De-duplicate bookmark match/folding helpers; enabled glyph wins on a shared line

- Extract MatchesBookmark for the token + assembly identity that tied a bookmark
  to a member; GetLineForBookmark and DocumentContainsBookmarkToken each spelled
  it out (four copies), so a change to the match rule had to be made everywhere.
- Add a FoldingSection overload to FoldingsViewState.Restore and route the
  bookmark folding restore through it, dropping a duplicated checksum + match loop.
- When two bookmarks resolve to the same gutter line, draw the enabled glyph so
  the line never reads as disabled while an active bookmark sits on it.
- Drop an out-of-band reference in a test comment.

Assisted-by: Claude:claude-opus-4-8:Claude Code

ILSpy.Tests/Bookmarks/BookmarkNavigationStepTests.cs

@@ -30,7 +30,7 @@ namespace ICSharpCode.ILSpy.Tests.Bookmarks;
 [TestFixture]
 public class BookmarkNavigationStepTests
 {
-	// Three bookmarks, the middle one disabled (the reported scenario).
+	// Three bookmarks with the middle one disabled, so next/previous must step over it.
 	static readonly IReadOnlyList<bool> ThreeMiddleDisabled = new[] { true, false, true };
 
 	[Test]

ILSpy/Bookmarks/BookmarkMargin.cs

@@ -210,7 +210,12 @@ namespace ICSharpCode.ILSpy.Bookmarks
 				{
 					if (bookmark.LineNumber != line)
 						Dispatcher.UIThread.Post(() => bookmark.UpdateRenderedLineNumber(line), DispatcherPriority.Background);
-					map[line] = bookmark.Enabled ? Images.Bookmark : Images.BookmarkDisable;
+					// When two bookmarks resolve to the same line, an enabled one wins so the line never
+					// reads as disabled while an active bookmark sits on it.
+					if (bookmark.Enabled)
+						map[line] = Images.Bookmark;
+					else if (!map.ContainsKey(line))
+						map[line] = Images.BookmarkDisable;
 				}
 			}
 			return glyphByLine = map;

ILSpy/TextView/DecompilerTextView.axaml.cs

@@ -821,30 +821,9 @@ namespace ICSharpCode.ILSpy.TextView
 		}
 
 		void RestoreBookmarkFoldings(Bookmarks.BookmarkViewState viewState)
-			=> RestoreCurrentFoldings(viewState.ToDecompilerTextViewState().Foldings);
-
-		void RestoreCurrentFoldings(FoldingsViewState.Snapshot? saved)
 		{
-			if (saved == null || activeFoldingManager is not { } manager)
-				return;
-
-			var current = FoldingsViewState.Capture(manager.AllFoldings);
-			if (current.Checksum != saved.Value.Checksum)
-				return;
-
-			foreach (var folding in manager.AllFoldings)
-			{
-				bool wasExpanded = false;
-				foreach (var (start, end) in saved.Value.Expanded)
-				{
-					if (start == folding.StartOffset && end == folding.EndOffset)
-					{
-						wasExpanded = true;
-						break;
-					}
-				}
-				folding.IsFolded = !wasExpanded;
-			}
+			if (viewState.ToDecompilerTextViewState().Foldings is { } saved && activeFoldingManager is { } manager)
+				FoldingsViewState.Restore(manager.AllFoldings, saved);
 		}
 
 		// Scrolls so <paramref name="line"/> sits in the middle of the viewport. AvaloniaEdit's
@@ -888,7 +867,7 @@ namespace ICSharpCode.ILSpy.TextView
 					return null;
 				foreach (var method in debug.Methods)
 				{
-					if (method.Token == bookmark.Token && method.AssemblyFullName == bookmark.AssemblyFullName
+					if (MatchesBookmark(method, bookmark)
 						&& method.TryGetLineForOffset(bookmark.ILOffset, out var bodyLine))
 					{
 						if (updateRenderedLine)
@@ -912,9 +891,7 @@ namespace ICSharpCode.ILSpy.TextView
 			{
 				foreach (var segment in references)
 				{
-					if (segment.IsDefinition && segment.Reference is IEntity entity
-						&& (uint)System.Reflection.Metadata.Ecma335.MetadataTokens.GetToken(entity.MetadataToken) == bookmark.Token
-						&& entity.ParentModule?.MetadataFile?.FullName == bookmark.AssemblyFullName)
+					if (segment.IsDefinition && segment.Reference is IEntity entity && MatchesBookmark(entity, bookmark))
 					{
 						var line = Editor.Document.GetLineByOffset(segment.StartOffset).LineNumber;
 						if (updateRenderedLine)
@@ -926,13 +903,24 @@ namespace ICSharpCode.ILSpy.TextView
 			return null;
 		}
 
+		// The token + assembly identity that ties a bookmark to a member in the current document. The
+		// module identity is checked too, so a token value shared across assemblies can't match the
+		// wrong member. Both forms (the body-anchor debug map and a reference segment's entity) are
+		// kept in step here rather than spelled out at each call site.
+		static bool MatchesBookmark(Bookmarks.MethodDebugInfo method, Bookmarks.Bookmark bookmark)
+			=> method.Token == bookmark.Token && method.AssemblyFullName == bookmark.AssemblyFullName;
+
+		static bool MatchesBookmark(IEntity entity, Bookmarks.Bookmark bookmark)
+			=> (uint)MetadataTokens.GetToken(entity.MetadataToken) == bookmark.Token
+				&& entity.ParentModule?.MetadataFile?.FullName == bookmark.AssemblyFullName;
+
 		static bool DocumentContainsBookmarkToken(DecompilerTabPageModel model, Bookmarks.Bookmark bookmark)
 		{
 			if (model.DebugInfo != null)
 			{
 				foreach (var method in model.DebugInfo.Methods)
 				{
-					if (method.Token == bookmark.Token && method.AssemblyFullName == bookmark.AssemblyFullName)
+					if (MatchesBookmark(method, bookmark))
 						return true;
 				}
 			}
@@ -941,9 +929,7 @@ namespace ICSharpCode.ILSpy.TextView
 			{
 				foreach (var segment in model.References)
 				{
-					if (segment.Reference is IEntity entity
-						&& (uint)MetadataTokens.GetToken(entity.MetadataToken) == bookmark.Token
-						&& entity.ParentModule?.MetadataFile?.FullName == bookmark.AssemblyFullName)
+					if (segment.Reference is IEntity entity && MatchesBookmark(entity, bookmark))
 						return true;
 				}
 			}

ILSpy/TextView/FoldingsViewState.cs

@@ -88,19 +88,33 @@ namespace ICSharpCode.ILSpy.TextView
 			if (checksum != saved.Checksum)
 				return false;
 			foreach (var folding in newFoldings)
+				folding.DefaultClosed = !IsExpanded(saved, folding.StartOffset, folding.EndOffset);
+			return true;
+		}
+
+		/// <summary>
+		/// Applies <paramref name="saved"/> to live <paramref name="foldings"/> already installed in a
+		/// FoldingManager by toggling <see cref="FoldingSection.IsFolded"/>. Returns <c>true</c> when the
+		/// layout still matches the snapshot; <c>false</c> (leaving the foldings untouched) on a mismatch.
+		/// </summary>
+		public static bool Restore(IEnumerable<FoldingSection> foldings, Snapshot saved)
+		{
+			var sections = foldings as IReadOnlyList<FoldingSection> ?? foldings.ToList();
+			if (Capture(sections).Checksum != saved.Checksum)
+				return false;
+			foreach (var folding in sections)
+				folding.IsFolded = !IsExpanded(saved, folding.StartOffset, folding.EndOffset);
+			return true;
+		}
+
+		static bool IsExpanded(Snapshot saved, int start, int end)
+		{
+			foreach (var (s, e) in saved.Expanded)
 			{
-				bool wasExpanded = false;
-				foreach (var (start, end) in saved.Expanded)
-				{
-					if (start == folding.StartOffset && end == folding.EndOffset)
-					{
-						wasExpanded = true;
-						break;
-					}
-				}
-				folding.DefaultClosed = !wasExpanded;
+				if (s == start && e == end)
+					return true;
 			}
-			return true;
+			return false;
 		}
 	}
 }