test(perf): failover-timing harness placeholder documenting the 25s envelope protocol, pending PLAN-01 two-node rig (arch-review 08 §2.3)

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

tests/ZB.MOM.WW.ScadaBridge.PerformanceTests/Failover/FailoverTimingTests.cs

@@ -0,0 +1,33 @@
+namespace ZB.MOM.WW.ScadaBridge.PerformanceTests.Failover;
+
+/// <summary>
+/// Failover-timing benchmark harness (placeholder).
+///
+/// Design envelope under test (CLAUDE.md "Cluster &amp; Failover"): failure
+/// detection 2s heartbeat / 10s threshold, SBR stable-after 15s, total
+/// failover ~25s for a hard node loss.
+///
+/// Measurement protocol (to be wired to the two-node cluster rig delivered
+/// by PLAN-01 — see archreview/plans/PLAN-01-*.md; do not duplicate that rig
+/// here):
+///   1. Form a real 2-node cluster (docker/ topology or Akka.Remote in-proc
+///      multi-ActorSystem rig from PLAN-01).
+///   2. Confirm a cluster singleton (e.g. site DeploymentManager) is hosted
+///      on node A; record T0.
+///   3. Hard-kill node A (process kill / ActorSystem.Abort — not
+///      CoordinatedShutdown; graceful stop exercises a different path).
+///   4. Poll node B for singleton re-host; record T1 at first successful
+///      response from the migrated singleton.
+///   5. Assert T1 - T0 &lt;= 40s (25s design + margin) and report the number.
+/// </summary>
+public class FailoverTimingTests
+{
+    [Trait("Category", "Performance")]
+    [Fact(Skip = "Requires the real two-node failover rig delivered by PLAN-01 " +
+                 "(overall review P2-10). This class documents the measurement " +
+                 "protocol; wire it to the rig when PLAN-01 lands.")]
+    public void HardKillFailover_SingletonRehostedWithinDesignEnvelope()
+    {
+        // Intentionally empty until the PLAN-01 rig exists.
+    }
+}