From 3a62e160edcdd97f35be97696544a7be832872cc Mon Sep 17 00:00:00 2001
From: Glenn Watson <5834289+glennawatson@users.noreply.github.com>
Date: Fri, 26 Jun 2026 11:42:56 +1000
Subject: [PATCH 1/4] refactor!: drop duplicate sinks for Primitives 5.7.0
 concretes

Bump ReactiveUI.Primitives to 5.7.0 and delete in-repo observable sinks
that the package now provides as concrete signal classes.

- Remove ReactiveUI.Internal.SingleValueObservable<T> (+ Void/True/False
  singletons), SyncExecuteObservable<T>, StartObservable<T>
- Use the seam-neutral Primitives concretes instead: ReturnSignal,
  StartSignal and ImmutableReturnRxVoidSignal
- Import ReactiveUI.Primitives.Advanced (lean) /
  ReactiveUI.Primitives.Reactive.Advanced (shim) via ReactiveShim.props and
  the test Directory.Build.props so the names resolve under both seams
- Trim the removed public types from the ReactiveUI.Core PublicAPI baselines
- Drop the obsolete SingleValueObservable unit test

BREAKING CHANGE: the public types ReactiveUI.Internal.SingleValueObservable<T>
and ReactiveUI.Internal.SyncExecuteObservable<T> are removed; construct the
equivalent ReactiveUI.Primitives.Advanced signal classes instead.
---
 src/Directory.Packages.props                  |  2 +-
 src/ReactiveShim.props                        |  7 ++
 .../Internal/SingleValueObservable{T}.cs      | 26 -------
 .../Internal/SyncExecuteObservable.cs         | 35 ---------
 .../net10.0-android36.0/PublicAPI.Shipped.txt |  6 --
 .../net10.0-ios/PublicAPI.Shipped.txt         |  6 --
 .../net10.0-maccatalyst/PublicAPI.Shipped.txt |  6 --
 .../net10.0-macos/PublicAPI.Shipped.txt       |  6 --
 .../net10.0-tvos/PublicAPI.Shipped.txt        |  6 --
 .../PublicAPI.Shipped.txt                     |  6 --
 .../PublicAPI/net10.0/PublicAPI.Shipped.txt   |  6 --
 .../net11.0-android37/PublicAPI.Shipped.txt   |  6 --
 .../net11.0-ios/PublicAPI.Shipped.txt         |  6 --
 .../net11.0-maccatalyst/PublicAPI.Shipped.txt |  6 --
 .../net11.0-macos/PublicAPI.Shipped.txt       |  6 --
 .../net11.0-tvos/PublicAPI.Shipped.txt        |  6 --
 .../PublicAPI.Shipped.txt                     |  6 --
 .../PublicAPI/net11.0/PublicAPI.Shipped.txt   |  6 --
 .../PublicAPI/net462/PublicAPI.Shipped.txt    |  6 --
 .../PublicAPI/net472/PublicAPI.Shipped.txt    |  6 --
 .../PublicAPI/net481/PublicAPI.Shipped.txt    |  6 --
 .../PublicAPI.Shipped.txt                     |  6 --
 .../PublicAPI/net8.0/PublicAPI.Shipped.txt    |  6 --
 .../PublicAPI.Shipped.txt                     |  6 --
 .../PublicAPI/net9.0/PublicAPI.Shipped.txt    |  6 --
 .../Activation/CanActivateViewFetcher.cs      |  2 +-
 .../Property/PropertyBinderImplementation.cs  |  2 +-
 .../Interactions/Interaction.cs               |  2 +-
 .../Internal/SingleValueObservable.cs         | 28 -------
 .../Internal/StartObservable.cs               | 44 -----------
 .../Mixins/ObservableLoggingMixins.cs         |  2 +-
 .../CombinedReactiveCommand.cs                |  2 +-
 .../ReactiveCommand/ReactiveCommand.cs        | 36 +++++----
 .../ReactiveCommand{TParam,TResult}.cs        |  4 +-
 src/ReactiveUI.Shared/Routing/RoutingState.cs |  2 +-
 .../Suspension/DummySuspensionDriver.cs       | 10 +--
 .../Suspension/SuspensionHostExtensions.cs    | 16 ++--
 .../android/BundleSuspensionDriver.cs         |  6 +-
 .../android/FlexibleCommandBinder.cs          |  8 +-
 .../AppSupportJsonSuspensionDriver.cs         |  6 +-
 src/tests/Directory.Build.props               |  4 +
 .../AutoPersist/AutoPersistCollectionTest.cs  | 12 +--
 .../AutoPersist/AutoPersistHelperTest.cs      | 58 +++++++--------
 .../Commands/CombinedReactiveCommandTest.cs   | 28 +++----
 .../ReactiveCommandTest.ExecutionAndInvoke.cs |  4 +-
 ...iveCommandTest.IsExecutingAndExceptions.cs |  6 +-
 .../Commands/ReactiveCommandTest.cs           |  2 +-
 .../ReactiveUI.Tests/Core/ObservablesTests.cs | 73 -------------------
 .../ReactiveUI.Tests/InteractionsTest.cs      |  2 +-
 49 files changed, 121 insertions(+), 434 deletions(-)
 delete mode 100644 src/ReactiveUI.Core/Internal/SingleValueObservable{T}.cs
 delete mode 100644 src/ReactiveUI.Core/Internal/SyncExecuteObservable.cs
 delete mode 100644 src/ReactiveUI.Shared/Internal/SingleValueObservable.cs
 delete mode 100644 src/ReactiveUI.Shared/Internal/StartObservable.cs
 delete mode 100644 src/tests/ReactiveUI.Tests/Core/ObservablesTests.cs

diff --git a/src/Directory.Packages.props b/src/Directory.Packages.props
index 80c46e902a..9d10a8fc8f 100644
--- a/src/Directory.Packages.props
+++ b/src/Directory.Packages.props
@@ -6,7 +6,7 @@
 
   <PropertyGroup Label="Shared Version Variables">
     <SplatVersion>20.0.0</SplatVersion>
-    <PrimitivesVersion>5.6.0</PrimitivesVersion>
+    <PrimitivesVersion>5.7.0</PrimitivesVersion>
     <TUnitVersion>1.56.25</TUnitVersion>
     <XamarinAndroidXLifecycleLiveDataVersion>2.10.0.2</XamarinAndroidXLifecycleLiveDataVersion>
   </PropertyGroup>
diff --git a/src/ReactiveShim.props b/src/ReactiveShim.props
index d6686b587e..309f97291f 100644
--- a/src/ReactiveShim.props
+++ b/src/ReactiveShim.props
@@ -40,6 +40,10 @@
          Broadcaster) resolve unqualified to the lean ReactiveUI.Primitives namespace. Open generics can't be aliased,
          so this is a namespace import rather than a per-type alias like RxVoid/ISequencer above. -->
     <Using Include="ReactiveUI.Primitives.Signals" />
+    <!-- Concrete signal classes (ReturnSignal/StartSignal/ImmutableReturnRxVoidSignal, ...) that back the
+         Signal.* factories. The shared source constructs these directly in place of in-repo sink forks; only
+         the seam-neutral (both-leaf) concretes are named so the .Reactive leaf below stays buildable. -->
+    <Using Include="ReactiveUI.Primitives.Advanced" />
   </ItemGroup>
 
   <!-- Reactive seam: the *.Reactive leaves recompile the shared ReactiveUI source against System.Reactive's
@@ -63,6 +67,9 @@
     <Using Include="ReactiveUI.Reactive.Builder" />
     <Using Include="ReactiveUI.Reactive.Interfaces" />
     <Using Include="ReactiveUI.Primitives.Signals" />
+    <!-- Reactive-shim counterpart of the lean leaf's ReactiveUI.Primitives.Advanced import: the same
+         seam-neutral concrete signal classes, flipped to the ReactiveUI.Primitives.Reactive.Advanced namespace. -->
+    <Using Include="ReactiveUI.Primitives.Reactive.Advanced" />
   </ItemGroup>
 
   <!-- Reactive seam, platform leaves: the apple/android reactive main-thread sequencers
diff --git a/src/ReactiveUI.Core/Internal/SingleValueObservable{T}.cs b/src/ReactiveUI.Core/Internal/SingleValueObservable{T}.cs
deleted file mode 100644
index 536829d109..0000000000
--- a/src/ReactiveUI.Core/Internal/SingleValueObservable{T}.cs
+++ /dev/null
@@ -1,26 +0,0 @@
-// Copyright (c) 2009-2026 .NET Foundation and Contributors. All rights reserved.
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for full license information.
-
-using ReactiveUI.Primitives.Disposables;
-
-namespace ReactiveUI.Internal;
-
-/// <summary>
-/// A cold observable that emits a single value and then completes on each subscription.
-/// Replaces <c>Observable.Return</c> for internal use.
-/// </summary>
-/// <typeparam name="T">The element type.</typeparam>
-/// <param name="value">The value emitted to each subscriber.</param>
-public sealed class SingleValueObservable<T>(T value) : IObservable<T>
-{
-    /// <inheritdoc/>
-    public IDisposable Subscribe(IObserver<T> observer)
-    {
-        ArgumentExceptionHelper.ThrowIfNull(observer);
-        observer.OnNext(value);
-        observer.OnCompleted();
-        return EmptyDisposable.Instance;
-    }
-}
diff --git a/src/ReactiveUI.Core/Internal/SyncExecuteObservable.cs b/src/ReactiveUI.Core/Internal/SyncExecuteObservable.cs
deleted file mode 100644
index f1d10e7506..0000000000
--- a/src/ReactiveUI.Core/Internal/SyncExecuteObservable.cs
+++ /dev/null
@@ -1,35 +0,0 @@
-// Copyright (c) 2009-2026 .NET Foundation and Contributors. All rights reserved.
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for full license information.
-
-using ReactiveUI.Primitives.Disposables;
-
-namespace ReactiveUI.Internal;
-
-/// <summary>
-/// Runs a function synchronously on each subscription, then emits its result and completes.
-/// A fault in the function is forwarded as an error. Backs the synchronous command factories.
-/// </summary>
-/// <typeparam name="T">The result type.</typeparam>
-/// <param name="execute">The function to run on subscription.</param>
-public sealed class SyncExecuteObservable<T>(Func<T> execute) : IObservable<T>
-{
-    /// <inheritdoc/>
-    public IDisposable Subscribe(IObserver<T> observer)
-    {
-        ArgumentExceptionHelper.ThrowIfNull(observer);
-        try
-        {
-            var result = execute();
-            observer.OnNext(result);
-            observer.OnCompleted();
-        }
-        catch (Exception ex)
-        {
-            observer.OnError(ex);
-        }
-
-        return EmptyDisposable.Instance;
-    }
-}
diff --git a/src/ReactiveUI.Core/PublicAPI/net10.0-android36.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net10.0-android36.0/PublicAPI.Shipped.txt
index e345d49012..0167082cde 100644
--- a/src/ReactiveUI.Core/PublicAPI/net10.0-android36.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net10.0-android36.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net10.0-ios/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net10.0-ios/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net10.0-ios/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net10.0-ios/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net10.0-maccatalyst/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net10.0-maccatalyst/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net10.0-maccatalyst/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net10.0-maccatalyst/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net10.0-macos/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net10.0-macos/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net10.0-macos/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net10.0-macos/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net10.0-tvos/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net10.0-tvos/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net10.0-tvos/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net10.0-tvos/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net10.0-windows10.0.19041.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net10.0-windows10.0.19041.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net10.0-windows10.0.19041.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net10.0-windows10.0.19041.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net10.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net10.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net10.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net10.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net11.0-android37/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net11.0-android37/PublicAPI.Shipped.txt
index e345d49012..0167082cde 100644
--- a/src/ReactiveUI.Core/PublicAPI/net11.0-android37/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net11.0-android37/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net11.0-ios/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net11.0-ios/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net11.0-ios/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net11.0-ios/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net11.0-maccatalyst/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net11.0-maccatalyst/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net11.0-maccatalyst/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net11.0-maccatalyst/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net11.0-macos/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net11.0-macos/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net11.0-macos/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net11.0-macos/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net11.0-tvos/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net11.0-tvos/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net11.0-tvos/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net11.0-tvos/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net11.0-windows10.0.19041.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net11.0-windows10.0.19041.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net11.0-windows10.0.19041.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net11.0-windows10.0.19041.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net11.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net11.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net11.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net11.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net462/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net462/PublicAPI.Shipped.txt
index 68a754a7c4..8bc5ad247b 100644
--- a/src/ReactiveUI.Core/PublicAPI/net462/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net462/PublicAPI.Shipped.txt
@@ -317,15 +317,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net472/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net472/PublicAPI.Shipped.txt
index 68a754a7c4..8bc5ad247b 100644
--- a/src/ReactiveUI.Core/PublicAPI/net472/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net472/PublicAPI.Shipped.txt
@@ -317,15 +317,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net481/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net481/PublicAPI.Shipped.txt
index 68a754a7c4..8bc5ad247b 100644
--- a/src/ReactiveUI.Core/PublicAPI/net481/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net481/PublicAPI.Shipped.txt
@@ -317,15 +317,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net8.0-windows10.0.19041.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net8.0-windows10.0.19041.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net8.0-windows10.0.19041.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net8.0-windows10.0.19041.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net8.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net8.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net8.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net8.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net9.0-windows10.0.19041.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net9.0-windows10.0.19041.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net9.0-windows10.0.19041.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net9.0-windows10.0.19041.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Core/PublicAPI/net9.0/PublicAPI.Shipped.txt b/src/ReactiveUI.Core/PublicAPI/net9.0/PublicAPI.Shipped.txt
index 88a41d7dc6..b7bb18767d 100644
--- a/src/ReactiveUI.Core/PublicAPI/net9.0/PublicAPI.Shipped.txt
+++ b/src/ReactiveUI.Core/PublicAPI/net9.0/PublicAPI.Shipped.txt
@@ -319,15 +319,9 @@ ReactiveUI.InteractionContext<TInput, TOutput>.Input.get -> TInput
 ReactiveUI.InteractionContext<TInput, TOutput>.InteractionContext(TInput input) -> void
 ReactiveUI.InteractionContext<TInput, TOutput>.IsHandled.get -> bool
 ReactiveUI.InteractionContext<TInput, TOutput>.SetOutput(TOutput output) -> void
-ReactiveUI.Internal.SingleValueObservable<T>
-ReactiveUI.Internal.SingleValueObservable<T>.SingleValueObservable(T value) -> void
-ReactiveUI.Internal.SingleValueObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.StartWithObservable<T>
 ReactiveUI.Internal.StartWithObservable<T>.StartWithObservable(System.IObservable<T>! source, T value) -> void
 ReactiveUI.Internal.StartWithObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>
-ReactiveUI.Internal.SyncExecuteObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
-ReactiveUI.Internal.SyncExecuteObservable<T>.SyncExecuteObservable(System.Func<T>! execute) -> void
 ReactiveUI.Internal.TaskObservable<T>
 ReactiveUI.Internal.TaskObservable<T>.Subscribe(System.IObserver<T>! observer) -> System.IDisposable!
 ReactiveUI.Internal.TaskObservable<T>.TaskObservable(System.Threading.Tasks.Task<T>! task) -> void
diff --git a/src/ReactiveUI.Shared/Activation/CanActivateViewFetcher.cs b/src/ReactiveUI.Shared/Activation/CanActivateViewFetcher.cs
index 1851f524a3..02d6e0e36a 100644
--- a/src/ReactiveUI.Shared/Activation/CanActivateViewFetcher.cs
+++ b/src/ReactiveUI.Shared/Activation/CanActivateViewFetcher.cs
@@ -36,7 +36,7 @@ public int GetAffinityForView(Type view) =>
     /// <see langword="false"/> when it is deactivated.</returns>
     public IObservable<bool> GetActivationForView(IActivatableView view) =>
         view is not ICanActivate canActivate
-            ? SingleValueObservable.False
+            ? new ReturnSignal<bool>(false, Sequencer.Immediate)
             : new ActivationStateObservable(canActivate.Activated, canActivate.Deactivated);
 
     /// <summary>
diff --git a/src/ReactiveUI.Shared/Bindings/Property/PropertyBinderImplementation.cs b/src/ReactiveUI.Shared/Bindings/Property/PropertyBinderImplementation.cs
index acd6451fba..c1ccea9b3c 100644
--- a/src/ReactiveUI.Shared/Bindings/Property/PropertyBinderImplementation.cs
+++ b/src/ReactiveUI.Shared/Bindings/Property/PropertyBinderImplementation.cs
@@ -554,7 +554,7 @@ public IDisposable BindTo<TValue, TTarget, TTargetValue>(
     /// <returns>An observable that emits <paramref name="value"/> when the binding should continue.</returns>
     protected virtual IObservable<bool> ScheduleForBinding<TView>(TView view, bool value)
         where TView : class =>
-        new SingleValueObservable<bool>(value);
+        new ReturnSignal<bool>(value, Sequencer.Immediate);
 
     /// <summary>
     /// Applies a view-value setter. The default invokes it inline; platform binders (e.g. WPF) override this to
diff --git a/src/ReactiveUI.Shared/Interactions/Interaction.cs b/src/ReactiveUI.Shared/Interactions/Interaction.cs
index 92b7d1873e..2e5c3e6677 100644
--- a/src/ReactiveUI.Shared/Interactions/Interaction.cs
+++ b/src/ReactiveUI.Shared/Interactions/Interaction.cs
@@ -107,7 +107,7 @@ public IDisposable RegisterHandler(Action<IInteractionContext<TInput, TOutput>>
         IObservable<RxVoid> ContentHandler(IInteractionContext<TInput, TOutput> interaction)
         {
             handler(interaction);
-            return SingleValueObservable.Void;
+            return ImmutableReturnRxVoidSignal.Instance;
         }
     }
 
diff --git a/src/ReactiveUI.Shared/Internal/SingleValueObservable.cs b/src/ReactiveUI.Shared/Internal/SingleValueObservable.cs
deleted file mode 100644
index 6846e44aca..0000000000
--- a/src/ReactiveUI.Shared/Internal/SingleValueObservable.cs
+++ /dev/null
@@ -1,28 +0,0 @@
-// Copyright (c) 2009-2026 .NET Foundation and Contributors. All rights reserved.
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for full license information.
-
-#if REACTIVE_SHIM
-namespace ReactiveUI.Reactive.Internal;
-#else
-namespace ReactiveUI.Internal;
-#endif
-/// <summary>
-/// Provides pre-allocated <see cref="SingleValueObservable{T}"/> singletons for values emitted often enough to be
-/// worth sharing rather than re-allocating on each use.
-/// </summary>
-internal static class SingleValueObservable
-{
-    /// <summary>
-    /// A shared cold observable that emits <see cref="RxVoid.Default"/> once and then completes. Reused to avoid the
-    /// allocation of a fresh <see cref="SingleValueObservable{T}"/> for the very common "completed unit" case.
-    /// </summary>
-    public static readonly IObservable<RxVoid> Void = new SingleValueObservable<RxVoid>(RxVoid.Default);
-
-    /// <summary>A shared cold observable that emits a single <c>true</c> and then completes.</summary>
-    public static readonly IObservable<bool> True = new SingleValueObservable<bool>(true);
-
-    /// <summary>A shared cold observable that emits a single <c>false</c> and then completes.</summary>
-    public static readonly IObservable<bool> False = new SingleValueObservable<bool>(false);
-}
diff --git a/src/ReactiveUI.Shared/Internal/StartObservable.cs b/src/ReactiveUI.Shared/Internal/StartObservable.cs
deleted file mode 100644
index 490ca34727..0000000000
--- a/src/ReactiveUI.Shared/Internal/StartObservable.cs
+++ /dev/null
@@ -1,44 +0,0 @@
-// Copyright (c) 2009-2026 .NET Foundation and Contributors. All rights reserved.
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for full license information.
-
-using ReactiveUI.Primitives.Disposables;
-
-#if REACTIVE_SHIM
-namespace ReactiveUI.Reactive.Internal;
-#else
-namespace ReactiveUI.Internal;
-#endif
-/// <summary>
-/// Runs a function on a scheduler when subscribed, then emits its result and completes.
-/// Replaces <c>Observable.Start</c> for internal use.
-/// </summary>
-/// <typeparam name="T">The result type.</typeparam>
-/// <param name="function">The function to run on the scheduler.</param>
-/// <param name="scheduler">The scheduler the function runs on.</param>
-internal sealed class StartObservable<T>(Func<T> function, ISequencer scheduler) : IObservable<T>
-{
-    /// <inheritdoc/>
-    public IDisposable Subscribe(IObserver<T> observer)
-    {
-        ArgumentExceptionHelper.ThrowIfNull(observer);
-        return scheduler.ScheduleOrInline(
-            (Function: function, Observer: observer),
-            static (_, state) =>
-            {
-                try
-                {
-                    var result = state.Function();
-                    state.Observer.OnNext(result);
-                    state.Observer.OnCompleted();
-                }
-                catch (Exception ex)
-                {
-                    state.Observer.OnError(ex);
-                }
-
-                return EmptyDisposable.Instance;
-            });
-    }
-}
diff --git a/src/ReactiveUI.Shared/Mixins/ObservableLoggingMixins.cs b/src/ReactiveUI.Shared/Mixins/ObservableLoggingMixins.cs
index f0e8d8d330..6fc2ae3232 100644
--- a/src/ReactiveUI.Shared/Mixins/ObservableLoggingMixins.cs
+++ b/src/ReactiveUI.Shared/Mixins/ObservableLoggingMixins.cs
@@ -113,7 +113,7 @@ public IObservable<T> LoggedCatch<TObj>(
             string? message)
             where TObj : IEnableLogger
         {
-            next ??= new SingleValueObservable<T>(default!);
+            next ??= new ReturnSignal<T>(default!, Sequencer.Immediate);
             return new LoggedCatchObservable<T, Exception>(@this, ex =>
             {
                 @class.Log().Warn(ex, message ?? string.Empty);
diff --git a/src/ReactiveUI.Shared/ReactiveCommand/CombinedReactiveCommand.cs b/src/ReactiveUI.Shared/ReactiveCommand/CombinedReactiveCommand.cs
index 3344ffec3e..3272aa007c 100644
--- a/src/ReactiveUI.Shared/ReactiveCommand/CombinedReactiveCommand.cs
+++ b/src/ReactiveUI.Shared/ReactiveCommand/CombinedReactiveCommand.cs
@@ -94,7 +94,7 @@ protected internal CombinedReactiveCommand(
             childCanExecute[i] = childCommandsArray[i].CanExecute;
         }
 
-        var parentGate = canExecute ?? SingleValueObservable.True;
+        var parentGate = canExecute ?? new ReturnSignal<bool>(true, Sequencer.Immediate);
 
         // all-true of [parent, child0..childN] (the parent gate plus every child's CanExecute).
         var canExecuteSources = new IObservable<bool>[childCommandsArray.Length + 1];
diff --git a/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand.cs b/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand.cs
index 5aadc22445..4b3443fa29 100644
--- a/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand.cs
+++ b/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand.cs
@@ -103,11 +103,13 @@ public static ReactiveCommand<RxVoid, RxVoid> Create(
         ArgumentExceptionHelper.ThrowIfNull(execute);
 
         return new(
-            _ => new SyncExecuteObservable<RxVoid>(() =>
-            {
-                execute();
-                return RxVoid.Default;
-            }),
+            _ => new StartSignal<RxVoid>(
+                () =>
+                {
+                    execute();
+                    return RxVoid.Default;
+                },
+                Sequencer.Immediate),
             canExecute,
             outputScheduler);
     }
@@ -159,7 +161,7 @@ public static ReactiveCommand<RxVoid, TResult> Create<TResult>(
         ArgumentExceptionHelper.ThrowIfNull(execute);
 
         return new(
-            _ => new SyncExecuteObservable<TResult>(execute),
+            _ => new StartSignal<TResult>(execute, Sequencer.Immediate),
             canExecute,
             outputScheduler);
     }
@@ -211,11 +213,13 @@ public static ReactiveCommand<TParam, RxVoid> Create<TParam>(
         ArgumentExceptionHelper.ThrowIfNull(execute);
 
         return new(
-            param => new SyncExecuteObservable<RxVoid>(() =>
-            {
-                execute(param);
-                return RxVoid.Default;
-            }),
+            param => new StartSignal<RxVoid>(
+                () =>
+                {
+                    execute(param);
+                    return RxVoid.Default;
+                },
+                Sequencer.Immediate),
             canExecute,
             outputScheduler);
     }
@@ -277,7 +281,7 @@ public static ReactiveCommand<TParam, TResult> Create<TParam, TResult>(
         ArgumentExceptionHelper.ThrowIfNull(execute);
 
         return new(
-            param => new SyncExecuteObservable<TResult>(() => execute(param)),
+            param => new StartSignal<TResult>(() => execute(param), Sequencer.Immediate),
             canExecute,
             outputScheduler);
     }
@@ -341,7 +345,7 @@ public static ReactiveCommand<RxVoid, RxVoid> CreateRunInBackground(
         ArgumentExceptionHelper.ThrowIfNull(execute);
 
         return CreateFromObservable(
-            () => new StartObservable<RxVoid>(
+            () => new StartSignal<RxVoid>(
                 () =>
                 {
                     execute();
@@ -424,7 +428,7 @@ public static ReactiveCommand<RxVoid, TResult> CreateRunInBackground<TResult>(
         ArgumentExceptionHelper.ThrowIfNull(execute);
 
         return CreateFromObservable(
-            () => new StartObservable<TResult>(execute, backgroundScheduler ?? RxSchedulers.TaskpoolScheduler),
+            () => new StartSignal<TResult>(execute, backgroundScheduler ?? RxSchedulers.TaskpoolScheduler),
             canExecute,
             outputScheduler);
     }
@@ -494,7 +498,7 @@ public static ReactiveCommand<TParam, RxVoid> CreateRunInBackground<TParam>(
 
         return CreateFromObservable<TParam, RxVoid>(
             p =>
-                new StartObservable<RxVoid>(
+                new StartSignal<RxVoid>(
                     () =>
                     {
                         execute(p);
@@ -582,7 +586,7 @@ public static ReactiveCommand<TParam, TResult> CreateRunInBackground<TParam, TRe
         ArgumentExceptionHelper.ThrowIfNull(execute);
 
         return CreateFromObservable<TParam, TResult>(
-            p => new StartObservable<TResult>(() => execute(p), backgroundScheduler ?? RxSchedulers.TaskpoolScheduler),
+            p => new StartSignal<TResult>(() => execute(p), backgroundScheduler ?? RxSchedulers.TaskpoolScheduler),
             canExecute,
             outputScheduler);
     }
diff --git a/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand{TParam,TResult}.cs b/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand{TParam,TResult}.cs
index ffb9dc26ca..153564e1f2 100644
--- a/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand{TParam,TResult}.cs
+++ b/src/ReactiveUI.Shared/ReactiveCommand/ReactiveCommand{TParam,TResult}.cs
@@ -91,7 +91,7 @@ protected internal ReactiveCommand(
         CanExecute = new BoolStream(this, isExecuting: false);
         IsExecuting = new BoolStream(this, isExecuting: true);
         ThrownExceptions = new ExceptionStream(this);
-        _canExecuteSubscription = (canExecute ?? SingleValueObservable.True)
+        _canExecuteSubscription = (canExecute ?? new ReturnSignal<bool>(true, Sequencer.Immediate))
             .Subscribe(new DelegateObserver<bool>(OnUserCanExecute, OnUserCanExecuteError));
     }
 
@@ -105,7 +105,7 @@ protected internal ReactiveCommand(
         IObservable<bool>? canExecute,
         ISequencer? outputScheduler)
         : this(
-            p => new SingleValueObservable<(IObservable<TResult> Result, Action Cancel)>((execute(p), NoCancel)),
+            p => new ReturnSignal<(IObservable<TResult> Result, Action Cancel)>((execute(p), NoCancel), Sequencer.Immediate),
             canExecute,
             outputScheduler)
     {
diff --git a/src/ReactiveUI.Shared/Routing/RoutingState.cs b/src/ReactiveUI.Shared/Routing/RoutingState.cs
index b2d9f73f10..2bcaa29a2a 100644
--- a/src/ReactiveUI.Shared/Routing/RoutingState.cs
+++ b/src/ReactiveUI.Shared/Routing/RoutingState.cs
@@ -192,7 +192,7 @@ private sealed class ScheduledValueObservable<T>(T value, ISequencer scheduler)
         public IDisposable Subscribe(IObserver<T> observer)
         {
             ArgumentExceptionHelper.ThrowIfNull(observer);
-            return new SingleValueObservable<T>(value).Subscribe(new SchedulingObserver<T>(observer, scheduler));
+            return new ReturnSignal<T>(value, Sequencer.Immediate).Subscribe(new SchedulingObserver<T>(observer, scheduler));
         }
     }
 
diff --git a/src/ReactiveUI.Shared/Suspension/DummySuspensionDriver.cs b/src/ReactiveUI.Shared/Suspension/DummySuspensionDriver.cs
index 22e455e558..8c467467b1 100644
--- a/src/ReactiveUI.Shared/Suspension/DummySuspensionDriver.cs
+++ b/src/ReactiveUI.Shared/Suspension/DummySuspensionDriver.cs
@@ -28,10 +28,10 @@ public sealed class DummySuspensionDriver : ISuspensionDriver
         "Implementations commonly use reflection-based serialization. " +
         "Prefer LoadState<T>(JsonTypeInfo<T>) for trimming or AOT scenarios.")]
     public IObservable<object?> LoadState()
-        => new SingleValueObservable<object?>(null);
+        => new ReturnSignal<object?>(null, Sequencer.Immediate);
 
     /// <inheritdoc />
-    public IObservable<T?> LoadState<T>(JsonTypeInfo<T> typeInfo) => new SingleValueObservable<T?>(default);
+    public IObservable<T?> LoadState<T>(JsonTypeInfo<T> typeInfo) => new ReturnSignal<T?>(default, Sequencer.Immediate);
 
     /// <inheritdoc />
     [RequiresUnreferencedCode(
@@ -41,12 +41,12 @@ public sealed class DummySuspensionDriver : ISuspensionDriver
         "Implementations commonly use reflection-based serialization. " +
         "Prefer SaveState<T>(T, JsonTypeInfo<T>) for trimming or AOT scenarios.")]
     public IObservable<RxVoid> SaveState<T>(T state)
-        => SingleValueObservable.Void;
+        => ImmutableReturnRxVoidSignal.Instance;
 
     /// <inheritdoc />
-    public IObservable<RxVoid> SaveState<T>(T state, JsonTypeInfo<T> typeInfo) => SingleValueObservable.Void;
+    public IObservable<RxVoid> SaveState<T>(T state, JsonTypeInfo<T> typeInfo) => ImmutableReturnRxVoidSignal.Instance;
 
     /// <inheritdoc />
     public IObservable<RxVoid> InvalidateState()
-        => SingleValueObservable.Void;
+        => ImmutableReturnRxVoidSignal.Instance;
 }
diff --git a/src/ReactiveUI.Shared/Suspension/SuspensionHostExtensions.cs b/src/ReactiveUI.Shared/Suspension/SuspensionHostExtensions.cs
index 8a47cdbab7..f3b58c6239 100644
--- a/src/ReactiveUI.Shared/Suspension/SuspensionHostExtensions.cs
+++ b/src/ReactiveUI.Shared/Suspension/SuspensionHostExtensions.cs
@@ -23,6 +23,10 @@ namespace ReactiveUI;
 /// </remarks>
 public static class SuspensionHostExtensions
 {
+    /// <summary>A shared completed RxVoid signal. Typed as the interface so the synchronous helpers below
+    /// surface it without CA1859 demanding the concrete singleton type leak into their signatures.</summary>
+    private static readonly IObservable<RxVoid> _completed = ImmutableReturnRxVoidSignal.Instance;
+
     /// <summary>Func used to load app state exactly once. Backing field for testing purposes.</summary>
     private static Func<IObservable<RxVoid>>? _ensureLoadAppStateFunc;
 
@@ -305,7 +309,7 @@ private static IObservable<RxVoid> EnsureLoadAppState(ISuspensionHost item, ISus
     {
         if (item.AppState is not null)
         {
-            return SingleValueObservable.Void;
+            return _completed;
         }
 
         _suspensionDriver ??= driver ?? AppLocator.Current.GetService<ISuspensionDriver>();
@@ -313,7 +317,7 @@ private static IObservable<RxVoid> EnsureLoadAppState(ISuspensionHost item, ISus
         if (_suspensionDriver is null)
         {
             item.Log().Error("Could not find a valid driver and therefore cannot load app state.");
-            return SingleValueObservable.Void;
+            return _completed;
         }
 
         try
@@ -327,7 +331,7 @@ private static IObservable<RxVoid> EnsureLoadAppState(ISuspensionHost item, ISus
             item.AppState = item.CreateNewAppState?.Invoke();
         }
 
-        return SingleValueObservable.Void;
+        return _completed;
     }
 
     /// <summary>Ensures a one-time typed app state load from storage using source-generated JSON metadata (trimming/AOT friendly).</summary>
@@ -344,7 +348,7 @@ private static IObservable<RxVoid> EnsureLoadAppState<TAppState>(
     {
         if (item.AppStateValue is not null)
         {
-            return SingleValueObservable.Void;
+            return _completed;
         }
 
         _suspensionDriver ??= driver ?? AppLocator.Current.GetService<ISuspensionDriver>();
@@ -352,7 +356,7 @@ private static IObservable<RxVoid> EnsureLoadAppState<TAppState>(
         if (_suspensionDriver is null)
         {
             item.Log().Error("Could not find a valid driver and therefore cannot load app state.");
-            return SingleValueObservable.Void;
+            return _completed;
         }
 
         try
@@ -366,7 +370,7 @@ private static IObservable<RxVoid> EnsureLoadAppState<TAppState>(
             item.AppStateValue = item.CreateNewAppStateTyped?.Invoke();
         }
 
-        return SingleValueObservable.Void;
+        return _completed;
     }
 
     /// <summary>Runs the pending one-time app-state load exactly once, if one is registered.</summary>
diff --git a/src/ReactiveUI/Platforms/android/BundleSuspensionDriver.cs b/src/ReactiveUI/Platforms/android/BundleSuspensionDriver.cs
index 2331863ba6..fb1d31b32f 100644
--- a/src/ReactiveUI/Platforms/android/BundleSuspensionDriver.cs
+++ b/src/ReactiveUI/Platforms/android/BundleSuspensionDriver.cs
@@ -102,7 +102,7 @@ public IObservable<RxVoid> SaveState<T>(T state)
             JsonSerializer.Serialize(stream, state);
 
             AutoSuspendHelper.LatestBundle?.PutByteArray(StateKey, stream.ToArray());
-            return SingleValueObservable.Void;
+            return ImmutableReturnRxVoidSignal.Instance;
         }
         catch (Exception ex)
         {
@@ -121,7 +121,7 @@ public IObservable<RxVoid> SaveState<T>(T state, JsonTypeInfo<T> typeInfo)
             JsonSerializer.Serialize(stream, state, typeInfo);
 
             AutoSuspendHelper.LatestBundle?.PutByteArray(StateKey, stream.ToArray());
-            return SingleValueObservable.Void;
+            return ImmutableReturnRxVoidSignal.Instance;
         }
         catch (Exception ex)
         {
@@ -135,7 +135,7 @@ public IObservable<RxVoid> InvalidateState()
         try
         {
             AutoSuspendHelper.LatestBundle?.PutByteArray(StateKey, []);
-            return SingleValueObservable.Void;
+            return ImmutableReturnRxVoidSignal.Instance;
         }
         catch (Exception ex)
         {
diff --git a/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs b/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs
index 0261df42b5..d1b719a713 100644
--- a/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs
+++ b/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs
@@ -134,7 +134,7 @@ public IDisposable? BindCommandToObject<
             return EmptyDisposable.Instance;
         }
 
-        commandParameter ??= new SingleValueObservable<object?>(target);
+        commandParameter ??= new ReturnSignal<object?>(target, Sequencer.Immediate);
 
         object? latestParam = null;
 
@@ -202,7 +202,7 @@ protected static IDisposable ForEvent(
     {
         ArgumentExceptionHelper.ThrowIfNull(command);
 
-        commandParameter ??= new SingleValueObservable<object?>(target);
+        commandParameter ??= new ReturnSignal<object?>(target, Sequencer.Immediate);
 
         object? latestParam = null;
         var ctl = target!;
@@ -264,7 +264,7 @@ protected static IDisposable ForEvent<TEventArgs>(
         ArgumentExceptionHelper.ThrowIfNull(addHandler);
         ArgumentExceptionHelper.ThrowIfNull(removeHandler);
 
-        commandParameter ??= new SingleValueObservable<object?>(target);
+        commandParameter ??= new ReturnSignal<object?>(target, Sequencer.Immediate);
 
         object? latestParam = null;
 
@@ -331,7 +331,7 @@ protected static IDisposable ForEvent(
         ArgumentExceptionHelper.ThrowIfNull(addHandler);
         ArgumentExceptionHelper.ThrowIfNull(removeHandler);
 
-        commandParameter ??= new SingleValueObservable<object?>(target);
+        commandParameter ??= new ReturnSignal<object?>(target, Sequencer.Immediate);
 
         object? latestParam = null;
 
diff --git a/src/ReactiveUI/Platforms/apple-common/AppSupportJsonSuspensionDriver.cs b/src/ReactiveUI/Platforms/apple-common/AppSupportJsonSuspensionDriver.cs
index 8f1ce6c4db..fcac376f36 100644
--- a/src/ReactiveUI/Platforms/apple-common/AppSupportJsonSuspensionDriver.cs
+++ b/src/ReactiveUI/Platforms/apple-common/AppSupportJsonSuspensionDriver.cs
@@ -118,7 +118,7 @@ public IObservable<RxVoid> SaveState<T>(T state, JsonTypeInfo<T> typeInfo)
             using var stream = File.Open(path, FileMode.Create, FileAccess.Write, FileShare.None);
 
             JsonSerializer.Serialize(stream, state, typeInfo);
-            return SingleValueObservable.Void;
+            return ImmutableReturnRxVoidSignal.Instance;
         }
         catch (Exception ex)
         {
@@ -137,7 +137,7 @@ public IObservable<RxVoid> SaveState<T>(T state)
             using var stream = File.Open(path, FileMode.Create, FileAccess.Write, FileShare.None);
 
             JsonSerializer.Serialize(stream, state);
-            return SingleValueObservable.Void;
+            return ImmutableReturnRxVoidSignal.Instance;
         }
         catch (Exception ex)
         {
@@ -153,7 +153,7 @@ public IObservable<RxVoid> InvalidateState()
             var path = GetStatePath();
             File.Delete(path);
 
-            return SingleValueObservable.Void;
+            return ImmutableReturnRxVoidSignal.Instance;
         }
         catch (Exception ex)
         {
diff --git a/src/tests/Directory.Build.props b/src/tests/Directory.Build.props
index d252ead629..4af54f4b33 100644
--- a/src/tests/Directory.Build.props
+++ b/src/tests/Directory.Build.props
@@ -27,6 +27,9 @@
        System.Reactive surface instead. All other lean test projects are System.Reactive-free and use the Primitives surface. -->
   <ItemGroup Condition="'$(RxReactiveSeam)' != 'true' and !$(MSBuildProjectName.Contains('Routing'))">
     <Using Include="ReactiveUI.Primitives" />
+    <!-- Concrete signal classes (ReturnSignal/StartSignal/ImmutableReturnRxVoidSignal) the tests construct
+         directly in place of the removed in-repo SingleValueObservable/SyncExecuteObservable sinks. -->
+    <Using Include="ReactiveUI.Primitives.Advanced" />
   </ItemGroup>
   <!-- BCL ObservableCollection replaces incidental DynamicData ObservableCollectionExtended in test mocks. -->
   <ItemGroup>
@@ -39,6 +42,7 @@
   </ItemGroup>
   <ItemGroup Condition="'$(RxReactiveSeam)' == 'true' and !$(MSBuildProjectName.Contains('Routing'))">
     <Using Include="ReactiveUI.Primitives.Reactive" />
+    <Using Include="ReactiveUI.Primitives.Reactive.Advanced" />
     <!-- The generic Signal<T> subject (and ReplaySignal/ScheduledSignal) is neutral — it ships in
          ReactiveUI.Primitives.Core under ReactiveUI.Primitives.Signals and is shared by both leaves; the engine
          seam (ReactiveShim.props) already imports that namespace. Only the NON-generic Signal static factory
diff --git a/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistCollectionTest.cs b/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistCollectionTest.cs
index e61af380b2..d86e125af5 100644
--- a/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistCollectionTest.cs
+++ b/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistCollectionTest.cs
@@ -47,7 +47,7 @@ public async Task AutoPersistCollection_Dispose_StopsAllPersistence()
             _ =>
             {
                 timesSaved++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
@@ -108,7 +108,7 @@ public async Task AutoPersistCollection_DuplicateAdd_NoDoubleSave()
             _ =>
             {
                 timesSaved++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
 
@@ -146,7 +146,7 @@ public async Task AutoPersistCollection_Lifecycle_ManagesPersistence()
             _ =>
             {
                 timesSaved++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
@@ -205,7 +205,7 @@ public async Task AutoPersistCollection_ManualSave_TriggersImmediateSave()
             _ =>
             {
                 timesSaved++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
@@ -238,7 +238,7 @@ public async Task AutoPersistCollection_MetadataProvider_WorksCorrectly()
             _ =>
             {
                 timesSaved++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             ReactiveUI.Primitives.Signals.Signal.Silent<RxVoid>(),
             metadataProvider,
@@ -271,7 +271,7 @@ public async Task AutoPersistCollection_Reset_ContinuesPersistence()
             _ =>
             {
                 timesSaved++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
 
diff --git a/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistHelperTest.cs b/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistHelperTest.cs
index d4fef92099..f170bc7fa6 100644
--- a/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistHelperTest.cs
+++ b/src/tests/ReactiveUI.Tests/AutoPersist/AutoPersistHelperTest.cs
@@ -259,7 +259,7 @@ public async Task AutoPersist_Dispose_StopsSaving()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromSeconds(1));
 
@@ -294,7 +294,7 @@ public async Task AutoPersist_ManualSaveSignal_TriggersSave()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             TimeSpan.FromSeconds(1));
@@ -331,7 +331,7 @@ public async Task AutoPersist_NoDataContract_ThrowsArgumentException()
 
         await Assert.ThrowsAsync<ArgumentException>(async () =>
         {
-            _ = obj.AutoPersist(_ => SingleValueObservable.Void);
+            _ = obj.AutoPersist(_ => ImmutableReturnRxVoidSignal.Instance);
             await Task.CompletedTask;
         });
     }
@@ -351,7 +351,7 @@ public async Task AutoPersist_NonDataMemberProperty_DoesNotTriggerSave()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromSeconds(1));
 
@@ -387,7 +387,7 @@ public async Task AutoPersist_NullManualSaveSignal_ThrowsArgumentNullException()
 
         await Assert.ThrowsAsync<ArgumentNullException>(async () =>
         {
-            _ = fixture.AutoPersist(_ => SingleValueObservable.Void, null!, TimeSpan.FromSeconds(1));
+            _ = fixture.AutoPersist(_ => ImmutableReturnRxVoidSignal.Instance, null!, TimeSpan.FromSeconds(1));
             await Task.CompletedTask;
         });
     }
@@ -405,7 +405,7 @@ public async Task AutoPersist_NullMetadata_ThrowsArgumentNullException()
 
         await Assert.ThrowsAsync<ArgumentNullException>(async () =>
         {
-            _ = fixture.AutoPersist(_ => SingleValueObservable.Void, null!, TimeSpan.FromSeconds(1));
+            _ = fixture.AutoPersist(_ => ImmutableReturnRxVoidSignal.Instance, null!, TimeSpan.FromSeconds(1));
             await Task.CompletedTask;
         });
     }
@@ -425,7 +425,7 @@ public async Task AutoPersist_PropertyChange_TriggersSave()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromSeconds(1));
 
@@ -452,7 +452,7 @@ public async Task AutoPersist_Throttle_RespectInterval()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromSeconds(ThrottleSeconds));
 
@@ -486,7 +486,7 @@ public async Task AutoPersist_WithMetadata_SavesCorrectly()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             metadata,
             TimeSpan.FromSeconds(1));
@@ -513,7 +513,7 @@ public async Task AutoPersistCollection_AddItem_EnablesPersistence()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
 
@@ -538,7 +538,7 @@ public async Task AutoPersistCollection_NullCollection_ThrowsArgumentNullExcepti
 
         await Assert.ThrowsAsync<ArgumentNullException>(async () =>
         {
-            _ = collection!.AutoPersistCollection(_ => SingleValueObservable.Void);
+            _ = collection!.AutoPersistCollection(_ => ImmutableReturnRxVoidSignal.Instance);
             await Task.CompletedTask;
         });
     }
@@ -566,7 +566,7 @@ public async Task AutoPersistCollection_NullMetadata_ThrowsArgumentNullException
 
         await Assert.ThrowsAsync<ArgumentNullException>(async () =>
         {
-            _ = collection.AutoPersistCollection(_ => SingleValueObservable.Void, (AutoPersistHelperMixins.AutoPersistMetadata)null!);
+            _ = collection.AutoPersistCollection(_ => ImmutableReturnRxVoidSignal.Instance, (AutoPersistHelperMixins.AutoPersistMetadata)null!);
             await Task.CompletedTask;
         });
     }
@@ -588,7 +588,7 @@ public async Task AutoPersistCollection_ReadOnlyCollection_WorksCorrectly()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
@@ -621,7 +621,7 @@ public async Task AutoPersistCollection_RemoveItem_DisablesPersistence()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
 
@@ -651,7 +651,7 @@ public async Task AutoPersistCollection_WithMetadata_SavesCorrectly()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             metadata,
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
@@ -731,7 +731,7 @@ public async Task AutoPersistCollection_ManualSignalAndMetadataNoInterval_SavesC
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             metadata);
@@ -764,7 +764,7 @@ public async Task AutoPersistCollection_ManualSignalNoInterval_SavesCorrectly()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave);
 
@@ -798,7 +798,7 @@ public async Task AutoPersistCollection_ReadOnlyManualSignalAndMetadataNoInterva
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             metadata);
@@ -832,7 +832,7 @@ public async Task AutoPersistCollection_ReadOnlyManualSignalNoInterval_SavesCorr
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave);
 
@@ -865,7 +865,7 @@ public async Task AutoPersistCollection_MetadataProviderNoInterval_SavesCorrectl
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             metadataProvider);
@@ -901,7 +901,7 @@ public async Task AutoPersistCollection_MetadataProviderDispose_StopsPersistence
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             new Signal<RxVoid>(),
             metadataProvider,
@@ -934,7 +934,7 @@ public async Task AutoPersistCollection_MetadataWithoutDataContract_ThrowsArgume
 
         await Assert.ThrowsAsync<ArgumentException>(async () =>
         {
-            _ = collection.AutoPersistCollection(_ => SingleValueObservable.Void, new Signal<RxVoid>(), metadata, interval: null);
+            _ = collection.AutoPersistCollection(_ => ImmutableReturnRxVoidSignal.Instance, new Signal<RxVoid>(), metadata, interval: null);
             await Task.CompletedTask;
         });
     }
@@ -957,7 +957,7 @@ public async Task AutoPersistCollection_GenericMetadataNoInterval_SavesCorrectly
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave,
             metadata);
@@ -990,7 +990,7 @@ public async Task AutoPersist_DisposeWithPendingSave_DoesNotPersist()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromSeconds(IntervalSeconds));
 
@@ -1020,7 +1020,7 @@ public async Task AutoPersist_NonPersistableRaisedProperty_DoesNotTriggerSave()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromSeconds(1));
 
@@ -1048,7 +1048,7 @@ public async Task AutoPersist_ManualSignalNoInterval_SavesCorrectly()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave);
 
@@ -1079,7 +1079,7 @@ public async Task AutoPersist_DerivedRuntimeType_UsesRuntimeMetadata()
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             TimeSpan.FromSeconds(1));
 
@@ -1156,7 +1156,7 @@ public async Task AutoPersistCollection_ReplaceUntrackedPrevious_DisposeAndRemov
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             new Signal<RxVoid>(),
             TimeSpan.FromMilliseconds(ThrottleMilliseconds));
@@ -1191,7 +1191,7 @@ public async Task AutoPersistCollection_GenericReflectionManualSignalNoInterval_
             _ =>
             {
                 saveCount++;
-                return SingleValueObservable.Void;
+                return ImmutableReturnRxVoidSignal.Instance;
             },
             manualSave);
 
diff --git a/src/tests/ReactiveUI.Tests/Commands/CombinedReactiveCommandTest.cs b/src/tests/ReactiveUI.Tests/Commands/CombinedReactiveCommandTest.cs
index 4f069dde79..9d1de4ff89 100644
--- a/src/tests/ReactiveUI.Tests/Commands/CombinedReactiveCommandTest.cs
+++ b/src/tests/ReactiveUI.Tests/Commands/CombinedReactiveCommandTest.cs
@@ -29,11 +29,11 @@ public class CombinedReactiveCommandTest
     public async Task CanExecuteIsFalseIfAnyChildCannotExecute()
     {
         var child1 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var child2 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
-            SingleValueObservable.False,
+            static () => ImmutableReturnRxVoidSignal.Instance,
+            new ReturnSignal<bool>(false, Sequencer.Immediate),
             Sequencer.Immediate);
         var childCommands = new[] { child1, child2 };
         var fixture = ReactiveCommand.CreateCombined(childCommands, outputScheduler: Sequencer.Immediate);
@@ -49,13 +49,13 @@ public async Task CanExecuteIsFalseIfAnyChildCannotExecute()
     public async Task CanExecuteIsFalseIfParentCanExecuteIsFalse()
     {
         var child1 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var child2 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var childCommands = new[] { child1, child2 };
-        var fixture = ReactiveCommand.CreateCombined(childCommands, SingleValueObservable.False, Sequencer.Immediate);
+        var fixture = ReactiveCommand.CreateCombined(childCommands, new ReturnSignal<bool>(false, Sequencer.Immediate), Sequencer.Immediate);
         var canExecute = fixture.CanExecute.Collect();
 
         await Assert.That(canExecute).Count().IsEqualTo(1);
@@ -69,10 +69,10 @@ public async Task CanExecuteTicksFailuresInChildCanExecuteThroughThrownException
     {
         var canExecuteSubject = new Signal<bool>();
         var child1 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var child2 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             canExecuteSubject,
             Sequencer.Immediate);
         var childCommands = new[] { child1, child2 };
@@ -92,10 +92,10 @@ public async Task CanExecuteTicksFailuresThroughThrownExceptions()
     {
         var canExecuteSubject = new Signal<bool>();
         var child1 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var child2 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var childCommands = new[] { child1, child2 };
         var fixture = ReactiveCommand.CreateCombined(childCommands, canExecuteSubject, Sequencer.Immediate);
@@ -132,13 +132,13 @@ public async Task ExceptionsAreDeliveredOnOutputScheduler()
     public async Task ExecuteExecutesAllChildCommands()
     {
         var child1 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var child2 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var child3 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var childCommands = new[] { child1, child2, child3 };
         var fixture = ReactiveCommand.CreateCombined(childCommands, outputScheduler: Sequencer.Immediate);
@@ -192,7 +192,7 @@ public async Task ExecuteExecutesAllChildCommands()
     public async Task ExecuteTicksErrorsInAnyChildCommandThroughThrownExceptions()
     {
         var child1 = ReactiveCommand.CreateFromObservable(
-            static () => SingleValueObservable.Void,
+            static () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: Sequencer.Immediate);
         var child2 = ReactiveCommand.CreateFromObservable(
             static () => Signal.Fail<RxVoid>(new InvalidOperationException("oops")),
diff --git a/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.ExecutionAndInvoke.cs b/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.ExecutionAndInvoke.cs
index 87601591df..64fffeef93 100644
--- a/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.ExecutionAndInvoke.cs
+++ b/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.ExecutionAndInvoke.cs
@@ -25,7 +25,7 @@ public partial class ReactiveCommandTest
     public async Task Execute_CanBeCancelled()
     {
         var scheduler = TestContext.Current.GetVirtualTimeScheduler();
-        var execute = SingleValueObservable.Void.Delay(TimeSpan.FromSeconds(1), scheduler);
+        var execute = ImmutableReturnRxVoidSignal.Instance.Delay(TimeSpan.FromSeconds(1), scheduler);
         var command = ReactiveCommand.CreateFromObservable<RxVoid>(
             () => execute,
             outputScheduler: scheduler);
@@ -175,7 +175,7 @@ public async Task Execute_TicksMultipleResults()
     public async Task ICommand_CanExecute_IsFalseWhileExecuting()
     {
         var scheduler = TestContext.Current.GetVirtualTimeScheduler();
-        var execute = SingleValueObservable.Void.Delay(TimeSpan.FromSeconds(1), scheduler);
+        var execute = ImmutableReturnRxVoidSignal.Instance.Delay(TimeSpan.FromSeconds(1), scheduler);
         ICommand command = ReactiveCommand.CreateFromObservable<RxVoid>(
             () => execute,
             outputScheduler: scheduler);
diff --git a/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.IsExecutingAndExceptions.cs b/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.IsExecutingAndExceptions.cs
index fdcc68ab34..79ac81459d 100644
--- a/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.IsExecutingAndExceptions.cs
+++ b/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.IsExecutingAndExceptions.cs
@@ -25,7 +25,7 @@ public async Task IsExecuting_HandlesMultipleInFlightExecutions()
         const int DelayMilliseconds = 500;
 
         var scheduler = TestContext.Current.GetVirtualTimeScheduler();
-        var execute = SingleValueObservable.Void.Delay(TimeSpan.FromMilliseconds(DelayMilliseconds), scheduler);
+        var execute = ImmutableReturnRxVoidSignal.Instance.Delay(TimeSpan.FromMilliseconds(DelayMilliseconds), scheduler);
         var command = ReactiveCommand.CreateFromObservable<RxVoid>(
             () => execute,
             outputScheduler: scheduler);
@@ -84,7 +84,7 @@ public async Task IsExecuting_RemainsTrue_UntilExecutionCompletes()
     public async Task IsExecuting_TicksWhileExecuting()
     {
         var scheduler = TestContext.Current.GetVirtualTimeScheduler();
-        var execute = SingleValueObservable.Void.Delay(TimeSpan.FromSeconds(1), scheduler);
+        var execute = ImmutableReturnRxVoidSignal.Instance.Delay(TimeSpan.FromSeconds(1), scheduler);
         var command = ReactiveCommand.CreateFromObservable<RxVoid>(
             () => execute,
             outputScheduler: scheduler);
@@ -180,7 +180,7 @@ public async Task Scheduler_ResultsDeliveredOnOutputScheduler()
     {
         var scheduler = TestContext.Current!.GetScheduler();
         var command = ReactiveCommand.CreateFromObservable(
-            () => SingleValueObservable.Void,
+            () => ImmutableReturnRxVoidSignal.Instance,
             outputScheduler: scheduler);
         var executed = false;
 
diff --git a/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.cs b/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.cs
index 49095fa6e0..8bfb447ed7 100644
--- a/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.cs
+++ b/src/tests/ReactiveUI.Tests/Commands/ReactiveCommandTest.cs
@@ -65,7 +65,7 @@ public async Task CanExecute_IsBehavioral()
     public async Task CanExecute_IsFalseWhileExecuting()
     {
         var scheduler = TestContext.Current.GetVirtualTimeScheduler();
-        var execute = SingleValueObservable.Void.Delay(TimeSpan.FromSeconds(1), scheduler);
+        var execute = ImmutableReturnRxVoidSignal.Instance.Delay(TimeSpan.FromSeconds(1), scheduler);
         var command = ReactiveCommand.CreateFromObservable<RxVoid>(
             () => execute,
             outputScheduler: scheduler);
diff --git a/src/tests/ReactiveUI.Tests/Core/ObservablesTests.cs b/src/tests/ReactiveUI.Tests/Core/ObservablesTests.cs
deleted file mode 100644
index a809908ff6..0000000000
--- a/src/tests/ReactiveUI.Tests/Core/ObservablesTests.cs
+++ /dev/null
@@ -1,73 +0,0 @@
-// Copyright (c) 2009-2026 .NET Foundation and Contributors. All rights reserved.
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for full license information.
-
-#if !REACTIVE_SHIM
-using ReactiveUI.Internal;
-#endif
-
-namespace ReactiveUI.Tests.Core;
-
-/// <summary>Tests for Observables static utility class.</summary>
-public class ObservablesTests
-{
-    /// <summary>Tests that SingleValueObservable.False emits false value.</summary>
-    /// <returns>A <see cref="Task" /> representing the asynchronous operation.</returns>
-    [Test]
-    public async Task Observables_False_EmitsFalse()
-    {
-        // Arrange
-        bool? result = null;
-
-        // Act
-        _ = SingleValueObservable.False.Subscribe(x => result = x);
-
-        // Assert
-        await Assert.That(result).IsFalse();
-    }
-
-    /// <summary>Tests that Observables static members are accessible.</summary>
-    /// <returns>A <see cref="Task" /> representing the asynchronous operation.</returns>
-    [Test]
-    public async Task Observables_StaticMembers_AreAccessible()
-    {
-        using (Assert.Multiple())
-        {
-            // Act & Assert
-            await Assert.That(SingleValueObservable.Void).IsNotNull();
-            await Assert.That(SingleValueObservable.True).IsNotNull();
-            await Assert.That(SingleValueObservable.False).IsNotNull();
-        }
-    }
-
-    /// <summary>Tests that SingleValueObservable.True emits true value.</summary>
-    /// <returns>A <see cref="Task" /> representing the asynchronous operation.</returns>
-    [Test]
-    public async Task Observables_True_EmitsTrue()
-    {
-        // Arrange
-        bool? result = null;
-
-        // Act
-        _ = SingleValueObservable.True.Subscribe(x => result = x);
-
-        // Assert
-        await Assert.That(result).IsTrue();
-    }
-
-    /// <summary>Tests that SingleValueObservable.Void emits RxVoid.Default value.</summary>
-    /// <returns>A <see cref="Task" /> representing the asynchronous operation.</returns>
-    [Test]
-    public async Task Observables_Unit_EmitsUnitDefault()
-    {
-        // Arrange
-        RxVoid? result = null;
-
-        // Act
-        _ = SingleValueObservable.Void.Subscribe(x => result = x);
-
-        // Assert
-        await Assert.That(result).IsEqualTo(RxVoid.Default);
-    }
-}
diff --git a/src/tests/ReactiveUI.Tests/InteractionsTest.cs b/src/tests/ReactiveUI.Tests/InteractionsTest.cs
index dbefe4df23..81036ed95b 100644
--- a/src/tests/ReactiveUI.Tests/InteractionsTest.cs
+++ b/src/tests/ReactiveUI.Tests/InteractionsTest.cs
@@ -103,7 +103,7 @@ public async Task HandlersCanContainAsynchronousCode()
             handler1AWasCalled = true;
         });
         var handler1B = interaction.RegisterHandler(x =>
-            SingleValueObservable.Void.Delay(TimeSpan.FromSeconds(1), scheduler)
+            ImmutableReturnRxVoidSignal.Instance.Delay(TimeSpan.FromSeconds(1), scheduler)
                 .Do(_ => x.SetOutput(OutputB)));
 
         using (handler1A)

From 846b60538281fb960958697e9edb4767c5b0e565 Mon Sep 17 00:00:00 2001
From: Glenn Watson <5834289+glennawatson@users.noreply.github.com>
Date: Fri, 26 Jun 2026 15:54:36 +1000
Subject: [PATCH 2/4] refactor: de-duplicate platform command binders with
 shared helpers

The near-identical EventHandler / EventHandler<TEventArgs> command-binding
overloads in the android and WinForms binders were copy-pasted, which
SonarCloud flagged as new duplication on the Primitives 5.7.0 PR. Hoist the
shared logic into one private static helper per binder instead.

- FlexibleCommandBinder: new BindEvent centralizes the command-parameter
  subscription, handler attach/detach and enabled-property sync. ForEvent
  (both overloads) and BindCommandToObject now only supply the typed handler
  wiring via a small closure.
- CreatesWinformsCommandBinding: new BindToHandler does the same for its two
  overloads, including the Component Enabled-property sync.
- Net ~57 fewer lines of platform code with identical behaviour (WinForms
  command-binding tests stay green).
---
 .../CreatesWinformsCommandBinding.cs          | 123 ++++++--------
 .../android/FlexibleCommandBinder.cs          | 156 +++++++-----------
 2 files changed, 111 insertions(+), 168 deletions(-)

diff --git a/src/ReactiveUI.Winforms/CreatesWinformsCommandBinding.cs b/src/ReactiveUI.Winforms/CreatesWinformsCommandBinding.cs
index b9ea756f6d..aa19b8a57e 100644
--- a/src/ReactiveUI.Winforms/CreatesWinformsCommandBinding.cs
+++ b/src/ReactiveUI.Winforms/CreatesWinformsCommandBinding.cs
@@ -239,53 +239,14 @@ public IDisposable? BindCommandToObject<
         ArgumentExceptionHelper.ThrowIfNull(addHandler);
         ArgumentExceptionHelper.ThrowIfNull(removeHandler);
 
-        if (command is null)
-        {
-            return EmptyDisposable.Instance;
-        }
-
-        object? latestParameter = null;
-
-        void Handler(object? s, TEventArgs e)
-        {
-            var param = Volatile.Read(ref latestParameter);
-            if (!command.CanExecute(param))
+        return command is null
+            ? EmptyDisposable.Instance
+            : BindToHandler(command, target, typeof(T), commandParameter, execute =>
             {
-                return;
-            }
-
-            command.Execute(param);
-        }
-
-        var ret = new MultipleDisposable { commandParameter.Subscribe(new DelegateObserver<object?>(x => Volatile.Write(ref latestParameter, x))) };
-
-        addHandler(Handler);
-        ret.Add(new ActionDisposable(() => removeHandler(Handler)));
-
-        // Handle Enabled property binding for Components
-        var targetType = typeof(T);
-        if (typeof(Component).IsAssignableFrom(targetType))
-        {
-            var enabledProperty = targetType.GetRuntimeProperty("Enabled");
-
-            if (enabledProperty is null)
-            {
-                return ret;
-            }
-
-            // Replaces FromEvent(CanExecuteChanged).StartWith(initial).Subscribe(...).
-            var canExecuteChanged = new FromEventObservable<bool>(onNext =>
-            {
-                void CanExecuteHandler(object? sender, EventArgs e) => onNext(command.CanExecute(Volatile.Read(ref latestParameter)));
-                command.CanExecuteChanged += CanExecuteHandler;
-                return new ActionDisposable(() => command.CanExecuteChanged -= CanExecuteHandler);
+                void Handler(object? s, TEventArgs e) => execute();
+                addHandler(Handler);
+                return new ActionDisposable(() => removeHandler(Handler));
             });
-
-            ret.Add(new StartWithObservable<bool>(canExecuteChanged, command.CanExecute(latestParameter))
-                .Subscribe(new DelegateObserver<bool>(x => enabledProperty.SetValue(target, x, null))));
-        }
-
-        return ret;
     }
 
     /// <summary>
@@ -316,14 +277,40 @@ public IDisposable? BindCommandToObject<
         ArgumentExceptionHelper.ThrowIfNull(addHandler);
         ArgumentExceptionHelper.ThrowIfNull(removeHandler);
 
-        if (command is null)
-        {
-            return EmptyDisposable.Instance;
-        }
+        return command is null
+            ? EmptyDisposable.Instance
+            : BindToHandler(command, target, typeof(T), commandParameter, execute =>
+            {
+                void Handler(object? s, EventArgs e) => execute();
+                addHandler(Handler);
+                return new ActionDisposable(() => removeHandler(Handler));
+            });
+    }
 
+    /// <summary>
+    /// Shared command-binding core: subscribes the command parameter, attaches the event handler that executes the
+    /// command when it can, and — for <see cref="Component"/> targets that expose an <c>Enabled</c> property — keeps
+    /// that property in sync with <see cref="ICommand.CanExecute(object?)"/>. Each public overload supplies
+    /// <paramref name="subscribeHandler"/> to wire its own strongly typed event delegate; everything else is identical.
+    /// </summary>
+    /// <param name="command">The command to bind.</param>
+    /// <param name="target">The target object whose <c>Enabled</c> property is synchronized.</param>
+    /// <param name="targetType">The declared target type used to discover the <c>Enabled</c> property.</param>
+    /// <param name="commandParameter">An observable that supplies command parameter values.</param>
+    /// <param name="subscribeHandler">Attaches a handler that invokes the supplied callback when the event fires and returns a disposable that detaches it.</param>
+    /// <returns>A disposable that unbinds the command.</returns>
+    private static MultipleDisposable BindToHandler(
+        ICommand command,
+        object target,
+        Type targetType,
+        IObservable<object?> commandParameter,
+        Func<Action, IDisposable> subscribeHandler)
+    {
         object? latestParameter = null;
 
-        void Handler(object? s, EventArgs e)
+        var ret = new MultipleDisposable { commandParameter.Subscribe(new DelegateObserver<object?>(x => Volatile.Write(ref latestParameter, x))) };
+
+        ret.Add(subscribeHandler(() =>
         {
             var param = Volatile.Read(ref latestParameter);
             if (!command.CanExecute(param))
@@ -332,34 +319,28 @@ void Handler(object? s, EventArgs e)
             }
 
             command.Execute(param);
-        }
-
-        var ret = new MultipleDisposable { commandParameter.Subscribe(new DelegateObserver<object?>(x => Volatile.Write(ref latestParameter, x))) };
-
-        addHandler(Handler);
-        ret.Add(new ActionDisposable(() => removeHandler(Handler)));
+        }));
 
-        // Handle Enabled property binding for Components
-        var targetType = typeof(T);
+        // We initially only accepted Controls here, but this is too restrictive: there are a number of
+        // Components that can trigger Commands and also have an Enabled property, just like Controls
+        // (for example System.Windows.Forms.ToolStripButton).
         if (typeof(Component).IsAssignableFrom(targetType))
         {
             var enabledProperty = targetType.GetRuntimeProperty("Enabled");
 
-            if (enabledProperty is null)
+            if (enabledProperty is not null)
             {
-                return ret;
+                // Replaces FromEvent(CanExecuteChanged).StartWith(initial).Subscribe(...).
+                var canExecuteChanged = new FromEventObservable<bool>(onNext =>
+                {
+                    void CanExecuteHandler(object? sender, EventArgs e) => onNext(command.CanExecute(Volatile.Read(ref latestParameter)));
+                    command.CanExecuteChanged += CanExecuteHandler;
+                    return new ActionDisposable(() => command.CanExecuteChanged -= CanExecuteHandler);
+                });
+
+                ret.Add(new StartWithObservable<bool>(canExecuteChanged, command.CanExecute(Volatile.Read(ref latestParameter)))
+                    .Subscribe(new DelegateObserver<bool>(x => enabledProperty.SetValue(target, x, null))));
             }
-
-            // Replaces FromEvent(CanExecuteChanged).StartWith(initial).Subscribe(...).
-            var canExecuteChanged = new FromEventObservable<bool>(onNext =>
-            {
-                void CanExecuteHandler(object? sender, EventArgs e) => onNext(command.CanExecute(Volatile.Read(ref latestParameter)));
-                command.CanExecuteChanged += CanExecuteHandler;
-                return new ActionDisposable(() => command.CanExecuteChanged -= CanExecuteHandler);
-            });
-
-            ret.Add(new StartWithObservable<bool>(canExecuteChanged, command.CanExecute(latestParameter))
-                .Subscribe(new DelegateObserver<bool>(x => enabledProperty.SetValue(target, x, null))));
         }
 
         return ret;
diff --git a/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs b/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs
index d1b719a713..9b3146e597 100644
--- a/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs
+++ b/src/ReactiveUI/Platforms/android/FlexibleCommandBinder.cs
@@ -134,13 +134,6 @@ public IDisposable? BindCommandToObject<
             return EmptyDisposable.Instance;
         }
 
-        commandParameter ??= new ReturnSignal<object?>(target, Sequencer.Immediate);
-
-        object? latestParam = null;
-
-        var parameterSub = commandParameter.Subscribe(new DelegateObserver<object?>(x => Volatile.Write(ref latestParam, x)));
-        addHandler(Handler);
-
         Action<object?, object?, object?[]?>? enabledSetter = null;
         try
         {
@@ -155,34 +148,12 @@ public IDisposable? BindCommandToObject<
             enabledSetter = null;
         }
 
-        IDisposable? canExecuteSub = null;
-        if (enabledSetter is not null)
+        return BindEvent(command, target, commandParameter, enabledSetter, execute =>
         {
-            enabledSetter(target, command.CanExecute(Volatile.Read(ref latestParam)), null);
-
-            canExecuteSub = new CanExecuteChangedObservable(command, () => command.CanExecute(Volatile.Read(ref latestParam)))
-                .Subscribe(new DelegateObserver<bool>(x => enabledSetter(target, x, null)));
-        }
-
-        return canExecuteSub is null
-            ? new MultipleDisposable(
-                parameterSub,
-                new ActionDisposable(() => removeHandler(Handler)))
-            : new MultipleDisposable(
-                parameterSub,
-                canExecuteSub,
-                new ActionDisposable(() => removeHandler(Handler)));
-
-        void Handler(object? sender, TEventArgs e)
-        {
-            var param = Volatile.Read(ref latestParam);
-            if (!command.CanExecute(param))
-            {
-                return;
-            }
-
-            command.Execute(param);
-        }
+            void Handler(object? sender, TEventArgs e) => execute();
+            addHandler(Handler);
+            return new ActionDisposable(() => removeHandler(Handler));
+        });
     }
 
     /// <summary>Creates a commands binding from event and a property.</summary>
@@ -264,41 +235,12 @@ protected static IDisposable ForEvent<TEventArgs>(
         ArgumentExceptionHelper.ThrowIfNull(addHandler);
         ArgumentExceptionHelper.ThrowIfNull(removeHandler);
 
-        commandParameter ??= new ReturnSignal<object?>(target, Sequencer.Immediate);
-
-        object? latestParam = null;
-
-        var parameterSub = commandParameter.Subscribe(new DelegateObserver<object?>(x => Volatile.Write(ref latestParam, x)));
-
-        addHandler(Handler);
-
-        if (enabledSetter is null)
-        {
-            return new MultipleDisposable(
-                parameterSub,
-                new ActionDisposable(() => removeHandler(Handler)));
-        }
-
-        enabledSetter(target, command.CanExecute(Volatile.Read(ref latestParam)), null);
-
-        var canExecuteSub = new CanExecuteChangedObservable(command, () => command.CanExecute(Volatile.Read(ref latestParam)))
-            .Subscribe(new DelegateObserver<bool>(x => enabledSetter(target, x, null)));
-
-        return new MultipleDisposable(
-            parameterSub,
-            canExecuteSub,
-            new ActionDisposable(() => removeHandler(Handler)));
-
-        void Handler(object? sender, TEventArgs e)
+        return BindEvent(command, target, commandParameter, enabledSetter, execute =>
         {
-            var param = Volatile.Read(ref latestParam);
-            if (!command.CanExecute(param))
-            {
-                return;
-            }
-
-            command.Execute(param);
-        }
+            void Handler(object? sender, TEventArgs e) => execute();
+            addHandler(Handler);
+            return new ActionDisposable(() => removeHandler(Handler));
+        });
     }
 
     /// <summary>
@@ -331,19 +273,63 @@ protected static IDisposable ForEvent(
         ArgumentExceptionHelper.ThrowIfNull(addHandler);
         ArgumentExceptionHelper.ThrowIfNull(removeHandler);
 
+        return BindEvent(command, target, commandParameter, enabledSetter, execute =>
+        {
+            void Handler(object? sender, EventArgs e) => execute();
+            addHandler(Handler);
+            return new ActionDisposable(() => removeHandler(Handler));
+        });
+    }
+
+    /// <summary>Registers an observable factory for the specified type and property.</summary>
+    /// <param name="type">Type.</param>
+    /// <param name="affinity">The affinity for the type.</param>
+    /// <param name="createBinding">Creates the binding.</param>
+    protected void Register(
+        Type type,
+        int affinity,
+        Func<ICommand?, object?, IObservable<object?>, IDisposable> createBinding) =>
+        _config[type] = new() { Affinity = affinity, CreateBinding = createBinding };
+
+    /// <summary>
+    /// Shared command-binding core: subscribes the command parameter, attaches the event handler that executes the
+    /// command when it can, and optionally keeps an enabled-like property in sync with
+    /// <see cref="ICommand.CanExecute(object?)"/>. Each public overload supplies <paramref name="subscribeHandler"/>
+    /// to wire its own strongly typed event delegate; everything else is identical, so it lives here once.
+    /// </summary>
+    /// <param name="command">The command to bind.</param>
+    /// <param name="target">The event source object.</param>
+    /// <param name="commandParameter">Observable producing command parameter values. If <see langword="null"/>, <paramref name="target"/> is used.</param>
+    /// <param name="enabledSetter">Optional setter for an enabled-like property; enabled synchronization is skipped when <see langword="null"/>.</param>
+    /// <param name="subscribeHandler">Attaches a handler that invokes the supplied callback when the event fires and returns a disposable that detaches it.</param>
+    /// <returns>A disposable that unbinds the command and stops enabled synchronization.</returns>
+    private static MultipleDisposable BindEvent(
+        ICommand command,
+        object? target,
+        IObservable<object?>? commandParameter,
+        Action<object?, object?, object?[]?>? enabledSetter,
+        Func<Action, IDisposable> subscribeHandler)
+    {
         commandParameter ??= new ReturnSignal<object?>(target, Sequencer.Immediate);
 
         object? latestParam = null;
 
         var parameterSub = commandParameter.Subscribe(new DelegateObserver<object?>(x => Volatile.Write(ref latestParam, x)));
 
-        addHandler(Handler);
+        var handlerSub = subscribeHandler(() =>
+        {
+            var param = Volatile.Read(ref latestParam);
+            if (!command.CanExecute(param))
+            {
+                return;
+            }
+
+            command.Execute(param);
+        });
 
         if (enabledSetter is null)
         {
-            return new MultipleDisposable(
-                parameterSub,
-                new ActionDisposable(() => removeHandler(Handler)));
+            return new MultipleDisposable(parameterSub, handlerSub);
         }
 
         enabledSetter(target, command.CanExecute(Volatile.Read(ref latestParam)), null);
@@ -351,33 +337,9 @@ protected static IDisposable ForEvent(
         var canExecuteSub = new CanExecuteChangedObservable(command, () => command.CanExecute(Volatile.Read(ref latestParam)))
             .Subscribe(new DelegateObserver<bool>(x => enabledSetter(target, x, null)));
 
-        return new MultipleDisposable(
-            parameterSub,
-            canExecuteSub,
-            new ActionDisposable(() => removeHandler(Handler)));
-
-        void Handler(object? sender, EventArgs e)
-        {
-            var param = Volatile.Read(ref latestParam);
-            if (!command.CanExecute(param))
-            {
-                return;
-            }
-
-            command.Execute(param);
-        }
+        return new MultipleDisposable(parameterSub, canExecuteSub, handlerSub);
     }
 
-    /// <summary>Registers an observable factory for the specified type and property.</summary>
-    /// <param name="type">Type.</param>
-    /// <param name="affinity">The affinity for the type.</param>
-    /// <param name="createBinding">Creates the binding.</param>
-    protected void Register(
-        Type type,
-        int affinity,
-        Func<ICommand?, object?, IObservable<object?>, IDisposable> createBinding) =>
-        _config[type] = new() { Affinity = affinity, CreateBinding = createBinding };
-
     /// <summary>
     /// Emits the command's current can-execute value each time <see cref="ICommand.CanExecuteChanged"/> fires —
     /// replacing <c>Observable.FromEvent</c> over that event. The handler is detached when the subscription is disposed.

From 50900ded6f55ac666ac481cc22032b8dc69f01d8 Mon Sep 17 00:00:00 2001
From: Glenn Watson <5834289+glennawatson@users.noreply.github.com>
Date: Fri, 26 Jun 2026 17:31:33 +1000
Subject: [PATCH 3/4] ci: exclude emulator/device-only platform code from Sonar
 coverage
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The SonarCloud scan runs on windows-latest, so it executes the core, WPF,
WinUI and WinForms tests — that platform code stays measured (the WinForms
command binder reads ~99%). It cannot run the android/apple per-OS code under
ReactiveUI/Platforms/{android,apple-common,ios,mac,tvos,uikit-common,
mobile-common}, which needs an emulator, device or mac runner, so those files
always report 0% coverage and drag the new-code coverage gate down.

Exclude exactly those per-OS directories from coverage only. Platforms/net and
Platforms/netstandard2.0 stay measured (the core tests exercise them), and
every excluded file is still fully analysed for bugs, smells and duplication —
this is not a duplication exclusion.
---
 .github/workflows/sonarcloud.yml | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/sonarcloud.yml b/.github/workflows/sonarcloud.yml
index c29dd12042..97ef982be0 100644
--- a/.github/workflows/sonarcloud.yml
+++ b/.github/workflows/sonarcloud.yml
@@ -18,10 +18,18 @@ jobs:
             sonarProjectKey: reactiveui_ReactiveUI
             sonarOrganization: reactiveui
             sonarExclusions: '**/tests/**,**/integrationtests/**,**/benchmarks/**,**/examples/**,**/TestResults/**'
-            # Shared/Platform fused Rx-replacement observables are compile-linked into every platform assembly and
-            # only exercisable via platform (WPF/WinForms/MAUI/mobile) tests, so exclude them from coverage like
-            # generated code. The Shared/ root helpers stay measured (covered by the core test suite).
-            sonarCoverageExclusions: '**/tests/**,**/integrationtests/**,**/benchmarks/**,**/examples/**,**/*Tests/**,**/*Tests.cs,**/Generated/**,**/Shared/Platform/**'
+            # Coverage exclusions (sonar.coverage.exclusions) — code the Sonar scan cannot execute, so counting it
+            # would only ever report 0%. This is COVERAGE ONLY; every excluded file is still fully analysed for bugs,
+            # smells and duplication.
+            #  - Shared/Platform fused Rx-replacement observables are compile-linked into every platform assembly and
+            #    only exercisable via platform tests; the Shared/ root helpers stay measured (core test suite covers them).
+            #  - The scan runs on windows-latest (see workflow-common-sonarcloud.yml runsOn) so it builds and runs the
+            #    core + WPF + WinUI + WinForms tests — that platform code stays measured (e.g. CreatesWinformsCommandBinding
+            #    sits at ~99%). What it CANNOT run is the android/apple per-OS code under ReactiveUI/Platforms/{android,
+            #    apple-common,ios,mac,tvos,uikit-common,mobile-common}: those need an emulator/device or a mac runner, so
+            #    their tests never execute in CI and the files always read 0%. Exclude exactly those per-OS dirs from
+            #    coverage (Platforms/net and Platforms/netstandard2.0 stay measured — they run under the core tests).
+            sonarCoverageExclusions: '**/tests/**,**/integrationtests/**,**/benchmarks/**,**/examples/**,**/*Tests/**,**/*Tests.cs,**/Generated/**,**/Shared/Platform/**,**/Platforms/android/**,**/Platforms/apple-common/**,**/Platforms/ios/**,**/Platforms/mac/**,**/Platforms/tvos/**,**/Platforms/uikit-common/**,**/Platforms/mobile-common/**'
             # CPD (copy/paste detection) exclusions:
             #  - tests/integrationtests/Benchmarks/examples are non-shipping code. The examples are
             #    demo apps that deliberately parallel each other (each sample reimplements the same

From 66b9739da77567e109f88c18f0c88c677de17a3e Mon Sep 17 00:00:00 2001
From: Glenn Watson <5834289+glennawatson@users.noreply.github.com>
Date: Fri, 26 Jun 2026 18:48:30 +1000
Subject: [PATCH 4/4] fix(maui): run RoutedViewHost initial sync on the main
 thread
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The constructor kicked off the initial navigation-stack reconciliation with a
fire-and-forget Task.Run, mutating MAUI navigation state from a thread-pool
thread. That raced with any push happening right after construction: the
background SyncNavigationStacksAsync could interleave its own PushAsync with the
caller's, leaving CurrentPage pointing at the wrong page. It surfaced as the
intermittent RoutedViewHostTest.InvalidateCurrentViewModel_MatchingViewModelType_
UpdatesViewModel failure on the slower macOS CI runner.

Marshal the initial sync onto RxSchedulers.MainThreadScheduler instead — the
same pattern the rest of the class already uses (OnNavigateRequested). UI
navigation is now only ever mutated on the UI thread and the initial sync is
serialized with later navigation rather than racing it.

Verified: full ReactiveUI.Maui.Tests suite 202/202; RoutedViewHostTest stressed
20x with zero failures.
---
 src/ReactiveUI.Maui/RoutedViewHost.cs | 36 ++++++++++++++++++---------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/src/ReactiveUI.Maui/RoutedViewHost.cs b/src/ReactiveUI.Maui/RoutedViewHost.cs
index 1571dd8b34..edc1c6dc00 100644
--- a/src/ReactiveUI.Maui/RoutedViewHost.cs
+++ b/src/ReactiveUI.Maui/RoutedViewHost.cs
@@ -64,18 +64,11 @@ public RoutedViewHost()
         SubscribeToPopped();
         SubscribeToPoppedToRoot();
 
-        // Perform initial sync asynchronously
-        _ = Task.Run(async () =>
-        {
-            try
-            {
-                await SyncNavigationStacksAsync();
-            }
-            catch (Exception ex)
-            {
-                this.Log().Error(ex, "Failed to perform initial navigation stack sync");
-            }
-        });
+        // Perform the initial navigation-stack sync on the main thread rather than a thread-pool thread. MAUI
+        // navigation state must only be mutated from the UI thread, and marshalling here serialises the initial
+        // sync with any subsequent navigation instead of racing it on a background thread (the previous Task.Run
+        // could interleave its own PushAsync with a caller's push and leave CurrentPage pointing at the wrong page).
+        _ = RxSchedulers.MainThreadScheduler.Schedule(() => _ = PerformInitialNavigationSyncAsync());
     }
 
     /// <summary>Gets or sets the <see cref="RoutingState"/> of the view model stack.</summary>
@@ -225,6 +218,25 @@ protected async Task SyncNavigationStacksAsync()
         }
     }
 
+    /// <summary>Performs the one-time initial navigation-stack sync, logging any failure instead of faulting an unobserved task.</summary>
+    /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
+    [RequiresUnreferencedCode(
+        "This method uses reflection to determine the view model type at runtime, which may be incompatible with trimming.")]
+    [RequiresDynamicCode(
+        "If some of the generic arguments are annotated (either with DynamicallyAccessedMembersAttribute, or generic constraints), " +
+        "trimming can't validate that the requirements of those annotations are met.")]
+    private async Task PerformInitialNavigationSyncAsync()
+    {
+        try
+        {
+            await SyncNavigationStacksAsync();
+        }
+        catch (Exception ex)
+        {
+            this.Log().Error(ex, "Failed to perform initial navigation stack sync");
+        }
+    }
+
     /// <summary>Subscribes to <see cref="RoutingState.NavigationStack"/> changes and resyncs when the stack is cleared.</summary>
     [RequiresUnreferencedCode(
         "This method uses reflection to determine the view model type at runtime, which may be incompatible with trimming.")]