perf(runtime): split trigger evals from the blocking pool; bounded, deadline-aware execution

src/ZB.MOM.WW.ScadaBridge.HealthMonitoring/ISiteHealthCollector.cs

@@ -25,6 +25,20 @@ public interface ISiteHealthCollector
     /// </summary>
     void IncrementDeadLetter();
 
+    /// <summary>
+    /// WP3.1: increments the per-interval count of script/alarm runs SHED because
+    /// <c>MaxConcurrentRunsPerScript</c> runs were already in flight for that script. A raw
+    /// per-interval count like the script/alarm error counters — a sustained non-zero value
+    /// means a trigger is firing faster than its script can complete. Every shed is counted
+    /// here even when its accompanying site event is rate-limited away.
+    /// Default interface implementation is a no-op so existing test fakes continue to
+    /// compile without per-fake updates.
+    /// </summary>
+    void IncrementScriptRunShed()
+    {
+        // Default no-op so test fakes do not need to be updated.
+    }
+
     /// <summary>
     /// Increment the per-interval count of
     /// <c>FallbackAuditWriter</c> primary failures. Bridged from the
@@ -173,7 +187,13 @@ public interface ISiteHealthCollector
     /// <param name="queueDepth">Script tasks waiting to run.</param>
     /// <param name="busyThreads">Worker threads currently executing a script.</param>
     /// <param name="oldestBusyAgeSeconds">Age (seconds) of the oldest in-flight script, or <c>null</c> when idle.</param>
-    void SetScriptSchedulerStats(int queueDepth, int busyThreads, double? oldestBusyAgeSeconds)
+    /// <param name="detachedThreads">
+    /// WP3.1: worker threads the stuck-script watchdog has detached and replaced because
+    /// their script wedged past its deadline plus grace, and which have not yet returned.
+    /// A non-zero, non-draining value means script bodies are permanently blocking threads.
+    /// </param>
+    void SetScriptSchedulerStats(
+        int queueDepth, int busyThreads, double? oldestBusyAgeSeconds, int detachedThreads = 0)
     {
         // Default no-op so test fakes do not need to be updated.
     }