fix(site-runtime): resolve SiteRuntime-012,013,015,016 — doc accuracy, shared LoggerFactory, execution-actor coverage; SiteRuntime-014 deferred

src/ScadaLink.SiteRuntime/Scripts/ScopeAccessors.cs

@@ -4,8 +4,18 @@ namespace ScadaLink.SiteRuntime.Scripts;
 /// Scope-aware view onto the instance's attributes, anchored at a path prefix.
 /// <c>Attributes["X"]</c> on the root scope resolves to canonical name "X";
 /// on a composition with prefix "TempSensor" it resolves to "TempSensor.X".
-/// Reads block on the actor Ask; async variants are provided for callers
-/// that prefer to await explicitly.
+///
+/// <para>
+/// Thread-model note (SiteRuntime-012): the indexer get/set block synchronously
+/// on the Instance Actor Ask (and, for data-connected attributes, the DCL
+/// round-trip). This is safe because script bodies execute on the dedicated
+/// <see cref="ScriptExecutionScheduler"/> threads (SiteRuntime-009), not the
+/// shared <see cref="System.Threading.ThreadPool"/> — so a blocked accessor
+/// cannot starve unrelated Akka dispatchers or HTTP request handling. The async
+/// variants (<see cref="GetAsync"/>/<see cref="SetAsync"/>) are still preferred
+/// where the script can await, as they avoid holding a dedicated thread idle for
+/// the duration of each round-trip.
+/// </para>
 /// </summary>
 public class AttributeAccessor
 {