Indexed large data sources in steps so the others get their turn (#1052)

app/MindWork AI Studio/Tools/Services/Indexing/FilePartition.cs

@@ -0,0 +1,14 @@
+namespace AIStudio.Tools.Services.Indexing;
+
+/// <summary>
+/// The files of a data source, sorted by what one run of the file indexer does with them.
+/// </summary>
+/// <remarks>
+/// Only the last group costs time. The others are counted before the first file is read, so the
+/// progress of a step starts where the step before left off, rather than at zero.
+/// </remarks>
+/// <param name="UnchangedCount">How many files were indexed and have not changed since.</param>
+/// <param name="StillUnreadable">The files which failed for a reason of their own and have not changed since, each with the stored reason.</param>
+/// <param name="FailedEarlierInPass">Why each file failed which failed during an earlier step of the pass, and is not tried again before the next pass.</param>
+/// <param name="ToRead">The files the run reads, in the order it reads them.</param>
+internal sealed record FilePartition(int UnchangedCount, IReadOnlyList<KeyValuePair<string, PermanentIndexingFailureRecord>> StillUnreadable, IReadOnlyList<DataSourceEmbeddingFailure> FailedEarlierInPass, IReadOnlyList<FileInfo> ToRead);