diff --git a/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json b/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json
index 9145edce..aebd3c96 100644
--- a/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json
+++ b/archreview/plans/R2-06-serverhistorian-failfast-plan.md.tasks.json
@@ -43,7 +43,7 @@
     {
       "id": "T6",
       "subject": "Warning parity: malformed-endpoint warning in ServerHistorianOptions.Validate() + Runtime.Tests case; commit 1 (S-11) after T1-T6 green",
-      "status": "pending",
+      "status": "completed",
       "blockedBy": [
         "T4"
       ]
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
index 2ffedff4..98f4eb56 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
@@ -69,7 +69,16 @@ public sealed class ServerHistorianOptions
     public int MaxTieClusterOverfetch { get; init; } = 65536;
 
     /// <summary>Returns operator-facing misconfiguration warnings for an <c>Enabled</c> historian
-    /// (empty when disabled or correctly configured). Pure — the registration logs each entry.</summary>
+    /// (empty when disabled or correctly configured). Pure — the registration logs each entry.
+    /// <para>
+    ///     These are <b>warnings only</b>. The Host layers a fail-fast startup validator
+    ///     (<c>ServerHistorianOptionsValidator</c>, wired via <c>AddValidatedOptions</c>) on top of this
+    ///     for the <b>provably-crashing</b> subset — an empty/malformed <c>Endpoint</c> that is consumed
+    ///     by an enabled historian or an enabled <c>AlarmHistorian</c> — so that config fails host start
+    ///     with a named error instead of a raw <c>UriFormatException</c> crash-loop (archreview 06/S-11).
+    ///     The empty-<c>ApiKey</c> / non-positive-<c>MaxTieClusterOverfetch</c> entries stay warnings
+    ///     because they degrade rather than crash.
+    /// </para></summary>
     /// <returns>Zero or more human-readable warning messages (never carrying secret values).</returns>
     public IReadOnlyList<string> Validate()
     {
@@ -77,6 +86,13 @@ public sealed class ServerHistorianOptions
         if (!Enabled) return warnings;
         if (string.IsNullOrWhiteSpace(Endpoint))
             warnings.Add("ServerHistorian:Endpoint is empty while the historian is enabled — the read client has no gateway address to dial.");
+        // archreview 06/S-11 warning parity: a non-empty but unparseable / non-absolute-http(s) Endpoint
+        // is just as fatal (it throws in the gateway client factory). Warn on it here so the Runtime-side
+        // registration logs describe malformed endpoints too, consistent with the Host's fail-fast
+        // ServerHistorianOptionsValidator (which turns this same condition into a startup failure).
+        else if (!Uri.TryCreate(Endpoint, UriKind.Absolute, out var uri)
+                 || (uri.Scheme != Uri.UriSchemeHttp && uri.Scheme != Uri.UriSchemeHttps))
+            warnings.Add($"ServerHistorian:Endpoint ('{Endpoint}') is not an absolute http(s) URI while the historian is enabled — the read client cannot dial it (e.g. https://host:5222).");
         if (string.IsNullOrWhiteSpace(ApiKey))
             warnings.Add("ServerHistorian:ApiKey is empty while the historian is enabled — the gateway gRPC surface will reject unauthenticated calls.");
         // MaxTieClusterOverfetch is intentionally checked AFTER the Enabled early-return above:
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs
index d4e2eb04..88acedae 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Historian/ServerHistorianOptionsTests.cs
@@ -21,6 +21,16 @@ public sealed class ServerHistorianOptionsTests
         Assert.Contains(w, m => m.Contains("Endpoint"));
     }
 
+    [Fact]
+    public void Enabled_with_malformed_endpoint_warns()
+    {
+        // archreview 06/S-11 warning parity: a non-empty but unparseable / non-absolute Endpoint warns
+        // too, so the Runtime-side registration logs describe malformed endpoints (not just empty ones),
+        // keeping this surface consistent with the Host's fail-fast ServerHistorianOptionsValidator.
+        var w = new ServerHistorianOptions { Enabled = true, Endpoint = "not a uri", ApiKey = "histgw_x_y" }.Validate();
+        Assert.Contains(w, m => m.Contains("Endpoint"));
+    }
+
     [Fact]
     public void Enabled_without_apikey_warns()
     {