M2: implement SendEventAsync — event-send rides WCF AddS2, not the storage pipe

Roadmap Milestone 2 (event sending). Capture disproved the assumption that event
delivery uses the non-WCF storage-engine pipe (which would block it like revision
writes): a native AddStreamedValue(HistorianEvent) leaves over WCF as AddS2
(IHistoryServiceContract2.AddStreamValues2). CM_EVENT is a built-in registered tag,
so the 129 TagNotFoundInCache gate that blocks AddS2 for user tags does not apply.

- R2.1: NativeTraceHarness "event-send" scenario + Capture-EventSend.ps1; two
  captures diffed to separate constant framing from value-dependent fields.
- R2.2: HistorianEventWriteProtocol serializes the AddS2 pBuf (storage sample buffer
  wrapping the event VTQ) — golden-byte tested. Decoded "OS" sig + length fields +
  CM_EVENT tag id + EventTime/ReceivedTime FILETIMEs + Opc 192 + 0x118D descriptor +
  event Id + Namespace + EventType + version 5 + typed property bag.
- R2.3/R2.4: HistorianWcfEventOrchestrator.SendEventAsync (Open2 event-mode 0x501 ->
  reuse CM_EVENT RTag2/EnsT2 -> AddStreamValues2) + HistorianClient.SendEventAsync.
- R2.5: gated live test; server accepts the AddS2 (success, empty error buffer).

Server requires delivered byte[].Length == declared packet length (uint32@0x04); the
native relies on the MDAS encoder adding a pad byte, so the SDK emits an explicit
trailing 0x00 (else AddS2 rejects with "CValuStream buffer size vs packet length
mismatch"). Original events only (RevisionVersion=0) with string properties; other
property types + revision/update/delete throw ProtocolEvidenceMissingException.

Caveat (documented): accepted events are not persisted on the local dev box; the
native client behaves identically (event ingestion pipeline inactive) — not an SDK
gap. 212 unit tests pass; 16/16 event tests pass live.

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

scripts/Capture-EventSend.ps1

@@ -0,0 +1,110 @@
+<#
+.SYNOPSIS
+    Captures the native AVEVA client's event-SEND wire traffic (HCAL roadmap R2.1) to
+    determine whether AddStreamedValue(HistorianEvent) rides the WCF MDAS path (capturable
+    + implementable as a pure-managed-WCF SDK op) or the storage-engine shared-memory pipe
+    (like revision writes — which would block M2 as a WCF SDK).
+
+.DESCRIPTION
+    Drives the .NET-Framework NativeTraceHarness's `event-send` scenario against the live
+    Historian with an IL-rewritten copy of aahClientManaged.dll whose
+    ClientMessageEncoder.WriteMessage AND ReadMessage are instrumented to log every MDAS
+    body (the same pipeline that produced every other proven request/response shape). The
+    harness opens an Event connection (ReadOnly=false), builds a clearly-marked test
+    HistorianEvent, calls AddStreamedValue(HistorianEvent), then CloseStorageConnection to
+    flush the queued event onto the wire.
+
+    Decode with scripts/decode-event-send-capture.py: if a StartStorage/AddStreamValues/
+    EnqueueEventDataPacket body appears on WCF.WriteMessage.Body, M2 is viable over WCF and
+    the body carries the PackToVtq event value blob to decode (R2.2). If NOTHING event-shaped
+    appears on the WCF path even though the native AddStreamedValue returned success, the
+    delivery used the storage-engine pipe and M2 is architecturally blocked over WCF — the
+    same conclusion as the revision-write path (docs/plans/revision-write-path.md).
+
+.NOTES
+    Writes a real (clearly-marked) test event into the historian's event history. Artifacts
+    are diagnostic and gitignored. Sanitize before copying anything into docs/ — never commit
+    raw capture NDJSON, credentials, hostnames, or customer tag names.
+#>
+[CmdletBinding()]
+param(
+    [string]$ServerName = "localhost",
+    [int]$TcpPort = 32568,
+    [string]$EventType = "User.Write",
+    [int]$FlushSeconds = 6,
+    [string]$Configuration = "Debug"
+)
+
+$ErrorActionPreference = "Stop"
+$repoRoot = Split-Path -Parent $PSScriptRoot
+Set-Location $repoRoot
+
+$reProj      = Join-Path $repoRoot "tools\AVEVA.Historian.ReverseEngineering\AVEVA.Historian.ReverseEngineering.csproj"
+$harnessProj = Join-Path $repoRoot "tools\AVEVA.Historian.NativeTraceHarness\AVEVA.Historian.NativeTraceHarness.csproj"
+$instrProj   = Join-Path $repoRoot "tools\AVEVA.Historian.ReverseInstrumentation\AVEVA.Historian.ReverseInstrumentation.csproj"
+
+$captureDir  = Join-Path $repoRoot "artifacts\reverse-engineering\instrumented-wcf-event-send"
+$currentCopy = Join-Path $captureDir "current-copy"
+$instrDll    = Join-Path $captureDir "aahClientManaged.dll"
+$capturePath = Join-Path $captureDir "event-send-capture-latest.ndjson"
+
+Write-Host "== Building tooling ($Configuration) ==" -ForegroundColor Cyan
+dotnet build $reProj      -c $Configuration --nologo -v q | Out-Null
+dotnet build $instrProj   -c $Configuration --nologo -v q | Out-Null
+dotnet build $harnessProj -c $Configuration --nologo -v q | Out-Null
+
+$instrSourceDll = Get-ChildItem -Recurse (Join-Path $repoRoot "tools\AVEVA.Historian.ReverseInstrumentation\bin\$Configuration") `
+    -Filter "AVEVA.Historian.ReverseInstrumentation.dll" | Select-Object -First 1 -ExpandProperty FullName
+if (-not $instrSourceDll) { throw "ReverseInstrumentation.dll not found under bin\$Configuration." }
+
+Write-Host "== Instrumenting WriteMessage + ReadMessage ==" -ForegroundColor Cyan
+New-Item -ItemType Directory -Force -Path $captureDir | Out-Null
+# Chain via a distinct intermediate file (reading+writing the same path drops the second
+# hook on the mixed-mode native image). Final dll carries both hooks with distinct Phase
+# strings: WCF.WriteMessage.Body and WCF.ReadMessage.Body.
+$writeOnly = Join-Path $captureDir "aahClientManaged.write.dll"
+dotnet run --no-build -c $Configuration --project $reProj -- `
+    instrument-wcf-writemessage (Join-Path $repoRoot "current\aahClientManaged.dll") $writeOnly | Out-Null
+dotnet run --no-build -c $Configuration --project $reProj -- `
+    instrument-wcf-readmessage $writeOnly $instrDll | Out-Null
+
+Write-Host "== Staging current-copy ==" -ForegroundColor Cyan
+robocopy (Join-Path $repoRoot "current") $currentCopy /MIR /NJH /NJS /NDL /NP /NC /NS | Out-Null
+Copy-Item -Force $instrDll (Join-Path $currentCopy "aahClientManaged.dll")
+Copy-Item -Force $instrSourceDll (Join-Path $currentCopy "AVEVA.Historian.ReverseInstrumentation.dll")
+
+$harnessDll = Join-Path $currentCopy "aahClientManaged.dll"
+if (Test-Path $capturePath) { Remove-Item -Force $capturePath }
+$env:AVEVA_HISTORIAN_RE_CAPTURE = $capturePath
+
+Write-Host "== Capturing event-send ==" -ForegroundColor Green
+$harnessArgs = @(
+    "--scenario", "event-send",
+    "--event-send-confirm",
+    "--server-name", $ServerName,
+    "--tcp-port", "$TcpPort",
+    "--event-type", $EventType,
+    "--event-send-flush-seconds", "$FlushSeconds",
+    "--current-dir", $currentCopy,
+    "--managed-dll-path", $harnessDll
+)
+
+$harnessJson = $null
+try {
+    $prevEap = $ErrorActionPreference
+    $ErrorActionPreference = "Continue"
+    $harnessJson = & dotnet run --no-build -c $Configuration --project $harnessProj -- @harnessArgs 2>&1
+} catch {
+    Write-Host "   (event-send raised: $($_.Exception.Message))" -ForegroundColor Yellow
+} finally {
+    $ErrorActionPreference = $prevEap
+}
+
+Remove-Item Env:\AVEVA_HISTORIAN_RE_CAPTURE -ErrorAction SilentlyContinue
+
+$recCount = if (Test-Path $capturePath) { (Get-Content $capturePath | Where-Object { $_.Trim() }).Count } else { 0 }
+Write-Host "`n== Capture summary ==" -ForegroundColor Cyan
+Write-Host "   -> $recCount records -> $capturePath"
+Write-Host "Harness output (look for AddStreamedEvent Success / ErrorCode):" -ForegroundColor Cyan
+$harnessJson | Select-Object -Last 60
+Write-Host "`nDecode with: python scripts\decode-event-send-capture.py" -ForegroundColor Cyan