perf(site-call-audit): filtered IX_SiteCalls_NonTerminal index — KPI predicates seek the live queue instead of scanning 365 days

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Configurations/SiteCallEntityTypeConfiguration.cs

@@ -66,8 +66,9 @@ public class SiteCallEntityTypeConfiguration : IEntityTypeConfiguration<SiteCall
         // SourceNode (SourceNode-stamping): node-local identifier of the
         // cluster member that produced the call (e.g. "node-a", "central-a"). NULL is
         // valid for rows that pre-date this feature and for reconciled rows from a
-        // retired node. ASCII — varchar(64). No index — Site Call Audit KPIs are
-        // per-site, not per-node, on this table.
+        // retired node. ASCII — varchar(64). Not a key column of any index, but it rides
+        // as an INCLUDE column on IX_SiteCalls_NonTerminal below so the per-node KPI
+        // breakdown reads it covered off the filtered live-queue index.
         builder.Property(s => s.SourceNode)
             .HasColumnType("varchar(64)")
             .HasMaxLength(64)
@@ -85,5 +86,16 @@ public class SiteCallEntityTypeConfiguration : IEntityTypeConfiguration<SiteCall
         builder.HasIndex(s => new { s.Status, s.UpdatedAtUtc })
             .IsDescending(false, true)
             .HasDatabaseName("IX_SiteCalls_Status_Updated");
+
+        // NonTerminal backs every "live queue" KPI predicate (TerminalAtUtc IS NULL):
+        // buffered/stuck/oldest counts run every 60 s from the KPI recorder plus every
+        // 10 s Health-dashboard poll. Filtered: the non-terminal population is the live
+        // queue, not the 365-day archive — each count becomes a small seek instead of a
+        // clustered scan (arch-review 04, P1). SourceSite/SourceNode/Status ride as
+        // INCLUDE columns so the per-site + per-node KPI breakdowns stay covered.
+        builder.HasIndex(s => s.CreatedAtUtc)
+            .HasDatabaseName("IX_SiteCalls_NonTerminal")
+            .HasFilter("[TerminalAtUtc] IS NULL")
+            .IncludeProperties(nameof(SiteCall.SourceSite), nameof(SiteCall.SourceNode), nameof(SiteCall.Status));
     }
 }