fix(dashboard): ShowTagValues now gates the alarms hub and /browse live values

src/ZB.MOM.WW.MxGateway.Server/Dashboard/DashboardLiveDataService.cs

@@ -1,5 +1,7 @@
+using Microsoft.Extensions.Options;
 using ZB.MOM.WW.MxGateway.Contracts.Proto;
 using ZB.MOM.WW.MxGateway.Server.Alarms;
+using ZB.MOM.WW.MxGateway.Server.Configuration;
 using ZB.MOM.WW.MxGateway.Server.Sessions;
 
 namespace ZB.MOM.WW.MxGateway.Server.Dashboard;
@@ -11,6 +13,16 @@ namespace ZB.MOM.WW.MxGateway.Server.Dashboard;
 ///     expires. All access is serialised through <see cref="_gate"/> so the
 ///     single backing worker only ever sees one in-flight command.
 /// </summary>
+/// <remarks>
+///     This service is also where <c>MxGateway:Dashboard:ShowTagValues</c> is
+///     applied to the Browse panel: with the flag false (the default) the
+///     formatted value never leaves this boundary — the projected
+///     <see cref="DashboardTagValue"/> carries
+///     <see cref="DashboardTagValue.RedactedValueText"/> instead. Putting the
+///     decision at the service rather than in the page keeps it to one place and
+///     keeps a value out of the render tree entirely, rather than relying on
+///     every current and future view to remember to suppress it.
+/// </remarks>
 public sealed class DashboardLiveDataService : IDashboardLiveDataService, IAsyncDisposable
 {
     private const string BackendName = "Galaxy";
@@ -38,6 +50,15 @@ public sealed class DashboardLiveDataService : IDashboardLiveDataService, IAsync
     private readonly ILogger<DashboardLiveDataService> _logger;
     private readonly SemaphoreSlim _gate = new(1, 1);
 
+    /// <summary>
+    ///     <c>MxGateway:Dashboard:ShowTagValues</c>. False (the default)
+    ///     substitutes <see cref="DashboardTagValue.RedactedValueText"/> for every
+    ///     value this service hands the Browse panel; quality, data type, source
+    ///     timestamp, and any error still describe the real read, so the panel
+    ///     remains a diagnostic surface without being a value-disclosure one.
+    /// </summary>
+    private readonly bool _showTagValues;
+
     // Least-recently-read-last advise set: the list holds every currently advised
     // tag ordered most- to least-recently read, the dictionary indexes into it.
     // Both are only ever touched under _gate, which already serialises all viewers.
@@ -53,15 +74,19 @@ public sealed class DashboardLiveDataService : IDashboardLiveDataService, IAsync
     /// <summary>Initializes the live-data service.</summary>
     /// <param name="sessionManager">Gateway session manager.</param>
     /// <param name="alarmService">Gateway central alarm service.</param>
+    /// <param name="options">Gateway options supplying <c>Dashboard:ShowTagValues</c>.</param>
     /// <param name="logger">Diagnostic logger.</param>
     public DashboardLiveDataService(
         ISessionManager sessionManager,
         IGatewayAlarmService alarmService,
+        IOptions<GatewayOptions> options,
         ILogger<DashboardLiveDataService> logger)
     {
+        ArgumentNullException.ThrowIfNull(options);
         _sessionManager = sessionManager ?? throw new ArgumentNullException(nameof(sessionManager));
         _alarmService = alarmService ?? throw new ArgumentNullException(nameof(alarmService));
         _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _showTagValues = options.Value.Dashboard.ShowTagValues;
     }
 
     /// <inheritdoc />
@@ -96,8 +121,12 @@ public sealed class DashboardLiveDataService : IDashboardLiveDataService, IAsync
                 .ReadBulkAsync(serverHandle, tagAddresses.ToArray(), ReadTimeout, cancellationToken)
                 .ConfigureAwait(false);
 
+            // The only place the /browse live-value gate is evaluated: the page
+            // renders whatever ValueText it is handed, so a second check in the
+            // view could only ever disagree with this one.
             DashboardTagValue[] values = results
                 .Select(DashboardTagValue.FromBulkReadResult)
+                .Select(value => _showTagValues ? value : value with { ValueText = DashboardTagValue.RedactedValueText })
                 .ToArray();
             return new DashboardLiveReadResult(values, null, session.SessionId, session.WorkerProcessId);
         }