Merge b647-focas-alarms: FOCAS native alarms reach Part 9 conditions (ALARM: address) + respawn keeps acks host-side (#647)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests/OpcUaClientAlarmTests.cs

@@ -232,6 +232,21 @@ public sealed class OpcUaClientAlarmTests
         OpcUaClientDriver.AlarmTransitions((priorActive, priorAcked), (active, acked)).ShouldBe(expected);
     }
 
+    /// <summary>
+    ///     Gitea #647 review — with no prior this driver told the host (first sight after start or a deploy respawn),
+    ///     an unacknowledged upstream target goes out as Retrigger, never Raise: the host keeps an existing ack across
+    ///     a Raise on an already-active condition, so only a Retrigger makes the host match the upstream's unack.
+    ///     An acknowledged target keeps its Raise (a re-statement there is exactly right).
+    /// </summary>
+    [Theory]
+    [InlineData(true, false, new[] { AlarmTransitionKind.Retrigger })]
+    [InlineData(false, false, new[] { AlarmTransitionKind.Retrigger, AlarmTransitionKind.Clear })]
+    [InlineData(true, true, new[] { AlarmTransitionKind.Raise, AlarmTransitionKind.Acknowledge })]
+    public void An_unknown_prior_tells_an_unacked_upstream_with_Retrigger(bool active, bool acked, AlarmTransitionKind[] expected)
+    {
+        OpcUaClientDriver.AlarmTransitions((false, true), (active, acked), priorKnown: false).ShouldBe(expected);
+    }
+
     // ---- #619 re-review: the transition table must reach EVERY target from EVERY prior. ----
 
     /// <summary>The host projector's semantics, restated: the only thing the driver's kinds act upon.</summary>
@@ -357,7 +372,9 @@ public sealed class OpcUaClientAlarmTests
 
         drv.RouteAlarmEvent(ConditionFields(true, false), TripIndex, handle);
         drv.RouteAlarmEvent(ConditionFields(true, true), TripIndex, handle);
-        seen.Select(e => e.Kind).ShouldBe([AlarmTransitionKind.Raise, AlarmTransitionKind.Acknowledge]);
+        // First sight of an UNACKED upstream condition is a Retrigger (#647 review: the host keeps an ack across a
+        // Raise on an already-active condition, and only the upstream knows it is unacknowledged).
+        seen.Select(e => e.Kind).ShouldBe([AlarmTransitionKind.Retrigger, AlarmTransitionKind.Acknowledge]);
 
         drv.RouteAlarmEvent(ConditionFields(true, true), TripIndex, handle);   // the refresh copy
         seen.Count.ShouldBe(2);