Keep fenced and dotted filename suggestions intact [patch]

ImageDescriber.Test/ScanTests.cs

@@ -87,6 +87,62 @@ public void SanitizeFileNameHandlesSimpleName()
 		Assert.AreEqual("sunset-over-ocean.webp", result.WeakString);
 	}
 
+	[TestMethod]
+	public void SanitizeFileNameTakesNameFromInsideCodeFence()
+	{
+		FileName result = Scan.SanitizeFileName("```\nsunset-over-lake\n```", ".jpg".As<FileExtension>());
+
+		Assert.AreEqual("sunset-over-lake.jpg", result.WeakString);
+	}
+
+	[TestMethod]
+	public void SanitizeFileNameTakesNameFromInsideCodeFenceWithLanguage()
+	{
+		FileName result = Scan.SanitizeFileName("```text\r\nsunset-over-lake\r\n```", ".jpg".As<FileExtension>());
+
+		Assert.AreEqual("sunset-over-lake.jpg", result.WeakString);
+	}
+
+	[TestMethod]
+	public void SanitizeFileNameTakesNameFromInlineCodeFence()
+	{
+		FileName result = Scan.SanitizeFileName("```sunset-over-lake```", ".jpg".As<FileExtension>());
+
+		Assert.AreEqual("sunset-over-lake.jpg", result.WeakString);
+	}
+
+	[TestMethod]
+	public void SanitizeFileNameSkipsLeadingBlankLines()
+	{
+		FileName result = Scan.SanitizeFileName("\nsunset-over-lake\n", ".jpg".As<FileExtension>());
+
+		Assert.AreEqual("sunset-over-lake.jpg", result.WeakString);
+	}
+
+	[TestMethod]
+	public void SanitizeFileNameKeepsDotFollowedByText()
+	{
+		FileName result = Scan.SanitizeFileName("st.-louis-arch-at-dusk", ".jpg".As<FileExtension>());
+
+		Assert.AreEqual("st.-louis-arch-at-dusk.jpg", result.WeakString);
+	}
+
+	[TestMethod]
+	public void SanitizeFileNameKeepsDotInTime()
+	{
+		FileName result = Scan.SanitizeFileName("sunset-at-5.30pm", ".jpg".As<FileExtension>());
+
+		Assert.AreEqual("sunset-at-5.30pm.jpg", result.WeakString);
+	}
+
+	[TestMethod]
+	public void SanitizeFileNameStripsUpperCaseImageExtension()
+	{
+		FileName result = Scan.SanitizeFileName("photo.JPEG", ".png".As<FileExtension>());
+
+		Assert.AreEqual("photo.png", result.WeakString);
+	}
+
 	[TestMethod]
 	public void HashFilesSkipsFilesThatCannotBeRead()
 	{

ImageDescriber/ImageScanner.cs

@@ -31,22 +31,26 @@
 		}
 
 		List<AbsoluteFilePath> imageFiles = [];
 		foreach (string file in Directory.EnumerateFiles(path.WeakString, "*", SearchOption.AllDirectories))
 		{
-			string ext = Path.GetExtension(file);
-			if (string.IsNullOrEmpty(ext))
-			{
-				continue;
-			}
-
-			// FileExtension compares ordinally, and cameras and Windows tools write .JPG/.PNG,
-			// so fold to the lower-case form the set holds before looking it up.
-			if (ImageExtensions.Contains(ext.ToLowerInvariant().As<FileExtension>()))
+			if (IsImageExtension(Path.GetExtension(file)))
 			{
 				imageFiles.Add(file.As<AbsoluteFilePath>());
 			}
 		}
 
 		return imageFiles;
 	}
+
+	internal static bool IsImageExtension(string extension)
+	{
+		if (string.IsNullOrEmpty(extension))
+		{
+			return false;
+		}
+
+		// FileExtension compares ordinally, and cameras and Windows tools write .JPG/.PNG,
+		// so fold to the lower-case form the set holds before looking it up.
+		return ImageExtensions.Contains(extension.ToLowerInvariant().As<FileExtension>());
+	}
 }

ImageDescriber/Verbs/Scan.cs

@@ -246,18 +246,17 @@ internal static IReadOnlyList<string> DescribeImages(
 
 	internal static FileName SanitizeFileName(string rawSuggestion, FileExtension extension)
 	{
-		string name = rawSuggestion.Trim().Trim('"', '\'', '`');
-
-		// Take only the first line if the model returned multiple lines
-		int newlineIndex = name.IndexOf('\n', StringComparison.Ordinal);
-		if (newlineIndex >= 0)
-		{
-			name = name[..newlineIndex].Trim();
-		}
-
-		// Strip any extension the model may have included
-		string existingExt = System.IO.Path.GetExtension(name);
-		if (!string.IsNullOrEmpty(existingExt))
+		// Take the first line with content, so a name wrapped in a code fence or preceded by a
+		// blank line is kept, and only then trim the quotes and backticks around it
+		string name = rawSuggestion
+			.Split('\n')
+			.Select(line => line.Trim())
+			.FirstOrDefault(line => line.Length > 0 && !IsCodeFence(line)) ?? string.Empty;
+		name = name.Trim('"', '\'', '`').Trim();
+
+		// Strip an image extension the model may have included. A suggestion normally has no
+		// extension, so any other dot is part of the name ("st.-louis-arch", "sunset-at-5.30pm")
+		if (ImageScanner.IsImageExtension(System.IO.Path.GetExtension(name)))
 		{
 			name = System.IO.Path.GetFileNameWithoutExtension(name);
 		}
@@ -283,4 +282,10 @@ internal static FileName SanitizeFileName(string rawSuggestion, FileExtension ex
 
 		return $"{name}{extension}".As<FileName>();
 	}
+
+	// An opening or closing fence ("```" or "```text"), as opposed to a name written inline
+	// between two fences on one line ("```sunset```")
+	private static bool IsCodeFence(string line) =>
+		line.StartsWith("```", StringComparison.Ordinal)
+		&& (line.Length < 6 || !line.EndsWith("```", StringComparison.Ordinal));
 }