diff --git a/archreview/plans/R2-01-s7-fault-hardening-plan.md.tasks.json b/archreview/plans/R2-01-s7-fault-hardening-plan.md.tasks.json
index 8136a897..c6b2dd2e 100644
--- a/archreview/plans/R2-01-s7-fault-hardening-plan.md.tasks.json
+++ b/archreview/plans/R2-01-s7-fault-hardening-plan.md.tasks.json
@@ -28,7 +28,7 @@
     {
       "id": 4,
       "subject": "Defensive when-filters on ensure-wrapper OCE rethrows (:488/:1000) + poll-loop OCE catches (:1383/:1396/:1404)",
-      "status": "pending",
+      "status": "completed",
       "blockedBy": [3]
     },
     {
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs
index 31afceed..1e93068b 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs
@@ -495,7 +495,10 @@ public sealed class S7Driver
             {
                 plc = await EnsureConnectedAsync(cancellationToken).ConfigureAwait(false);
             }
-            catch (OperationCanceledException) { throw; }
+            // Rethrow ONLY caller cancellation. A timeout-born OCE (none expected after the
+            // EnsureConnectedAsync conversion, but e.g. an S7.Net-internal CTS) must degrade the
+            // batch below, not escape as teardown (STAB-14).
+            catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested) { throw; }
             catch (Exception ex)
             {
                 for (var i = 0; i < fullReferences.Count; i++)
@@ -1007,7 +1010,9 @@ public sealed class S7Driver
             {
                 plc = await EnsureConnectedAsync(cancellationToken).ConfigureAwait(false);
             }
-            catch (OperationCanceledException) { throw; }
+            // Rethrow ONLY caller cancellation — a timeout-born OCE degrades the batch below rather
+            // than escaping as teardown (STAB-14 defense-in-depth, mirrors ReadAsync).
+            catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested) { throw; }
             catch (Exception ex)
             {
                 for (var i = 0; i < writes.Count; i++)
@@ -1401,7 +1406,10 @@ public sealed class S7Driver
             await PollOnceAsync(state, forceRaise: true, ct).ConfigureAwait(false);
             consecutiveFailures = 0;
         }
-        catch (OperationCanceledException) { return; }
+        // Only a teardown OCE (the loop's own token) exits the loop; any other OCE (e.g. a
+        // connect-timeout that slipped past the wrapper filter) falls to the backoff path below
+        // so the loop lives (STAB-14 defense-in-depth).
+        catch (OperationCanceledException) when (ct.IsCancellationRequested) { return; }
         catch (Exception ex)
         {
             // First-read error — polling continues; log so the operator has an event trail.
@@ -1415,14 +1423,17 @@ public sealed class S7Driver
             // ticks reset consecutiveFailures back to 0 so the cadence snaps back to Interval.
             var delay = ComputeBackoffDelay(state.Interval, consecutiveFailures);
             try { await Task.Delay(delay, ct).ConfigureAwait(false); }
-            catch (OperationCanceledException) { return; }
+            // Task.Delay can only observe ct-triggered OCE, so this filter is purely for uniformity.
+            catch (OperationCanceledException) when (ct.IsCancellationRequested) { return; }
 
             try
             {
                 await PollOnceAsync(state, forceRaise: false, ct).ConfigureAwait(false);
                 consecutiveFailures = 0;
             }
-            catch (OperationCanceledException) { return; }
+            // Only teardown exits; any non-teardown OCE (e.g. a slipped-through connect timeout)
+            // backs off instead of killing the loop (STAB-14 defense-in-depth).
+            catch (OperationCanceledException) when (ct.IsCancellationRequested) { return; }
             catch (Exception ex)
             {
                 // Sustained polling error — loop continues with backoff; log + update health.