diff --git a/tests/SharpEmu.Libs.Tests/Gpu/GpuCommands/CommandStreamQueueTests.cs b/tests/SharpEmu.Libs.Tests/Gpu/GpuCommands/CommandStreamQueueTests.cs
index 5e461d1..b942cbf 100644
--- a/tests/SharpEmu.Libs.Tests/Gpu/GpuCommands/CommandStreamQueueTests.cs
+++ b/tests/SharpEmu.Libs.Tests/Gpu/GpuCommands/CommandStreamQueueTests.cs
@@ -154,6 +154,83 @@ public sealed class CommandStreamQueueTests
         Assert.Equal(new[] { "begin 0 1", "begin 1 3", "begin 0 2" }, host.Calls.Where(call => call.StartsWith("begin", StringComparison.Ordinal)));
     }
 
+    [Fact]
+    public void ControlBarrier_RunsBetweenTheAcceptedSliceAndLaterAdmissions()
+    {
+        var (host, queue) = NewQueue();
+        Enqueue(host, queue, Graphics, 1, CreateInstanceCountPacket(1));
+        var cancelled = false;
+        host.PendingCommands.Enqueue(() =>
+        {
+            Assert.True(queue.TryEnqueueControlBarrier(
+                () => host.Calls.Add("mapping_change"),
+                () => cancelled = true));
+            Enqueue(host, queue, Graphics + 0x100, 2, CreateInstanceCountPacket(2));
+        });
+
+        Assert.Equal(SliceResult.Completed, queue.ProcessOne());
+        Assert.DoesNotContain("mapping_change", host.Calls);
+        Assert.Equal(SliceResult.Completed, queue.ProcessOne());
+        Assert.Equal(SliceResult.Completed, queue.ProcessOne());
+
+        var first = host.Calls.IndexOf("begin 0 1");
+        var barrier = host.Calls.IndexOf("mapping_change");
+        var second = host.Calls.IndexOf("begin 0 2");
+        Assert.True(first >= 0 && barrier > first && second > barrier, string.Join(", ", host.Calls));
+        Assert.False(cancelled);
+    }
+
+    [Fact]
+    public void ControlBarrier_PreservesCrossQueueProgressWhileAnOlderHeadIsBlocked()
+    {
+        var (host, queue) = NewQueue();
+        host.WriteDword(Label, 0);
+        Enqueue(host, queue, Graphics, 1, WaitEqual(Label, 1));
+        Assert.Equal(SliceResult.BlockedWithoutProgress, queue.ProcessOne());
+        Assert.True(queue.TryEnqueueControlBarrier(() => host.Calls.Add("mapping_change"), () => { }));
+        EnqueueCompute(host, queue, 0x20, Compute, 2, CreateInstanceCountPacket(2));
+
+        Assert.Equal(SliceResult.Completed, queue.ProcessOne());
+        Assert.DoesNotContain("mapping_change", host.Calls);
+        host.WriteDword(Label, 1);
+        queue.RetryBlocked();
+        Assert.Equal(SliceResult.Completed, queue.ProcessOne());
+        Assert.Equal(SliceResult.Completed, queue.ProcessOne());
+
+        var compute = host.Calls.IndexOf("begin 1 2");
+        var retriedGraphics = host.Calls.FindLastIndex(call => call == "begin 0 1");
+        var barrier = host.Calls.IndexOf("mapping_change");
+        Assert.True(compute >= 0 && retriedGraphics > compute && barrier > retriedGraphics, string.Join(", ", host.Calls));
+    }
+
+    [Fact]
+    public void ControlBarrier_IsCancelledWhenTheQueueIsDiscarded()
+    {
+        var (_, queue) = NewQueue();
+        var ran = false;
+        var cancelled = false;
+        Assert.True(queue.TryEnqueueControlBarrier(() => ran = true, () => cancelled = true));
+
+        queue.DiscardAll();
+
+        Assert.False(ran);
+        Assert.True(cancelled);
+        Assert.False(queue.HasPending);
+    }
+
+    [Fact]
+    public void ShutdownDrain_RunsAnAcceptedControlBarrier()
+    {
+        var (_, queue) = NewQueue();
+        var ran = false;
+        Assert.True(queue.TryEnqueueControlBarrier(() => ran = true, () => { }));
+        queue.StopAccepting();
+
+        Assert.Equal(IdleOutcome.Completed, queue.DrainForShutdown(cancelBlockedOnNoProgress: true));
+        Assert.True(ran);
+        Assert.False(queue.HasPending);
+    }
+
     [Fact]
     public void BlockedHead_IsRequeuedAndRetriedWithoutStoppingOtherQueues()
     {
diff --git a/tests/SharpEmu.Libs.Tests/Gpu/Scheduling/GpuWorkerRelayTests.cs b/tests/SharpEmu.Libs.Tests/Gpu/Scheduling/GpuWorkerRelayTests.cs
index 6fb32ec..16c8477 100644
--- a/tests/SharpEmu.Libs.Tests/Gpu/Scheduling/GpuWorkerRelayTests.cs
+++ b/tests/SharpEmu.Libs.Tests/Gpu/Scheduling/GpuWorkerRelayTests.cs
@@ -18,9 +18,9 @@ public sealed class GpuWorkerRelayTests : IDisposable
         private readonly Thread _thread;
         private bool _stop;
 
-        public TestWorker()
+        public TestWorker(Func<Action, Action, bool>? tryEnqueueAfterPendingWork = null)
         {
-            Relay = new GpuWorkerRelay(Wake);
+            Relay = new GpuWorkerRelay(Wake, tryEnqueueAfterPendingWork);
             _thread = new Thread(Run) { IsBackground = true };
         }
 
@@ -160,6 +160,116 @@ public sealed class GpuWorkerRelayTests : IDisposable
         device.Complete(1);
     }
 
+    [Fact]
+    public void AfterPendingWork_BypassesTheCommandStreamBarrier()
+    {
+        var barrierCalled = false;
+        using var worker = new TestWorker(
+            (_, _) =>
+            {
+                barrierCalled = true;
+                return true;
+            });
+        worker.Start();
+        var workRan = false;
+        var ranOnWorker = false;
+
+        Assert.True(worker.Relay.TryRunAfterPendingWork(() =>
+        {
+            workRan = true;
+            ranOnWorker = worker.Relay.IsGpuQueueThread;
+        }));
+        Assert.True(workRan);
+        Assert.True(ranOnWorker);
+        Assert.False(barrierCalled);
+    }
+
+    [Fact]
+    public void AfterPendingWork_ReturnsFalseWhenTheWorkerIsClosed()
+    {
+        var barrierCalled = false;
+        var relay = new GpuWorkerRelay(
+            () => { },
+            (_, _) =>
+            {
+                barrierCalled = true;
+                return true;
+            });
+        relay.StopAcceptingWork();
+
+        Assert.False(relay.TryRunAfterPendingWork(() => { }));
+        Assert.False(barrierCalled);
+    }
+
+    [Fact]
+    public async Task AfterAcceptedCommandStreams_WaitsForTheControlBarrier()
+    {
+        Action? run = null;
+        Action? cancel = null;
+        var relay = new GpuWorkerRelay(
+            () => { },
+            (work, cancellation) =>
+            {
+                run = work;
+                cancel = cancellation;
+                return true;
+            });
+        var workRan = false;
+
+        var completion = Task.Run(() =>
+            relay.TryRunAfterAcceptedCommandStreams(() => workRan = true));
+        Assert.True(WaitUntil(() => Volatile.Read(ref run) is not null));
+        Assert.False(await CompletesWithin(completion, 50));
+
+        run!();
+
+        Assert.True(await completion.WaitAsync(TimeSpan.FromSeconds(2)));
+        Assert.True(workRan);
+        Assert.NotNull(cancel);
+    }
+
+    [Fact]
+    public async Task AfterAcceptedCommandStreams_CancellationReleasesTheCaller()
+    {
+        Action? cancel = null;
+        var relay = new GpuWorkerRelay(
+            () => { },
+            (_, cancellation) =>
+            {
+                cancel = cancellation;
+                return true;
+            });
+
+        var completion = Task.Run(() => Record.Exception(() =>
+            relay.TryRunAfterAcceptedCommandStreams(() => { })));
+        Assert.True(WaitUntil(() => Volatile.Read(ref cancel) is not null));
+        cancel!();
+
+        Assert.IsType<OperationCanceledException>(
+            await completion.WaitAsync(TimeSpan.FromSeconds(2)));
+    }
+
+    [Fact]
+    public async Task AfterAcceptedCommandStreams_RethrowsTheWorkException()
+    {
+        Action? run = null;
+        var relay = new GpuWorkerRelay(
+            () => { },
+            (work, _) =>
+            {
+                run = work;
+                return true;
+            });
+        var expected = new InvalidOperationException("ordered state change failed");
+
+        var completion = Task.Run(() => Record.Exception(() =>
+            relay.TryRunAfterAcceptedCommandStreams(() => throw expected)));
+        Assert.True(WaitUntil(() => Volatile.Read(ref run) is not null));
+        run!();
+
+        Assert.Same(expected, await completion.WaitAsync(TimeSpan.FromSeconds(2)));
+    }
+
     [Fact]
     public void CommandsRunBeforeGuestWork()
     {