diff --git a/src/ZB.MOM.WW.ScadaBridge.Communication/Actors/SiteAlarmAggregatorActor.cs b/src/ZB.MOM.WW.ScadaBridge.Communication/Actors/SiteAlarmAggregatorActor.cs
index 869d9886..c1c53432 100644
--- a/src/ZB.MOM.WW.ScadaBridge.Communication/Actors/SiteAlarmAggregatorActor.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.Communication/Actors/SiteAlarmAggregatorActor.cs
@@ -63,15 +63,15 @@ public sealed class SiteAlarmAggregatorActor : ReceiveActor, IWithTimers
     /// <summary>True while a coalesced publish is armed (dirty deltas awaiting one tick). Actor-thread only.</summary>
     private bool _publishPending;
 
-    /// <summary>Delay between gRPC reconnection attempts. Settable for tests.</summary>
-    internal static TimeSpan ReconnectDelay { get; set; } = TimeSpan.FromSeconds(5);
+    /// <summary>Delay between gRPC reconnection attempts (ctor-injected; production default 5s).</summary>
+    private readonly TimeSpan _reconnectDelay;
 
     /// <summary>
     /// How long a freshly-opened gRPC stream must stay up before its retry budget is
-    /// considered recovered (mirrors <see cref="DebugStreamBridgeActor.StabilityWindow"/>).
-    /// Settable for tests.
+    /// considered recovered (mirrors <see cref="DebugStreamBridgeActor.StabilityWindow"/>);
+    /// ctor-injected (production default 60s).
     /// </summary>
-    internal static TimeSpan StabilityWindow { get; set; } = TimeSpan.FromSeconds(60);
+    private readonly TimeSpan _stabilityWindow;
 
     private int _retryCount;
     private bool _useNodeA = true;
@@ -143,6 +143,10 @@ public sealed class SiteAlarmAggregatorActor : ReceiveActor, IWithTimers
     /// into one publish per window (review 02 round 2, N6); <see cref="TimeSpan.Zero"/>
     /// restores per-delta publishing (legacy). Seed/reconcile publishes stay immediate.
     /// </param>
+    /// <param name="reconnectDelay">Delay between gRPC reconnection attempts (production 5s).</param>
+    /// <param name="stabilityWindow">
+    /// How long a fresh gRPC stream must stay up before its retry budget recovers (production 60s).
+    /// </param>
     public SiteAlarmAggregatorActor(
         string siteIdentifier,
         string correlationId,
@@ -152,7 +156,9 @@ public sealed class SiteAlarmAggregatorActor : ReceiveActor, IWithTimers
         string grpcNodeAAddress,
         string grpcNodeBAddress,
         TimeSpan reconcileInterval,
-        TimeSpan publishCoalesce)
+        TimeSpan publishCoalesce,
+        TimeSpan reconnectDelay,
+        TimeSpan stabilityWindow)
     {
         _siteIdentifier = siteIdentifier;
         _correlationId = correlationId;
@@ -163,6 +169,8 @@ public sealed class SiteAlarmAggregatorActor : ReceiveActor, IWithTimers
         _grpcNodeBAddress = grpcNodeBAddress;
         _reconcileInterval = reconcileInterval;
         _publishCoalesce = publishCoalesce;
+        _reconnectDelay = reconnectDelay;
+        _stabilityWindow = stabilityWindow;
 
         // Live delta from the site-wide alarm stream (marshalled in via Self.Tell).
         // A received delta must NOT reset the retry budget (a flapping stream that
@@ -499,7 +507,7 @@ public sealed class SiteAlarmAggregatorActor : ReceiveActor, IWithTimers
         _grpcCts?.Dispose();
         _grpcCts = new CancellationTokenSource();
 
-        Timers.StartSingleTimer(StabilityTimerKey, new GrpcAlarmStreamStable(), StabilityWindow);
+        Timers.StartSingleTimer(StabilityTimerKey, new GrpcAlarmStreamStable(), _stabilityWindow);
 
         var generation = ++_streamGeneration;
         var client = _grpcFactory.GetOrCreate(_siteIdentifier, endpoint);
@@ -558,7 +566,7 @@ public sealed class SiteAlarmAggregatorActor : ReceiveActor, IWithTimers
         if (_retryCount == 1)
             Self.Tell(new ReconnectAlarmStream());
         else
-            Timers.StartSingleTimer(ReconnectTimerKey, new ReconnectAlarmStream(), ReconnectDelay);
+            Timers.StartSingleTimer(ReconnectTimerKey, new ReconnectAlarmStream(), _reconnectDelay);
     }
 
     private void CleanupGrpc()
diff --git a/src/ZB.MOM.WW.ScadaBridge.Communication/SiteAlarmLiveCacheService.cs b/src/ZB.MOM.WW.ScadaBridge.Communication/SiteAlarmLiveCacheService.cs
index 568dc538..13ec0c1b 100644
--- a/src/ZB.MOM.WW.ScadaBridge.Communication/SiteAlarmLiveCacheService.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.Communication/SiteAlarmLiveCacheService.cs
@@ -234,7 +234,9 @@ public sealed class SiteAlarmLiveCacheService : ISiteAlarmLiveCache
                     grpcA,
                     grpcB,
                     _options.LiveAlarmCacheReconcileInterval,
-                    _options.LiveAlarmCachePublishCoalesce));
+                    _options.LiveAlarmCachePublishCoalesce,
+                    TimeSpan.FromSeconds(5),    // reconnect delay — former ReconnectDelay static default
+                    TimeSpan.FromSeconds(60))); // stability window — former StabilityWindow static default
 
                 entry.Actor = system.ActorOf(props, $"site-alarm-aggregator-{entry.SiteId}-{Guid.NewGuid():N}");
                 entry.StartRetryTimer?.Dispose();
diff --git a/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteAlarmAggregatorActorTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteAlarmAggregatorActorTests.cs
index e4e7b21d..35c09662 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteAlarmAggregatorActorTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteAlarmAggregatorActorTests.cs
@@ -24,10 +24,12 @@ public class SiteAlarmAggregatorActorTests : TestKit
 
     public SiteAlarmAggregatorActorTests() : base(@"akka.loglevel = WARNING")
     {
-        SiteAlarmAggregatorActor.ReconnectDelay = TimeSpan.FromMilliseconds(50);
-        SiteAlarmAggregatorActor.StabilityWindow = TimeSpan.FromSeconds(30);
     }
 
+    // Former process-global static test seams, now ctor-injected per actor (R2 T12).
+    private static readonly TimeSpan TestReconnectDelay = TimeSpan.FromMilliseconds(50);
+    private static readonly TimeSpan TestStabilityWindow = TimeSpan.FromSeconds(30);
+
     // ── Test doubles ────────────────────────────────────────────────────────────
 
     /// <summary>
@@ -146,7 +148,9 @@ public class SiteAlarmAggregatorActorTests : TestKit
         var props = Props.Create(() => new SiteAlarmAggregatorActor(
             SiteId, "corr-1", seed.Seed, sink.Publish, factory, GrpcNodeA, GrpcNodeB,
             reconcileInterval ?? TimeSpan.FromMinutes(10),
-            publishCoalesce ?? TimeSpan.Zero));
+            publishCoalesce ?? TimeSpan.Zero,
+            TestReconnectDelay,
+            TestStabilityWindow));
 
         var actor = Sys.ActorOf(props);
         return (actor, seed, sink, factory);