fix(edit logging): sanitize input text

src/Extensions/DiffPaneModelExtensions.cs

@@ -12,17 +12,17 @@ public static class DiffPaneModelExtensions
         {
             if (line.Type is ChangeType.Deleted)
             {
-                builder.Append("- ");
+                builder.Append("-- ");
             }
 
             if (line.Type is ChangeType.Inserted)
             {
-                builder.Append("+ ");
+                builder.Append("++ ");
             }
 
             if (line.Type is not ChangeType.Imaginary)
             {
-                builder.AppendLine(line.Text);
+                builder.AppendLine(line.Text.SanitizeForDiffBlock());
             }
         }
 

src/Extensions/StringExtensions.cs

@@ -16,6 +16,18 @@ public static class StringExtensions
         return s.Replace("```", "​`​`​`​");
     }
 
+    /// <summary>
+    ///     Sanitizes a string for use in <see cref="Markdown.BlockCode(string, string)" /> when "language" is "diff" by
+    ///     prepending a zero-width space before syntax highlighting characters (+ and -).
+    /// </summary>
+    /// <remarks>This does not call <see cref="SanitizeForBlockCode"/>, you have to do so yourself if needed.</remarks>
+    /// <param name="s">The string to sanitize.</param>
+    /// <returns>The sanitized string that can be safely used in <see cref="Markdown.BlockCode(string, string)" /> with "diff" as the language.</returns>
+    public static string SanitizeForDiffBlock(this string s)
+    {
+        return $"​{s}";
+    }
+
     /// <summary>
     ///     Sanitizes a string (see <see cref="SanitizeForBlockCode" />) and formats the string to use Markdown Block Code
     ///     formatting with a specified