1 files changed, 30 insertions, 0 deletions
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/IDescendantQueryProvider.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/IDescendantQueryProvider.cs
new file mode 100644
index 0000000000..9e3d510b9c
--- /dev/null
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/IDescendantQueryProvider.cs
@@ -0,0 +1,30 @@
+using System;
+using System.Linq;
+using Jellyfin.Database.Implementations.MatchCriteria;
+
+namespace Jellyfin.Database.Implementations;
+
+/// <summary>
+/// Provider interface for descendant queries using recursive CTEs.
+/// Each database provider implements this with provider-specific SQL.
+/// </summary>
+public interface IDescendantQueryProvider
+{
+    /// <summary>
+    /// Gets a queryable of all descendant IDs for a parent item.
+    /// Uses recursive CTE to traverse AncestorIds and LinkedChildren infinitely.
+    /// </summary>
+    /// <param name="context">Database context.</param>
+    /// <param name="parentId">Parent item ID.</param>
+    /// <returns>Queryable of descendant item IDs.</returns>
+    IQueryable<Guid> GetAllDescendantIds(JellyfinDbContext context, Guid parentId);
+
+    /// <summary>
+    /// Gets a queryable of all folder IDs that have any descendant matching the specified criteria.
+    /// Uses recursive CTE for infinite depth traversal. Can be used in LINQ .Contains() expressions.
+    /// </summary>
+    /// <param name="context">Database context.</param>
+    /// <param name="criteria">The matching criteria to apply.</param>
+    /// <returns>Queryable of folder IDs.</returns>
+    IQueryable<Guid> GetFolderIdsMatching(JellyfinDbContext context, FolderMatchCriteria criteria);
+}