M3 R3.2 SHIPPED: AddHistoricalValuesAsync — historical backfill writes over gRPC (live-validated)

Public HistorianClient.AddHistoricalValuesAsync(tag, values) inserts non-streamed original
(backfill) values for an existing tag over the 2023 R2 gRPC front door. The pure-managed SDK
wrote a value and read it back live (gated test AddHistoricalValuesAsync_OverGrpc_WritesAndReadsBack
PASSED against the real server).

- HistorianGrpcHistoricalWriteOrchestrator: write-enabled (0x401) session ->
  RetrievalService.GetTagInfosFromName (resolves the per-tag GUID = the tag-info TypeId, and
  registers the tag on the session) -> HistoryService.AddStreamValues("ON" buffer) per sample.
- HistorianHistoricalValue (public record: TimestampUtc, Value, OpcQuality=192).
- gRPC-only: non-RemoteGrpc transports throw ProtocolEvidenceMissingException (the 2020 WCF
  non-streamed write is architecturally blocked, D2).
- Float value encoding only (the captured type); other types rejected by the serializer.

275 unit tests pass; the new gated live write/read-back test is green against the 2023 R2 server.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC

src/AVEVA.Historian.Client/HistorianClient.cs

@@ -128,6 +128,34 @@ public sealed class HistorianClient : IAsyncDisposable
         return new HistorianWcfEventOrchestrator(_options).SendEventAsync(historianEvent, cancellationToken);
     }
 
+    /// <summary>
+    /// Inserts historical (non-streamed original / backfill) values for an existing tag. Captured
+    /// live from the native 2023 R2 client: the write rides <c>HistoryService.AddStreamValues</c>
+    /// (an "ON" storage-sample buffer) over the gRPC front door — see
+    /// <c>docs/plans/revision-write-path.md</c> §"R3.1 CAPTURED". Only the
+    /// <see cref="HistorianTransport.RemoteGrpc"/> transport is supported (the 2020 WCF path is
+    /// architecturally blocked — D2); other transports throw
+    /// <see cref="ProtocolEvidenceMissingException"/>. The tag must already exist
+    /// (create it with <see cref="EnsureTagAsync"/>). Value encoding is captured for Float tags.
+    /// </summary>
+    public Task<bool> AddHistoricalValuesAsync(
+        string tag,
+        IReadOnlyList<HistorianHistoricalValue> values,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(tag);
+        ArgumentNullException.ThrowIfNull(values);
+
+        if (_options.Transport != HistorianTransport.RemoteGrpc)
+        {
+            throw new ProtocolEvidenceMissingException(
+                "AddHistoricalValuesAsync is only supported over the 2023 R2 RemoteGrpc transport; the 2020 WCF " +
+                "non-streamed write is architecturally blocked (see docs/plans/revision-write-path.md, D2).");
+        }
+
+        return new Grpc.HistorianGrpcHistoricalWriteOrchestrator(_options).AddHistoricalValuesAsync(tag, values, cancellationToken);
+    }
+
     public IAsyncEnumerable<string> BrowseTagNamesAsync(string filter = "*", CancellationToken cancellationToken = default)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(filter);