "+" } });
+			natClass.Name.SetUserWritingSystem(string.Format(MEStrings.ksRuleNCSharedNameFormat,
+				natClass.Name.UserDefaultWritingSystem.Text));
+			AddStrucDescNCContext(AddRegularRule("rule A"), natClass);
+
+			Assert.That(NCRecordList(natClass), Is.Empty);
+		}
+
+		/// <summary>
+		/// A class used by more than one rule is considered user defined,
+		/// so it should display in the NC list.
+		/// </summary>
+		[Test]
+		public void ClassSharedByTwoRules_IsIncluded()
+		{
+			IPhNCFeatures natClass = AddAutoGeneratedFeatureNaturalClass("s to n",
+				new Dictionary<string, string> { { "vd", "+" } });
+			AddStrucDescNCContext(AddRegularRule("rule A"), natClass);
+			AddStrucDescNCContext(AddRegularRule("rule B"), natClass);
+
+			Assert.That(NCRecordList(natClass), Is.EqualTo(new[] { natClass.Hvo }));
+		}
+	}
+}