fix(centralui): enable Test Bindings for MxGateway connections

The Test Bindings button was disabled (greyed out) for any attribute bound
to a non-OPC-UA connection. BuildTestableRows() filtered to protocol ==
"OpcUa", a stale gate left over from when OPC UA was the only protocol.
ReadTagValuesCommand is protocol-agnostic (routes through
IDataConnection.ReadBatchAsync, which MxGatewayDataConnection implements),
so the filter only blocked the UI — mirroring the already-fixed IsBrowsable.

Remove the OPC-UA-only filter and update the stale comments. Add a bUnit
regression test (theory over MxGateway + OpcUa) asserting the button is
enabled for a readable-protocol binding.

Verified live: dialog opens for an MxGateway binding and returns a
Good-quality read.

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Deployment/InstanceConfigure.razor

@@ -158,9 +158,10 @@
                         <button class="btn btn-success btn-sm" @onclick="SaveBindings" disabled="@_saving">Save Bindings</button>
                         @* Test Bindings: one-shot live read of every bound attribute
                            whose row has a connection picked AND an effective tag
-                           path. Disabled when no testable rows. Currently OPC UA
+                           path. Disabled when no testable rows. Protocol-agnostic —
-                           only — other protocols (none yet) would need their own
+                           any connection whose adapter implements ReadBatchAsync
-                           wire+adapter support to round-trip through ReadTagValuesCommand. *@
+                           (OPC UA and MxGateway today) round-trips through
+                           ReadTagValuesCommand. *@
                         <button class="btn btn-outline-primary btn-sm"
                                 @onclick="OpenTestBindings"
                                 disabled="@(!HasTestableBindings())">
@@ -612,8 +613,10 @@
 
     /// <summary>
     /// Builds the list of testable rows: attributes that have a connection
-    /// picked AND a non-empty effective tag path AND an OPC UA connection
+    /// picked AND a non-empty effective tag path. Protocol-agnostic — every
-    /// (the only protocol routed through <c>ReadTagValuesCommand</c> today).
+    /// data-connection adapter implements <c>ReadBatchAsync</c>, so the read
+    /// routes through <c>ReadTagValuesCommand</c> regardless of protocol
+    /// (OPC UA and MxGateway today).
     /// </summary>
     private List<TestBindingsDialog.BindingRowToTest> BuildTestableRows()
     {
@@ -626,10 +629,11 @@
             var conn = _siteConnections.FirstOrDefault(c => c.Id == connId);
             if (conn is null) continue;
 
-            // OPC UA only — other protocols don't have a site-side
+            // Protocol-agnostic: ReadTagValuesCommand routes through the
-            // ReadTagValuesCommand handler wired up yet.
+            // site-side IDataConnection.ReadBatchAsync contract, which every
-            if (!string.Equals(conn.Protocol, "OpcUa", StringComparison.OrdinalIgnoreCase))
+            // adapter implements (OPC UA and MxGateway today). A not-connected
-                continue;
+            // or unsupported connection short-circuits to a typed banner in the
+            // dialog rather than being filtered out here — mirrors IsBrowsable.
 
             var effectivePath = _bindingOverrides.GetValueOrDefault(attr.Name)
                                 ?? GetTemplateDefault(attr.Name);

tests/ZB.MOM.WW.ScadaBridge.CentralUI.Tests/Deployment/InstanceConfigureAuditDrillinTests.cs

@@ -104,4 +104,63 @@ public class InstanceConfigureAuditDrillinTests : BunitContext
             Assert.Contains("Recent audit activity", link.TextContent);
         });
     }
+
+    /// <summary>
+    /// Regression: the Test Bindings button must be enabled for an attribute
+    /// bound to an MxGateway connection. The site-side ReadTagValuesCommand
+    /// path is protocol-agnostic (routes through IDataConnection.ReadBatchAsync,
+    /// which MxGateway implements), so the UI must not gate the button on
+    /// protocol == "OpcUa". Previously BuildTestableRows filtered to OPC UA
+    /// only, leaving the button greyed for MxGateway bindings.
+    /// </summary>
+    [Theory]
+    [InlineData("MxGateway")]
+    [InlineData("OpcUa")]
+    public void TestBindingsButton_Enabled_ForReadableProtocol(string protocol)
+    {
+        var instance = new Instance("Pump-42")
+        {
+            Id = 42,
+            TemplateId = 1,
+            SiteId = 1,
+            State = ZB.MOM.WW.ScadaBridge.Commons.Types.Enums.InstanceState.NotDeployed,
+        };
+
+        _templateRepo.GetInstanceByIdAsync(42, Arg.Any<CancellationToken>()).Returns(instance);
+        _templateRepo.GetTemplateByIdAsync(1, Arg.Any<CancellationToken>())
+            .Returns(new Template("Pump") { Id = 1 });
+        _siteRepo.GetAllSitesAsync(Arg.Any<CancellationToken>())
+            .Returns(new List<Site> { new("Plant A", "plant-a") { Id = 1 } });
+        _templateRepo.GetAreasBySiteIdAsync(1, Arg.Any<CancellationToken>())
+            .Returns(new List<Area>());
+        // One data-sourced attribute (non-empty DataSourceReference => testable row).
+        _templateRepo.GetAttributesByTemplateIdAsync(1, Arg.Any<CancellationToken>())
+            .Returns(new List<TemplateAttribute>
+            {
+                new("Speed") { Id = 1, DataSourceReference = "TestMachine_001.TestHistoryValue" },
+            });
+        // A connection on the attribute's chosen protocol.
+        _siteRepo.GetDataConnectionsBySiteIdAsync(1, Arg.Any<CancellationToken>())
+            .Returns(new List<DataConnection> { new("Shared", protocol, 1) { Id = 7 } });
+        _templateRepo.GetBindingsByInstanceIdAsync(42, Arg.Any<CancellationToken>())
+            .Returns(new List<InstanceConnectionBinding>
+            {
+                new("Speed") { Id = 1, InstanceId = 42, DataConnectionId = 7 },
+            });
+        _templateRepo.GetOverridesByInstanceIdAsync(42, Arg.Any<CancellationToken>())
+            .Returns(new List<InstanceAttributeOverride>());
+        _templateRepo.GetAlarmsByTemplateIdAsync(1, Arg.Any<CancellationToken>())
+            .Returns(new List<TemplateAlarm>());
+        _templateRepo.GetAlarmOverridesByInstanceIdAsync(42, Arg.Any<CancellationToken>())
+            .Returns(new List<InstanceAlarmOverride>());
+
+        var cut = Render<InstanceConfigurePage>(p => p.Add(c => c.Id, 42));
+
+        cut.WaitForAssertion(() =>
+        {
+            var testButton = cut.FindAll("button").Single(b => b.TextContent.Trim() == "Test Bindings");
+            Assert.False(testButton.HasAttribute("disabled"),
+                $"Test Bindings should be enabled for a {protocol} binding.");
+        });
+    }
 }