src/ZB.MOM.WW.ScadaBridge.Host/SiteServiceRegistration.cs

@@ -27,6 +27,24 @@ namespace ZB.MOM.WW.ScadaBridge.Host;
 /// </summary>
 public static class SiteServiceRegistration
 {
+    /// <summary>
+    /// Every <see cref="System.Diagnostics.Metrics.Meter"/> OpenTelemetry is told to observe.
+    /// </summary>
+    /// <remarks>
+    /// <c>ZbTelemetryOptions.Meters</c> is an ALLOWLIST, and an unlisted meter's instruments
+    /// are simply never observed — no error, no warning, no missing-metric signal anywhere.
+    /// The LocalDb replication meter was silently absent from the rig's <c>/metrics</c>
+    /// scrape until the Phase 1 live gate went looking for it (the plan had assumed it
+    /// flowed through automatically). Hoisted to a named constant so the list is
+    /// assertable; adding a meter anywhere in the product means adding it here.
+    /// </remarks>
+    public static readonly string[] ObservedMeters =
+    [
+        ScadaBridgeTelemetry.MeterName,
+        // Emitted only on site nodes; harmless on central, which never records against it.
+        LocalDbMetrics.MeterName,
+    ];
+
     /// <summary>Registers all DI services required for the site role.</summary>
     /// <param name="services">The service collection to register into.</param>
     /// <param name="config">Application configuration for options binding.</param>
@@ -262,7 +280,7 @@ public static class SiteServiceRegistration
             o.ServiceName = "scadabridge";
             o.SiteId = config["ScadaBridge:Node:SiteId"] ?? "central";
             o.NodeRole = config["ScadaBridge:Node:Role"];
-            o.Meters = [ScadaBridgeTelemetry.MeterName];
+            o.Meters = ObservedMeters;
             if (Enum.TryParse<ZbExporter>(config["ScadaBridge:Telemetry:Exporter"], ignoreCase: true, out var exporter))
                 o.Exporter = exporter;
             var otlp = config["ScadaBridge:Telemetry:OtlpEndpoint"];

tests/ZB.MOM.WW.ScadaBridge.Host.Tests/SiteLocalDbWiringTests.cs

@@ -3,7 +3,9 @@ using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using ZB.MOM.WW.ScadaBridge.HealthMonitoring;
+using ZB.MOM.WW.Telemetry;
 using ZB.MOM.WW.LocalDb;
 using ZB.MOM.WW.LocalDb.Replication;
 using ZB.MOM.WW.ScadaBridge.Host;
@@ -196,6 +198,23 @@ public class SiteLocalDbWiringTests : IDisposable
         Assert.Null(report.LocalDbOplogBacklog);
     }
 
+    [Fact]
+    public void Site_Telemetry_Allowlists_TheLocalDbReplicationMeter()
+    {
+        // ZbTelemetryOptions.Meters is an ALLOWLIST: an unlisted Meter's instruments are
+        // never observed, with no error and no missing-metric warning anywhere. The
+        // replication meter was silently absent from the rig's /metrics scrape until the
+        // live gate looked for it, so pin the allowlist rather than trusting the next
+        // reader to remember.
+        //
+        // This asserts on the allowlist constant, not on OTel's observed-meter set:
+        // AddZbTelemetry applies its options to a local instance and never registers
+        // IOptions, so there is nothing resolvable to interrogate. The end-to-end proof
+        // that localdb_* actually reaches /metrics is the Task 12 live gate; this test
+        // exists to stop the entry being dropped again.
+        Assert.Contains(LocalDbMetrics.MeterName, SiteServiceRegistration.ObservedMeters);
+    }
+
     [Fact]
     public void Site_LocalDb_CreatesTheConfiguredFile()
     {