From 9d0ce99a5d9ac4e274a9f70602f839b21f31af37 Mon Sep 17 00:00:00 2001
From: daniel-c-harvey <the.real.daniel.harvey@gmail.com>
Date: Fri, 19 Jun 2026 15:23:20 -0400
Subject: [PATCH] fix: PlayRelease always materialises a defensive copy so
 Items alias can't wipe the queue on jump; add aliasing regression test

---
 .../Services/QueueService.cs                  |  2 +-
 DeepDrftTests/QueueServiceTests.cs            | 27 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/DeepDrftPublic.Client/Services/QueueService.cs b/DeepDrftPublic.Client/Services/QueueService.cs
index 8696ec1..aca4c80 100644
--- a/DeepDrftPublic.Client/Services/QueueService.cs
+++ b/DeepDrftPublic.Client/Services/QueueService.cs
@@ -56,7 +56,7 @@ public sealed class QueueService : IQueueService, IDisposable
 
     public async Task PlayRelease(IEnumerable<TrackDto> tracks, int startIndex = 0)
     {
-        var list = tracks as IReadOnlyList<TrackDto> ?? tracks.ToList();
+        var list = tracks.ToList();
         if (list.Count == 0) return;
 
         var start = Math.Clamp(startIndex, 0, list.Count - 1);
diff --git a/DeepDrftTests/QueueServiceTests.cs b/DeepDrftTests/QueueServiceTests.cs
index 5087c4b..f9bd8a3 100644
--- a/DeepDrftTests/QueueServiceTests.cs
+++ b/DeepDrftTests/QueueServiceTests.cs
@@ -144,6 +144,33 @@ public class QueueServiceTests
         });
     }
 
+    [Test]
+    public async Task PlayRelease_ViaLiveQueueItems_PreservesTracksAndJumpsToIndex()
+    {
+        // Regression guard for the aliasing bug: OnQueueJump calls PlayRelease(QueueService.Items, index).
+        // Items returns the backing list directly; without a defensive copy, the cast
+        // "tracks as IReadOnlyList<TrackDto>" aliases _items, so _items.Clear() also clears list,
+        // and _items.AddRange(list) adds nothing — wiping the queue and playing nothing.
+        await _queue.PlayRelease(Tracks(4)); // populate the live queue
+
+        // Jump to index 2 via the live Items reference, exactly as OnQueueJump does.
+        await _queue.PlayRelease(_queue.Items, 2);
+
+        Assert.Multiple(() =>
+        {
+            // The queue must survive — all four tracks still present, in order.
+            Assert.That(_queue.Items, Has.Count.EqualTo(4));
+            Assert.That(_queue.Items.Select(t => t.EntryKey),
+                Is.EqualTo(new[] { "track-1", "track-2", "track-3", "track-4" }));
+            // CurrentIndex must be the jumped-to slot.
+            Assert.That(_queue.CurrentIndex, Is.EqualTo(2));
+            // Current must be the right track.
+            Assert.That(_queue.Current!.EntryKey, Is.EqualTo("track-3"));
+            // The player must have streamed the jumped-to track.
+            Assert.That(_player.SelectedTracks.Last().EntryKey, Is.EqualTo("track-3"));
+        });
+    }
+
     // --- Arm: prerender-safe load without streaming (release embed) ---
 
     [Test]