Fix image URLs

src/Elastic.Markdown/Myst/InlineParsers/DiagnosticLinkInlineParser.cs

@@ -391,11 +391,29 @@ public static string UpdateRelativeUrl(ParserContext context, string url)
 					newUrl = newUrl[3..];
 					offset--;
 				}
+				newUrl = Path.GetFullPath(Path.Combine(urlPathPrefix, snippet.RelativeFolder, url))
+					.OptionalWindowsReplace().TrimStart('/');
 			}
 			else
 				newUrl = $"/{Path.Combine(urlPathPrefix, relativePath).OptionalWindowsReplace().TrimStart('/')}";
+		}
 
+		if (context.Build.AssemblerBuild && context.TryFindDocument(fi) is MarkdownFile currentMarkdown)
+		{
+			// Acquire navigation-aware path
+			if (context.PositionalNavigation.MarkdownNavigationLookup.TryGetValue(currentMarkdown, out var currentNavigation) && !string.IsNullOrEmpty(currentNavigation.Url))
+			{
+				var currentUrl = currentNavigation.Url;
+				if (currentUrl.LastIndexOf('/') > 0)
+				{
+					var basePath = currentUrl[..currentUrl.LastIndexOf('/')];
+					newUrl = Path.GetFullPath(Path.Combine(basePath, url));
+				}
+			}
+			newUrl = $"/{Path.Combine(newUrl.StartsWith(urlPathPrefix) ? string.Empty : urlPathPrefix, newUrl.TrimStart('/'))
+				.OptionalWindowsReplace().TrimStart('/')}";
 		}
+
 		// When running on Windows, path traversal results must be normalized prior to being used in a URL
 		// Path.GetFullPath() will result in the drive letter being appended to the path, which needs to be pruned back.
 		if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))