diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/MeshGrpcMapConventionTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/MeshGrpcMapConventionTests.cs
new file mode 100644
index 00000000..0b00c28f
--- /dev/null
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/MeshGrpcMapConventionTests.cs
@@ -0,0 +1,66 @@
+using Shouldly;
+using Xunit;
+
+namespace ZB.MOM.WW.OtOpcUa.Host.IntegrationTests;
+
+/// <summary>
+///     R3-01 T7 — a source-scan guard, following the solution-root-walk idiom
+///     <c>ZB.MOM.WW.OtOpcUa.Driver.S7.Cli.Tests.FlushLoggingConventionTests</c> uses. Complements the
+///     endpoint-metadata census (<c>MeshGrpcAnonymousMetadataTests</c>): the census catches a map
+///     added to <c>MeshGrpcEndpoints</c> without the <c>AllowAnonymous</c> convention, but it cannot
+///     catch a map added to <c>Program.cs</c> that bypasses the helper entirely — that shape never
+///     goes through <c>MapOtOpcUaMeshGrpcServices</c> at all, so the census would simply never see it.
+/// </summary>
+/// <remarks>
+///     Would have FAILED at HEAD before T1: <c>Program.cs</c> used to carry the five map sites
+///     inline (<c>MapZbLocalDbSync()</c>, four <c>MapGrpcService&lt;T&gt;()</c> calls) with no
+///     <c>MapOtOpcUaMeshGrpcServices</c> call at all.
+/// </remarks>
+public sealed class MeshGrpcMapConventionTests
+{
+    private static readonly string ProgramCsPath = LocateProgramCs();
+
+    [Fact]
+    public void ProgramCs_ContainsNoDirectMeshGrpcMapSites_AndExactlyOneMapperCall()
+    {
+        var source = File.ReadAllText(ProgramCsPath);
+
+        // Guard-of-the-guard: a bad path (an empty file, or one that never had the mapper in the
+        // first place) must not pass this test by finding nothing to count.
+        source.ShouldNotBeNullOrWhiteSpace();
+        source.ShouldContain("MapOtOpcUaMeshGrpcServices(");
+
+        CountOccurrences(source, "MapGrpcService<").ShouldBe(0,
+            "every MapGrpcService<T>() call must live inside MeshGrpcEndpoints.MapOtOpcUaMeshGrpcServices, " +
+            "not inline in Program.cs (03/S14 — a map added outside the helper is invisible to the " +
+            "endpoint-metadata census).");
+        CountOccurrences(source, "MapZbLocalDbSync(").ShouldBe(0,
+            "the LocalDb sync map must live inside MeshGrpcEndpoints.MapOtOpcUaMeshGrpcServices, not inline " +
+            "in Program.cs, for the same reason as MapGrpcService<T>() above.");
+        CountOccurrences(source, "MapOtOpcUaMeshGrpcServices(").ShouldBe(1,
+            "Program.cs must call the mapper exactly once; more than one call would map the mesh gRPC " +
+            "services twice (a route conflict) and zero calls would drop them entirely.");
+    }
+
+    private static int CountOccurrences(string source, string needle)
+    {
+        var count = 0;
+        var index = 0;
+        while ((index = source.IndexOf(needle, index, StringComparison.Ordinal)) >= 0)
+        {
+            count++;
+            index += needle.Length;
+        }
+
+        return count;
+    }
+
+    private static string LocateProgramCs()
+    {
+        var dir = new DirectoryInfo(AppContext.BaseDirectory);
+        while (dir is not null && !File.Exists(Path.Combine(dir.FullName, "ZB.MOM.WW.OtOpcUa.slnx")))
+            dir = dir.Parent;
+        dir.ShouldNotBeNull("Could not find solution root (ZB.MOM.WW.OtOpcUa.slnx).");
+        return Path.Combine(dir!.FullName, "src", "Server", "ZB.MOM.WW.OtOpcUa.Host", "Program.cs");
+    }
+}