Keep CSV-exported paths that contain "; " intact [patch]

ImageDescriber.Test/ImportTests.cs

@@ -244,6 +244,38 @@ public void CsvExportThenImportRoundTripsEveryField()
 		}
 	}
 
+	[TestMethod]
+	public void CsvExportThenImportKeepsPathsThatContainTheOldSeparator()
+	{
+		string folder = Path.Combine(Path.GetTempPath(), "Photos", "Smith; Jones wedding");
+		ImageDescription original = new()
+		{
+			Hash = new string('d', 64),
+			SuggestedFileName = "wedding.jpg".As<FileName>(),
+			KnownPaths = [Path.Combine(folder, "IMG_001.jpg").As<AbsoluteFilePath>(), Path.Combine(folder, "IMG_002; copy.jpg").As<AbsoluteFilePath>()],
+			Model = "llava".As<OllamaModelName>(),
+			DescribedAt = new DateTime(2026, 9, 27, 1, 8, 10, DateTimeKind.Utc),
+			FileSizeBytes = 3,
+			Description = "A wedding.",
+		};
+
+		List<ImageDescription> imported = Import.ParseCsv(Export.BuildCsv([original]));
+
+		Assert.HasCount(1, imported);
+		Assert.AreSequenceEqual(original.KnownPaths, imported[0].KnownPaths);
+	}
+
+	[TestMethod]
+	public void SplitKnownPathsReadsBothTheCurrentAndTheLegacyFormat()
+	{
+		string[] expected = ["/a/b.jpg", "/c/d.jpg"];
+
+		Assert.AreSequenceEqual(expected, Import.SplitKnownPaths("/a/b.jpg\n/c/d.jpg\n"));
+		Assert.AreSequenceEqual(expected, Import.SplitKnownPaths("/a/b.jpg\r\n/c/d.jpg\r\n"));
+		Assert.AreSequenceEqual(expected, Import.SplitKnownPaths("/a/b.jpg; /c/d.jpg"));
+		Assert.IsEmpty(Import.SplitKnownPaths(string.Empty));
+	}
+
 	[TestMethod]
 	public void ParseCsvRecordsKeepsLineBreaksInsideQuotedFields()
 	{

ImageDescriber/Verbs/Export.cs

@@ -74,7 +74,9 @@ internal static string BuildCsv(IEnumerable<ImageDescription> descriptions)
 
 		foreach (ImageDescription desc in descriptions)
 		{
-			string joinedPaths = string.Join("; ", desc.KnownPaths.Select(p => p.WeakString));
+			// End every path with a line break, which the quoted field keeps and no path contains.
+			// "; " would do as a separator only until a folder name contains it.
+			string joinedPaths = string.Concat(desc.KnownPaths.Select(p => p.WeakString + KnownPathTerminator));
 			string[] fields =
 			[
 				desc.Hash,
@@ -94,5 +96,7 @@ internal static string BuildCsv(IEnumerable<ImageDescription> descriptions)
 		return sb.ToString();
 	}
 
+	internal const char KnownPathTerminator = '\n';
+
 	private static string QuoteCsvField(string value) => $"\"{value.Replace("\"", "\"\"", StringComparison.Ordinal)}\"";
 }

ImageDescriber/Verbs/Import.cs

@@ -178,9 +178,7 @@ internal static List<ImageDescription> ParseCsv(string text)
 				// Fields: Hash, SuggestedFileName, KnownPaths, Model, DescribedAt, FileSizeBytes, Description
 				string hash = fields[0];
 				FileName suggestedFileName = fields[1].As<FileName>();
-				List<AbsoluteFilePath> knownPaths = [.. fields[2]
-					.Split("; ", StringSplitOptions.RemoveEmptyEntries)
-					.Select(p => p.As<AbsoluteFilePath>())];
+				List<AbsoluteFilePath> knownPaths = [.. SplitKnownPaths(fields[2]).Select(p => p.As<AbsoluteFilePath>())];
 				OllamaModelName model = fields[3].As<OllamaModelName>();
 				DateTime describedAt = DateTime.Parse(fields[4], CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind);
 				long fileSizeBytes = long.Parse(fields[5], CultureInfo.InvariantCulture);
@@ -214,6 +212,17 @@ internal static List<ImageDescription> ParseCsv(string text)
 		return entries;
 	}
 
+	/// <summary>
+	/// Splits a KnownPaths field. Current exports end every path with a line break; exports
+	/// written before that joined the paths with "; ", so a field without one is read that way.
+	/// </summary>
+	internal static string[] SplitKnownPaths(string field) =>
+		field.Contains(Export.KnownPathTerminator, StringComparison.Ordinal)
+			? [.. field.Split(Export.KnownPathTerminator, StringSplitOptions.RemoveEmptyEntries)
+				.Select(p => p.TrimEnd('\r'))
+				.Where(p => p.Length > 0)]
+			: field.Split("; ", StringSplitOptions.RemoveEmptyEntries);
+
 	internal static List<string> ParseCsvLine(string line) =>
 		ParseCsvRecords(line).Select(r => r.Fields).FirstOrDefault() ?? [];