fix: scope reminder test clock to reminder service

src/Orleans.Reminders/ReminderService/LocalReminderService.cs

@@ -561,7 +561,10 @@ private async Task ReadAndReconcileRange(ISingleRange range, int rangeSerialNumb
         private void ReconcileTableEntry(ReminderEntry entry, long tableSequence, DateTime now, List<Task> stopTasks)
         {
             var key = new ReminderIdentity(entry.GrainId, entry.ReminderName);
-            var shouldLoad = IsReminderWithinLoadingWindow(entry, now, reminderOptions.ReminderLoadingWindow);
+            var nextTick = CalculateNextTickTime(entry, now);
+            // Keep distant schedules in storage; exact-due entries are intentionally skipped to simplify fake-time tests.
+            var isWithinLoadingWindow = nextTick <= now.AddClamped(reminderOptions.ReminderLoadingWindow);
+            var shouldLoad = nextTick > now && isWithinLoadingWindow;
             if (!localReminders.TryGetValue(key, out var localReminder))
             {
                 // Distant reminders remain exclusively in storage until a later refresh brings their next tick
@@ -592,7 +595,7 @@ private void ReconcileTableEntry(ReminderEntry entry, long tableSequence, DateTi
                 return;
             }
 
-            if (!shouldLoad)
+            if (!isWithinLoadingWindow || (state is LocalReminderState.Tombstone && !shouldLoad))
             {
                 LogTraceRemovingReminder(localReminder);
                 stopTasks.Add(

src/Orleans.Testing.Reminders/ReminderTestClock.cs

@@ -1,9 +1,9 @@
 #nullable enable
 
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Time.Testing;
 using Orleans.Hosting;
+using Orleans.Reminders;
 using Orleans.TestingHost;
 
 namespace Orleans.Testing.Reminders;
@@ -13,8 +13,8 @@ namespace Orleans.Testing.Reminders;
 /// </summary>
 /// <remarks>
 /// Attach an instance to an <see cref="InProcessTestClusterBuilder"/> before building the cluster.
-/// The attached clock replaces the silo <see cref="TimeProvider"/> and tunes
-/// <see cref="ReminderOptions"/> for deterministic reminder scheduling.
+/// The attached clock replaces the reminder subsystem's keyed <see cref="TimeProvider"/> and tunes
+/// <see cref="ReminderOptions"/> for deterministic reminder scheduling without affecting unrelated silo timers.
 /// </remarks>
 public sealed class ReminderTestClock : IDisposable
 {
@@ -74,7 +74,7 @@ public static ReminderTestClock Attach(
 
         builder.ConfigureSilo((_, siloBuilder) =>
         {
-            siloBuilder.Services.Replace(ServiceDescriptor.Singleton<TimeProvider>(clock.TimeProvider));
+            siloBuilder.Services.AddKeyedSingleton<TimeProvider>(ReminderTimeProviderNames.Reminders, clock.TimeProvider);
             siloBuilder.Services.PostConfigure<ReminderOptions>(options =>
             {
                 options.MinimumReminderPeriod = clock.MinimumReminderPeriod;

test/Orleans.Reminders.Tests/TimerTests/ReminderTests_TableGrain.cs

@@ -6,6 +6,7 @@
 using System.Reactive.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Orleans.Internal;
+using Orleans.Reminders;
 using Orleans.Testing.Reminders;
 using Orleans.TestingHost;
 using TestExtensions;
@@ -36,6 +37,8 @@ public class Fixture : BaseInProcessTestClusterFixture
 
             protected override void ConfigureTestCluster(InProcessTestClusterBuilder builder)
             {
+                // The controlled-read tests validate ordering within one reminder owner.
+                builder.Options.InitialSilosCount = 1;
                 _reminderClock = builder.AddReminderTestClock();
                 builder.ConfigureSilo((_, siloBuilder) =>
                 {
@@ -78,6 +81,19 @@ public ReminderTests_TableGrain(Fixture fixture) : base(fixture.ReminderClock, f
 
         // Basic tests
 
+        [Fact]
+        public void ReminderTestClock_IsScopedToReminderService()
+        {
+            foreach (var silo in HostedCluster.Silos)
+            {
+                var unkeyedProvider = silo.ServiceProvider.GetRequiredService<TimeProvider>();
+                var reminderProvider = silo.ServiceProvider.GetRequiredKeyedService<TimeProvider>(ReminderTimeProviderNames.Reminders);
+
+                Assert.Same(TimeProvider.System, unkeyedProvider);
+                Assert.NotSame(unkeyedProvider, reminderProvider);
+            }
+        }
+
         /// <summary>
         /// Tests basic reminder operations including stopping reminders by reference.
         /// </summary>