fix(driver-twincat): resolve Medium code-review finding (Driver.TwinCAT-005)

Inject optional ILogger<TwinCATDriver> (NullLogger default) and log
connect success/failure, ADS read errors, symbol-browse fallback,
native-notification registration failures, and host-state transitions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

code-reviews/Driver.TwinCAT/findings.md

@@ -134,7 +134,7 @@ date/time semantics are intended to be exposed properly, track a follow-up to de
 | Severity | Medium |
 | Category | OtOpcUa conventions |
 | Location | `TwinCATDriver.cs` (whole file), `AdsTwinCATClient.cs` (whole file) |
-| Status | Open |
+| Status | Resolved |
 
 **Description:** The driver performs no logging. `CLAUDE.md` Library Preferences mandate
 Serilog with a rolling daily file sink. Connect failures, ADS error codes, symbol-browse
@@ -147,7 +147,7 @@ success/failure per device, ADS errors with code, symbol-browse fallback (the `D
 catch), native-notification registration failures, and host state transitions
 (`TransitionDeviceState`).
 
-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-22 — added optional `ILogger<TwinCATDriver>` constructor parameter (defaults to `NullLogger`); logs connect success/failure in `EnsureConnectedAsync`, ADS read errors in `ReadAsync`, symbol-browse fallback in `DiscoverAsync`, notification-registration failures in `SubscribeAsync`, and host-state transitions in `TransitionDeviceState`.
 
 ### Driver.TwinCAT-006
 

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDriver.cs

@@ -1,4 +1,6 @@
 using System.Collections.Concurrent;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
 using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 
 namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;
@@ -16,6 +18,7 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
     private TwinCATDriverOptions _options;
     private readonly string _driverInstanceId;
     private readonly ITwinCATClientFactory _clientFactory;
+    private readonly ILogger<TwinCATDriver> _logger;
     private readonly PollGroupEngine _poll;
     private readonly Dictionary<string, DeviceState> _devices = new(StringComparer.OrdinalIgnoreCase);
     private readonly Dictionary<string, TwinCATTagDefinition> _tagsByName = new(StringComparer.OrdinalIgnoreCase);
@@ -26,12 +29,14 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
     public event EventHandler<RediscoveryEventArgs>? OnRediscoveryNeeded;
 
     public TwinCATDriver(TwinCATDriverOptions options, string driverInstanceId,
-        ITwinCATClientFactory? clientFactory = null)
+        ITwinCATClientFactory? clientFactory = null,
+        ILogger<TwinCATDriver>? logger = null)
     {
         ArgumentNullException.ThrowIfNull(options);
         _options = options;
         _driverInstanceId = driverInstanceId;
         _clientFactory = clientFactory ?? new AdsTwinCATClientFactory();
+        _logger = logger ?? NullLogger<TwinCATDriver>.Instance;
         _poll = new PollGroupEngine(
             reader: ReadAsync,
             onChange: (handle, tagRef, snapshot) =>
@@ -155,8 +160,13 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
                 if (status == TwinCATStatusMapper.Good)
                     _health = new DriverHealth(DriverState.Healthy, now, null);
                 else
+                {
+                    _logger.LogWarning(
+                        "TwinCAT driver '{DriverInstanceId}' ADS read error 0x{Status:X8} for '{Reference}'",
+                        _driverInstanceId, status, reference);
                     _health = new DriverHealth(DriverState.Degraded, _health.LastSuccessfulRead,
                         $"ADS status {status:X8} reading {reference}");
+                }
             }
             catch (OperationCanceledException) { throw; }
             catch (Exception ex)
@@ -286,10 +296,14 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
                     }
                 }
                 catch (OperationCanceledException) { throw; }
-                catch
+                catch (Exception ex)
                 {
                     // Symbol-loader failure is non-fatal to discovery — pre-declared tags already
-                    // shipped + operators see the failure in driver health on next read.
+                    // shipped. Log so operators can correlate the partial discovery.
+                    _logger.LogWarning(ex,
+                        "TwinCAT driver '{DriverInstanceId}' symbol browse failed for device " +
+                        "'{HostAddress}'; falling back to pre-declared tags only",
+                        _driverInstanceId, device.HostAddress);
                 }
             }
         }
@@ -339,11 +353,15 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
                 registrations.Add(reg);
             }
         }
-        catch
+        catch (Exception ex)
         {
             // On any registration failure, tear down everything we got so far + rethrow. Leaves
             // the subscription in a clean "never existed" state rather than a half-registered
             // state the caller has to clean up.
+            _logger.LogWarning(ex,
+                "TwinCAT driver '{DriverInstanceId}' native-notification registration failed; " +
+                "tearing down {Count} partial registrations",
+                _driverInstanceId, registrations.Count);
             foreach (var r in registrations) { try { r.Dispose(); } catch { } }
             throw;
         }
@@ -411,6 +429,9 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
             state.HostState = newState;
             state.HostStateChangedUtc = DateTime.UtcNow;
         }
+        _logger.LogInformation(
+            "TwinCAT driver '{DriverInstanceId}' device '{HostAddress}' state: {OldState} → {NewState}",
+            _driverInstanceId, state.Options.HostAddress, old, newState);
         OnHostStatusChanged?.Invoke(this,
             new HostStatusChangedEventArgs(state.Options.HostAddress, old, newState));
     }
@@ -456,9 +477,15 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
             {
                 await client.ConnectAsync(device.ParsedAddress, _options.Timeout, ct)
                     .ConfigureAwait(false);
+                _logger.LogInformation(
+                    "TwinCAT driver '{DriverInstanceId}' connected to {HostAddress}",
+                    _driverInstanceId, device.Options.HostAddress);
             }
-            catch
+            catch (Exception ex)
             {
+                _logger.LogWarning(ex,
+                    "TwinCAT driver '{DriverInstanceId}' failed to connect to {HostAddress}",
+                    _driverInstanceId, device.Options.HostAddress);
                 client.OnSymbolVersionChanged -= HandleSymbolVersionChanged;
                 client.Dispose();
                 throw;