Ask before local data sources are indexed again (#983)

app/MindWork AI Studio/Tools/Services/EmbeddingChangeImpact.cs

@@ -0,0 +1,47 @@
+using AIStudio.Settings;
+
+namespace AIStudio.Tools.Services;
+
+/// <summary>
+/// Answers whether an edit throws the stored index of a data source away.
+/// </summary>
+/// <remarks>
+/// Nothing here knows which settings matter. Both questions are answered by building the embedding
+/// signature twice and comparing the two, so the single place which decides stays
+/// BuildEmbeddingSignature and this cannot drift away from what an indexing run then does.
+/// </remarks>
+internal static class EmbeddingChangeImpact
+{
+    /// <summary>
+    /// Whether an edited embedding provider invalidates what is stored for one of its data sources.
+    /// </summary>
+    /// <param name="dataSource">The data source, which the edit leaves alone.</param>
+    /// <param name="before">The embedding provider as it is stored.</param>
+    /// <param name="after">The embedding provider as it would be stored.</param>
+    /// <returns>True when the stored index would be discarded.</returns>
+    public static bool AffectsStoredIndex(IDataSource dataSource, EmbeddingProvider before, EmbeddingProvider after) =>
+        !string.Equals(
+            DataSourceEmbeddingService.BuildEmbeddingSignature(dataSource, before),
+            DataSourceEmbeddingService.BuildEmbeddingSignature(dataSource, after),
+            StringComparison.Ordinal);
+
+    /// <summary>
+    /// Whether an edited data source invalidates what is stored for it.
+    /// </summary>
+    /// <remarks>
+    /// Each side is asked with the embedding provider it points at, never both with the same one. A
+    /// data source carries only the id of its provider, while the signature carries what that provider
+    /// is, so comparing both sides against one of them would report a changed embedding as no change
+    /// at all -- and the next indexing run would then rebuild everything unannounced.
+    /// </remarks>
+    /// <param name="before">The data source as it is stored.</param>
+    /// <param name="beforeProvider">The embedding provider it points at today.</param>
+    /// <param name="after">The data source as it would be stored.</param>
+    /// <param name="afterProvider">The embedding provider it would point at.</param>
+    /// <returns>True when the stored index would be discarded.</returns>
+    public static bool AffectsStoredIndex(IDataSource before, EmbeddingProvider beforeProvider, IDataSource after, EmbeddingProvider afterProvider) =>
+        !string.Equals(
+            DataSourceEmbeddingService.BuildEmbeddingSignature(before, beforeProvider),
+            DataSourceEmbeddingService.BuildEmbeddingSignature(after, afterProvider),
+            StringComparison.Ordinal);
+}