diff --git a/tests/PSProxmoxVE.Core.Tests/Services/BackupServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/BackupServiceTests.cs
index 915b0bc..4feafaf 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/BackupServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/BackupServiceTests.cs
@@ -57,15 +57,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void CreateBackup_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-            var config = new Dictionary<string, string> { ["vmid"] = "100" };
-
-            Assert.Throws<ArgumentNullException>("session", () => service.CreateBackup(null!, Node, config));
-        }
-
         [Fact]
         public void CreateBackup_NullConfig_ThrowsArgumentNullException()
         {
@@ -149,14 +140,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Empty(jobs);
         }
 
-        [Fact]
-        public void GetBackupJobs_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.GetBackupJobs(null!));
-        }
-
         // ---------------------------------------------------------------
         // GetBackupJob (single)
         // ---------------------------------------------------------------
@@ -192,22 +175,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("pbs-store", job.Storage);
         }
 
-        [Fact]
-        public void GetBackupJob_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.GetBackupJob(null!, "backup-001"));
-        }
-
-        [Fact]
-        public void GetBackupJob_NullId_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("id", () => service.GetBackupJob(CreateSession(), null!));
-        }
-
         // ---------------------------------------------------------------
         // CreateBackupJob
         // ---------------------------------------------------------------
@@ -244,15 +211,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void CreateBackupJob_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-            var config = new Dictionary<string, string> { ["vmid"] = "100" };
-
-            Assert.Throws<ArgumentNullException>("session", () => service.CreateBackupJob(null!, config));
-        }
-
         [Fact]
         public void CreateBackupJob_NullConfig_ThrowsArgumentNullException()
         {
@@ -292,24 +250,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void UpdateBackupJob_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-            var config = new Dictionary<string, string> { ["enabled"] = "1" };
-
-            Assert.Throws<ArgumentNullException>("session", () => service.UpdateBackupJob(null!, "id", config));
-        }
-
-        [Fact]
-        public void UpdateBackupJob_NullId_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-            var config = new Dictionary<string, string> { ["enabled"] = "1" };
-
-            Assert.Throws<ArgumentNullException>("id", () => service.UpdateBackupJob(CreateSession(), null!, config));
-        }
-
         [Fact]
         public void UpdateBackupJob_NullConfig_ThrowsArgumentNullException()
         {
@@ -340,22 +280,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             mockClient.Verify(c => c.DeleteAsync("cluster/backup/backup-001"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveBackupJob_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.RemoveBackupJob(null!, "id"));
-        }
-
-        [Fact]
-        public void RemoveBackupJob_NullId_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("id", () => service.RemoveBackupJob(CreateSession(), null!));
-        }
-
         // ---------------------------------------------------------------
         // GetNotBackedUp
         // ---------------------------------------------------------------
@@ -404,14 +328,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Empty(result);
         }
 
-        [Fact]
-        public void GetNotBackedUp_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new BackupService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.GetNotBackedUp(null!));
-        }
-
         // ---------------------------------------------------------------
         // Constructor
         // ---------------------------------------------------------------
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/CloudInitServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/CloudInitServiceTests.cs
index 1d20cac..b578d21 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/CloudInitServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/CloudInitServiceTests.cs
@@ -117,40 +117,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             mockClient.Verify(c => c.PutAsync("nodes/pve1/qemu/100/cloudinit", null), Times.Once);
         }
 
-        [Fact]
-        public void GetCloudInitConfig_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new CloudInitService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetCloudInitConfig(null!, "pve1", 100));
-        }
-
-        [Fact]
-        public void SetCloudInitConfig_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new CloudInitService(mockClient.Object);
-            var config = new Dictionary<string, object> { ["ciuser"] = "test" };
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.SetCloudInitConfig(null!, "pve1", 100, config));
-        }
-
-        [Fact]
-        public void RegenerateCloudInitImage_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new CloudInitService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.RegenerateCloudInitImage(null!, "pve1", 100));
-        }
-
         [Fact]
         public void Constructor_NullClient_ThrowsArgumentNullException()
         {
@@ -197,13 +163,5 @@ namespace PSProxmoxVE.Core.Tests.Services
             // Assert
             mockClient.Verify(c => c.GetAsync("nodes/pve%20node/qemu/100/config"), Times.Once);
         }
-
-        [Fact]
-        public void GetFullVmConfig_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new CloudInitService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>(() => service.GetFullVmConfig(null!, "pve1", 100));
-        }
     }
 }
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/ClusterConfigServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/ClusterConfigServiceTests.cs
index 185220c..03970a2 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/ClusterConfigServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/ClusterConfigServiceTests.cs
@@ -380,50 +380,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Contains("did not contain a 'data' field", ex.Message);
         }
 
-        [Fact]
-        public void GetClusterConfig_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new ClusterConfigService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetClusterConfig(null!));
-        }
-
-        [Fact]
-        public void GetConfigNodes_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new ClusterConfigService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetConfigNodes(null!));
-        }
-
-        [Fact]
-        public void GetClusterOptions_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new ClusterConfigService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetClusterOptions(null!));
-        }
-
-        [Fact]
-        public void GetNextId_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new ClusterConfigService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetNextId(null!));
-        }
-
         [Fact]
         public void Constructor_NullClient_ThrowsArgumentNullException()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/ClusterServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/ClusterServiceTests.cs
index bd4ed5a..6592dc8 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/ClusterServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/ClusterServiceTests.cs
@@ -96,28 +96,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             mockClient.Verify(c => c.GetAsync("cluster/resources?type=vm"), Times.Once);
         }
 
-        [Fact]
-        public void GetClusterStatus_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new ClusterService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetClusterStatus(null!));
-        }
-
-        [Fact]
-        public void GetClusterResources_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new ClusterService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetClusterResources(null!));
-        }
-
         [Fact]
         public void Constructor_NullClient_ThrowsArgumentNullException()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/ContainerServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/ContainerServiceTests.cs
index f5f2599..85ddd0d 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/ContainerServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/ContainerServiceTests.cs
@@ -190,33 +190,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal($"nodes/pve%20node/lxc/{TestVmId}/snapshot/snap%20name/rollback", captured.Path);
         }
 
-        [Fact]
-        public void CreateContainerSnapshot_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new ContainerService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session",
-                () => service.CreateContainerSnapshot(null!, TestNode, TestVmId, "my-snap"));
-        }
-
-        [Fact]
-        public void RemoveContainerSnapshot_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new ContainerService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session",
-                () => service.RemoveContainerSnapshot(null!, TestNode, TestVmId, "my-snap"));
-        }
-
-        [Fact]
-        public void RollbackContainerSnapshot_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new ContainerService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session",
-                () => service.RollbackContainerSnapshot(null!, TestNode, TestVmId, "my-snap"));
-        }
-
         [Fact]
         public void RollbackContainerSnapshot_WhitespaceSnapname_ThrowsArgumentNullException()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/FirewallServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/FirewallServiceTests.cs
index b0831d4..4969578 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/FirewallServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/FirewallServiceTests.cs
@@ -259,14 +259,6 @@ namespace PSProxmoxVE.Core.Tests.Services
         // Guard clauses
         // -------------------------------------------------------------------------
 
-        [Fact]
-        public void GetGroupRules_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new FirewallService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.GetGroupRules(null!, Group));
-        }
-
         [Fact]
         public void GetGroupRules_WhitespaceGroup_ThrowsArgumentNullException()
         {
@@ -275,58 +267,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Throws<ArgumentNullException>("group", () => service.GetGroupRules(CreateSession(), " "));
         }
 
-        [Fact]
-        public void CreateGroupRule_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new FirewallService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session",
-                () => service.CreateGroupRule(null!, Group, new Dictionary<string, string>()));
-        }
-
-        [Fact]
-        public void CreateGroupRule_WhitespaceGroup_ThrowsArgumentNullException()
-        {
-            var service = new FirewallService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("group",
-                () => service.CreateGroupRule(CreateSession(), " ", new Dictionary<string, string>()));
-        }
-
-        [Fact]
-        public void UpdateGroupRule_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new FirewallService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session",
-                () => service.UpdateGroupRule(null!, Group, 0, new Dictionary<string, string>()));
-        }
-
-        [Fact]
-        public void UpdateGroupRule_WhitespaceGroup_ThrowsArgumentNullException()
-        {
-            var service = new FirewallService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("group",
-                () => service.UpdateGroupRule(CreateSession(), " ", 0, new Dictionary<string, string>()));
-        }
-
-        [Fact]
-        public void RemoveGroupRule_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new FirewallService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.RemoveGroupRule(null!, Group, 0));
-        }
-
-        [Fact]
-        public void RemoveGroupRule_WhitespaceGroup_ThrowsArgumentNullException()
-        {
-            var service = new FirewallService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("group", () => service.RemoveGroupRule(CreateSession(), " ", 0));
-        }
-
         // -------------------------------------------------------------------------
         // FirewallScope.TryValidate
         // -------------------------------------------------------------------------
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/HaServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/HaServiceTests.cs
index 3300e90..c9ef2de 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/HaServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/HaServiceTests.cs
@@ -452,54 +452,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             mockClient.Verify(c => c.DeleteAsync("cluster/ha/rules/rule1"), Times.Once);
         }
 
-        // -----------------------------------------------------------------
-        // Null session tests
-        // -----------------------------------------------------------------
-
-        [Fact]
-        public void GetResources_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new HaService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetResources(null!));
-        }
-
-        [Fact]
-        public void GetGroups_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new HaService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetGroups(null!));
-        }
-
-        [Fact]
-        public void GetStatus_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new HaService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetStatus(null!));
-        }
-
-        [Fact]
-        public void GetRules_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new HaService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetRules(null!));
-        }
-
         [Fact]
         public void Constructor_NullClient_ThrowsArgumentNullException()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/NetworkServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/NetworkServiceTests.cs
index cb74e02..3d6bcd5 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/NetworkServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/NetworkServiceTests.cs
@@ -149,12 +149,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.GetAsync($"nodes/{Node}/network?type=any%20bridge"), Times.Once);
         }
 
-        [Fact]
-        public void GetNetworks_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>("session", () => _service.GetNetworks(null!, Node));
-        }
-
         [Fact]
         public void GetNetworks_WhitespaceNode_ThrowsArgumentNullException()
         {
@@ -243,13 +237,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("nodes/pve%20node/network", captured.Path);
         }
 
-        [Fact]
-        public void CreateNetwork_NullSession_ThrowsArgumentNullException()
-        {
-            var config = new Dictionary<string, object> { ["iface"] = "vmbr1" };
-            Assert.Throws<ArgumentNullException>("session", () => _service.CreateNetwork(null!, Node, config));
-        }
-
         [Fact]
         public void CreateNetwork_NullConfig_ThrowsArgumentNullException()
         {
@@ -299,13 +286,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("nodes/pve%20node/network/vmbr%200", captured.Path);
         }
 
-        [Fact]
-        public void SetNetwork_NullSession_ThrowsArgumentNullException()
-        {
-            var config = new Dictionary<string, object> { ["type"] = "bridge" };
-            Assert.Throws<ArgumentNullException>("session", () => _service.SetNetwork(null!, Node, "vmbr0", config));
-        }
-
         [Fact]
         public void SetNetwork_WhitespaceIface_ThrowsArgumentNullException()
         {
@@ -339,12 +319,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.VerifyNoOtherCalls();
         }
 
-        [Fact]
-        public void RemoveNetwork_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>("session", () => _service.RemoveNetwork(null!, Node, "vmbr1"));
-        }
-
         // -----------------------------------------------------------------
         // ApplyNetworkConfig
         // -----------------------------------------------------------------
@@ -401,12 +375,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("OK", task.ExitStatus);
         }
 
-        [Fact]
-        public void ApplyNetworkConfig_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>("session", () => _service.ApplyNetworkConfig(null!, Node));
-        }
-
         // -----------------------------------------------------------------
         // GetSdnZones / GetSdnVnets / GetSdnSubnets
         // -----------------------------------------------------------------
@@ -434,12 +402,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Empty(zones);
         }
 
-        [Fact]
-        public void GetSdnZones_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>("session", () => _service.GetSdnZones(null!));
-        }
-
         [Fact]
         public void GetSdnVnets_ReturnsVnetArray()
         {
@@ -463,12 +425,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Empty(vnets);
         }
 
-        [Fact]
-        public void GetSdnVnets_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>("session", () => _service.GetSdnVnets(null!));
-        }
-
         [Fact]
         public void GetSdnSubnets_RequestsVnetSubnetsPath()
         {
@@ -502,12 +458,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Empty(subnets);
         }
 
-        [Fact]
-        public void GetSdnSubnets_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>("session", () => _service.GetSdnSubnets(null!, Vnet));
-        }
-
         [Fact]
         public void GetSdnSubnets_WhitespaceVnet_ThrowsArgumentNullException()
         {
@@ -532,13 +482,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("zone1", result.Zone);
         }
 
-        [Fact]
-        public void CreateSdnZone_NullSession_ThrowsArgumentNullException()
-        {
-            var config = new Dictionary<string, object> { ["zone"] = "zone1" };
-            Assert.Throws<ArgumentNullException>("session", () => _service.CreateSdnZone(null!, config));
-        }
-
         // -----------------------------------------------------------------
         // CreateSdnVnet
         // -----------------------------------------------------------------
@@ -557,13 +500,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("vnet1", result.Vnet);
         }
 
-        [Fact]
-        public void CreateSdnVnet_NullSession_ThrowsArgumentNullException()
-        {
-            var config = new Dictionary<string, object> { ["vnet"] = "vnet1" };
-            Assert.Throws<ArgumentNullException>("session", () => _service.CreateSdnVnet(null!, config));
-        }
-
         // -----------------------------------------------------------------
         // CreateSdnSubnet
         // -----------------------------------------------------------------
@@ -595,20 +531,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("cluster/sdn/vnets/vnet%201/subnets", captured.Path);
         }
 
-        [Fact]
-        public void CreateSdnSubnet_NullSession_ThrowsArgumentNullException()
-        {
-            var config = new Dictionary<string, object> { ["subnet"] = "10.0.0.0/24" };
-            Assert.Throws<ArgumentNullException>("session", () => _service.CreateSdnSubnet(null!, Vnet, config));
-        }
-
-        [Fact]
-        public void CreateSdnSubnet_WhitespaceVnet_ThrowsArgumentNullException()
-        {
-            var config = new Dictionary<string, object> { ["subnet"] = "10.0.0.0/24" };
-            Assert.Throws<ArgumentNullException>("vnet", () => _service.CreateSdnSubnet(_session, " ", config));
-        }
-
         // -----------------------------------------------------------------
         // RemoveSdnSubnet
         // -----------------------------------------------------------------
@@ -636,12 +558,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 c => c.DeleteAsync("cluster/sdn/vnets/vnet%201/subnets/10.0.0.0%2F24"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveSdnSubnet_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>("session", () => _service.RemoveSdnSubnet(null!, Vnet, "10.0.0.0/24"));
-        }
-
         // -----------------------------------------------------------------
         // RemoveSdnZone / RemoveSdnVnet
         // -----------------------------------------------------------------
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/NodeServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/NodeServiceTests.cs
index 49096ec..959fd48 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/NodeServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/NodeServiceTests.cs
@@ -283,39 +283,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void GetNodes_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new NodeService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetNodes(null!));
-        }
-
-        [Fact]
-        public void GetNodeStatus_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new NodeService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetNodeStatus(null!, "pve1"));
-        }
-
-        [Fact]
-        public void GetNodeStatus_NullNode_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new NodeService(mockClient.Object);
-
-            // Act & Assert
-            Assert.Throws<ArgumentNullException>(() => service.GetNodeStatus(CreateSession(), null!));
-        }
-
         [Fact]
         public void Constructor_NullClient_ThrowsArgumentNullException()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/SnapshotServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/SnapshotServiceTests.cs
index f682aaa..b79e1b3 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/SnapshotServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/SnapshotServiceTests.cs
@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using Moq;
@@ -325,37 +324,5 @@ namespace PSProxmoxVE.Core.Tests.Services
             // Assert
             Assert.Equal($"nodes/pve%20node/qemu/{VmId}/snapshot/snap%20name/rollback", captured.Path);
         }
-
-        [Fact]
-        public void GetSnapshots_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new SnapshotService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.GetSnapshots(null!, Node, VmId));
-        }
-
-        [Fact]
-        public void CreateSnapshot_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new SnapshotService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.CreateSnapshot(null!, Node, VmId, "snap"));
-        }
-
-        [Fact]
-        public void RemoveSnapshot_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new SnapshotService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.RemoveSnapshot(null!, Node, VmId, "snap"));
-        }
-
-        [Fact]
-        public void RollbackSnapshot_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new SnapshotService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.RollbackSnapshot(null!, Node, VmId, "snap"));
-        }
     }
 }
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/StorageServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/StorageServiceTests.cs
index cc1af84..dec4695 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/StorageServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/StorageServiceTests.cs
@@ -147,12 +147,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Empty(result);
         }
 
-        [Fact]
-        public void GetStorages_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetStorages(null!));
-        }
-
         // -----------------------------------------------------------------
         // GetStorageContent
         // -----------------------------------------------------------------
@@ -194,24 +188,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.GetAsync("nodes/pve1/storage/local/content?content=iso"), Times.Once);
         }
 
-        [Fact]
-        public void GetStorageContent_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetStorageContent(null!, "pve1", "local"));
-        }
-
-        [Fact]
-        public void GetStorageContent_NullNode_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetStorageContent(_session, null!, "local"));
-        }
-
-        [Fact]
-        public void GetStorageContent_NullStorage_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetStorageContent(_session, "pve1", null!));
-        }
-
         // -----------------------------------------------------------------
         // CreateStorage
         // -----------------------------------------------------------------
@@ -303,12 +279,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal(string.Empty, result.Storage);
         }
 
-        [Fact]
-        public void CreateStorage_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.CreateStorage(null!, new Dictionary<string, object>()));
-        }
-
         [Fact]
         public void CreateStorage_NullConfig_ThrowsArgumentNullException()
         {
@@ -334,18 +304,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.PutAsync("storage/nfs-backup", config), Times.Once);
         }
 
-        [Fact]
-        public void UpdateStorage_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.UpdateStorage(null!, "local", new Dictionary<string, string>()));
-        }
-
-        [Fact]
-        public void UpdateStorage_NullStorage_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.UpdateStorage(_session, null!, new Dictionary<string, string>()));
-        }
-
         [Fact]
         public void UpdateStorage_NullConfig_ThrowsArgumentNullException()
         {
@@ -384,18 +342,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.DeleteAsync("storage/..%2Faccess%2Fusers%2Fx"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveStorage_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveStorage(null!, "local"));
-        }
-
-        [Fact]
-        public void RemoveStorage_NullStorage_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveStorage(_session, null!));
-        }
-
         // -----------------------------------------------------------------
         // GetStorageStatus
         // -----------------------------------------------------------------
@@ -418,24 +364,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("dir", result.Type);
         }
 
-        [Fact]
-        public void GetStorageStatus_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetStorageStatus(null!, "pve1", "local"));
-        }
-
-        [Fact]
-        public void GetStorageStatus_NullNode_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetStorageStatus(_session, null!, "local"));
-        }
-
-        [Fact]
-        public void GetStorageStatus_NullStorage_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetStorageStatus(_session, "pve1", null!));
-        }
-
         // -----------------------------------------------------------------
         // RemoveContent
         // -----------------------------------------------------------------
@@ -454,18 +382,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.DeleteAsync("nodes/pve1/storage/local/content/local%3Aiso%2Fdebian-12.iso"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveContent_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveContent(null!, "pve1", "local", "vol"));
-        }
-
-        [Fact]
-        public void RemoveContent_NullVolume_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveContent(_session, "pve1", "local", null!));
-        }
-
         // -----------------------------------------------------------------
         // UpdateContent
         // -----------------------------------------------------------------
@@ -489,12 +405,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 config), Times.Once);
         }
 
-        [Fact]
-        public void UpdateContent_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.UpdateContent(null!, "pve1", "local", "vol", new Dictionary<string, string>()));
-        }
-
         [Fact]
         public void UpdateContent_NullConfig_ThrowsArgumentNullException()
         {
@@ -571,13 +481,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("nodes/pve%20node/storage/local%20storage/upload", captured.Path);
         }
 
-        [Fact]
-        public void UploadIso_WhitespaceContentType_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UploadIso(_session, "pve1", "local", "/tmp/test.iso", contentType: " "));
-        }
-
         [Fact]
         public void UploadIso_TimeoutOverride_PassesItToClientConstruction()
         {
@@ -606,18 +509,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal(TimeSpan.FromMinutes(30), service.SeenTimeout);
         }
 
-        [Fact]
-        public void UploadIso_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.UploadIso(null!, "pve1", "local", "/tmp/test.iso"));
-        }
-
-        [Fact]
-        public void UploadIso_NullFilePath_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.UploadIso(_session, "pve1", "local", null!));
-        }
-
         // -----------------------------------------------------------------
         // DownloadUrl
         // -----------------------------------------------------------------
@@ -709,34 +600,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal(TimeSpan.FromMinutes(30), service.SeenTimeout);
         }
 
-        [Fact]
-        public void DownloadUrl_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.DownloadUrl(null!, "pve1", "local", "https://example.com/f.iso", "f.iso", "iso"));
-        }
-
-        [Fact]
-        public void DownloadUrl_NullUrl_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.DownloadUrl(_session, "pve1", "local", null!, "f.iso", "iso"));
-        }
-
-        [Fact]
-        public void DownloadUrl_NullFilename_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.DownloadUrl(_session, "pve1", "local", "https://example.com/f.iso", null!, "iso"));
-        }
-
-        [Fact]
-        public void DownloadUrl_NullContentType_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.DownloadUrl(_session, "pve1", "local", "https://example.com/f.iso", "f.iso", null!));
-        }
-
         // -----------------------------------------------------------------
         // AllocateDisk
         // -----------------------------------------------------------------
@@ -764,13 +627,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("pve1", result.Node);
         }
 
-        [Fact]
-        public void AllocateDisk_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.AllocateDisk(null!, "pve1", "local", new Dictionary<string, string>()));
-        }
-
         [Fact]
         public void AllocateDisk_NullConfig_ThrowsArgumentNullException()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/TaskServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/TaskServiceTests.cs
index 58b050f..aa09841 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/TaskServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/TaskServiceTests.cs
@@ -58,19 +58,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.True(task.IsSuccessful);
         }
 
-        [Fact]
-        public void GetTask_NullSession_ThrowsArgumentNullException()
-        {
-            // Arrange
-            var mockClient = new Mock<IPveHttpClient>();
-            var service = new TaskService(mockClient.Object);
-
-            // Act & Assert
-            var ex = Assert.Throws<ArgumentNullException>(() =>
-                service.GetTask(null!, TestNode, TestUpid));
-            Assert.Equal("session", ex.ParamName);
-        }
-
         [Fact]
         public void GetTaskLog_HappyPath_ReturnsLogEntries()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/TemplateServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/TemplateServiceTests.cs
index 2af0c22..8f6151f 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/TemplateServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/TemplateServiceTests.cs
@@ -75,22 +75,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal(Node, task.Node);
         }
 
-        [Fact]
-        public void CreateTemplate_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new TemplateService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.CreateTemplate(null!, Node, VmId));
-        }
-
-        [Fact]
-        public void CreateTemplate_NullNode_ThrowsArgumentNullException()
-        {
-            var service = new TemplateService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("node", () => service.CreateTemplate(CreateSession(), null!, VmId));
-        }
-
         [Fact]
         public void CreateTemplate_EmptyNode_ThrowsArgumentNullException()
         {
@@ -145,14 +129,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             mockClient.Verify(c => c.GetAsync("nodes/pve%20node/qemu"), Times.Once);
         }
 
-        [Fact]
-        public void GetTemplates_NullSession_ThrowsArgumentNullException()
-        {
-            var service = new TemplateService(new Mock<IPveHttpClient>().Object);
-
-            Assert.Throws<ArgumentNullException>("session", () => service.GetTemplates(null!, Node));
-        }
-
         [Fact]
         public void GetTemplates_AllNodes_AggregatesAcrossNodesAndStampsNode()
         {
diff --git a/tests/PSProxmoxVE.Core.Tests/Services/UserServiceTests.cs b/tests/PSProxmoxVE.Core.Tests/Services/UserServiceTests.cs
index b6d2ab6..da4a8b8 100644
--- a/tests/PSProxmoxVE.Core.Tests/Services/UserServiceTests.cs
+++ b/tests/PSProxmoxVE.Core.Tests/Services/UserServiceTests.cs
@@ -53,12 +53,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.GetAsync("access/users"), Times.Once);
         }
 
-        [Fact]
-        public void GetUsers_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetUsers(null!));
-        }
-
         [Fact]
         public void GetUser_ReturnsSingleUser()
         {
@@ -75,12 +69,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal(1, result.Enabled);
         }
 
-        [Fact]
-        public void GetUser_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetUser(null!, "root@pam"));
-        }
-
         [Fact]
         public void GetUser_NullUserId_ThrowsArgumentNullException()
         {
@@ -111,18 +99,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void CreateUser_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.CreateUser(null!, "user@pve"));
-        }
-
-        [Fact]
-        public void CreateUser_NullUserId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.CreateUser(_session, null!));
-        }
-
         [Fact]
         public void SetUser_PutsFormData()
         {
@@ -146,20 +122,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void SetUser_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.SetUser(null!, "user@pve", new Dictionary<string, object>()));
-        }
-
-        [Fact]
-        public void SetUser_NullUserId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.SetUser(_session, null!, new Dictionary<string, object>()));
-        }
-
         [Fact]
         public void SetUser_NullConfig_ThrowsArgumentNullException()
         {
@@ -181,18 +143,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.DeleteAsync("access/users/deploy%40pve"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveUser_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveUser(null!, "user@pve"));
-        }
-
-        [Fact]
-        public void RemoveUser_NullUserId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveUser(_session, null!));
-        }
-
         // =================================================================
         // API Tokens
         // =================================================================
@@ -219,18 +169,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("root@pam", result[1].UserId);
         }
 
-        [Fact]
-        public void GetApiTokens_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetApiTokens(null!, "root@pam"));
-        }
-
-        [Fact]
-        public void GetApiTokens_NullUserId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetApiTokens(_session, null!));
-        }
-
         [Fact]
         public void CreateApiToken_ReturnsTokenWithSecret()
         {
@@ -249,27 +187,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("aabbccdd-1122-3344-5566-778899aabbcc", result.Value);
         }
 
-        [Fact]
-        public void CreateApiToken_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.CreateApiToken(null!, "root@pam", "token1"));
-        }
-
-        [Fact]
-        public void CreateApiToken_NullUserId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.CreateApiToken(_session, null!, "token1"));
-        }
-
-        [Fact]
-        public void CreateApiToken_NullTokenId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.CreateApiToken(_session, "root@pam", null!));
-        }
-
         [Fact]
         public void RemoveApiToken_CallsDeleteWithCorrectPath()
         {
@@ -284,27 +201,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.DeleteAsync("access/users/root%40pam/token/automation"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveApiToken_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.RemoveApiToken(null!, "root@pam", "token1"));
-        }
-
-        [Fact]
-        public void RemoveApiToken_NullUserId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.RemoveApiToken(_session, null!, "token1"));
-        }
-
-        [Fact]
-        public void RemoveApiToken_NullTokenId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.RemoveApiToken(_session, "root@pam", null!));
-        }
-
         [Fact]
         public void UpdateApiToken_CallsPutWithCorrectPath()
         {
@@ -320,13 +216,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.PutAsync("access/users/root%40pam/token/automation", config), Times.Once);
         }
 
-        [Fact]
-        public void UpdateApiToken_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateApiToken(null!, "root@pam", "token1", new Dictionary<string, string>()));
-        }
-
         [Fact]
         public void UpdateApiToken_NullConfig_ThrowsArgumentNullException()
         {
@@ -361,12 +250,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("VM.PowerMgmt,VM.Console", result[2].Privileges);
         }
 
-        [Fact]
-        public void GetRoles_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetRoles(null!));
-        }
-
         [Fact]
         public void CreateRole_PostsFormData()
         {
@@ -385,18 +268,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void CreateRole_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.CreateRole(null!, "role1"));
-        }
-
-        [Fact]
-        public void CreateRole_NullRoleId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.CreateRole(_session, null!));
-        }
-
         [Fact]
         public void UpdateRole_PutsPrivileges()
         {
@@ -414,27 +285,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void UpdateRole_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateRole(null!, "role1", "privs"));
-        }
-
-        [Fact]
-        public void UpdateRole_NullRoleId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateRole(_session, null!, "privs"));
-        }
-
-        [Fact]
-        public void UpdateRole_NullPrivileges_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateRole(_session, "role1", null!));
-        }
-
         [Fact]
         public void RemoveRole_CallsDeleteWithCorrectPath()
         {
@@ -449,18 +299,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.DeleteAsync("access/roles/BackupOperator"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveRole_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveRole(null!, "role1"));
-        }
-
-        [Fact]
-        public void RemoveRole_NullRoleId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveRole(_session, null!));
-        }
-
         // =================================================================
         // Groups
         // =================================================================
@@ -486,12 +324,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("operators", result[1].GroupId);
         }
 
-        [Fact]
-        public void GetGroups_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetGroups(null!));
-        }
-
         [Fact]
         public void CreateGroup_PostsFormData()
         {
@@ -510,18 +342,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void CreateGroup_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.CreateGroup(null!, "group1"));
-        }
-
-        [Fact]
-        public void CreateGroup_NullGroupId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.CreateGroup(_session, null!));
-        }
-
         [Fact]
         public void UpdateGroup_PutsConfig()
         {
@@ -537,20 +357,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.PutAsync("access/groups/devops", config), Times.Once);
         }
 
-        [Fact]
-        public void UpdateGroup_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateGroup(null!, "group1", new Dictionary<string, string>()));
-        }
-
-        [Fact]
-        public void UpdateGroup_NullGroupId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateGroup(_session, null!, new Dictionary<string, string>()));
-        }
-
         [Fact]
         public void UpdateGroup_NullConfig_ThrowsArgumentNullException()
         {
@@ -572,18 +378,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.DeleteAsync("access/groups/devops"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveGroup_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveGroup(null!, "group1"));
-        }
-
-        [Fact]
-        public void RemoveGroup_NullGroupId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveGroup(_session, null!));
-        }
-
         // =================================================================
         // Domains / Realms
         // =================================================================
@@ -612,12 +406,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Equal("ldap", result[2].Type);
         }
 
-        [Fact]
-        public void GetDomains_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetDomains(null!));
-        }
-
         [Fact]
         public void CreateDomain_PostsConfig()
         {
@@ -639,13 +427,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.PostAsync("access/domains", config), Times.Once);
         }
 
-        [Fact]
-        public void CreateDomain_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.CreateDomain(null!, new Dictionary<string, string>()));
-        }
-
         [Fact]
         public void CreateDomain_NullConfig_ThrowsArgumentNullException()
         {
@@ -668,20 +449,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.PutAsync("access/domains/corp-ad", config), Times.Once);
         }
 
-        [Fact]
-        public void UpdateDomain_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateDomain(null!, "pam", new Dictionary<string, string>()));
-        }
-
-        [Fact]
-        public void UpdateDomain_NullRealm_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.UpdateDomain(_session, null!, new Dictionary<string, string>()));
-        }
-
         [Fact]
         public void UpdateDomain_NullConfig_ThrowsArgumentNullException()
         {
@@ -703,18 +470,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             _mockClient.Verify(c => c.DeleteAsync("access/domains/corp-ad"), Times.Once);
         }
 
-        [Fact]
-        public void RemoveDomain_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveDomain(null!, "pam"));
-        }
-
-        [Fact]
-        public void RemoveDomain_NullRealm_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.RemoveDomain(_session, null!));
-        }
-
         // =================================================================
         // Password
         // =================================================================
@@ -737,27 +492,6 @@ namespace PSProxmoxVE.Core.Tests.Services
                 Times.Once);
         }
 
-        [Fact]
-        public void ChangePassword_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.ChangePassword(null!, "user@pve", "pass"));
-        }
-
-        [Fact]
-        public void ChangePassword_NullUserId_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.ChangePassword(_session, null!, "pass"));
-        }
-
-        [Fact]
-        public void ChangePassword_NullPassword_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.ChangePassword(_session, "user@pve", null!));
-        }
-
         // =================================================================
         // Permissions / ACLs
         // =================================================================
@@ -851,12 +585,6 @@ namespace PSProxmoxVE.Core.Tests.Services
             Assert.Empty(result);
         }
 
-        [Fact]
-        public void GetPermissions_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() => _service.GetPermissions(null!));
-        }
-
         [Fact]
         public void SetPermission_PutsAclData()
         {
@@ -964,26 +692,5 @@ namespace PSProxmoxVE.Core.Tests.Services
                     d.Count == 3)),
                 Times.Once);
         }
-
-        [Fact]
-        public void SetPermission_NullSession_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.SetPermission(null!, "/", "Admin"));
-        }
-
-        [Fact]
-        public void SetPermission_NullPath_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.SetPermission(_session, null!, "Admin"));
-        }
-
-        [Fact]
-        public void SetPermission_NullRoles_ThrowsArgumentNullException()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                _service.SetPermission(_session, "/", null!));
-        }
     }
 }