Record 2023 R2 binary-dive verdicts; fix revision-probe scope comment

Mined the full decompiled stock 2023 R2 managed client as the oracle for every
still-pending gRPC item. Governing fact: ArchestrA.HistorianAccess is a C++/CLI
shim into native HistorianClient; the managed Grpc*Client wrappers have zero
call sites, so buffer-building/dispatch for the pending items is native (absent
from the binaries). Sharpened verdicts into handoff.md:

- Items 4/5/6 + OpenStorageConnection: hard-confirmed walled, with real reasons
  (SQL gated out client-side via IsManagedHistorian; no Revision RPC in the gRPC
  contract; LoadBlocks response is a native blob behind the storage console handle).
- Items 3 (SendEvent) and 7 (DeleteTEP): moved from vague to precise, LOCAL-box
  capturable targets (PackToVtq btValues / DeleteTagExtendedPropertiesByName
  BtInput with deleteFromServer=true).

Also correct the HistorianGrpcRevisionProbe doc comment: it probes the
non-streamed ORIGINAL-insert path (AddNonStreamValues), a distinct capability
from revision EDITS (native AddRevisionValues trio, no gRPC RPC) — the prior
comment conflated them.

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

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

@@ -20,6 +20,18 @@ namespace AVEVA.Historian.Client.Grpc;
 /// write-enabled session and calls <c>AddNonStreamValuesBegin</c>, surfacing whatever the server
 /// returns. It writes NO data — if Begin succeeds it immediately calls <c>AddNonStreamValuesEnd</c>
 /// with <c>bCommit=false</c> to discard the transaction.
+///
+/// <para><b>Scope note (corrected 2026-06-23 after a 2023 R2 binary re-read).</b> Despite the type
+/// name, this probes the <i>non-streamed ORIGINAL / backfill insert</i> capability
+/// (<c>AddNonStreamValues</c>), which is a <b>distinct capability from a revision EDIT</b>
+/// (overwriting an existing historized value with a new revision). The stock high-level client
+/// reaches a revision edit via a separate native transaction trio
+/// <c>HistorianClient.AddRevisionValuesBegin/AddRevisionValue/AddRevisionValuesEnd</c>
+/// (<c>ArchestrA.HistorianAccess.AddRevisionValues</c>, REVISION_MODE ∈ InsertLatest/UpdateSingle/
+/// UpdateMultiple). That trio has <b>NO corresponding RPC in the gRPC contract</b> (no "Revision"
+/// message type exists in <c>Archestra.Grpc.Contract</c>) — it rides the native storage-engine
+/// transaction channel only. So R4.2 revision edits remain unreachable over gRPC regardless of this
+/// probe's outcome; this probe neither covers nor unblocks them.</para>
 /// </summary>
 internal sealed class HistorianGrpcRevisionProbe
 {