feat(grpc): HistorianSessionKind + …OnSession seams (read/status/tag-write)

src/AVEVA.Historian.Client/Grpc/HistorianGrpcReadOrchestrator.cs

@@ -126,28 +126,51 @@ internal sealed class HistorianGrpcReadOrchestrator
         return RunRawQueryOnSession(connection, clientHandle, tag, startUtc, endUtc, maxValues, cancellationToken);
     }
 
+    // Spike/Phase-1 seam (pending.md A1): run an aggregate query against an EXTERNALLY-supplied,
+    // already-authenticated connection + client handle — i.e. NO Create()/handshake here.
+    // RunAggregateChain delegates to this so the per-call path and the reuse path share one query
+    // implementation (DRY).
+    internal List<HistorianAggregateSample> RunAggregateQueryOnSession(
+        HistorianGrpcConnection connection,
+        uint clientHandle,
+        string tag,
+        DateTime startUtc,
+        DateTime endUtc,
+        RetrievalMode mode,
+        TimeSpan interval,
+        CancellationToken ct)
+    {
+        return RunAggregateQuery(connection, clientHandle, tag, startUtc, endUtc, mode, interval, ct);
+    }
+
     private List<HistorianAggregateSample> RunAggregateChain(
         string tag, DateTime startUtc, DateTime endUtc, RetrievalMode mode, TimeSpan interval, CancellationToken cancellationToken)
     {
         using HistorianGrpcConnection connection = HistorianGrpcChannelFactory.Create(_options);
         uint clientHandle = OpenAuthenticatedConnection(connection, cancellationToken);
-        return RunAggregateQuery(connection, clientHandle, tag, startUtc, endUtc, mode, interval, cancellationToken);
+        return RunAggregateQueryOnSession(connection, clientHandle, tag, startUtc, endUtc, mode, interval, cancellationToken);
     }
 
-    private List<HistorianSample> RunAtTimeChain(string tag, IReadOnlyList<DateTime> timestampsUtc, CancellationToken cancellationToken)
+    // Spike/Phase-1 seam (pending.md A1): run an at-time query against an EXTERNALLY-supplied,
+    // already-authenticated connection + client handle — i.e. NO Create()/handshake here.
+    // RunAtTimeChain delegates to this so the per-call path and the reuse path share one
+    // implementation (DRY).
+    internal List<HistorianSample> RunAtTimeOnSession(
+        HistorianGrpcConnection connection,
+        uint clientHandle,
+        string tag,
+        IReadOnlyList<DateTime> timestampsUtc,
+        CancellationToken ct)
     {
         if (timestampsUtc.Count == 0)
         {
             return [];
         }
 
-        using HistorianGrpcConnection connection = HistorianGrpcChannelFactory.Create(_options);
-        uint clientHandle = OpenAuthenticatedConnection(connection, cancellationToken);
-
         List<HistorianSample> results = new(timestampsUtc.Count);
         foreach (DateTime ts in timestampsUtc)
         {
-            cancellationToken.ThrowIfCancellationRequested();
+            ct.ThrowIfCancellationRequested();
             DateTime tsUtc = ts.ToUniversalTime();
             List<HistorianAggregateSample> aggregates = RunAggregateQuery(
                 connection,
@@ -157,7 +180,7 @@ internal sealed class HistorianGrpcReadOrchestrator
                 tsUtc + TimeSpan.FromTicks(1),
                 RetrievalMode.Interpolated,
                 TimeSpan.FromTicks(2),
-                cancellationToken);
+                ct);
 
             if (aggregates.Count == 0)
             {
@@ -179,6 +202,18 @@ internal sealed class HistorianGrpcReadOrchestrator
         return results;
     }
 
+    private List<HistorianSample> RunAtTimeChain(string tag, IReadOnlyList<DateTime> timestampsUtc, CancellationToken cancellationToken)
+    {
+        if (timestampsUtc.Count == 0)
+        {
+            return [];
+        }
+
+        using HistorianGrpcConnection connection = HistorianGrpcChannelFactory.Create(_options);
+        uint clientHandle = OpenAuthenticatedConnection(connection, cancellationToken);
+        return RunAtTimeOnSession(connection, clientHandle, tag, timestampsUtc, cancellationToken);
+    }
+
     private uint OpenAuthenticatedConnection(HistorianGrpcConnection connection, CancellationToken cancellationToken)
         => HistorianGrpcHandshake.OpenAuthenticatedConnection(connection, _options, cancellationToken);