fix(site-runtime): seed republished overrides into Script Actors without firing scripts; alarms still evaluate (review 2026-10-21 01/SR-U1, decision M1)

HandleOverridesLoaded now sends children a site-local AttributeValueSeed
(stream still gets the AttributeValueChanged). ScriptActor updates its
snapshot, Conditional truth value and Expression last result (seed-only eval,
never fires); AlarmActor evaluates it as a normal change.

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/ScriptActor.cs

@@ -117,6 +117,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
     // against the latest snapshot. Both flags are touched only on the actor thread.
     private bool _evalInFlight;
     private bool _evalPending;
+    // 01/SR-U1: true when the pending evaluation was requested only by seeds (never fires).
+    private bool _evalPendingSeedOnly;
 
     // WhileTrue trigger state: the most recent truth value of a Conditional
     // trigger's comparison, used to detect false->true / true->false edges.
@@ -205,6 +207,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
 
         // Handle attribute value changes for value-change and conditional triggers
         Receive<AttributeValueChanged>(HandleAttributeValueChanged);
+        // Review 2026-10-21 01/SR-U1: a value seeded at instance start updates trigger state only.
+        Receive<Messages.AttributeValueSeed>(HandleAttributeValueSeed);
 
         // Handle interval tick
         Receive<IntervalTick>(_ => TrySpawnExecution(null));
@@ -338,6 +342,31 @@ public class ScriptActor : ReceiveActor, IWithTimers
         }
     }
 
+    /// <summary>
+    /// Review 2026-10-21 01/SR-U1 (user decision M1): adopts a value the Instance Actor seeded at
+    /// start (a persisted static override loaded after this actor was created with the deploy
+    /// default) WITHOUT launching a run. The snapshot and the trigger's edge state are brought up
+    /// to date — a Conditional's truth value, an Expression's last result (evaluated, never fired) —
+    /// so the NEXT real change is judged against the real value: no spurious edge from the replay,
+    /// and no missed edge afterwards. A WhileTrue trigger whose condition already holds is seeded
+    /// true without starting its re-fire timer; it fires on its next false→true edge.
+    /// </summary>
+    private void HandleAttributeValueSeed(Messages.AttributeValueSeed seed)
+    {
+        var changed = seed.Change;
+        _attributeSnapshot[changed.AttributeName] = changed.Value;
+
+        if (_triggerConfig is ConditionalTriggerConfig conditional &&
+            conditional.AttributeName == changed.AttributeName)
+        {
+            _conditionState = EvaluateCondition(conditional, changed.Value);
+        }
+        else if (_triggerConfig is ExpressionTriggerConfig)
+        {
+            StartExpressionEvaluation(seedOnly: true);
+        }
+    }
+
     /// <summary>
     /// Starts an off-dispatcher evaluation of the compiled trigger expression (P1).
     /// The expression previously ran synchronously on the actor's dispatcher thread
@@ -359,10 +388,20 @@ public class ScriptActor : ReceiveActor, IWithTimers
     /// the work is queued — so gate-wait time burns the same budget and a saturated gate
     /// yields a timely false instead of an unbounded stall.</para>
     /// </summary>
-    private void StartExpressionEvaluation()
+    /// <param name="seedOnly">
+    /// 01/SR-U1: the result only seeds <see cref="_lastExpressionResult"/> and never fires. A
+    /// coalesced pending evaluation stays seed-only unless a real change also asked for it.
+    /// </param>
+    private void StartExpressionEvaluation(bool seedOnly = false)
     {
         if (_compiledTriggerExpression == null || _triggerConfig is not ExpressionTriggerConfig) return;
-        if (_evalInFlight) { _evalPending = true; return; } // coalesce bursts: one in flight, one pending
+        if (_evalInFlight)
+        {
+            // coalesce bursts: one in flight, one pending (seed-only only if every request was)
+            _evalPendingSeedOnly = _evalPending ? _evalPendingSeedOnly && seedOnly : seedOnly;
+            _evalPending = true;
+            return;
+        }
         _evalInFlight = true;
 
         var snapshot = new Dictionary<string, object?>(_attributeSnapshot); // point-in-time copy, actor thread
@@ -407,7 +446,7 @@ public class ScriptActor : ReceiveActor, IWithTimers
                 cts.Dispose();
             }
         }).PipeTo(self,
-            success: r => new ExpressionEvalResult(r),
+            success: r => new ExpressionEvalResult(r, seedOnly),
             failure: ex => new ExpressionEvalFailed(ex));
     }
 
@@ -422,13 +461,21 @@ public class ScriptActor : ReceiveActor, IWithTimers
         _evalInFlight = false;
         if (_triggerConfig is ExpressionTriggerConfig exprConfig)
         {
-            if (exprConfig.Mode == TriggerMode.WhileTrue)
+            if (msg.SeedOnly)
+            {
+                // 01/SR-U1: a seed adopts the truth value and never fires.
+            }
+            else if (exprConfig.Mode == TriggerMode.WhileTrue)
                 HandleWhileTrueTransition(msg.Result, _lastExpressionResult);
             else if (msg.Result && !_lastExpressionResult)
                 TrySpawnExecution(null);
             _lastExpressionResult = msg.Result;
         }
-        if (_evalPending) { _evalPending = false; StartExpressionEvaluation(); }
+        if (_evalPending)
+        {
+            _evalPending = false;
+            StartExpressionEvaluation(_evalPendingSeedOnly);
+        }
     }
 
     /// <summary>
@@ -873,7 +920,7 @@ public class ScriptActor : ReceiveActor, IWithTimers
     /// carries the boolean truth value so the OnTrue/WhileTrue edge logic runs on
     /// the actor thread.
     /// </summary>
-    private sealed record ExpressionEvalResult(bool Result);
+    private sealed record ExpressionEvalResult(bool Result, bool SeedOnly = false);
 
     /// <summary>
     /// Piped back to self when the off-dispatcher evaluation TASK itself faults