Auto: abcip-4.3 — diagnostic / system tags as browseable variables

Closes #240

scripts/e2e/test-abcip.ps1

@@ -39,6 +39,13 @@
 .PARAMETER SlowBridgeNodeId
   Optional NodeId for a Tag declared with ScanRateMs >= 1000. Pair with
   FastBridgeNodeId to enable the scan-rate assertion.
+
+.PARAMETER SystemConnectionStatusNodeId
+  Optional NodeId for the synthetic _System/_ConnectionStatus variable
+  emitted by AB CIP discovery (PR abcip-4.3). When supplied, the script
+  runs the SystemTagBrowse assertion — reads the value through the OPC UA
+  server + asserts it surfaces one of the canonical HostState strings.
+  NodeId form: ns=<n>;s=AbCip/<gateway>/_System/_ConnectionStatus.
 #>
 
 param(
@@ -48,7 +55,12 @@ param(
     [string]$OpcUaUrl = "opc.tcp://localhost:4840",
     [Parameter(Mandatory)] [string]$BridgeNodeId,
     [string]$FastBridgeNodeId,
-    [string]$SlowBridgeNodeId
+    [string]$SlowBridgeNodeId,
+    # PR abcip-4.3 — NodeId for the synthetic _System/_ConnectionStatus variable that
+    # discovery emits under each device. Optional — when wired, runs the
+    # SystemTagBrowse assertion that browses + reads the system folder through the OPC UA
+    # server. NodeId form: ns=<n>;s=AbCip/<gateway>/_System/_ConnectionStatus.
+    [string]$SystemConnectionStatusNodeId
 )
 
 $ErrorActionPreference = "Stop"
@@ -208,5 +220,28 @@ $results += [PSCustomObject]@{
     }
 }
 
+# PR abcip-4.3 — _System/_ConnectionStatus browse-and-read assertion. Reads the live
+# diagnostic snapshot via the OPC UA Client CLI; the value comes straight from the
+# AbCipSystemTagSource (no libplctag round-trip). When the probe loop is healthy + the
+# gateway is reachable, the value should be "Running"; on a stopped fixture it would be
+# "Stopped". The assertion accepts any of the four canonical states, plus the "Unknown"
+# transient that surfaces before the first probe iteration completes.
+if ($SystemConnectionStatusNodeId) {
+    Write-Header "SystemTagBrowse (_System/_ConnectionStatus from $SystemConnectionStatusNodeId)"
+    $sysReadArgs = @($opcUaCli.PrefixArgs) + @("read", "-u", $OpcUaUrl, "-n", $SystemConnectionStatusNodeId)
+    $sysOut = & $opcUaCli.File @sysReadArgs 2>&1
+    $sysJoined = ($sysOut -join "`n")
+    $sysMatched = $sysJoined -match "Running|Stopped|Unknown|Faulted"
+    $results += [PSCustomObject]@{
+        Name   = "SystemTagBrowse"
+        Passed = $sysMatched
+        Detail = if ($sysMatched) {
+            "_ConnectionStatus surfaced one of Running / Stopped / Unknown / Faulted via OPC UA"
+        } else {
+            "_ConnectionStatus did not surface a recognised HostState — got '$sysJoined'"
+        }
+    }
+}
+
 Write-Summary -Title "AB CIP e2e" -Results $results
 if ($results | Where-Object { -not $_.Passed }) { exit 1 }