Offer a repair for data sources with an unreadable index

app/MindWork AI Studio/Tools/Services/DataSourceEmbeddingService.State.cs

@@ -5,6 +5,43 @@ namespace AIStudio.Tools.Services;
 
 public sealed partial class DataSourceEmbeddingService
 {
+    /// <summary>
+    /// Throws away everything stored for one data source and starts a fresh indexing run.
+    /// </summary>
+    /// <remarks>
+    /// The one way out of an index which cannot be read, and nothing in the app takes it by itself:
+    /// a rebuild sends every document of the data source to the embedding provider once more, which
+    /// costs money with a cloud provider and hours with a large data source. It happens because the
+    /// user asked for it, after being told both.
+    ///
+    /// An active run is stopped first, the same way deleting a data source does it. The repair is
+    /// offered for a failed data source only, so there should be none -- but a file watcher may
+    /// well have queued one between the click and this call, and discarding the index next to a
+    /// live run would leave it half thrown away.
+    /// </remarks>
+    /// <param name="dataSourceId">The data source to build anew.</param>
+    public async Task RepairDataSourceAsync(string dataSourceId)
+    {
+        if (!this.TryGetConfiguredDataSource(dataSourceId, out var dataSource) || !this.IsSupportedInternalDataSource(dataSource))
+            return;
+
+        logger.LogWarning(
+            "Repairing data source '{DataSourceName}' ({DataSourceId}) on the user's request: the stored index is discarded and built anew.",
+            dataSource.Name,
+            dataSource.Id);
+
+        var activeRun = this.CancelActiveDataSourceRun(dataSource);
+        this.ClearQueuedDataSourceState(dataSourceId);
+        if (activeRun is not null)
+            await activeRun.Completion.Task;
+
+        await this.ResetPersistedStateAsync(dataSourceId, null, null, CancellationToken.None);
+        this.statuses.TryRemove(dataSourceId, out _);
+        this.PublishStatusChanged();
+
+        await this.QueueDataSourceAsync(dataSource, true, DataSourceEmbeddingRefreshMode.MANUAL_RETRY);
+    }
+
     private async Task ResetPersistedStateAsync(
         string dataSourceId,
         VectorStoreClient? vectorStore,