Address bookmarks review: lifecycle and sentinel fixes

Tidies up the bookmarks feature in response to review feedback:

- BookmarkMargin subscribed to the shared BookmarkManager.Changed event
  in its constructor and never unsubscribed, so the singleton kept a
  closed tab's margin (and its pulse timer) alive. The subscription now
  follows the margin's time in the visual tree.
- LineHighlightAdorner.DisplayLineHighlight always added a fresh renderer
  with its own timers; navigating repeatedly within the highlight
  lifetime stacked them. Existing highlights are now dismissed first.
- ApplyOutput always built a new DecompiledDebugInfo, contradicting the
  property's documented contract (null for non-C#, the Empty sentinel
  when C# yielded no methods). It now honors that contract.
- The throwaway StringWriter used for sequence-point capture is disposed.

The MemberName doc comment still described a stale-token guard that was
deliberately removed: a token can resolve to a compiler-generated member
(e.g. a local function) whose name differs from the stored display name,
and a name check would wrongly reject a valid navigation. Comment fixed
to match the actual token-only navigation.

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

ILSpy/Bookmarks/Bookmark.cs

@@ -65,9 +65,10 @@ namespace ICSharpCode.ILSpy.Bookmarks
 		public int ILOffset { get; init; }
 
 		/// <summary>
-		/// Display name of the anchored member, shown in the pane's "Location" column and used as a
-		/// stale-token guard: if a reloaded module's token no longer resolves to this member, the
-		/// bookmark is treated as missing rather than silently pointing at the wrong code.
+		/// Display name of the anchored member, shown in the pane's "Location" column. Navigation
+		/// resolves purely by token and does not compare this name: a token can legitimately point at
+		/// a compiler-generated member (e.g. a local function) whose resolved name differs from this
+		/// stored display name, and a name check would wrongly reject that valid navigation.
 		/// </summary>
 		public required string MemberName { get; init; }
 

ILSpy/Bookmarks/BookmarkMargin.cs

@@ -53,12 +53,28 @@ namespace ICSharpCode.ILSpy.Bookmarks
 		{
 			this.owner = owner;
 			manager = AppEnv.AppComposition.TryGetExport<BookmarkManager>();
-			if (manager != null)
-				manager.Changed += OnBookmarksChanged;
 			pulseTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(16) };
 			pulseTimer.Tick += OnPulseTick;
 		}
 
+		// The manager is a shared singleton, so its Changed event would otherwise keep a closed tab's
+		// margin (and its pulse timer) alive. Track the subscription to the margin's time in the tree.
+		protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+		{
+			base.OnAttachedToVisualTree(e);
+			if (manager != null)
+				manager.Changed += OnBookmarksChanged;
+		}
+
+		protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
+		{
+			base.OnDetachedFromVisualTree(e);
+			if (manager != null)
+				manager.Changed -= OnBookmarksChanged;
+			pulseTimer.Stop();
+			pulseLine = -1;
+		}
+
 		void OnBookmarksChanged(object? sender, EventArgs e) => InvalidateVisual();
 
 		/// <summary>Plays the one-shot bounce on the bookmark glyph at <paramref name="line"/>.</summary>

ILSpy/TextView/DecompilerTabPageModel.cs

@@ -734,7 +734,11 @@ namespace ICSharpCode.ILSpy.TextView
 			Foldings = output.Foldings;
 			References = output.References;
 			DefinitionLookup = output.DefinitionLookup;
-			DebugInfo = new Bookmarks.DecompiledDebugInfo(output.MethodDebugInfos);
+			DebugInfo = syntaxExtension != ".cs"
+				? null
+				: output.MethodDebugInfos.Count > 0
+					? new Bookmarks.DecompiledDebugInfo(output.MethodDebugInfos)
+					: Bookmarks.DecompiledDebugInfo.Empty;
 			UIElements = output.UIElements;
 			Text = text;
 		}

ILSpy/TextView/LineHighlightAdorner.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Diagnostics;
+using System.Linq;
 
 using AvaloniaEdit.Editing;
 using AvaloniaEdit.Rendering;
@@ -89,6 +90,11 @@ namespace ICSharpCode.ILSpy.TextView
 		{
 			ArgumentNullException.ThrowIfNull(textArea);
 
+			// Clear any still-running highlight first, so quick successive navigations replace rather
+			// than stack adorners (each carries its own pair of timers driving redraws).
+			foreach (var existing in textArea.TextView.BackgroundRenderers.OfType<LineHighlightAdorner>().ToArray())
+				existing.Dismiss();
+
 			var adorner = new LineHighlightAdorner(textArea, line);
 			textArea.TextView.BackgroundRenderers.Add(adorner);
 			adorner.frameTimer.Start();