diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DeployHappyPathTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DeployHappyPathTests.cs
index e0fb69b7..076c9c4c 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DeployHappyPathTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DeployHappyPathTests.cs
@@ -40,7 +40,7 @@ public sealed class DeployHappyPathTests
             await using var db = await CreateDbAsync(harness);
             var d = await db.Deployments.AsNoTracking().FirstOrDefaultAsync(d => d.DeploymentId == deploymentId, Ct);
             return d?.Status == DeploymentStatus.Sealed;
-        }, TimeSpan.FromSeconds(15));
+        }, TwoNodeClusterHarness.DeploySealTimeout);
 
         await using var db = await CreateDbAsync(harness);
         var deployment = await db.Deployments.AsNoTracking()
@@ -74,7 +74,7 @@ public sealed class DeployHappyPathTests
             var d = await db.Deployments.AsNoTracking()
                 .FirstOrDefaultAsync(d => d.DeploymentId == first.DeploymentId!.Value.Value, Ct);
             return d?.Status == DeploymentStatus.Sealed;
-        }, TimeSpan.FromSeconds(15));
+        }, TwoNodeClusterHarness.DeploySealTimeout);
 
         // Same DB state → same revision hash → AdminOperations short-circuits with NoChanges,
         // OR (if it accepts) the second dispatch is idempotent (DriverHostActor recognises
@@ -90,7 +90,7 @@ public sealed class DeployHappyPathTests
                 var d = await db.Deployments.AsNoTracking()
                     .FirstOrDefaultAsync(d => d.DeploymentId == second.DeploymentId!.Value.Value, Ct);
                 return d?.Status == DeploymentStatus.Sealed;
-            }, TimeSpan.FromSeconds(15));
+            }, TwoNodeClusterHarness.DeploySealTimeout);
 
             second.RevisionHash!.Value.Value.ShouldBe(first.RevisionHash!.Value.Value);
         }
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/EquipmentNamespaceMaterializationTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/EquipmentNamespaceMaterializationTests.cs
index 3811e137..dd78d608 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/EquipmentNamespaceMaterializationTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/EquipmentNamespaceMaterializationTests.cs
@@ -85,7 +85,7 @@ public sealed class EquipmentNamespaceMaterializationTests
                 return true;
             }
             return false;
-        }, TimeSpan.FromSeconds(15));
+        }, TwoNodeClusterHarness.DeploySealTimeout);
 
         var composition = DeploymentArtifact.ParseComposition(artifact);
 
@@ -182,7 +182,7 @@ public sealed class EquipmentNamespaceMaterializationTests
                 return true;
             }
             return false;
-        }, TimeSpan.FromSeconds(20));
+        }, TwoNodeClusterHarness.DeploySealTimeout);
 
         await using (var db = await CreateDbAsync(harness))
         {
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FailoverDuringDeployTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FailoverDuringDeployTests.cs
index c64480e7..ebe35df7 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FailoverDuringDeployTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FailoverDuringDeployTests.cs
@@ -87,7 +87,7 @@ public sealed class FailoverDuringDeployTests
             await using var pollDb = await CreateDbAsync(harness);
             return await pollDb.NodeDeploymentStates.AsNoTracking()
                 .CountAsync(s => s.DeploymentId == deploymentId, Ct) == 2;
-        }, TimeSpan.FromSeconds(15));
+        }, TwoNodeClusterHarness.DeploySealTimeout);
 
         await using var db = await CreateDbAsync(harness);
         var nodeStates = await db.NodeDeploymentStates.AsNoTracking()
@@ -143,7 +143,7 @@ public sealed class FailoverDuringDeployTests
             var d = await pollDb.Deployments.AsNoTracking()
                 .FirstOrDefaultAsync(d => d.DeploymentId == deploymentId, Ct);
             return d?.Status == DeploymentStatus.Sealed;
-        }, TimeSpan.FromSeconds(15));
+        }, TwoNodeClusterHarness.DeploySealTimeout);
 
         await using var db = await CreateDbAsync(harness);
         var nodeStates = await db.NodeDeploymentStates.AsNoTracking()
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FleetDiagnosticsRoundTripTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FleetDiagnosticsRoundTripTests.cs
index 2d8afa3c..d7243abc 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FleetDiagnosticsRoundTripTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/FleetDiagnosticsRoundTripTests.cs
@@ -67,7 +67,7 @@ public sealed class FleetDiagnosticsRoundTripTests
             {
                 var snap = await diagnostics.GetDiagnosticsAsync(nodeId, Ct);
                 return snap.CurrentRevision == expectedRev;
-            }, TimeSpan.FromSeconds(15));
+            }, TwoNodeClusterHarness.DeploySealTimeout);
         }
     }
 
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/TwoNodeClusterHarness.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/TwoNodeClusterHarness.cs
index c9e73d42..9e2558b5 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/TwoNodeClusterHarness.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/TwoNodeClusterHarness.cs
@@ -96,6 +96,16 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     // host:port into NodeId so the cluster membership stays distinct on different ports.
     public const string LoopbackHost = "127.0.0.1";
 
+    /// <summary>
+    ///     How long a deploy-seal assertion waits. Generous on purpose: since per-cluster mesh
+    ///     Phase 1 the coordinator waits for a real ApplyAck from every configured node before
+    ///     sealing, so this measures an end-to-end two-node deploy rather than — as it did when the
+    ///     expected-ack set came up empty — an immediate seal. The old 15s had enormous margin
+    ///     against "instant" and thin margin against the real thing, which showed up as deploy
+    ///     tests failing only under full-suite CPU contention.
+    /// </summary>
+    public static readonly TimeSpan DeploySealTimeout = TimeSpan.FromSeconds(45);
+
     /// <summary>Gets the Akka ActorSystem for node A.</summary>
     public ActorSystem NodeASystem => NodeA.Services.GetRequiredService<ActorSystem>();
     /// <summary>Gets the Akka ActorSystem for node B.</summary>